What the experts say
Nigel Hetherington reviews some of the research work that has been conducted with a selection of nutritional supplements and stimulant drinks
Whether it is for personal achievement or to meet international demands the height of the bar facing the athlete continues to rise. As a consequence, the search for any means of enhancing performance beyond the dreams of the athlete, yet often only by the slightest of margins prevails. Ergogenic aids, whether they are physiological, nutritional, psychological or mechanical, can enable the athlete to achieve unprecedented levels of performance. The real issue facing the coach and the performer is not if they should employ ergogenic aids but which are actually safe and likely to work for them and which are ethically, morally and legally acceptable?
Opinion and anecdote still count in the world of sports performance enhancement. The reality is that although much research has been published in the relatively young field of Sports Science a great deal still remains untested or, at best, only partly understood. The human body is a highly complex biological system capable of a range of responses to environmental and biochemical changes. Many studies still tend to focus on isolated tests and assume that for a given stimulus all humans respond in the same way. Conclusions are often drawn from a somewhat myopic perspective. Some trials are simply sponsored by a given commercial organization and only results that give the desired result are published - apparently cynical but fundamentally true. The reality is that many parameters can vary at the same time, most of which will be outside of the control of the experimenter. Probably, and not purely by coincidence, too many coaches still feel that a generic program or process will produce the optimum result for all athletes. Clearly this cannot be true. Interestingly however, the experience of a coach working with one individual athlete probably yields a higher level of knowledge of that individual than most short-term scientific studies currently achieve. However, we have to guard against a coach's belief that, for example, the taking of a given supplement or the following of a certain regime was the main reason for the athlete's performance. It may have been that whatever the athlete had eaten or whatever broadly applicable program they followed they would still produced the performance, probably due to a whole combination of factors.
We also have to consider the placebo effect. By this we mean that sometimes we see a response because the athlete knew one was expected. Also, if an experiment is insufficiently 'controlled' then the outcome may not have had any bearing on the stimulus. For example, athletes who are less trained will generally respond better initially to a new stimulus e.g. a specific gain in strength, than their well-conditioned counterparts. So, unless all our athletes are exactly matched we are on an uneven playing field from the outset.
Only the conducting of good science and a history of reproducible findings under well controlled conditions will truly light the way for the predictable use of some ergogenic aids and draw to a close the lack of clarity that often prevails between fallacy and fact.
Differentiating between what is smart and will produce a 'short-cut' to success for the athlete and what is quite simply dodgy and may carry unacceptable risks is not necessarily clear-cut. From the perspective of many nutritional and physiological ergogenic aids, though the World Anti-Doping Agency (WADA) now has responsibility for banned substances and processes, there still exist means by which an athlete can harm themselves with everyday substances and processes that cannot be legislated for. For example, the taking of a supplement not requiring the determination of all constituents by the manufacturer could and has been proven to contain banned or potentially harmful substances. The belief that if a little of something is good then even more must be better still prevails which can lead to the stressing of the system and undesirable side-effects. A continued growth in education in these areas is essential for all in sport to ensure that good experience is gained.
Fluid intake can impact on performance in many ways including maintenance of a good water balance to support effective heat loss, intra-cellular function (a loss of around 1 litre of water can lead to a significant loss in performance of up to 5% - imagine what that might mean to your athlete's performance in the marathon or during extra-time in a field game?), as a medium for carrying other critical functional substances including sodium (see below) and an energy source such as simple carbohydrates. Finally, fluid intake can be used as the means of delivery for a whole array of other ergogenic substances.
Caffeine, a substance with potential stimulant activity, was removed from the WADA list of banned substances at the beginning of 2004. This will probably cause a review of ergogenic research findings on this substance. A recent paper from Ireland investigated commercial stimulant drinks and reviewed both the reported activity of caffeine by itself as well as in products containing combined stimulants. Though the results of the review are very broad and in many cases inconclusive regarding specific stimulant activity several recommendations relevant to possible consumption by athletes were made. Stimulant drinks:
This opens the debate to all manner of sports drinks and nutritional aids which all have to be considered on the basis of what is normal and how the body will react. Starting at the simplest level - the body's need for water replenishment - is where isotonic drinks come in. The background here is covered in an article highlighting the trade-off situation between too little and too much fluid depending on the demands of the activity and environmental conditions - e.g. ambient temperature. A general guideline is to replace fluids at the same rate at which they are being lost - typically 500 to 800ml/h is recommended - 'half a pint every half hour'. These fluids should ideally contain carbohydrate for energy replenishment at the rate of 30-60g of rapidly absorbed carbohydrate per hour of exercise and sodium (for activities lasting over 2 hours).
