NHD Issue 149 Sports nutrition

COVER STORY

SPORTS NUTRITION

Sports Nutrition is thought to be the foundation of athletic success, in achieving fitness goals and optimising performance, training and physique. Here, Farihah looks at how sports nutrition can differ from everyday basic nutrition needs.

Back in March, I looked at the pitfalls of overhydration in marathon runners and other sportspeople, exercise-associated hyponatremia (EAH), as well as discussed the physical conditions which require sports drinks to be taken.14 The niche of sports nutrition has arguably blown up in recent years, with ‘health and wellness’ bloggers cropping up on every corner of social media. Suddenly, there is protein added to everything (so it must be healthy…) and ‘macros’ are tracked with military discipline by zealous gym-goers. But, what do sportspeople and athletes really need to be mindful of and how does their dietary management differ from day-today nutrition?

ENERGY OUT, ENERGY IN . . .

Although sports nutrition is a vital consideration for athletes in order to optimise performance in a certain sport, a good chunk of the population would agree that their own fitness goals are often to lose weight or get a bit fitter, whether this is for health or aesthetic reasons. The epitome of exercise and weight loss is the energy deficit equation.1 Though there are a myriad of factors influencing a person’s ability to gain and lose weight, in the simplest terms, it boils down to one formula: to expend more energy than you gain. This could either be achieved via exercising and burning more calories than you are

Farihah Choudhury Masters Student, London School of Hygiene and Tropical Medicine

eating, or by eating fewer calories than you would do typically, so that your body metabolises your store of fat for energy. A combination of diet change and regular physical activity is most sustainable for long-term health, not just for weight loss or gain.2 Undoubtedly, weight loss and healthfulness are strongly individual and what works specifically for one person will rarely work for another.

So, whilst energy deficit equations are a good way for an individual to understand the ultimate process of weight loss, the complexities around it for each individual need to be addressed fundamentally when working out exercise and diet plans.

Unless you are actively trying to lose weight, when you are performing vigorous exercise, it is vital to re-energise correctly and replace lost energy and fluids, otherwise you risk losing weight unwillingly. In athletes, Relative Energy Deficiency in Sports (RED-S) is characterised by excessive exercise and/ or insufficient caloric intake, which can, in turn, affect physiological processes, metabolism, mental health, bone health and more.3

Farihah is taking a MSc in Nutrition for Global Health.

She is interested in public health nutrition, in particular lifestyle disease, including obesity as a product of changing food environments, food sustainability and food culture & anthropology.

REFERENCES Please visit: https://www. nhdmag.com/ references.html

CARB-LOADING

Many people will be familiar with the concept of ‘carb-loading’ prior to www.NHDmag.com November 2019 - Issue 149

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COVER STORY exercising, whether this be a half marathon or a weights session at the gym. Carbohydrates are metabolised as glycogen in the muscles and liver and will provide gradual energy release to fuel energy exertion when performing physical exercise. Carbohydrates are mobilised by the body first and glycogen stores are limited, so it is important to replenish this store prior to exercise.4 Higher carbohydrate intake is more important to those who partake in endurance exercise, such as long-distance running and football.

Though there may be different motivations, some people opt to exercise fasted, whilst others like to eat before exercising, particularly if exercising first thing in the morning. If the fitness goal is weight loss, there is some evidence to suggest that exercising in the fasted state encourages the body to metabolise fat as fuel, but there is no conclusive evidence to confirm this.5 Others may choose not to eat before going to the gym, simply because of time constraints or personal preference.

PROTEIN-PACKED SNACKS

Adequate protein consumption is vital for muscle repair and growth following exercise.

It is recommended that on average, adults in the UK should consume 0.75g of protein for every kilogram of bodyweight per day.4 This may fluctuate slightly depending on how much physical exercise you do. But how much protein is too much protein?

