Go Paleo?

Paleo

What you will learn:

  • What the Paleo diet is
  • A critical analysis of its validity
  • A critical analysis of its application
  • My recommendations

Who this is applicable to:

  • Anyone considering following the Paleo diet
  • Anyone currently following the Paleo diet
  • Any cavemen that want some reassurance and guidance
  • Anyone interested in nutrition

Who should not read this:

  • Anyone who has a close, passionate heartfelt relationship with Paleo, this may hurt.

Enjoy, and please leave feedback. Unlike many, I am open to critique; it is the only way I will ever improve as a practitioner, coach and a person.

First off, apologies for the lack of blog activity over the last few months, I hope this more than makes up for the barren few months.

Ok, the Paleo diet. The diet that has become synonymous with health, and pretty much adopted as law by the sport of CrossFit, for one reason or another. The diet that is so popular that people are now investing time and effort to conjure up ways of making all time greats such as cookies and muffins, Paleo.

The Paleo diet is proposed as one of the healthiest diets of modern times, a diet that mimics the diets of our caveman ancestors. Who were apparently really healthy?

Now, before I begin I must clarify that it is by no means my intention to criticise the Paleo diet, or proponents and supporters of the Paleo diet. Rather I am going to objectively analyse the theory and application of the Paleo principles using the existing evidence-base and scientific literature, highlighting and commenting upon both its strengths and weaknesses. I think this is necessary in order to create an evidence-based scientifically sound diet. Please be open-minded.

A long, long time ago…

The Paleolithic era was characterised by men hunting their food, living active lifestyles and eating fruits and vegetables that grew on nearby trees and in nearby pastures, utilising only stone tools. The introduction of heavy machinery during the agricultural revolution around 10,000 years ago allowed for more intensive farming and grain production. This shift toward production of grains and intensive farming methods is believed to be responsible for the “diseases of civilisation”. It is proposed that the human genome is not adapted to the consumption of these new foods.

The Paleo diet essentially proposes that the foods common of modern times are allergens of great detriment to health. Interestingly recent research has indicated that eight major foods or food groups account for 90% of total food allergies (1). Four of those eight foods are Paleo-approved foods – nuts, eggs, fish and shellfish – seems strange, right? Just out of interest the other major allergens are milk, peanuts, wheat and soybeans.

Quite a radical ideology, although its already showing some weakness let’s discuss.

Now I’ll begin by saying that I don’t disagree that the Paleo diet does well in its promotion of various meats, seafood, vegetables, fruits and nuts, all of which when consumed within a calorie controlled diet will offer a host of health benefits over the highly processed diet so common of recent Western times.

But what I disagree with is the Paleo diets dim view of other foods. There is currently no scientific data to support the suggestion that the Paleo diet is any better than a fibre and macronutrient matched non-Paleo diet. As demonstrated by a myriad of recent peer-reviewed research papers there are great health benefits of some of the non-Paleo foods, including dairy and whole-grains, so avoidance of these foods would be detrimental to human health.

But first may I remind you that since the agricultural revolution, mankind has undertaken two more significant shifts towards being fat and lazy. Both the industrial revolution that occurred approximately 200 years ago, and the digital revolution that we are currently experiencing are characterised by significant reductions in activity and human movement, and a great upshift in food intake and availability. The industrial revolution saw men transition from man-powered machinery to hand powered sit on the seat of your pants machinery. The digital revolution marked the global introduction of the Internet and smart phones, now we don’t even have to leave the comfort of our armchair to buy a pint of milk!

Both of these periods are defined by marked shifts in energy intake and energy expenditure, resulting in a large, prolonged energy imbalance. Restaurants now compete with each other by offering slightly bigger portion sizes, that famous American catchphrase ‘would you like cheese with that’ can be directly translated to ‘would you like an extra 250 Calories with that’. Food is now available on every corner, 24-hours a day.

Do we really have to look back 10,000 years ago to find out what a healthy diet is? In truth researchers don’t accurately know what happened back then, although some researchers have made estimates (2). There is however, evidence from at least 105,000 years ago that man consumed grains and legumes (3), well before the advent of agriculture. One piece of research found a “large assemblage of starch granules” on the surfaces of Stone Age tools, suggesting reliance upon grass, grains and legumes as a dietary resource (4), further research supports this finding (3; 5).

there is also evidence of cannibalism (7). The archaeological evidence is weak, meaning researchers are solely reliant upon correlational estimates, with no idea of the frequency or amount of food, just estimates of food types.

The Paleolithic era was defined by extreme human resourcefulness. The Paleolithic people ate out of necessity, they did what they could to survive, making use of only what they could find around them. They ate with a degree of flexibility, with food choices dependent on geography, location, and the season. If they happened to stumble across a chocolate bar and a pint of milk, they would have consumed it, for sure, in a mere act of survival.

For a more detailed discussion on this debate I would suggest you watch this extremely informative YouTube video by an archaeological scientist (8). Obviously proponents of the Paleo diet are ignorant of all of this data, as it does not align well with their ideology, their story.

What’s more is and I quote from a recent piece of research “however, there is a rapid increase in population associated with domestication of plants, so although in some regions individual health suffers after the Neolithic revolution, as a species humans have greatly expanded their population worldwide”. The development of mankind actually benefitted from the domestication of plants and animals, completely contradicting the suggestions made by Paleo diet proponents (9).

Now I would agree that the overconsumption of heavily processed foods is one of the causes of the increase in the “diseases of civilisation”. But the devil is in the dosage, not the agricultural revolution 10,000 years ago.

A look at the research into dietary patterns of modern times reveals…

Research has comprehensively demonstrated that humans in 2010 consumed 445 kcal more than back in 1970, where back in 1970 the average energy intake was 2,169 kcal per person per day, and in 2010 that figure was 2,614 kcal (10).

Further research has also revealed that occupation-related energy expenditure has reduced by 142 kcals since the 1960’s (11). Combined, the increase in energy intake and the reduction in energy expenditure alone has resulted in a 587 kcal positive energy balance, which over 50-years equates to a total of 10,712,750 kcal. Even with a basic understanding of the energy balance and thermodynamics it is evident that this energy imbalance is more than enough to explain the current epidemic of “diseases of civilisation”.

Interestingly, this research also concludes that the increase in energy intake appears to be more than sufficient to explain weight gain in the global population (11). They go on to suggest that for the situation to be rectified, a reversal of this trend must occur, and I quote “for the US population to return to the mean weights of the 1970’s, the increased energy intake of 350 kcal/day for children (which equates to roughly 1 can of coke and 1 snickers bar, or roughly 1 avocado for the Paleo peoples) and 500 kcal/day for adults (which equates to roughly 1 large hamburger, or roughly 1 avocado and 4 slices of bacon for the Paleo peoples) would need to be reversed”.

So the research clearly demonstrates that we eat more and move less than we did in the 1970’s. This alone is a significant finding. Applying the basic principles of the energy balance and thermodynamics it is hardly surprising that we are currently experiencing an obesity epidemic with the incidence of “diseases of civilisation” at an all time high.

Furthermore, research has conclusively demonstrated that excess weight is clearly associated with the development of many of the “diseases of civilisation”, including cardiovascular disease, type 2 diabetes, hypertension, stroke, dyslipidemia, osteoarthritis, and some cancers (13). Research also concludes, and I quote “the prevalence of obesity-related comorbidities emphasizes the need for a concerted effort to prevent and treat obesity rather than just its associated comorbidities” (14). To this end any diet that aims to treat or prevent the “diseases of civilisation” should be tailored towards treating and preventing obesity. So any diet that sustains a caloric deficit consistently for long-periods will treat and prevent the “diseases of civilisation”. Complex ideologies such as those employed within the Paleo philosophy are unnecessary.

Are the grains, dairy & legumes to blame?

Proponents of the Paleo diet are wrong to suggest the population are fat and unhealthy because they are eating foods that humans are not supposed to eat. Humans are supposed to eat everything and anything they can in order to survive. Humans are supposed to be resourceful. The issue is simple. The issue is that humans now eat more, more of everything, and move less, much less. That is the issue.

Fundamentally, addressing this issue does not take radical rocket science it just takes common sense. The reversal of this current trend will result in a shift towards normal body weight and improved health in the global population.

Grains, dairy and legumes could be to blame for the rise in obesity and ill health. But not solely. An increase in their consumption has contributed to the increase in energy intake, which has resulted in obesity and ill health. But there is nothing about grains, dairy and legumes that can result in obesity and ill health when consumed within an individuals daily energy and macronutrient requirements. When portion sizes are controlled.

Strive for energy balance. That should be the message in the media.

It is easy for journalists to write compelling stories about sugar, grains and dairy being the cause of this. Something as simple as an energy imbalance would not sell newspapers, it would not make headlines and it sure as hell wouldn’t get anyone to the top of the Amazon bestseller list!

A closer look at the foods demonised by Paleo.

Paleo proponents are strongly against the consumption of dairy products, grains, gluten, aspartame and added sweeteners, there are probably many more as the list continues to grow and the list of acceptable foods narrows daily.

Without going into too much detail, dairy products do not adversely effect biomarkers of inflammation (15). Dairy products are actually considered to be some of the most nutrient dense foods in existence (16), the avoidance of dairy could actually be detrimental to health. Research has indicated that the consumption of 3 or more servings of dairy each day is associated with better nutrient status, improved bone health, lower blood pressure, and reduced risk of cardiovascular disease and type 2 diabetes (17, 18). Dairy products are the best provider of dietary calcium, with research indicating that that dairy products provide calcium with ensured absorption (19). A final note on pasteurisation, pasteurisation does not significantly change the nutritional value of milk (20). Pasteurisation is actually the most effective method of enhancing the microbiological safety of milk and dairy products (21).

No studies indicate any long-term health risks from consuming aspartame through drinking diet soda. Research has demonstrated that diet soda is not harmful to health, well-being, or body composition, nor do they impair fat loss or stimulate insulin release (22, 23, 24). Furthermore, the inclusion of artificial sweeteners in an energy-restricted diet did not impair weight loss (25), in fact in many cases is promoted weight loss (26).

People with medically diagnosed celiac disease, wheat allergies or gluten sensitivities should avoid gluten consumption. With large-scale research into the global population indicating that less than 10% of people have medically diagnosed celiac disease (27). But there is no evidence that having an allergy increases your risk of disease (28) and there is no evidence that gluten is detrimental to the health of any individual without any of the aforementioned diseases or allergies.

The existing evidence also clearly demonstrates that whole grain and legume consumption offers a host of beneficial health effects. Including improved blood lipid profiles, improved glucose control, reduced inflammation, and reduced risk of stroke and coronary heart disease (29).

