It has been my experience that a high proportion of both recreational and competitive athletes who take nutritional supplements do so on recommendation by a friend or because they believe their particular product(s) are used (and by implication endorsed) by particular ³lite athletes. Most have little or no real understanding of the true role or potential benefits of nutritional supplements in an athlete’s diet, which makes their use a fairly meaningless gesture. What I hope to achieve with this article is to encourage sportsmen and women to think more carefully about nutritional and other forms of supplement before using them.
To offer any real benefits to performance, supplements need to be used appropriately in support of exercise training. Your nutritional strategy should be planned in detail as part of your overall training programme in order to maximise performance gains at each stage of the programme. The following questions should be answered as part of the planning stage:
l. What do I want to achieve during this training cycle/programme?
2. Is a supplement actually needed – or is my diet adequate for my training needs?
3. What form should that supplement take (ie solid or fluid)?
4. If using an ergogenic aid, what role does this compound play in my body – and will it actually help me achieve my aim?
5. What does the available literature say about the benefits and adverse affects of my chosen supplement?
Whatever your sporting activity or training goal, every training plan should have a long-term aim. And your training plan should include lesser short-term goals, each designed to bring you closer to the peak of your physical capacity. Each of these short-term goals may involve specific forms of training, because modern athletes need a variety of skills within their arsenal to be competitive and to cope with the high physical demands of competition. Most training programmes will involve varying degrees of strength, speed and endurance, although the relative importance of each will depend on the chosen sport. Once your various objectives have been set in place and the overall training plan formulated, you can begin designing the nutritional strategies to support that training.
Designing your nutritional strategy
This process required careful consideration in order to maximise potential improvements in performance. An obvious starting point is to take a close look at your regular diet and consider how well its nutritional content meets the demands of current and planned training loads. It is well known that athletes need higher-than-average amounts of nutrients like carbohydrate and protein. But if your current dietary intake is adequate to support your training, there is no point in taking supplements, since taking in more nutrients than you need will not improve your performance.
How do you assess the adequacy of your diet? One way is to record all the foods and fluids you consume over a typical 24-hour period in a food diary and estimate the amount of carbohydrate, protein and fat included. Nutritional information labels used for most foods give a reasonable indication of their carbohydrate, protein and fat content. The table overleaf presents an example of such a record.
The next step is to compare your actual intake of each nutrient with the recommended level for an athlete in training. Carbohydrate needs, for example, can range from 5g/perkg body weight for moderate training up to 10g/perkg body weight for more intensive training, while protein requirements range from 1.2-1.7g/perkg body weight(1). Thus the typical daily diet of the ‘athlete’ in the table would probably need to be supplemented by extra carbohydrate and protein. However, because there will probably be significant day-to-day, week-to-week and month-to-month variation in nutrient requirements, your intake will need to be constantly monitored and adjusted to match variations in training load. Armed with the information derived from such exercises, you can plan an overall nutritional strategy that is precisely tailored to your individual needs.
What about ergogenic aids?
Having focused thus far on traditional nutritional supplements, what about the more complex – and controversial – issue of ergogenic aids? What if you are considering using a supplement like creatine, which research has shown can aid performance in certain sports. Again, it is important to be clear about why you are thinking of using such a compound, what role it plays in the body, what current research has to say about its performance benefits, what are the potential adverse effects and, finally, how its use might help you towards your long-term goal. Let’s take these questions one by one.
First, what does creatine do? Creatine, in the form of phosphocreatine, is one of the elements involved in the production of adenosine triphosphate (ATP) – the compound controlling the release of energy in the body. Phosphocreatine has a number of roles to play in energy metabolism during exercise: first it acts to buffer changes in levels of muscle ATP as the body moves between rest and exercise or from moderate to more intensive exercise; secondly, during more intense exercise it helps supply ATP to the working muscles; thirdly, it helps to control pH levels in exercising muscles. The store of phosphocreatine within the muscle is relatively small, so during high-intensity exercise there is only enough to support ATP production for a few seconds (1).
How does creatine benefit performance? The vast majority of research points to the conclusion that supplementation with creatine may enhance performance in activities involving short bouts of high-intensity exercise – especially those of a repetitive nature. Boosting muscle phosphocreatine by means of supplementation has been shown to improve sprint-based performance in such activities as swimming, running and cycling. Benefits have also been reported for resistance exercise (2). Once you know how creatine might – and cannot – help, you can decide whether it would be helpful to support your particular training goal.
Does supplementation lead to side effects? There are some reports of adverse effects, including fatigue, vomiting, diarrhoea, stomach cramps and anxiety. But much of the evidence for these effects is anecdotal and, as yet, there is no proof that they are actually caused by taking creatine. The fact is that many compounds that occur naturally in the body are derived from the food we eat. Some are important to help the body perform at its best but can cause harm if taken in excess. The fact that the use of creatine is so widespread, with no proven side effects associated with its use, should provide some reassurance. Until proven otherwise, creatine should be considered safe – providing it is used correctly (3).
In summary, then, my main message is that you should think carefully before embarking on any programme of dietary supplementation. Be clear about what you are aiming to achieve, how you need to supplement your diet and which particular supplements are best suited to the task. Then incorporate the chosen supplement(s) carefully into your training plan in order to maximise the potential benefits to your performance. It is usually a mistake to take a supplement simply because someone else has said it worked for them. All athletes are different, with differing responses to training and therefore differing nutritional needs.
1. Medicine & Science in Sport & Exercise, vol 32, pp 706-717, 2000
2. Foods Nutrition and Sports Performance, pp 36-79, 1999
3. Sports Medicine, vol 30, pp 155-170