to Enhance Performance
L R Mc Naughton, B. Dalton, J. Tarr, D. Buck
Affiliations: L.R. Mc Naughton,
PhD, B. Dalton, J. Tarr, D. Buck, Center for Human Movement, University
of Tasmania at Launceston, Tasmania, Australia
Acknowledgments: Will G. Hopkins (reviewer), Jeffrey A. Potteiger (reviewer), Mary Ann Wallace (editing)
Correspondence: L.McNaughton=AT=utas.edu.au (L.R. Mc Naughton)
Reference: Mc Naughton, L. R., Dalton, B., Tarr, J., Buck, D. (1997). Neutralize acid to enhance performance. Sportscience Training & Technology http://www.sportsci.org/traintech/buffer/lrm.htm
Date: Sept 1997
Summary. Sodium bicarbonate and sodium citrate enhance performance when consumed before high-intensity events. A gain of 1-2% is possible in events lasting a few minutes, and similar gains are likely in events of up to an hour. The substances work by helping to neutralize the acid produced by active muscles. Effective doses (20-30 gm) can make you you vomit or give you diarrhea. Use of the substances for competition may be illegal.
During high-intensity exercise, muscles keep up with the demand for energy by converting some carbohydrate to lactic acid. A build-up of acid inside the muscle cells is one of the factors responsible for fatigue. Reducing the build-up of acid should reduce fatigue and allow the athlete to go faster or further.
The body's defenses against an increase in acidity are the bicarbonate, phosphate, and protein "buffers", which help to neutralize the acid produced by intense exercise. Attempts to enhance performance by increasing the effectiveness of the buffers have focused mainly on bicarbonate. Taking a sufficient quantity of sodium bicarbonate (baking soda) before high-intensity event should make the muscles and blood less acidic during the event and should enhance physical performance. Sodium citrate is another substance that should enhance performance by buffering the acidity of intense exercise. Here we give a brief review of research on the effects of bicarbonate and citrate on the performance of athletes.
Over 30 studies of bicarbonate or citrate "loading" have been published--too many to review here. We describe three of these studies to illustrate the research (including one performed in our laboratory), and give a digest of five recent reviews.
Effect on Performance
Interest in the effects of buffers on performance began to pick up with publication of the work of Jones et al. (1977). Their study involved five male athletes who acted as their own controls, performing cycle ergometry after ingestion of calcium carbonate (a placebo), ammonium chloride (to increase acidity in the tissues to see if performance got worse), or sodium bicarbonate (to see if performance got better). The exercise protocol consisted of 40 minutes of exercise at low to moderate intensity, followed by exercise to exhaustion at high intensity (95% of maximum oxygen uptake). In the bicarbonate condition, exhaustion time was approximately twice that of the placebo, while in the acidic condition it was about half that of the placebo.
A number of studies in the early 1980s suggested that ingestion of sodium bicarbonate could be effective in improving short-term exercise performance. For example, Wilkes et al. (1983) compared the effects of sodium bicarbonate and control treatments (no treatment, and an inert placebo) in six competitive 800-m runners. The bicarbonate was given over a two-hour period at a dose equivalent to 21 gm for a 70-kg person (0.3 g per kg of body weight). For each of the three conditions, the athletes completed a competitive 800-m race. Average performance was 2% faster in the bicarbonate condition than in the control or placebo conditions.
In a similar study, but using a higher dose of sodium bicarbonate (0.4 g/kg, or 28 gm for a 70-kg person), Goldfinch et al. (l988) investigated the 400-m race performance of six trained runners. Athletes competed in pairs to simulate real competition. The performance of the bicarbonate group was 2% better than the control and placebo, which were not different from each other. The time difference was equivalent to a 10-m distance at the finish.
Reviews of these and many other studies support the idea that performance of short-term exercise can be enhanced by reducing the level of acidity. In a review of 29 studies of the effects of ingestion of sodium bicarbonate, Matson and Vu Tran (1993) concluded that the effect on performance varied between athletes, but that the greater the dosage and the shorter the exercise, the more likely that bicarbonate buffering would enhance performance. Maughan and Greenhaff (1991) concluded that ingestion of sodium bicarbonate can enhance performance of high intensity exercise lasting 1-10 minutes. Lindermann and Fahey (1991), Williams (1992), and Lindermann and Gosselink (1994) concluded that sodium bicarbonate can produce a significant ergogenic effect in maximal exercise lasting between 1 and 7 min. All these reviewers indicated that effective dosages for sodium bicarbonate were in the range 0.3-0.4 g/kg, or 21-28 gm for a 70-kg person.
Bicarbonate or citrate are not usually thought of as potential ergogenic aids for endurance events, because muscles accumulate less lactic acid in these events. However, Potteiger et al. (1996) recently tested the effect of sodium citrate on 30-km cycling performance. Performance times averaged almost 3% faster than those in the placebo condition. The effects of ingestion of citrate or bicarbonate on other endurance events now need to be determined.
The International Olympic Committee (IOC) does not explicitly ban the use of sodium bicarbonate sodium citrate, or other buffering agents. However, their use may be considered a violation of the IOC Doping Rule, which states that athletes shall not use any physiological substance in an attempt to artificially enhance performance. In horse racing, where the use of buffering agents is banned, limits have been set on the concentration of bicarbonate in blood samples taken before races. We believe it would be possible to set up a similar system to screen for the use of buffers by human athletes.