Paleo proponents also suggested legumes and grains are best avoided because they contain phytates and oxalates, believed to be anti-nutrients. Both phytic acid and oxalic acid impair the bioavailability of certain nutrients, particularly the micronutrients. That much is true, but green leafy vegetables contain high concentrations of oxalates and nuts are a rich source of phytic acid as the table below illustrates, as such both are anti-nutrients. But Paleo hasn’t demonized them? In fact nuts and green leafy vegetables are a mainstay? In all honesty, I’m confused, this is exactly what happens when you rely on unsubstantiated, unreliable, inaccurate sources of information.

Food sources of phytic acid as a percentage of dry weight (31)

Food

Minimum

Maximum

Brazil nuts

1.97

5.36

Almonds

1.35

3.22

Oat meal

0.89

2.40

Beans, pinto

2.38

2.38

Corn

0.75

2.22

Peanuts

1.05

1.76

Wheat

0.39

1.35

Whole wheat bread

0.43

1.05

Brown rice

0.84

0.99

Chick peas

0.56

0.56

Lentils

0.44

0.50

Research has concluded that there is no evidence to suggest that an alkaline diet is protective of bone health. Further, dietary acid load does not have a measurable negative effect on bone health (31, 32).

Looking at the existing evidence it can be comprehensively concluded that soy intake is not associated with serum sex hormone concentrations (33, 34).

Research also demonstrates that a number of omega-6 fatty acids, demonized for their inflammation promoting properties, actually exert beneficial effects on inflammation and in some cases are anti-inflammatory (35, 36).

And then the fairytale turns into a comedy…

Interestingly, since the advent of the Paleo diet there have been a number of companies and organisations that have developed ‘Paleo’ versions of their respected products to take financial advantage of the cult. Take protein powders for example (37) a number of companies have been manufacturing Paleo protein powders. Pretty sure they are missing the point of Paleo?

Also, the number and prevalence of Paleo friendly recipes across the worldwide web is now astronomical, and growing rapidly. These websites are bursting with beautiful Paleo versions of typical Western foods, cookies, muffins, ice cream, you name it there is a Paleo version for it!

These acts of trying to emulate traditional Western foods just underline and highlight the reality of how the Paleo diet is just another fad diet. A slight twist on the Atkins diet with a cute little storyline, a little dose of pseudoscience and the input and support of a few high profile Dr’s.

Concluding remarks

The theoretical basis of the Paleo diet is that the agricultural revolution occurred 10,000 years ago, this represents <1% of the evolutionary timeline. The whole thing is based upon flawed logic and assumption.

It is unnecessary to look back 10,000 years to determine what a healthy diet looks like, in truth that serves little more than to create compelling copy to use in book writing and marketing. Modern times indicate that some of the longest-living, healthiest humans on planet earth consume a diet rich in non-Paleo foods. Blue zone populations, the populations with the longest life expectancy in current existence commonly consume a largely plant based diet, with no over-eating or large portion sizes, locally grown foods, carbohydrate being the predominant macronutrient, all 5 of the Blue zones consume grains and legumes, frowned upon by Paleo proponents (38). Do we really need to look back 10,000 years to find out what a healthy diet looks like when we have populations on earth at present that live extremely healthy lifestyles for over a century?

Essentially the Paleo diet provides a fantastic foundation, the focus, and emphasis on lean proteins and minimally processed foods is great, although it is far too restrictive. The weight of the current scientific literature strongly disproves many, if not all of the Paleo diet ideologies. Developing successful dietary habits requires consideration of lifestyle, taste and preference, living like a man from the Stone Age in modern times is impossible. If you wish to be a true Paleo person you must be flexible and resourceful, make the most of your surroundings. That means eating a varied diet, with predominantly fresh produce, with focus on maintaining a long-term energy balance. Fretting over whether “its Paleo” is unnecessary.

A diet does not require a name in order to be healthy.

A critical analysis of the added ingredients in sports drinks

What you will learn:

  • A comprehensive analysis of the added ingredients in existing sports drinks
  • Practical recommendations for suitable & effective sports drinks based on the existing research
  • You will also learn some scientific jargon – always a bonus!

Who is this applicable to:

  • Triathletes
  • Endurance athletes
  • Team-sport athletes
  • Anyone who consumes sports drinks
  • Anyone interested in performance nutrition

Who should not read this:

  • Anyone that does not have an interest in performance nutrition?
  • Clean eaters
  • MCT fans

Enjoy, and please leave feedback. I am open to critique, it is the only way I will ever improve as a practitioner, coach and a person.


In a previous blog post I set about analysing the physiological and nutritional requirements of a triathlete, and discussed the application of carbohydrate feeding during such endurance exercise. I critically analysed the efficacy of the carbohydrate content of existing sports drink formulations and went on to give specific recommendations based solely on the carbohydrate content.

In this blog post I will go on to discuss the efficacy of other ingredients that are now often included in sports drink formulations. These added ingredients often add to the confusion when choosing sports drinks, and are marketed as ergogenic (performance enhancing), but are they? Let’s find out.

As discussed last week, the primary constituents of a sports drink are carbohydrate, water and electrolytes. The carbohydrate content provides a source of energy and serves to delay the onset of fatigue, which during prolonged exercise is associated with muscle glycogen depletion and reduced blood glucose concentrations. The water content prevents dehydration resulting from increased sweat losses, which can also impair endurance performance. The electrolyte content serves to replenish those lost through sweat during exercise.

Sodium retention is tightly regulated by the renin-angiotensin-aldosterone system, however under certain circumstances where large sweat sodium losses occur, typically in ultra endurance events, or where the consumption of fluid exceeds sweat loss, or fluid is replaced with low sodium beverages mild hyponatremia can ensue. Therefore sports drinks that include sodium in concentrations of 0.5 – 0.7 g/L of fluid (21 – 30 mmol/L) are recommended (1). The replacement of electrolytes during and after exercise is also useful for maintaining the thirst drive, and sodium concentrations of between 10 – 25 mmol/L enhance the palatability and voluntary consumption of fluids consumed during exercise. Most athletes’ electrolyte requirements are sufficiently provided by a balanced diet, although in prolonged endurance events replenishment through sports drink consumption is necessary. Interestingly a rehydration study following an exercise-induced loss of 2.5% body weight, subjects exhibited greater plasma volume recovery and lower urine volumes when they ingested chicken broth and chicken noodle soup as opposed to a traditional sports drink (2).

So in actual fact, post-race, a normal mixed meal would be sufficient in restoring electrolyte balance, so the electrolyte content of sports drinks is often over-exaggerated. That said, in longer duration events such as the ironman electrolyte replenishment maybe necessary.

Caffeine

The capacity of caffeine to enhance muscular performance was first realised over 100 years ago. A number of manufacturers now incorporate caffeine into their sports drink and gels formulations owing to it’s ability to stimulate the central nervous system, heighten alertness and focus, with metabolites of caffeine known to result in vasodilation and smooth muscle relaxation. Caffeine-mediated increases in oxygen uptake, catecholamine release and metabolic rate have also been reported, along with reduced perceived exertion.

A review concluded the mean improvement in endurance time-trial performance with caffeine ingestion was 3.2 ± 4.3%, although the authors did report a high degree of variability thought to result from a variety of factors including time of ingestion, ingestion mode, and subject habituation (3). Either way research comprehensively indicates caffeine in doses between 3 – 6 mg.kg body mass consumed approximately 1-hour before exercise augments endurance exercise performance. Despite popular belief the ergogenic effects of caffeine are similar in both non-habitual and habitual caffeine consumers (4) and 4-days of abstinence had no effect on the ergogenic effect of caffeine during time-trial performance (5).

Caffeine is completely absorbed 45-minutes after ingestion, with a half-life of 3 – 4 hours, so ingestion pre-exercise is warranted, although it’s ability to reduce perceived exertion makes ingestion during prolonged exercise advantageous. Manufacturers commonly include caffeine in doses of 50 – 100mg in sports drinks and gels, meaning the average 70kg triathlete would require anywhere between 2 and 8 gels or drinks to obtain the optimal dosage, so perhaps lone caffeine supplementation in the form of pro plus would be a more effective method.

Interestingly, High5 who produce EnergySource, which I recommended in the last article based on its favourable carbohydrate content also produce an EnergySource Xtreme, which boasts 47g carbohydrate per 50g sachet and a caffeine dosage of 150mg per 50g sachet. Ultimately, of all the existing formulations this product provides the most scientifically supported carbohydrate and caffeine content, where at the required rate of carbohydrate intake (at most 2 sachets per hour) you will also obtain an ergogenic dosage of caffeine (300mg), doff my hat to High5 again. Alternatively, two tablets of pro plus contain 100mg of caffeine.

Nitrates

Under hypoxic conditions (strenuous exercise) nitrate and nitrite is reduced to nitric oxide, which is known to have several effects on aerobic energy turnover in humans. Nitric oxide is a vasodilator, and appears to play a role in the regulation of oxygen delivery to the working muscles (6).

It is believed the increase in nitric oxide following nitrate ingestion reduces the oxygen cost of exercise through enhanced muscle efficiency by reducing the energy cost of contraction or enhanced mitochondrial efficiency – or both. Research indicates a dose of 300mg nitrate results in a peak in plasma nitrate within 2 – 3 hours, and reduces the oxygen uptake during steady-state submaximal exercise reflective of triathlon performance in club level, moderately trained subjects (VO2max > 50 ml/kg/min).

However, much of the existing evidence suggests that these results are not replicated in trained, elite subjects (VO2max < 65 ml/kg/min), with speculation that highly trained subjects already have optimal nitric oxide synthetic capabilities, making exogenous nitrate supplies useless (7).

A number of manufacturers include nitrate in dosages close to the required active dose of 300mg in their respected drinks, gels and shots. Science in sport for example includes a dosage of 250mg nitrate per Go gel + nitrate product, this combined with a carbohydrate dosage of 20g, not exactly optimal in regards carbohydrate dosage. The evidence appears to suggest these products are only effective in untrained, or moderately trained individuals; further studies are required to confirm this. It also appears that chronic as opposed to acute ingestion is required to optimise the ergogenic effect.

Carnitine

Carnitine is a naturally occurring acid that can either be synthesised or consumed from dietary sources. L-carnitine plays an important role in enabling the transport of long-chain fatty acids across the otherwise impermeable inner mitochondrial membrane. It is hypothesised that increased availability of L-carnitine will increase the capacity to transport and oxidise fatty acids in the mitochondria, posing significant benefit to endurance athletes.

