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Caffeine In Sports Performance

by Patrick Traylor

Caffeine has long been considered as a substance capable of enhancing physiological function (Jacobson 1987). As a result of its reported ergogenic effect, the IOC has banned the use of high levels of caffeine. At that time 15 mg ml-1 in urine was considered too much, this would be the equivalent to 5-6 cups of coffee in 1-2h time period (Jacobson, 1989). Caffeine is a trimethylxanthine compound that is not produced by the human body and therefore athletes take caffeine supplements in order to enhance their ability. I will look at a few studies proving that caffeine has a positive effect of exercise ability and also try to give a few reasons why caffeine may do this.

Wiles (1992) conducted a study with 32 subjects all of whom were middle distance runners or county or national level. The results showed that after the ingestion of caffeine the average 1500m times decreased by 4.2s in comparison to a decaffeinated drink (P<0.005). Also statistically significant increases in running speed were observed after the ingestion of caffeine. The mean increase was 0.6kmh-1 which over a period of 1min would correspond to a distance of 10m. VO2 data also showed a higher VO2 value during the caffeine-induced run in comparison to the run without caffeine (P<0.025). Total work performed during caffeine trails averaged 277.8±26.1kJ whereas the mean total work during the placebo trial was 246.7±21.5kJ (P<0.05) (Cole, 1996).

The evidence for beneficial effects of caffeine on performance seems strong, and this is usually attributed to its stimulation of adrenaline release which increases mobilization of fatty acids, this resulting in a glycogen sparing effect (Graham, 2001). This is countered by Raguso et al (1996) who stated that theophyllin, structurally and pharmacologically similar to caffeine, failed to alter either the rate of appearance or disappearance of FFA’s or glycerol. There have been a few studies done on caffeine’s on PRE and how it decreases it with the ingestion of caffeine (Doherty, 2005., Hudson et al. 2008). Graham (2001) proposed that this could be due to stimulatory effects on the brain by an action on adenosine receptors. This increases mental arousal and modifies the perception of effort and therefore could allow the increase of exercise duration and intensity.

Wiles (1992) showed that ingestion of 3g of caffeinated coffee could enhance oxygen uptake and running performance in sustained high-intensity exercise. These results are backed up buy numerous studies (Costill, 1993., Jacobson, 1987). The method of how it enhances the physiological system is still unclear and needs more research done on it in order to provide a clear-cut definition.

References

Cole, K.J., Costill, D.L., Starling, R.D., Goodpaster, B.H., Trappe, S.W., Fink, W.J. (1996). Effect of caffeine ingestion on perception of effort and sunsequent work production. Int J Sport Nutr. 6.1, 14-23.

Costill, D.L., Dalsky, G.P., Fink, W.J. (1978). Effects of caffeine ingestion on metabolism and exercise performance. Med Sci Sports.10, 155-8.

Doherty, M., Smith, P.M. (2005). Effects of caffeine ingestion on rating of perceived exertion during and after exercise: a meta-analysis. Scand J Med Sci Sports. 15.2, 69-78.

Graham, T.E. (2001). Caffeine, coffee and ephedrine: impact on exercise performance and metabolism. Can J Appl Physiol. 26, 103–109.

Hudson, G.M., Green, J.M., Bishop, P.A., Richardson, M.T. (2008). Effects of caffeine and aspirin on light resistance training performance, perceived exertion, and pain perception. J Strenght Cond Res. 22.6, 1950-7.

Jacobson, B.H. (1987). Caffeine - effect on health and athletic performance. Excel. 4, 14-15.

Jacobson, B.H., Kulling, F.A. (1989). Health and ergogenic effects of caffeine. Br J Sports Med. 23, 34-40.

Raguso, C.A., Coggan, A.R., Sidossis, L.S. (1996). Effect of theophylline on substrate metabolism during exercise. Metabolism. 45.9, 1153-60.

Wiles, J.D., Bird, S.R., Hopkins, J. (1992). Effect of caffeinated coffee on running speed, respiratory factors, blood lactate and perceived exertion during 1500m treadmill running. Br J Sports Med. 26, 116-120.