Athletes wishing to use these substances should try them first in training and then use them only for short-term, high intensity competitions. Dosages should be 20-30 gm (0.3-0.4 g per kg of body weight), taken with large quantities (0.5 L or greater) of water. Athletes in most studies have taken the substance between 60 and 90 minutes prior to exercise.
Likely side effects are gastrointestinal upsets such as vomiting and diarrhea (Mc Naughton, 1992). Frequent use could lead to cardiac arrhythmias, apathy, irritability and muscle spasms (Heigenhauser and Jones, 1991). Gastric ruptures have also been reported (Downs and Stonebridge,1989).
Sodium bicarbonate and sodium citrate seem to be effective in improving short-term, high intensity performance. There are sufficient data to suggest that buffering agents can improve performances in such events as the 400-m sprint, 1-km cycling time trial, and Olympic rowing. There are not enough data to make recommendations with regard to longer events.
Continued use of bicarbonate or citrate may help athletes become less susceptible to the side effects and may give even larger improvements in performance. The time course of the ergogenic effect of a single dose of these substances is uncertain. The longest duration of endurance exercise that benefits from their use needs to be determined. The best regimen of buffer use for endurance exercise (e.g., single bolus vs intermittent) is also an interesting question.
Downs, N., & Stonebridge, P. (1989). Gastric rupture due to excessive sodium bicarbonate ingestion. Scottish Medical Journal 34, 534-535.
Goldfinch, J., Mc Naughton, L.R., & Davies, P. (1988). Bicarbonate ingestion and its effects upon 400-m racing time. European Journal of Applied Physiology and Occupational Physiology, 57, 45-48.
Heigenhauser, G. & Jones, N.L. (1991) Bicarbonate loading. In D. Lamb & M. Williams (Eds.) Ergogenics:enhancement of performance in exercise and sport. (pp.183-212). Dubuque, Iowa: Brown & Benchmark.
Jones, N., Sutton, J.R., Taylor, R., & Toews, C.J. (1977). Effect of pH on cardiorespiratory and metabolic responses to exercise. Journal of Applied Physiology, 43, 959-964.
Lindermann, J.K., & Fahey, T.D. (1991). Sodium bicarbonate ingestion and exercise performance: An update. Sports Medicine, 11, 71-77.
Lindermann, J.K., & Gosselink, K.L. (1994). The effects of sodium bicarbonate ingestion on exercise performance, Sports Medicine, 18, 75-80.
Matson, L.G. and Vu Tran, Z. (1993). Effects of sodium bicarbonate ingestion on anaerobic performance: a meta-analytic review, International Journal of Sports Nutrition 3:2-28.
Maughan, R.J., & Greenhaff, P.L. (1991). High intensity exercise performance and acid-base balance: The influence of diet and induced metabolic alkalosis. In F. Brouns (Ed.). Advances in Nutrition and Top Sport (pp. 147-165). Basel:Karger.
Mc Naughton, L.R. (1992). Bicarbonate ingestion: Effects of dosage on 60s cycle ergometry. Journal of Sports Sciences, 10, 415-423.
Potteiger, J.A., Nickel, G.L., Webster, M.J., Haub, M.D., & Palmer, R.J. (1996). Sodium citrate ingestion enhances 30-km cycling performance. International Journal of Sports Medicine, 17, 7-11.
Wilkes, D., Gledhill, N., & Smyth, R. (1983). Effect of acute induced metabolic alkalosis on 800-m racing time, Medicine and Science in Sports and Exercise, 15, 277-280.
Williams, M.H. (1992). Bicarbonate loading, Gatorade
Sports Science Exchange, 4(36).
Will G Hopkins PhD
Senior Lecturer, University of Otago, Dunedin NZ; member of the Sportscience website team.
I agree with the recommendations for athletes competing in events lasting under 10 minutes. The gain in performance--one or two percent--will definitely enhance the medal prospects of athletes at the top end of the field. The gain is similar to that seen with a good taper; so when the stakes are high, athletes should be as serious about supplementing with bicarbonate or citrate as they are about getting their taper right.
I think the authors are too conservative with their advice for athletes competing in longer events. The work of Potteiger et al. is clear cut and implies gains of similar or even slightly greater magnitude for events of up to an hour in duration. I find this result particularly exciting, because it sheds light on the mystery of what limits performance in such events. I wouldn't be surprised if the same limitation applies in even longer events, provided the athlete doesn't run short of fuel. Exactly how acidity stops us going faster in endurance events is the next question to answer.
With top level performers looking to acquire an edge to enhance performance the use of sodium bicarbonate or sodium citrate is tempting. When consumed under the right timing and dosage conditions, the use of these substances can improve performance by 1-3%. This could make a difference between finishing first and finishing out of the "money".
Since aerobic athletes work at intensities at or above the lactate threshold during competition, the use of bicarbonate or citrate loading may facilitate lactate efflux from tissues, thereby making the intramuscular pH more favorable for contraction. Further work in the role of pH on lactate efflux from working tissues is clearly warranted.