This mechanism has been demonstrated in vitro, with elevated free-carnitine pools raising long-chain fatty acid oxidation by the mitochondria (8). The issue in vivo however exists in delivery of carnitine to the muscle across a large concentration gradient, where even substantial oral intakes will not result in measurable alterations in muscle carnitine concentrations. This would explain the comprehensive level of data showing no ergogenic effect of acute L-carnitine ingestion on metabolism or endurance performance (9).

Interestingly however, a recent study has demonstrated that combined hyperinsulinaemia, in the presence of hypercarnitinaemia can augment muscle carnitine content by approximately 14%, through increased Na+/K+ pump activity. The same lab went on to discover 24-weeks of L-carnitine supplementation in a dosage of 1.36 g/day, combined with a carbohydrate solution 160 g/day increased muscle carnitine stores by 21%, resulting in an increase in power output during the performance trial of 11% from baseline. Performance was not different between groups at 12-weeks of supplementation (10).

So methods of increasing skeletal muscle total carnitine content have been uncovered, although further research is required as current methods are not without their limitations. Either way, an acute dose of 2 g L-carnitine as found in popular sports drinks and gels will be ineffective. Again, science in sport are guilty of ignoring the existing evidence by including a dosage of 1g carnitine per Go gel + carnitine product.

Protein and/or amino acids

A number of sports drinks now contain protein or individual amino acids, typically in 4:1 ratio carbohydrate to protein, with some reports of enhanced performance in endurance exercise following consumption of sports drinks providing protein/amino acids compared to traditional carbohydrate-electrolyte formulations. The case for the consumption of drinks with combined protein and carbohydrate in the recovery period after exercise is strong, although the benefit of such drinks during exercise are contentious.

A meta-analysis explored the influence of protein ingestion during exercise on subsequent endurance performance suggested a methodological bias exists, only 3 of the qualifying studies were time-trial protocols, relevant to competitive triathlon performance, and only 3 controlled for caloric content and contained an isocaloric trial (11). The 3 time-trial protocols reported no significant improvement with protein ingestion. Studies that controlled for caloric content revealed a performance improvement of just 3.4% although not all of those were time-trial protocols, some were time to exhaustion. The authors concluded that compared to carbohydrate alone, co-ingestion of protein and carbohydrate during exercise enhanced the performance of time to exhaustion protocols, and also when supplements were matched for carbohydrate (isocarbohydrate). Thus, the ergogenic effect of protein seen in such studies may be because of a generic effect of adding calories (energy) as opposed to a unique benefit of protein.

Many have also suggested that BCAA ingestion during exercise may attenuate central fatigue and thus enhance endurance performance. Central fatigue is believed to occur when alterations within the central nervous system (CNS) decrease the ability to voluntarily send a signal to a neuromuscular junction and thus stimulate muscular contraction.

The central fatigue hypothesis predicts that the ingestion of BCAA’s during exercise will raise plasma BCAA concentrations and thus reduce the transport of free tryptophan into the brain; subsequently reducing the synthesis and release of the neurotransmitter serotonin and alleviating sensations of fatigue, therefore improving endurance performance (12). Although this mechanism makes good intuitive sense and fatigue during prolonged exercise is clearly influenced by a complex interaction between peripheral and central factors, the hypothesis lacks significant support and little is known about the mechanisms underlying CNS effect on fatigue through the obvious difficulty of studying an intact human brain (13).

Ultimately however, existing research has suggested that to be physiologically effective in reducing central fatigue, large doses of BCAA’s are probably required. Large doses are likely to increase the ammonia concentration in plasma, which is known to be toxic to the brain and muscle. It has also been suggested that buffering of ammonia could lead to early fatigue in working muscles by depleting glycolytically derived carbon skeletons (pyruvate) and draining intermediates of the tricarboxylic acid cycle. Large doses of BCAA during exercise may also slow, or impair water absorption across the gut, causing gastrointestinal disturbances.

Medium-chain triglycerides

Skeletal muscle contraction is fuelled by fat and carbohydrate during exercise, with fat being quantitatively the most important fuel for endurance exercise such as triathlon. Glycogen, particularly muscle glycogen is an important fuel if higher intensities are required – during a sprint finish in a triathlon perhaps. Body glycogen stores are small (8 to 16 MJ) and can be depleted within 60-minutes, whereas fat stores are extremely large even in very lean triathletes (192 MJ in an 80kg person with 15% body fat). Any adaptation that may preserve carbohydrate stores and increase fat oxidation can therefore enhance endurance capacity.

Medium-chain triacyglycerols (MCT’s) are composed of fatty acids with a chain length of 6–12 carbons, MCT’s bypass the lymphatic route and travel rapidly into portal circulation via passive diffusion, which make it a readily available energy source. The unique metabolism of MCT’s has resulted in great interest in the effects of these fatty acids on exercise performance, and to some manufacturers including MCT’s in their sports drink and/or gel formulations.

A comprehensive review of the effects of MCT ingestion during exercise on endurance performance was completed in 2004, studies including dosages between 30 – 116g MCT, timing of ingestion ranged from 1-hour pre-exercise and at 15-minute intervals during training, duration of exercise ranged from 120 – 180-minutes and intensity ranged from 57 – 60% VO2max (14). Only one of the 8 trials included showed a performance improvement and reduced glycogenolysis with MCT, and adverse gastrointestinal effects occurred at dosages greater than 50g MCT. More recently, and more relevant to triathlon performance, a group of cyclists ingested 200ml of a 10% carbohydrate solution or one containing 4.3% MCT and 10% carbohydrate every 20-minutes. Time-trial performance was significantly slower in the MCT trial and half of the subjects experienced adverse gastrointestinal discomfort (15).

I’m not aware of any existing products or manufacturer that include MCT’s within their formulation, although historically there have been a few examples. It appears that most manufacturers have, based on the existing evidence aborted all hope of an ergogenic effect of MCT in sports drinks.

Having critically analysed a number of the added ingredients included in popular sports drinks and gels it is evident that only caffeine is currently of proven benefit beyond the typical carbohydrate, electrolyte and water formulation. Nitrate containing formulations could be advantageous to untrained athletes in the dosages typical of existing formulations, while L-carnitine would be ergogenic if it could be effectively delivered to the muscle. Further research is required to illustrate the role of protein during exercise, and perhaps develop upon the role of BCAA’s in the central fatigue hypothesis, while MCT’s quite conclusively offer no performance benefit and could potentially negate performance.

Based on this evidence I would again point you towards High5’s EnergySource product, either the lone EnergySource product with a dosage of pro plus or the EnergySource Xtreme product, which boasts additional caffeine. As with all performance nutrition strategies, I would advise you err on the side of caution and practice consuming the above products in training prior to using them in competition – just in case.

References

  1. American College of Sports Medicine. Sawka, M., Burke, L., Eichner, E., Maughan, R., Montain, S., Stachenfeld, N. (2007). American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine and Science in Sports and Exercise, 39, 377-390.
  2. Ray, M., Brown, M., Ruden, T., Baier, S., Sharp, R., & King, D. (1998). Effect of sodium in a rehydration beverage when consumed as a fluid or meal. Journal of Applied Physiology, 85, 1329–1336.
  3. Ganio, M. S., Klau, J. F., Casa, D. J., Armstrong, L. E., & Maresh, C. M. (2009). Effect of caffeine on sport-specific endurance performance: a systematic review. Journal of Strength Conditioning Research, 23, 315-324.
  4. Van Soeren, M. H., Sathasivam, P., Spriet, L. L., & Graham, T. E. (1993). Caffeine metabolism and epinephrine responses during exercise in users and nonusers. Journal of Applied Physiology, 75, 805-812.
  5. Irwin, C., Desbrow, B., Ellis, A., Okeeffe, B., & Leveritt, M. (2011). Caffeine withdrawal and high-intensity endurance cycling performance. Journal of Sports Sciences, 29, 509-515.
  6.  Casey, D., Madery, B., Curry, T., Eisenach, J., Wilkins, B., & Joyner, M. (2010). Nitric oxide contributes to the augmented vasodilatation during hypoxic exercise. Journal of Physiology, 588, 373–385.
  7. Wilkerson, D. P., Hayward, G. M., Bailey, S. J., Vanhatalo, A., Blackwell, J. R., & Jones, A. M. (2012). Influence of acute dietary nitrate supplementation on 50 mile time trial performance in well-trained cyclists. European Journal of Applied Physiology, 112, 4127-4134.
  8. Fritz, I. B., (1967). An evaluation of the role of carnitine in regulating fatty acid oxidation and gluconeogenesis. Science, 158, 527-528.
  9. Colombani, P., Wenk, C., Kunz, I., Krahenbuhl, S., Kuhnt, M., Arnold, M., Frey-Rindova, P., Frey, W., & Langhans, W. (1996). Effects of L-carnitine supplementation on physical performance and energy metabolism of endurance-trained athletes: a double-blind crossover field study. European Journal of Applied Physiology & Occupational Physiology, 73, 434-439.
  10. Wall, B. T., Stephens, F. B., Constantin-Teodosiu, D., Marimuthu, K., Macdonald, I. A., & Greenhaff, P. L. (2011). Chronic oral ingestion of L-carnitine and carbohydrate increases muscle carnitine content and alters muscle fuel metabolism during exercise in humans. Journal of Physiology, 589, 963-973.
  11. Stearns, R., Emmanuel, H., Volek, J., & Casa, D. (2010). Effects of ingesting protein in combination with carbohydrate during exercise on endurance performance: a systematic review with meta-analysis. Journal of Strength Conditioning Research, 24, 2192 – 2202.
  12. Gleeson, M. (2005). Interrelationship between physical activity and branched-chain amino acids. Journal of Nutrition, 135, 1591 – 1595.
  13. Meeusen, R., Watson, P., Hasegawa, H., Roelands, B., & Piacentini, M. (2006). Central fatigue: the serotonin hypothesis and beyond. Sports Medicine, 36, 881 – 909.
  14. Jeukendrup, A., & Aldred, S. (2004). Fat supplementation, health, and endurance performance. Nutrition, 20, 678 – 688.
  15. Goedecke, J., Clark, V., Noakes, T., & Lambert, E. (2005). The effects of medium-chain triacylglycerol and carbohydrate ingestion on ultra-endurance exercise performance. International Journal of Sports Nutrition and Exercise Metabolism, 15, 15 – 27.

A pathway into performance nutrition

What you will learn:

  • My recommendations and suggestions for anyone looking toward a career in performance nutrition
  • My experiences
  • My challenges & how I overcame them

Who this is applicable to:

  • Anyone looking towards a career within performance nutrition

Who should not read this:

  • Anyone not looking towards a career in performance nutrition

Enjoy, and please leave feedback. Unlike many, I am open to critique; it is the only way I will ever improve as a practitioner, coach and as a person.


