Targeted nutrition and sport

Fortified food and food supplements were once confined to the chemist’s and the gym but, over the past fifteen years, they have flooded supermarkets and online shopping sites. Supplements specifically designed for competitive athletes  promise faster and more efficient recovery, increased muscle mass with less fat and/or an optimisation of effort. The mysterious names of the relevant molecules proclaim to have powers that appear scientifically proven to the layman : carnitine, creatine, antioxidants, beta-alanine...

Rösti, ugali and calorie feasts

Evidently, American swimming champion Michael Phelps was not a fan of food supplements. As the media reported in 2008, when training he ate 12,000 calories a day, mostly in fats, carbohydrates and sugars. Viktor Röthlin, a recently retired Swiss marathon runner and former European Champion, delighted in eating rösti (fried grated potatoes) the day before a race. Meanwhile, Kenyan rivals still swear by ugali, a sort of porridge made from cornmeal. As any sport enthusiast knows, it helps to eat a plateful of pasta the day before physical activity and to eat the pieces of banana offered during endurance sports. In short, the importance of carbohydrates for physical performance and recovery has now been proven, as have adequate hydration and the need to compensate mineral salts lost in perspiration.

From the laboratory to the agonies of the playing field

Biochemist Jacques  Décombaz’s professional studies focussed on the nutritional physiology of exercise and physical performance. He aimed to measure the value and effectiveness of nutritional intervention on energy metabolism during physical exertion. He is now retired, but continues to write a column on nutrition in a Swiss magazine for fellow runners(1)  and kindly acted as consultant in the preparation of this piece. Décombaz’s articles take us through the rise to fame of intricate molecules in the world of sport over the past twenty years, with accurate descriptions of metabolic mechanisms and of both the objectives and results. 

What remains of all this today? Time has dampened the initial enthusiasm. For example, molecules such as carnitine and creatine have had their heyday, the first for its role in burning fat and the second for speeding up recuperation and improving capacity for exercise. Laboratories have carried out extensive research on the interactions of these molecules with the body during phases of exertion and recovery. However, the chemistry of such interactions has proven more difficult to influence in real life. Carnitine and creatine are molecules that the body produces naturally and supplementing them has not actually enhanced athletic performance (although creatine has proved useful in rehabilitation). Even if creatine intake helps increase muscle mass, it also strongly promotes water retention. Hence, for athletes who want to keep their weight down, ingesting creatine is potentially counter-productive.

What are these droplets of fat for?

Small droplets of fat are also present in muscle fibres and serve a similar function to "handy small fuel cans for a carburettor". Scientists at the Nestlé Research Center(2) have been focussing on these droplets, called intramyocellular lipids (or IMCL) for some time, although their findings have not yet been substantiated. These small droplets are nevertheless very interesting in terms of nutrition and sport, as the muscles of endurance runners are streaked with them. While sedentary people may have fat on their hips, they actually have half as much fat in their muscles as a runner has. Runners need an abundant and regular source of energy and lipids provide them with two times more calories than the same amount of carbohydrates. These are stored as conveniently as possible, i.e. close to where the calories will be burned during prolonged exertion. Researchers imagined that improving runners’ capacity for storing such fat might provide a source of energy over a longer period of time. Yet so far such dietary measures have not influenced performance positively.

Athletes standing, photo serie by Howard Schatz

Wishful thinking or good for your morale?

"Since he stopped eating gluten, Novak Djokovic has become the world’s number one tennis player!" One company is not at all shy about using this slogan to promote the powers of its gluten-free products. Yet, while a gluten-free diet is highly fashionable today, dieticians and doctors tend to remain unheard when they assure people that cutting out gluten is of no benefit to their health unless they suffer from gluten intolerance. We still wish to believe that this regime is our modern-day panacea. Sportsmen and -women in their quest for achievement are no different to common mortals. From time immemorial people have sought to improve their strength, particularly by favouring certain types of food or ingredients. The athletes of antiquity were convinced of the virtues of bull’s meat, pork and mead. Today, such wishful thinking is channelled towards pills, jelly capsules and drinks fortified with vitamins, caffeine, proteins, carbohydrates, minerals and other micronutrients.

Effective or ineffective?

Supplements may, however, be justified in the context of elite sport, where the body is submitted to exceptional physical stress and strain. This is where encouraging results of experiments performed in vitro have the best chance of being applied to the biological component of exercise. It is a question of small individual dietary improvements and/or targeted supplements optimising the “energy machine”, depending on the kind of exertion (duration, strength, repetition...). However, dietary supplements have only modest influence on sporting success, as they account for no more than 1% or perhaps even only for a fraction of a percentage of improved performance. Yet, for someone with the ambition to win, that little extra is part of a whole that, on any given day, could lead to victory and even to a new record.

Simple, practical and easy to digest

It should now be clear that for sport enthusiasts or amateurs “sophisticated” dietary supplements actually have insignificant impact on performance. This is quite simply because such athletes have not yet stabilised their physical skills (muscle strength and resilience, lung capacity...) at a level where targeted food supplements could provide that little something extra which could actually make a difference. For amateur sports, a balanced diet, eating food that is rich in carbohydrates and fats at the right times, adequate hydration and a training strategy that alternates phases of exertion and recovery are all the key to activities that bring both pleasure and progress. Nonetheless, energy bars and sports drinks can be very practical in certain circumstances. Such products are compact, resistant, nutritious, digestible and easy to keep. They therefore provide a great snack for a trek in the mountains, counteract fatigue and reassure sportsmen they are prepared, come what may!

Annika Gil

Jacques Décombaz