A bizarre offshoot of the health and wellness industry dominating the First World is the marketing ploy of adding protein to typically non-protein yielding foods, such as chocolate bars or crisps, or pointedly signalling consumers to protein that already largely constitutes that food product, eg, in a packet of beef jerky. Part of this stems from a villainisation or misunderstanding of carbohydrates and fats – the trust in these two macronutrients fluctuates depending on which fitness influencer, celebrity or animal study is in vogue at the time. Ergo, we are left with protein, which is generally seen as ‘clean’ and unproblematic and, thus, it is ‘healthy’.

Part of this, of course, comes from a basic understanding that excess protein is not stored 12

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in the body so cannot contribute to unhealthy weight gain.

Alongside protein-fortified snacks, protein powder supplements have also been getting plenty of press in recent years, though mostly this is unnecessary; people in the UK consume more protein in their diets than the recommended guideline daily amount.4 Protein shakes can be useful, however, as a quick source of protein to ingest during and after exercising to aid muscle tissue repair and regeneration. They are sometimes used as meal replacements too, for those who are unable to ingest solid food. Food products specifically claiming to enhance sporting performance and promote athletic physique must be approached with caution, however, as this industry is generally unregulated.

PROTEIN DEFICIENCY AND EXCESS

Protein deficiency is extremely uncommon in developed countries, and it is a myth that there is not enough bioavailable protein in vegan and vegetarian diets, as the body is capable of taking incomplete amino acids and making them ‘complete’ via the amino acid recycling mechanism.6 The most severe type of protein deficiency is called kwashiorkor, and is prevalent in countries affected by war and famine.

Even for those looking to build or maintain muscle, though it is important to maintain adequate protein intake to allow for growth and repair of muscle, excess protein intake is mobilised by the body into energy and will not contribute to further muscle growth. 20g of high-quality protein has been shown to be the optimum protein intake for muscle protein synthesis following exercise.4 Plant-based protein and animal-based protein is absorbed differentially by the gut, which can affect net protein intake. Animal protein is generally easier to absorb than plant protein for humans, though this does not pose a compromising issue for those on a plant-based diet, as is demonstrated by vegan bodybuilders!7 After a certain point, excess protein cannot be used for muscle growth and repair and, instead, is used as energy. Excessive protein intake has been linked to renal issues and

COVER STORY

Chemically, sports drinks are fortified with electrolytes and sugar to replace lost electrolytes and to top up energy, at the same time keeping the drinker hydrated.

heightened cancer risk, but a systematic review by Pedersen et al on the effects of excess protein intake has shown that evidence for this relationship is inconclusive.8 There is a clear gap in the literature regarding overconsumption of protein.

Apparently, for optimal muscle tissue repair and subsequent muscle growth, protein should be consumed within the hour following exercise.9,10 This narrow post-workout anabolic window has been brought into question, however, so this recommendation should be taken with a pinch of salt.11 It has been suggested that this ‘window of opportunity’ may span longer than just an hour and, again, this may be different for each individual.

SPORTS DRINKS

Around a decade ago, there was a sports drinks craze whereby drinks such as Lucozade and Gatorade were esteemed as the optimal drink for athletes, as well as for the average citizen.

Chemically, sports drinks are fortified with electrolytes and sugar to replace lost electrolytes and to top up energy, at the same time keeping the drinker hydrated. Left unchecked, lost electrolytes can lead to mild or serious hyponatremia (low sodium/water

poisoning). However, it has been suggested that only those who exercise for 90 minutes or more consecutively, and/or are drinking excessive amounts of water, need to consider taking sports drinks.12 It has been estimated that 1/6th of marathon runners develop mild hyponatremia,13 which can be remedied by drinking sports beverages, or marginally reducing the amount of water ingested.

SUMMARY

Sports nutrition is a complex niche, where exercise goals are very much driven by the individual’s motivations for exercise and their dispositions to weight loss, muscle gain and several other factors. Nutrition in sports differs from day-to-day nutrition to optimise the outcomes of fitness goals and so, to really maximise performance, diet is key, alongside picking exercise regimes that work for each individual.

Sports dietitians and personal trainers can collaborate in this respect, to formulate complementary diet and exercise plans to help individuals achieve their goals. On a public health level too, dietitians can help to inform exercise recommendations for the general population. www.NHDmag.com November 2019 - Issue 149

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