I recently spoke at the 2014 Biological, Clinical and Nutrition Sciences Employability Conference about my pathway into Performance Nutrition and about my experiences pursuing a career I am so passionate about, so I thought I’d share my thoughts and the brief content of that presentation with the wider, worldwide audience.

So as you begin to read this, and for me to feel the need to write this in the first place may appear as though I have ‘made it’ within the performance nutrition industry. Well that is not the case. I have by no means ‘made it’ within the performance nutrition industry. In fact I am still a long way away from my achieving my goals as a performance nutritionist, and I still have a long way to go to become one of the leading performance nutritionists. But, at the age of 23 I feel like I have overcome the first hurdle, which is actually getting into and being recognised within the industry. So I thought I would share my experiences, and my recommendations to anyone else considering this pathway. Hopefully in an effort to ease the way for others to follow me, because I can tell you it has been tough!

Qualifications

Most, if not all professions require a certain set of academic credentials. Now I’m not a massive fan of qualifications, but I now realise just how important they are. I can honestly say that if I hadn’t completed my MSc I would definitely not have been given the opportunities that have since come my way. So whilst qualifications are not essential, they definitely help. I know a few extremely intelligent, and successful practitioners who have achieved recognition with the nutrition industry with just undergraduate degrees, some not even that.

Just as another example of how qualifications can be overestimated, I am a qualified Olympic Lifting instructor. Back in 2011, I received this qualification and proceeded to do absolutely diddly squat with it. Honestly, if I tried to teach someone the Olympic Lifts today there would be some serious injuries. Looking back, I have no idea why I even decided to do this qualification? I already knew that I wanted to become a performance nutritionist – the things you do when you’re young and dumb! But that doesn’t change the fact that I am still qualified. That is the extremely frustrating thing about qualifications – unless you apply what you have learnt then the qualification becomes a useless, and there is no real way to differentiate.

A piece of paper with my name on that suggests I am qualified to teach the Olympic lifts,

A piece of paper with my name on that suggests I am qualified to teach the Olympic lifts.

Fundamental knowledge

A foundation of fundamental knowledge and understanding is of critical importance. I see a number of people involved in the health and fitness industry that appear to have read into the more complex aspects of nutrition before getting a firm grasp of the basics. The basics being energy balance, the macronutrients, and macronutrient metabolism, micronutrients and water. My recommendation would be to focus on one topic each month, and research, read and read some more within that area, ask questions and take notes until you feel comfortable within that area. Then move onto the next. I used that systematic approach successfully, and I still utilise it now.

Whether this fundamental knowledge is gained in an academic environment or through personal reading and learning there is little difference in my opinion. At least not at undergraduate level, there is probably a difference at MSc. One will obviously gain piece of paper with a name, crest, date and stamp on, and the other won’t. Apart from that there is little else different other than the all to frequent hangovers and student debt.

That said however, I think now more than ever, academic credentials are extremely important. I can think of a number of occasions where my MSc and credentials have opened up opportunities that otherwise wouldn’t have been available. My work with Warrington Wolves Rugby League and performance nutrition workshops with the athletes at Loughborough University for example. So I would recommend the academic route.

Books & fundamental knowledge

Fundamental knowledge is not necessarily gained from lectures it is gained through reading and researching away form the lectures. The lectures merely open the door for you to then explore.

A question I am often asked is which book(s) would you recommend?

My answer is always the same; I much prefer journal articles. Journal articles have to undergo a peer-review process, which generally ensures the content is accurate and scientifically sound. Just about anyone can write and publish a book – just take a trip to the ‘Health & Fitness’ section in any bookstore. Plus a book could take anywhere between 12-months and 3-years to write and publish, by which time it is already out-dated, whilst new research is published in journals far more frequently.

That said, I did read and gain some fundamental knowledge form a handful of books while in university, most of which I still own. They are as follows:

That is not to say there are not any other good books out there but these are going to provide you with that fundamental understanding from which you can advance with confidence knowing that the foundations have been set.

From a journal perspective I would definitely recommend you get familiar with PubMed, and frequent PubMed surfing is a necessity. When looking at individual journals there are too many to list, but a few to consider are:

Journals are generally recognised by their impact factor, which is essentially the amount of current citations to articles that the journal published in the previous two years. The current impact factor of journals within sports science & medicine can be found here. As a student you will be given free access to the most relevant journals, make the most of this! Otherwise just abuse PubMed & possibly Science Direct.

Beyond this I would also recommend attending some industry related conferences, International Sport & Exercise Nutrition Conference springs to mind, although personally I have never attended although I have heard good reports. I would not suggest that conferences are necessary however, especially if you stay up to date with the most significant journals within the field. Although speakers often refer to unpublished data, ahead of print, but again just read and read and you’ll be fine.

I can also recommend some extremely beneficial sources of information in the form of blogs, and publications. They include:

My route

My interest in nutrition began following a series of unfortunate knee injuries when I was 18 from which I spent 12-months rehabilitating myself and my body, I spent time with renowned physiotherapists, knee surgeons, and strength conditioning coaches however nutrition was never even considered nor addressed. As I began to gain weight my interest in food increased and I took it upon myself to begin exploring the field to develop a basic understanding.

What I found was an absolute minefield.

Littered with contradiction and extremely confusing, misleading information being touted frequently by apparent ‘experts’ and marketing, marketing everywhere. I presume like most people, I had tried most things, based on the latest trend, media coverage and fad diet.

This ignited my initial interest and passion for nutrition.

In a way I was quite fortunate that I knew exactly what I wanted to do before I left 6th form. I then set about making the dream happen.

My route involved A Levels in biology, PE and geography, then onto a BSc in Sports Science and an MSc in Nutrition Science. This provided me with the invaluable fundamental knowledge of the human body, the sports sciences, physiology, psychology and nutrition. In the final year of my BSc I became specialised in sports nutrition. My undergraduate dissertation looked at the effects of sodium bicarbonate supplementation during simulated rugby performance, something I went on to research further at MSc.

I then went on to do an MSc in Exercise & Nutrition Science, although I did not do any of the exercise modules. In truth the MSc was fantastic, and above all taught me to how to be critical and how to properly and comprehensively critique research. This has been invaluable in my applied work since, and something that is becoming more and more popular within the lay realm.

From an academic perspective if I were to do it again I would not do much if anything differently. My undergraduate degree provided me with a great insight into the sports sciences, particularly important was the introduction to the various energy systems and pathways during exercise of varying intensities. My MSc taught me to be critical, and the sheer number of research papers I read – and continue to read – led to a significant increase in knowledge.

The book that helped me most through my MSc & beyond.

The book that helped me most through my MSc & beyond.

My recommended route:

Please bare in mind that their is no one way into performance nutrition, in truth there are a variety of pathways, this is simply my recommended pathway based upon my experiences.

A-level: Biology, Physical Education, and something easy to ensure you get the grades to allow you into one of the top universities.

Undergraduate: Sports Science

Post-graduate: Sports Nutrition

Other qualifications could include the IOC Diploma in Sports Nutrition or the ISSN taught Diploma, although I don’t have much experience or knowledge of how they work so cannot really comment. They do appear to offer a great deal in regards knowledge, but are lacking from a practical perspective, which is an issue. Either way I would still favour a university postgraduate degree.

The obvious question is do you stop there?

Well, that’s where I am right now and in truth I can’t answer that question. But I do feel that there are enough opportunities out there for performance nutritionists with just an MSc although a PhD would be pretty cool wouldn’t it? It also offers more credibility and probably, at a young age, more respect from some? It’s also a massive differentiating factor when competing for a job. I may be able to answer that question better in 5 or so years.

Recommended universities? I would recommend Loughborough, University of Bath, Leeds, Chester, Liverpool John Moores and Birmingham. I particularly like the MSc being developed my Graeme Close at Liverpool John Moores. Although there are many more, and at undergraduate I would imagine most are very similar. The university is a secondary factor in my opinion, if you work hard enough to develop your knowledge and practices it doesn’t really matter where you achieve your qualifications.

The missing link

No matter how talented a student is, there is always going to be a great divide between the academic research setting and practice. Practice with clients, with athletes or the general public requires more than just knowledge of energy balance, macronutrients, micronutrients and water. What works in the lab doesn’t always work in practice, how you deal with that and manipulate the prescription in order to resolve it is not taught in any qualification, at least not to my knowledge.

For that reason I would recommend gaining as much applied experience as you can whilst you are in university. I was fortunate in that I did an internship with the Welsh Rugby Union while I was at university. The time I spent with then Lead Performance Nutritionist, Dr Adam Carey was invaluable. I would recommend anyone looking towards a career in performance nutrition seek a similar role. Simply approach your local club, academy sides or associations and volunteer your services or alternatively ask an existing performance nutritionist if you can shadow him/her for a week, month, or year. I know of a few performance nutritionists in elite sport who would accommodate you in such a way. I take interns and I offer mentorship programmes (book a consultation if interested), as does Martin MacDonald. I am sure others do too – you just need to ask.

That brings me onto questions: do not be afraid to ask them! Lots of them, question everything and everyone. That way you will learn how and why.

 He who questions much, shall learn much, and retain much.

 Millions saw the apple fall, but Newton was the one who asked why.

 He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever.

Who questions much, shall learn much, and retain much.

Success leaves clues

One of the most compelling things I have been told this year is that ‘success leaves clues’. How true?

To be successful in any industry often rocket science is not required – simply copy and paste. Perhaps not literally however, as that may end in a law suit against you! There are a handful of people within performance nutrition that I look up to, admire and aspire to be like. I study their practices, I read their research, I also critique their work, allowing me to one day be as good if not better – hopefully.

Success leaves clues. Simply find your aspirational figure and study what and how they work and how they got there, then copy and paste, and add your own influence following a degree of critical thinking.

Conclusion

I can’t stress enough the importance of getting the fundamentals instilled and automated before you even think of moving forward. Energy balance, the macronutrients, micronutrition and water. Focus all of your initial energy and attention on these basic principles then, and only then move on. Doing it the other way around just doesn’t work. It may be cool to talk about hormonal function and inflammatory profile, but in many cases the people that talk about these things do not have a grasp of the basics. This is much like building a house on a hill without sufficient foundations – not much use?

In short, take the academic route, gain as much experience as possible through internships, placements or simply volunteer, attend conferences, ask questions and study the practices of those that you aspire to be.

Be patient and work hard, it is not easy I can assure you of that. There are desperate days where your head is turned by potentially easier, more lucrative paths. But if you are anything like me, working in sport, with elite athletes was my lifetime goal. All you need to do is commit to making that dream a reality. Remember, nothing in life that is worth anything to anyone is easy.

I hope this has been helpful to someone? Please leave feedback, and share on social media if you feel anyone else you know may benefit from reading this.