A Swiss study investigated regimes for sodium replacement in women during prolonged exercise, 4 hour runs in different weather conditions, and reported that hyponatremia is likely to develop from fluid overload but that this effect can be minimized by the taking of at least 680mg/h. Hyponatremia[4,5] (from 'hypo' - low, 'natrium' - sodium), which occurs when blood sodium levels fall abnormally low, is a relatively rare condition but has claimed the lives of marathon runners for example. The effect is to cause swelling of the brain resulting in seizures, coma and death. The condition can be brought on by excessive drinking of hypotonic fluids e.g. water, or prolonged exercise leading to excessive sodium loss.
During short duration, high intensity exercise water and electrolyte balance are less of a factor on performance than with endurance activities assuming they are optimized initially. A more critical factor is the generation of excess hydrogen ions in the blood by muscle from the anaerobic lactic energy pathway whereby carbohydrate is converted into energy without the need for oxygen - anaerobic glycolysis. If sufficiently intense this can lead to a loss of buffering capacity of the blood and ultimately a localized increase in blood pH in muscle tissue. This is a very uncomfortable situation for the body and leads to a rapid loss in performance characterized by the sensation of 'jelly legs' and often short-term muscular pain and nausea.
Reviews looking at buffering the system through the ingestion of bicarbonate[6,7] indicate that athletes involved in high intensity exercise for longer than 45 seconds and up to 10 minutes can benefit significantly. Several reports provide findings indicating that 800 metres and 400 metre runners can reduce their times by up to 2% from a single ingestion of bicarbonate - equivalent to a distance of 10 metres at the finish! Dosing is broadly recommended at between 0.3 to 0.4g/kg of body weight equivalent to 21 to 28g for a 70kg person, taken in 500ml of fluid one hour before exercise.
Another blood pH buffer candidate is sodium citrate. One report extended the effects of buffer ingestion in the form of citrate to a 30km cycling performance and found 3% improvements. This has recently been backed up by a study looking at 5km College runners in Estonia. The report concluded that citrate administration (0.5g/kg body mass taken in 1 litre of water 2 hours before the trials) improved performance by an average of 30 second (~2.5%) in run times averaging around 19 minutes.
The taking of nutritional supplements as ergogenic aids has grown in recent years. A recent study in Norway looked at what factors influenced the decision of athletes to take supplements. This involved over 1600 elite athletes (male and female) from all sports and a similar number of randomly selected individuals from the general population. A completed questionnaire with a response rate above 75% was received from all sectors. The most interesting outcome was that over 50% of elite athletes, male and female, stated that their coach was the main advisor for use of such supplements which included vitamins, minerals, Omega 3, antioxidants, ginseng, amino acids, creatine and energy supplements. Clearly this argues the case for coaches needing to be fully conversant with nutritional supplements, their effects and their legality.
Creatine supplementation has received extensive coverage in the last few years. A recent review of over 500 scientific publications provides us with some convincing arguments in favour of the ergogenic benefits. For example, about 70% of these papers report statistically significant results supporting performance enhancement as characterized through one of: a 5 to 15% increase in maximum power/strength; the same figures for work performed during maximal effort muscle contractions; a 1 to 5% improvement in a single-effort sprint and a 5 to 15% workload increase during repetitive sprints. Although not all reports conclude with positives, none report negatives in terms of performance outcomes. Coaches and athletes still have to make their own decisions but these findings appear to be conclusive at this stage and meet the criteria set out at the start of this article.
Creatine is not a universal panacea and, despite the fact that it has been shown to augment training induced strength gains, it gave no benefit to individuals recovering from anterior cruciate ligament reconstruction (based on 60 patients) over the first 12 weeks. The study involved measurement of knee extension / flexion, hip flexion and hip abduction / adduction against placebo treated patients and in comparison to measurements taken before surgical treatment. Even up to 6 months afterwards creatine showed no measurable benefit in a single leg hop comparison.
Amino acids and related substances have also been subjected to broad research for ergogenic activity. A recent study supports the benefits of a Glycine-Arganine complex (GAKIC) for reducing the decline in mean power output during a series of 5 supra-maximal cycle sprints lasting 10 seconds with 1 minute recoveries.
Finally, a recent study in healthy individuals failed to substantiate the ergogenic effects claimed for ginseng. Evidence does, however, exist to support the potential benefits of ginseng on the immune system. Children and pregnant / lactating women should not take ginseng.
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About the Author
Nigel Hetherington was the Head Track & Field Coach at the internationally acclaimed Singapore Sports School. He is a former National Performance Development Manager for Scottish Athletics and National Sprints Coach for Wales. Qualified and highly active as a British Athletics level 4 performance coach in all events he has coached athletes to National and International honours in sprints, hurdles as well as a World Record holder in the Paralympic shot. He has 10 years experience as senior coach educator and assessor trainer on behalf of British Athletics. Nigel is also an experienced athlete in sprint (World Masters Championship level) and endurance (3-hour marathon runner plus completed the 24 hour 'Bob Graham Round' ultra-endurance event up and down 42 mountain peaks in the English Lake District). He is a chartered chemist with 26 years' experience in scientific research and publishing.
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