The Effects of Caffeine on Run Time to Exhaustion and Maximal Accumulated Oxygen Deficit in Middle Distance Track and Field Athletes.

Abstract

The Purpose of the present study was to investigate the effects of oral caffeine ingestion on Maximal Accumulated Oxygen Deficit (MAOD) and run time to exhaustion (Tlim) during short-term, high-intensity exercise in well trained middle distance runners. Seven athletes (five males and two females) performed a preliminary test and two supra-maximal runs to exhaustion. VO2max was established so that the supra-maximal tests could be performed at an exercise intensity equivalent to 115% VO2max. Caffeine (3.5 mg·kg-1) in the form of commercially available energy gels or placebo was administered 60-min prior to the start of the supra-maximal tests using a single blind, counterbalanced design. On average participants had a longer Tlim (143.4 ±39.2 vs 135 ±41.5 s) and a greater MAOD (4.2 ±1.9 vs 3.8 ±2.1 L•O2 Equivalent) but a lower Peak RER (1.25 ±0.09 vs 1.3 ±0.08) during the caffeine compared to the placebo condition, though none of these differences were statistically significant. Linear regression and Pearson’s correlation demonstrated that a strong positive correlation existed between MAOD and Tlim, suggesting that caffeine can have small ergogenic effects on performance and anaerobic capacity. The fact that results failed to show significant changes is likely to be related to the small sample size and the degree of between-subject variation. In conclusion, caffeine appears to have ergogenic properties when used by trained athletes to enhance short-term high-intensity running, generating a possible case for the World Anti Doping Agency (WADA) to amend the legal status of the drug. However, additional research is needed to further establish the ergogenic effects of caffeine on middle distance performance. It may also be beneficial to look at the effects of caffeine on time trial performance to give results more ecological validity and on VO2 kinetics to help explain improvements in anaerobic power and capacity.