And if you are interested in learning more about my services then please contact me via phone: (+44)07912624022 or matt@mjnutrition.co.uk or book a FREE consultation using the link at the bottom of the COACHING page.

Nutrition & neurotransmission, the famed meat & nuts combine

What you will learn:

  • What a neurotransmitter is
  • The function of key neurotransmitters
  • The relationship between food & neurotransmitters
  • Optimising neurotransmitters with food
  • My recommendations based on the existing research

Who this is applicable to:

  • Everyone?
  • Especially nutrition nerds

Who should not read this:

  • Charles Poliquin?

Enjoy, and please leave feedback. Unlike many, I am open to critique, it is the only way I will ever improve as a practitioner, coach and a person.


The suggestion made by Charles Poliquin within the articles and multimedia section of the Poliquin groups website reads as follows: rotating meat and nuts breakfast… increased mental acuity and focused energy… allows for a slow and steady rise in blood sugar… to remain stable for an extended period of time… what you eat for breakfast sets up your entire neurotransmitter production for the day’.

All of these suggestions are made relative to popular breakfast choices that are generally higher in carbohydrate, including oats, cereal and bread.

Charles Poliquin for those who do not know is a well-respected highly successful strength and conditioning coach. I commend him for his achievements within the field of strength & conditioning, I actually own a number of his books, and his website http://www.strengthsensei.com/ is a fantastic resource.

It is not the aim of this article to openly criticise Poliquin’s practices or question his motives or intentions, nor will I launch an outright tirade on him. However I feel it is necessary to discuss the application of this much-famed breakfast. I have recently been vilified by a number of potential clients for advocating carbohydrate at breakfast. They citied Poliquin’s meat & nut breakfast and the research used within the meat & nut breakfast in their criticism of me. So I think it is only fair that I counter their suggestion and critique the breakfast in support of my stance in favour of a more flexible, practical approach to the first meal of the day.

As with all of my articles the extravagant claims will be examined meticulously, and honestly with frequent reference to the existing evidence-base. Note the evidence-base, not cherry picking favourable research. Particularly pertaining to the claims of optimised neurotransmission and neurotransmitter production for the day.

A neurotransmitter

A neurotransmitter is a chemical signal that allows for transmission of signals from one neuron to another, across a synapse. Neurotransmission allows for, and control muscle fibre contraction, bodily actions, emotions and feelings. The most significant neurotransmitters in the human body are acetylcholine, norepinephrine, dopamine, Gamma Amino Butyric Acid (GABA), glutamate, serotonin and endorphins. There is a substantial body of evidence to support the notion that nutrition has a significant influence on the appearance of blood and brain neurotransmitters (1, 2, 3).

Neurotransmitters and cognitive function

Research has demonstrated that serotonin is a known sleep-inducing agent (4), with human research indicating that serotonin reduces subjective alertness, objective performance, and increases feelings of relaxation and lethargy (5). The neurotransmitter dopamine on the other hand is associated with pleasurable reward, behaviour, cognition, mood, memory, movement, attention and learning. Interestingly dopamine is critically involved in the drug addiction process by inducing pleasant states or by relieving distress (6). Acetylcholine has a number of physiological functions; it is a widely distributed excitatory neurotransmitter that in the central nervous system and is involved in wakefulness, attentiveness and memory. Interestingly, Alzheimer’s disease is characterised by a significant reduction in acetylcholine concentration and function (7), highlighting its importance in human health performance.

Neurotransmitters and nutrition

Neurotransmitters are primarily synthesized from amino acids, particularly the branched chain amino acids (BCAA’s), tyrosine and tryptophan. The rates at which neurotransmitters are synthesized depends upon the availability of the amino acid precursor. Research from rodent studies in the 70’s and early 80’s demonstrated that increased concentrations of tryptophan resulted in an elevation in serotonin synthesis, and increasing concentrations of tyrosine resulted in elevations in dopamine and certain catecholamines (8).

 

This was supported by earlier research indicating that the administration of a single dose of tryptophan elevated brain tryptophan levels, and thus the levels of serotonin and its major metabolite 5-hydroxyindole acetic acid (5-HTP). The administration of tyrosine, elevated brain tyrosine levels, and thus catecholamine increased in the central nervous system (CNS), while the consumption of lecithin or choline (found in fat) increased brain choline levels and neuronal acetylcholine synthesis (9). Ultimately concluding that tryptophan was the precursor for serotonin, tyrosine was the precursor for dopamine and choline the precursor for acetylcholine.

All of these early studies utilised both observational and knock-out rodent models, using a single dose of the precursor, although similar effects have been seen following the consumption of dietary sources, real-food. Again using a rodent model Wurtman & Fernstrom (9) demonstrated that the consumption of a single protein-free high-carbohydrate meal elevated brain tryptophan levels. Similarly the consumption of a single 40% protein meal accelerated brain catecholamine synthesis through increased availability of tyrosine. Fernstrom (10) concluded that a minimal change of delta 0.07 in the tryptophan to large neutral amino acid ratio is required to influence mood following protein consumption, so a considerable shift in the ratio is required to have an effect on subsequent cognition.

This data clearly demonstrates that the neurotransmitters serotonin, dopamine and the catecholamine’s are under specific dietary control. Essentially this is the data Poliquin has built his meat and nut breakfast on, and in that regard he is correct. The acute effects of a high-carbohydrate protein-free meal, atypical of a modern Western diet breakfast (think oatmeal and cereals) does induce marked increases in serotonin synthesis, and thus may result in increased feelings of lethargy.

However, is the absolute avoidance of carbohydrate justifiable based on the current evidence? Is the process irreversible as Poliquin suggests, does breakfast dictate the neurotransmitters for the entire day?

If Poliquin had read a little further, instead of cherry picking the juiciest data he would have realised not.

Interestingly, in the same research by Wurtman & Fernstrom (9) found that the addition of protein to an otherwise protein-free high-carbohydrate meal suppressed the increases in brain tryptophan and serotonin synthesis, because protein contributes to the blood plasma considerably larger amounts of the other neutral amino acids (e.g., BCAA’s, phenylalanine) than of tryptophan. Tryptophan and other large neutral amino acids, most notably the BCAA’s leucine, isoleucine and valine share the same specific transporter across the blood-brain barrier and thus compete for uptake (11). Therefore brain 5-HTP synthesis will increase when there is an increase in the ratio of free tryptophan to BCAA’s in the blood (12), Thus explaining why the addition of protein to an otherwise protein-free high-carbohydrate meal can suppress serotonin synthesis.

This theory has also been confirmed in humans. Using 20 men, Lieberman et al. (13) administered single oral doses of tryptophan (50 mg/kg) and tyrosine (100 mg/kg) in a double-blind, crossover study. Tryptophan increased subjective fatigue and decreased self-ratings of vigour and alertness, but did not impair performance on any of the tests. Compared to placebo there was no difference in performance with tyrosine, although tyrosine administration did reduce reaction time relative to tryptophan. Lieberman et al (13) concluded that tryptophan has significant sedative-like properties, but unlike other sedatives this may not impair performance in a series of cognitive tests. However it is extremely unlikely – probably impossible in fact – that a human would ever consume 50 mg/kg tryptophan in a single dose from a dietary source thus would not necessarily have to worry about the negative mental effects of lone tryptophan consumption.

Poliquin strongly advocates the avoidance of carbohydrate at breakfast, in fear of neurotransmitter malfunction, mental breakdown and impaired performance has only a handful of cherry picked studies to support him. The truths being that the brain neurotransmitters are influenced by the ratio of free tryptophan to large neutral BCAA’s (14), so a mixed meal that is able to maintain a balance in that ratio is adequate to optimise neurotransmitter synthesis.

Further an increase in the ratio of free tryptophan to large neutral amino acids following a high-carbohydrate protein-free meal is reversible through the addition of protein to that meal, ultimately balancing the ratio again. This invalidates Poliquin’s suggestion that the first meal of the day dictates brain neurotransmitter production for that entire day.

Thanks must also go to my friend Alex Ritson for bringing to my attention the latest research out of John Fernstrom’s lab, that further supports this hypothesis (21).

Worth mentioning is this intricate study by Fischer et al. (14). They examined the cognitive effects of isoenergetic meals consisting of three carbohydrate ratios, a carbohydrate rich meal (4:1), a balanced meal (1:1), and a protein rich meal (1:4) in 15 healthy subjects, in an attempt to elucidate which breakfast combination is most suitable in a school environment. Unsurprisingly, attention and decision times were improved in the first hour with the high carbohydrate meal, owing to the provision of and greater rise in glucose metabolism. However, during the first hour it was both the balanced and higher protein meals that resulted in improved performance. Further, overall reaction times in a central task were fastest after both the balanced and high protein meal, thus suggesting a high protein meal or a balanced meal appear to result in better overall cognitive performance. Although the results also revealed participants subjective measures of ‘tasty’ and ‘pleasant’ were greater in the balanced meal than in the high protein meal, which suggests this would be the most effective in a practical sense.

Mechanisms

Having read the study by Fischer et al. (14) it would appear that carbohydrates contain significant amounts of tryptophan, thus increase free tryptophan concentrations after ingestion, elevating tryptophan uptake and stimulating serotonin synthesis. However, this is not the case. A bowl of oats for example – porridge or oatmeal depending which side of the pond you are – a common staple of many a Western breakfast, vilified by Poliquin for the potential negative effects on neurotransmission and mental performance. Well, the amino acid profile of 100g oats indicates a tryptophan concentration of 234 mg, compared to 694 mg isoleucine, 1284 mg leucine, and 937 mg valine, which collectively make up the BCAA’s (15). So a high carbohydrate breakfast does not contain that much tryptophan although accelerates serotonin synthesis through an increase in tryptophan uptake by the brain, huh?

It would appear that although the carbohydrate meal alone does not contain much tryptophan, the insulin secreted following the carbohydrate meal results in a rapid removal and significant decrease in plasma levels of the large neutral amino acids (tyrosine, phenylalanine, BCAA’s and methionine) that would ordinarily compete with tryptophan for uptake by the brain. Tryptophan then crosses the blood-brain barrier and is converted to serotonin (5).

It appears it is not actually the carbohydrate that causes the problem; it is in fact the insulin response to that carbohydrate that drives the large neutral amino acids out of the bloodstream, leaving tryptophan free to pass the blood brain barrier, with no competition.

Logic

The insulin index formulated by Holt et al. (16) clearly demonstrates that beef, the food favoured by Poliquin in his infamous meat and nut breakfast along with other more exotic meats elicits an insulin response of 7910 ± 2193 pmol/min/L and grain bread, a food demonized by Poliquin in fear of it frying all brain cells comes in at 6659 ± 837 pmol/min/L – insulin area under the curve. The insulin index clearly indicates beef is more insulinogenic than most forms of carbohydrate; therefore suggesting that the net effect in regards neurotransmitter synthesis of a high-protein carbohydrate-free meal may be similar to that of a mixed meal. The greater insulin response to beef consumption will lead to a reduction in the BCAA’s and other neutral amino acids, leaving free tryptophan to be taken up by the brain; interestingly 100g steak contains more tryptophan than the same portion of oats (288 mg) (15).

Logic, intuition and a basic understanding of the insulin index suggests this could be true, although a number of rodent studies have disproved the hypothesis, where Rouch et al. (17) revealed a high-protein diet significantly reduced serotonin concentrations for 2-hours, Wurtman & Fernstrom (9) reported similar findings. Interestingly, the reduction in serotonin following protein feeding is thought to be among the reasons why protein is more satiating that carbohydrate.

As discussed previously research has demonstrated that Poliquin’s suggestion that the first meal of the day dictates that whole days brain neurotransmitters is false, in that the process is reversible. Looking at some more of the evidence to disprove this claim a rodent study formulated to analyse the brain tryptophan concentrations and rates of serotonin synthesis in fasted rats fed a high-carbohydrate meal followed 2-hours later by a protein-containing meal. They demonstrated that when the high-carbohydrate meal was fed first, brain tryptophan concentrations increased as did serotonin synthesis, and these changes were reversed at 4-hours if the second meal contained protein. Interestingly the authors went on to conclude, quote: “brain tryptophan concentrations and serotonin synthesis are thus responsive to the sequential ingestion of protein and carbohydrate meals if there is a sufficient interval between meals”. Similarly, Rouch et al. (18) reported the plasma ratio of free tryptophan to large neutral amino acids was increased by a carbohydrate meal, and remained high for 2-hours, a subsequent casein (protein) meal reversed this change. Interestingly, a first casein meal reduced the ratio, and was not increased again by a subsequent carbohydrate meal. This finding actually favours Poliquin’s claims in that an initial high-protein carbohydrate-free meal is more favourable than a high-carbohydrate protein-free meal in regards neurotransmitter synthesis.

The reversible nature of neurotransmitter synthesis is supported by the central fatigue hypothesis in humans, which predicts that the ingestion of BCAA’s during exercise will raise plasma BCAA concentration and hence reduce transport of free tryptophan into the brain; subsequently reducing the formation of serotonin and alleviating sensations of fatigue and therefore improve endurance performance (19). To date this hypothesis still lacks support despite many years of research, although it does highlight the obvious reversible nature of neurotransmitter synthesis.

Conclusion and recommendations

My recommendation based on this evidence is that a single macronutrient meal can have a significant impact on the brain neurotransmitters. Where a protein-free high-carbohydrate meal typical of the meals consumed at breakfast by many Westerners – think oatmeal et al – can increase serotonin synthesis, and thus increase feelings of fatigue as Poliquin claims. However, a high-protein high-fat carbohydrate-free meal can increase dopamine and catecholamine synthesis. Granted you would favour dopamine and catecholamine synthesis, but with your daily macronutrient requirements in mind, combined with the fact that eating single macronutrient meals would be extremely tasteless and boring it would be more appropriate to consume mixed meals than to focus on meals free from certain macronutrients in fear of a surge of sleep-inducing neurotransmitters.

In conclusion the promotion of low-carbohydrate, high-protein, high-fat meat and nut breakfast is largely unsubstantiated, and supported by a few cherry picked studies. A mixed meal consisting of protein (possibly red meat if your finances allow), carbohydrate and fat (possibly nuts) is adequate, and in a practical sense is optimal.

References

  1. Wurtman, R., & Fernstrom, J. (1974). Nutrition and the Brain. Scientific American, 230, 84- 91.
  2. Growdon, J., Cohen, E., & Wurtman, R., (1977). Treatment of brain diseases with dietary precursors of neurotransmitters. Annals of Internal Medicine, 86, 337 – 339.
  3. Gelenberg, A., & Gibson, C., (1984). Tyrosine for the treatment of depression. Nutrition & Health, 3, 163 – 173.
  4. Hartman, E., & Spinweber, C., (1979). Sleep induced by L-tryptophan. Effect of dosages within the normal dietary intake. The Journal of Nervous and Mental Disease, 167, 497 – 499.
  5. Spring, B., (1984). Recent research on the behavioural effects of tryptophan and carbohydrate. Nutrition & Health, 3, 55 – 67.
  6. Le Foll, B., Gallo, A., Le Strat, Y., Lu, L., & Gorwood, P., (2009). Genetics of dopamine receptors and drug addiction: a comprehensive review. Behavioural Pharmacology, 20, 1 – 17.
  7. Francis, P., (2005). The interplay of neurotransmitters in Alzheimer’s disease. Central Nervous Systems Spectrums, 10, 6 – 9.
  8. 8.    Wurtman, R., Hefti, F., & Melamed, E., (1980). Precursor control of neurotransmitter synthesis. Pharmacological Reviews, 32, 315 – 335.
  9. Wurtman, R., & Fernstrom, J., (1975). Control of brain monoamine synthesis by diet and plasma amino acids. The American Journal of Clinical Nutrition, 28, 638 – 647.

10. Fernstrom, J., (1994). Dietary amino acids and brain function. Journal of the American Dietetic Association, 94, 71 – 77.

11. Maughan, R., (2000). Nutrition in sport. Blackwell Science, United Kingdom

12. Chaouloff, F., Kennett, G., Serrurrier, B., Merino, D., & Curzon, G. (1986). Amino acid analysis demonstrates that increased plasma free tryptophan causes the increase of brain tryptophan during exercise in the rat. Journal of Neurochemistry, 46, 1647 – 1650.

13. Lieberman, H., Corkin, S., Spring, B., Wurtman, R., & Growdon, J., (1985). The effects of dietary neurotransmitter precursors on human behaviour. American Journal or Clinical Nutrition, 42, 366 – 370.

14. Fischer, K., Colombani, P., Langhans, W., & Wenk, C. (2002). Carbohydrate to protein ratio in food and cognitive performance in the morning, Physiology & Behaviour, 75, 411 – 423.

15. http://nutritiondata.self.com/

16. Holt, S., Miller, J., & Petocz, P., (1997). An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods. American Journal of Clinical Nutrition, 66, 1264 – 1276.

17. Rouch, C., Nicolaidis, S., & Orosco, M., (1998). Determination, using microdialysis, of hypothalamic serotonin variations in response to different macronutrients. Physiology & Behaviour, 65, 653 – 657.

18. Rouch, C., Meile, M., & Orosco, M., (2003). Extracellular hypothalamic serotonin and plasma amino acids in response to sequential carbohydrate and protein meals. Nutritional Neuroscience, 6, 117 – 124.

19. Gleeson, M., (2005). Interrelationship between physical activity and branched-chain amino acids. The Journal of Nutrition, 135, 1591 – 1595.

20. Fernstrom, M., & Fernstrom, J. (1995). Brain tryptophan concentrations and serotonin synthesis remain responsive to food consumption after the ingestion of sequential meals, The American Journal of Clinical Nutrition, 61, 312 – 319.

21. Fernstrom, J., Langham, K., Marcellino, L., Irvine, Z., Fernstrom, M., & Kaye, W. (2013). The ingestion of different dietary proteins by humans induces large changes in the plasma tryptophan ratio, a predictor of brain tryptophan uptake and serotonin synthesis. Clinical Nutrition, 32, 1073 – 1076.

Carbohydrate feeding during endurance performance

What you will learn:

  • A needs analysis of triathlon performance
  • Fundamentals of carbohydrate feeding during endurance exercise
  • Critical analysis of existing sports drinks & products
  • My recommended sports drinks & products based on the existing research
  • You will also learn some scientific jargon – always a bonus!

Who is this applicable to:

  • Triathletes
  • Endurance athletes
  • Possibly team-sport athletes
  • Anyone interested in carbohydrates during exercise
  • Anyone interested in nutrition science?

Who should not read this:

  • Low carbohydrate advocates
  • Clean eaters

Enjoy, and please leave feedback. I am open to critique, it is the only way I will ever improve as a practitioner, coach and a person.


 

Before we go anywhere with this, we must look at physiological demands of the sport of triathlon in order to gain an understanding of the nutritional requirements.

Triathlon

The sport of triathlon requires athletes to sequentially swim, cycle and run over various distances – too much like hard work to me – therefore the physiological demands and nutritional challenges differ greatly from race to race. A case study revealed the carbohydrate energy expenditure alone was 15,762 kJ (~3,767 kcal) during the Grand Columbian half Ironman triathlon, and muscle glycogen concentrations were reduced to 36.6 mmol/kg wet wt -1/hr-1 from an initial 227.1 mmol/kg wet wt -1/hr-1 (1) – obviously a pretty successful carb load, something that will be covered in future blog posts.

Similarly, Noakes (2000) demonstrated near complete glycogen depletion following the 4.5-hour cycling stage of a simulated ironman triathlon, where elite male triathletes exercised at an intensity of 71% vo2max. It was interesting to note that following the 180km cycle, glycogen stores were almost completely depleted, although the triathletes were able to maintain running speeds of 16km/h for the remaining 160-minutes, at an intensity of ~66% vo2max, possibly due to the increased rate of intramuscular triglyceride oxidation (aka fat burning) of the elite participants (3). This study, among others clearly demonstrates the elevated energy and carbohydrate requirements of triathletes, in that regards the ingestion of carbohydrate pre- and during exercise will be have a performance enhancing effects.

Sports drinks

The sports drink industry is projected to reach $2bn by 2016, this phenomenal figure highlights the rapid rise in popularity of such drinks, essentially designed to delay the onset of fatigue and enhance athletic performance through the delivery of carbohydrate and fluid simultaneously. When an industry is this financially powerful it is necessary to critique it thoroughly and analyse the efficacy of its product. So in the following article we will do exactly that. Initially we will look at the carbohydrate content, and examine which drinks are most suitable from that perspective. In part two of this short series we will go on to explore the efficacy of the additional ingredients in modern sports drinks.

Fatigue

Fatigue is generally defined as a decrease in force production (4); although the precise cause of fatigue during endurance exercise of moderate intensity (65 – 75% vo2max) remains unknown (5) several factors are thought to be responsible, predominantly the depletion of glycogen stores, reduced blood glucose concentrations and hypoglycaemia.

Existing evidence suggests that the ingestion of carbohydrate during a prolonged exercise task is effective in increasing endurance and athletic performance through:

  • Improved maintenance of blood glucose concentrations
  • Increased rates of carbohydrate oxidation
  • Sparing on endogenous carbohydrate stores (stores within the body)

Carbohydrate oxidation simply refers to the energy obtained from the metabolism (breakdown) of carbohydrate, obviously important during exercise.

Carbohydrate feeding during exercise

A systematic review with meta-analysis of the existing carbohydrate during exercise (time trial) data concluded that the consumption of 30 – 60 g/hr carbohydrate in a 6 – 8% glucose concentration during exercise greater than 1-hour maintains blood glucose concentrations and high carbohydrate oxidation rates, and may improve time trial performance by ~2% (6). An improvement of 2% in sport of any kind is significant, an improvement of 2% in the 2013 ITU World Triathlon Grand Final in London was the difference between 1st and 26th place (International Triathlon Union, 2012). This clearly highlights the significance of carbohydrate during endurance exercise.

Such carbohydrate intakes achieve the maximal 1 – 1.1 g/min-1 carbohydrate oxidation rates, with higher intakes associated with increased incidence of gastrointestinal symptoms (stomach issues) and little additional effect.

Carbohydrate oxidation from glucose alone appears to be limited to rates of 1 – 1.1 g/min-1 owing to the fact that the sodium-dependant glucose transporter (SGLT1) becomes saturated at rates of 1 g/min (7, 8). More recent data however has illustrated a role for multiple-transportable carbohydrates, where multiple transport mechanisms can be utilised at the same time. Fructose utilises the transporter GLUT5, so saturating SGLT1 through glucose ingestion with the addition of fructose will allow for the delivery and oxidation of more carbohydrate per minute – score! Research has confirmed this, with observed carbohydrate oxidation rates around 65% greater than previously thought to be maximal (1 – 1.1 g/min from a single source). Such blends often utilise a 2:1 ratio glucose:fructose or maltodextrin:fructose, and can result in exogenous carbohydrate oxidation rates of 1.75 g/min.

These multiple-transportable carbohydrate formulations also offer the advantage of:

  • Enhanced fluid delivery
  • Improved oxidation efficiency
  • Reduced likelihood of gastrointestinal distress (9).

The increased rates of carbohydrate oxidation with multiple-transportable carbohydrates do result in improved time trial performance too, one study concluded the ingestion of a glucose:fructose (2:1 ratio) beverage resulted in an 8% improvement in time trial performance compared to the ingestion of a glucose only beverage, both beverages delivered carbohydrate at equal rates of 1.8 g/min (10). So sports drinks that contain both glucose and fructose ingested at high rates may be more beneficial than those that contain glucose alone (11).

To achieve such high oxidation rates, large dosages of carbohydrate are required; such large doses may not be practical or even possible during competition. Recent research investigating the dose-response relationship between carbohydrate and endurance performance suggested an intake of 78 g/hour in an 1:1:1 glucose-fructose-maltodextrin formulation was optimal during the ~160-minute cycling time trial employed in that study. I’d agree, such an intake aligns with the previous evidence. Therefore, for triathlon performance the ingestion of carbohydrate at rates of around 60 – 90 g/hour is recommended. Although certain individuals do experience some serious gastrointestinal issues regardless of the dosage so I would recommend developing an individualised feeding strategy with assistance from a professional performance nutritionist. The optimal carbohydrate mixture would be a combination of glucose and fructose, maltodextrin and fructose, or glucose, sucrose and fructose.

Recommended products

Existing sports drinks offer such formulations, lets look at some of the options:

Product Carbohydrate formulation Carbohydrate per product Required rate of ingestion
High5 EnergySource Maltodextrin & fructose (2:1 ratio) 45g / 50g sachet Up to 2 sachets per hour
Gatorade Perform Glucose & sucrose (glucose & fructose)* 33g / 36g sachet Up to 2.7 sachets or 3 bottles per hour
Lucozade Sport Elite Glucose & fructose (2:1 ratio) 45.5g / 500ml bottle Up to 2 bottles per hour
Coca cola (flat) Sucrose (glucose & fructose)* 53g / 500ml bottle Up to 1.7 500ml bottles
DIY formulation Maltodextrin (60g) & fructose (30g) N/A N/A

* ratio not stated.

Based on the existing products on the market, my recommendation would be High5 EnergySource, this appears to be optimal in regards carbohydrate formulation, and would probably be the most practical in that the sachet can be carried easily and mixed with water easily too. High5 also offer an EnergySource plus option that contains additional caffeine, we will go on to examine the beneficial effects of caffeine in the part two.

You will also notice that coca cola is included on the above list, a number of world leading endurance sports athletes now utilse coca cola during exercise as an ergogenic aid owing to its favourable carbohydrate content, it also contains caffeine (although only in small doses (32mg/330ml)) and offers the obvious advantage of being the most palatable option. Flat coca cola is being used by leading tour de France teams. The Australian Institute of Sport actually create a coca cola slush (ice) drink for their athletes as the body of supportive evidence of precooling strategies continues to grow rapidly (12). Obviously flat coca cola will reduce the gastrointestinal issues that accompany the ingestion of carbonated drinks, which could otherwise impair athletic performance.

Carbohydrate gels

Please note that some carbohydrate sports gels are promoted during endurance exercise, but owing to the reduced carbohydrate concentrations you would be required to consume around 4 – 5 of these gels every hour to reach the maximum threshold for carbohydrate oxidation. This offers obvious disadvantages. Firstly, you would need to carry a small back pack to transport them in and also you would have to spend a couple of seconds 4 – 5 times each hour opening and consuming the gels.

So for the longer endurance events, over 2-hours I would suggest you consume drinks as opposed to gels. Gels are advantageous during shorter endurance events, or when training to maintain blood glucose concentrations and provide lower doses of single source glucose for oxidation. I’m not aware of any gel that contains the optimal 2:1 ratio of glucose:fructose, any such formulation is likely to be extremely sweet, sticky, sickly and not suitable for consumption during an endurance event.

Conclusion

In conclusion a triathlete, or any endurance athlete would benefit from carbohydrate supplementation during exercise. I have provided a recommendation for a product based on the carbohydrate content alone, in part two I will go on to advise which additional ingredients will be of benefit to your performance and again provide recommended products/strategies.

If you enjoyed this blog post please Tweet it, share it on Facebook, and share it with your friends. And please leave your feedback, as I said, I am open to critique.

References:

  1. Gillum, T, L., Dumke, C, L., & Ruby, B, C. (2006). Muscle glycogenolysis and resynthesis in response to a half Ironman triathlon: a case study. International Journal of Sports Physiology & Performance, 1, 408-413.
  2. Noakes, T, D. (2000). Physiological models to understand causes of fatigue and the adaptations that predict or enhance athletic performance. Scandinavian Journal of Medicine & Science in Sports, 10, 123-145.
  3. Phillips, S, M., Green, H, J., Tarnopolsky, M, A., Heigenhauser, G, J., & Grant, S, M. (1996). Progressive effect of endurance training on metabolic adaptations in working skeletal muscle. American Journal of Physiology Endocrinology & Metabolism, 270, 265-272.
  4. Burke, L., & Deakin V. (2006). Clinical Sports Nutrition. (3rd edition). Australia. McGraw-Hill Australia Pty Ltd.
  5. Allen, D, G., Lamb, G, D., & Westerblad, H. (2008). Skeletal muscle fatigue: cellular mechanisms. Physiology Reviews, 88, 287-332.
  6. Temesi, J., Johnson, N., Raymond, J., Burdon, C., & O’Connor, H. (2011). Carbohydrate ingestion during endurance exercise improves performance in adults. Journal of Nutrition, 141, 890 – 897.
  7. Jeukendrup, A, E., Wagenmakers, A, J., Stegen, J, H., Gijsen, A, P., Brouns, F., & Saris, W, H. (1999). Carbohydrate ingestion can completely suppress endogenous glucose production during exercise. American Journal of Physiology, 276, 672-683.
  8. Wright, D, A., Sherman, W, M., & Dernbach, A. (1991). Carbohydrate feedings before, during, or in combination improve cycling endurance performance. Journal of Applied Physiology, 71, 1082–1088.
  9. Jeukendrup, A. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Current Opinion in Clinical Nutrition & Metabolic Care, 13, 452 – 457.
  10. Currell, K., & Jeukendrup, A. (2008). Superior endurance performance with ingestion of multiple transportable carbohydrates. Medicine & Science in Sports & Exercise, 40, 275 – 281.
  11. Jentjens, R., Achten, J., & Jeukendrup, A, E. (2004). High rates of exogenous carbohydrate oxidation from multiple transportable carbohydrates ingested during prolonged exercise. Medicine & Science in Sports & Exercise, 36, 1551-1558.
  12. Ross, M., Abbiss, C., Laursen, P., Martin, D., & Burke, L. (2013). Precooling methods and their effects on athletic performance: a systematic review and practical applications. Sports Medicine, 43, 207 – 225.

Carbohydrate sports drinks

Q. I’m a triathlete; do I need to consume sports drinks? If so, which ones are suitable?

Firstly, we must look at physiological demands of the sport of triathlon in order to gain an understanding of the nutritional requirements.

Matt_Jones

The sport of triathlon requires athletes to sequentially swim, cycle and run over various distances, therefore the physiological demands and nutritional challenges differ greatly from race to race. A case study revealed carbohydrate energy expenditure was 15,762 kJ during the Grand Columbian half Ironman triathlon, and muscle glycogen concentrations were reduced to 36.6 mmol/kg wet wt -1/hr-1 from an initial 227.1 mmol/kg wet wt -1/hr-1 (1). Similarly, Noakes (2000) demonstrated near complete glycogen depletion following the 4.5-hour cycling stage of a simulated ironman triathlon, where elite male triathletes exercised at an intensity of 71% vo2max. It was interesting to note that following the 180km cycle, glycogen stores were almost completely depleted, although the triathletes were able to maintain running speeds of 16km/h for the remaining 160-minutes, at an intensity of ~66% vo2max, possibly due to the increased rate of intramuscular triglyceride oxidation of the elite participants (3). This study, among others clearly demonstrates the elevated energy and carbohydrate requirements of triathletes, in that regards the ingestion of carbohydrate during exercise will be ergogenic.

The sports drink industry is projected to reach $2bn by 2016, this phenomenal figure highlights the rapid rise in popularity of such drinks, designed to delay the onset of fatigue and enhance athletic performance through the delivery of carbohydrate and fluid simultaneously. When an industry is this financially powerful it is necessary to critique it thoroughly and analyse the efficacy of its product, so in the following article we will do exactly that. Initially we will look at the carbohydrate content, and examine which drinks are most suitable from this perspective, in the second section we will go on to explore the efficacy of the additional ingredients in modern sports drinks.

Fatigue is generally defined as a decrease in force production (4); although the precise cause of fatigue during endurance exercise of moderate intensity (65 – 75% vo2max) remains unknown (5) several factors are thought to be responsible, predominantly the depletion of glycogen stores, reduced blood glucose concentrations and hypoglycaemia.

Existing evidence suggests that the ingestion of carbohydrate during a prolonged exercise task is effective in increasing endurance and athletic performance through improved maintenance of blood glucose concentrations, increased rates of carbohydrate oxidation and sparing on endogenous carbohydrate stores.

Carbohydrate oxidation refers to the energy obtained from the metabolism (breakdown) of carbohydrate, obviously important during exercise.

A systematic review with meta-analysis of the existing carbohydrate during exercise (time trial) data concluded that the consumption of 30 – 60 g/hr carbohydrate in a 6 – 8% glucose concentrations during exercise greater than 1-hour maintains blood glucose concentrations and high carbohydrate oxidation rates, and may improve time trial performance by ~2% (6). An improvement of 2% in sport of any kind is significant, an improvement of 2% in the 2013 ITU World Triathlon Grand Final in London was the difference between 1st and 26th place (International Triathlon Union, 2012), so fairly significant!

Such carbohydrate intakes achieve the maximal 1 – 1.1 g/min-1 oxidation rates, with higher intakes associated with increased incidence of gastrointestinal symptoms and little additional effect. Carbohydrate oxidation from single source glucose appears to be limited to rates of 1 – 1.1 g/min-1 owing to the fact that the sodium-dependant glucose transporter (SGLT1) becomes saturated at rates of 1 g/min (7, 8). More recent data however has illustrated a role for multiple-transportable carbohydrates, where multiple transport mechanisms can be utilised at the same time. Fructose utilises the transporter GLUT5, so saturating SGLT1 through glucose ingestion with the addition of fructose will allow for the delivery and oxidation of more carbohydrate. Research has confirmed this, with observed carbohydrate oxidation rates around 65% greater than previously thought to be maximal (1 – 1.1 g/min from a single source). Such blends often utilise a 2:1 ratio glucose:fructose or maltodextrin:fructose, and can result in exogenous carbohydrate oxidation rates of 1.75 g/min.

These multiple-transportable carbohydrate formulations also offer the advantage of enhancing fluid delivery and improving oxidation efficiency, and reducing the likelihood of gastrointestinal distress (9). The increased rates of carbohydrate oxidation with multiple-transportable carbohydrates do result in improved time trial performance too, one study concluded the ingestion of a glucose:fructose (2:1 ratio) beverage resulted in an 8% improvement in time trial performance compared to the ingestion of a glucose only beverage, both beverages delivered carbohydrate at equal rates of 1.8 g/min (10). So sports drinks that contain both glucose and fructose ingested at high rates may be more beneficial than those that contain glucose alone (11).

To achieve such high oxidation rates, large dosages of carbohydrate are required; such large doses may not be practical or even possible during competition. Therefore, for triathlon performance the ingestion of carbohydrate at rates of 90 g/hour is recommended. The optimal carbohydrate mixture would be a combination of glucose and fructose, maltodextrin and fructose, or glucose, sucrose and fructose.

Existing sports drinks offer such formulations, lets look at some of the options:

Product Carbohydrate formulation Carbohydrate per product Required rate of ingestion
High5 EnergySource Maltodextrin & fructose (2:1 ratio) 45g / 50g sachet Up to 2 sachets per hour
Gatorade Perform Glucose & sucrose (glucose & fructose)* 33g / 36g sachet Up to 2.7 sachets or 3 bottles per hour
Lucozade Sport Elite Glucose & fructose (2:1 ratio) 45.5g / 500ml bottle Up to 2 bottles per hour
Coca cola (flat) Sucrose (glucose & fructose)* 53g / 500ml bottle Up to 1.7 500ml bottles
DIY formulation Maltodextrin (60g) & fructose (30g) N/A N/A

* ratio not stated.

Based on the existing products on the market, my recommendation would be High5 EnergySource, this appears to be optimal in regards carbohydrate formulation, and would probably be the most practical. High5 also offer an EnergySource plus option that contains additional caffeine, we will go on to examine the beneficial effects of caffeine in the second section of this post. You will also notice that coca cola is included on the above list, a number of world leading endurance sports athletes now utilse coca cola during exercise as an ergogenic aid owing to its carbohydrate content, it also contains caffeine (although only in small doses (32mg/330ml)) and offers the obvious advantage of being the tastiest option. Flat coca cola is being used by leading tour de France teams and the Australian Institute of Sport actually create a coca cola slush (ice) drink for their athletes. Obviously flat coca cola will reduce the gastrointestinal issues that accompany the ingestion of carbonated drinks, which could otherwise impair athletic performance.

Please note that some carbohydrate sports gels are promoted during endurance exercise, but owing to the reduced carbohydrate concentrations you would be required to consume around 4 – 5 of these gels every hour, which offers obvious disadvantages. Firstly, you’d need to carry a small back pack to transport them in and also you’d have to spend a couple of seconds 4 – 5 times each hour opening and consuming the gels. So for the longer endurance events, over 1-hour I would suggest drinks as opposed to gels be consumed. Gels are advantageous during shorter endurance events, or when training to maintain blood glucose concentrations and provide lower doses of single source glucose for oxidation. I’m not aware of any gel that contains the optimal 2:1 ratio of glucose:fructose, any such formulation is likely to be extremely sweet, sticky, sickly and not suitable for consumption during an endurance event.

In answer to the question, yes, as a triathlete you will require carbohydrate supplementation during exercise. I have provided a recommendation for a product based on the carbohydrate content alone, in the second section I will go on to advise which additional ingredients will be of benefit to your performance and again provide recommended products/strategies.

If you enjoyed this blog post please share it with your friends, and if you have any questions I’m currently running a bi-monthly Q&A blog post where I will answer any of your nutrition related questions in a full blog post, two questions answered each month. So please get in contact with your nutrition related questions!

References:

  1. Gillum, T, L., Dumke, C, L., & Ruby, B, C. (2006). Muscle glycogenolysis and resynthesis in response to a half Ironman triathlon: a case study. International Journal of Sports Physiology & Performance, 1, 408-413.
  2. Noakes, T, D. (2000). Physiological models to understand causes of fatigue and the adaptations that predict or enhance athletic performance. Scandinavian Journal of Medicine & Science in Sports, 10, 123-145.
  3. Phillips, S, M., Green, H, J., Tarnopolsky, M, A., Heigenhauser, G, J., & Grant, S, M. (1996). Progressive effect of endurance training on metabolic adaptations in working skeletal muscle. American Journal of Physiology Endocrinology & Metabolism, 270, 265-272.
  4. Burke, L., & Deakin V. (2006). Clinical Sports Nutrition. (3rd edition). Australia. McGraw-Hill Australia Pty Ltd.
  5. Allen, D, G., Lamb, G, D., & Westerblad, H. (2008). Skeletal muscle fatigue: cellular mechanisms. Physiology Reviews, 88, 287-332.
  6. Temesi, J., Johnson, N., Raymond, J., Burdon, C., & O’Connor, H. (2011). Carbohydrate ingestion during endurance exercise improves performance in adults. Journal of Nutrition, 141, 890 – 897.
  7. Jeukendrup, A, E., Wagenmakers, A, J., Stegen, J, H., Gijsen, A, P., Brouns, F., & Saris, W, H. (1999). Carbohydrate ingestion can completely suppress endogenous glucose production during exercise. American Journal of Physiology, 276, 672-683.
  8. Wright, D, A., Sherman, W, M., & Dernbach, A. (1991). Carbohydrate feedings before, during, or in combination improve cycling endurance performance. Journal of Applied Physiology, 71, 1082–1088.
  9. Jeukendrup, A. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Current Opinion in Clinical Nutrition & Metabolic Care, 13, 452 – 457.
  10. Currell, K., & Jeukendrup, A. (2008). Superior endurance performance with ingestion of multiple transportable carbohydrates. Medicine & Science in Sports & Exercise, 40, 275 – 281.
  11. Jentjens, R., Achten, J., & Jeukendrup, A, E. (2004). High rates of exogenous carbohydrate oxidation from multiple transportable carbohydrates ingested during prolonged exercise. Medicine & Science in Sports & Exercise, 36, 1551-1558.

References:

1. Gillum, T, L., Dumke, C, L., & Ruby, B, C. (2006). Muscle glycogenolysis and resynthesis in response to a half Ironman triathlon: a case study. International Journal of Sports Physiology & Performance, 1, 408-413.
2. Noakes, T, D. (2000). Physiological models to understand causes of fatigue and the adaptations that predict or enhance athletic performance. Scandinavian Journal of Medicine & Science in Sports, 10, 123-145.
3. Phillips, S, M., Green, H, J., Tarnopolsky, M, A., Heigenhauser, G, J., & Grant, S, M. (1996). Progressive effect of endurance training on metabolic adaptations in working skeletal muscle. American Journal of Physiology Endocrinology & Metabolism, 270, 265-272.
4. Burke, L., & Deakin V. (2006). Clinical Sports Nutrition. (3rd edition). Australia. McGraw-Hill Australia Pty Ltd.
5. Allen, D, G., Lamb, G, D., & Westerblad, H. (2008). Skeletal muscle fatigue: cellular mechanisms. Physiology Reviews, 88, 287-332.
6. Temesi, J., Johnson, N., Raymond, J., Burdon, C., & O’Connor, H. (2011). Carbohydrate ingestion during endurance exercise improves performance in adults. Journal of Nutrition, 141, 890 – 897.
7. Jeukendrup, A, E., Wagenmakers, A, J., Stegen, J, H., Gijsen, A, P., Brouns, F., & Saris, W, H. (1999). Carbohydrate ingestion can completely suppress endogenous glucose production during exercise. American Journal of Physiology, 276, 672-683.
8. Wright, D, A., Sherman, W, M., & Dernbach, A. (1991). Carbohydrate feedings before, during, or in combination improve cycling endurance performance. Journal of Applied Physiology, 71, 1082–1088.
9. Jeukendrup, A. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Current Opinion in Clinical Nutrition & Metabolic Care, 13, 452 – 457.
10. Currell, K., & Jeukendrup, A. (2008). Superior endurance performance with ingestion of multiple transportable carbohydrates. Medicine & Science in Sports & Exercise, 40, 275 – 281.
11. Jentjens, R., Achten, J., & Jeukendrup, A, E. (2004). High rates of exogenous carbohydrate oxidation from multiple transportable carbohydrates ingested during prolonged exercise. Medicine & Science in Sports & Exercise, 36, 1551-1558.