Journal Title (Medline/Pubmed accepted abbreviation): Amino Acids
Page Numbers: 555-561
Summary of background and research design:
Background: Taurine is an amino acid that is found in relatively high concentrations in the muscle and brain. Its function is to maintain salt and calcium concentrations and to modulate oxidative stress. It is also a popular supplement in energy drinks. Because many studies evaluate the effect of taurine with other supplements on exercise performance, it is still unclear what effects taurine has alone on muscle function and exercise performance.
Hypothesis: Taurine supplementation will improve speed on a 3-km time trial in middle-distance runners.
Subjects: Eight competitive middle-distance runners, age 19.9 ± 1.2 y.
Experimental design: randomized, double-blind, crossover trial
Taurine- 1,000 mg taurine in a capsule
Placebo- an empty capsule
Protocol: The participants reported to the laboratory twice for two 3-km time trials with one of each of the treatments. The trials were separated by one week. The participants arrived at the laboratory and consumed one of the two treatments (a single, acute administration). After one hour and 45 min, they began a 15 min warm up on a treadmill. They then completed a 3-km time trial on a treadmill set a 0% gradient. They were able to adjust the speed at their will during the trial. They had information regarding their distance covered but not the time elapsed. Respiratory gases, heart rate, and ratings of perceived exertion were collected every 500 m. Finger-prick blood samples were collected for analysis of lactate concentration immediate before and after the time trial.
Summary of research findings:
- With taurine, the runners completed the time trial in 646.6 ± 52.8 sec and without taurine they completed it in 658.5 ± 58.2 sec (p = 0.013). Seven of the eight runners performed better with taurine.
- Relative oxygen uptake, heart rate, and ratings of perceived exertion did not differ between conditions.
- Lactate concentrations did not differ between conditions.
- Magnitude-based inference results conclude that there is a 99.3% chance that taurine was beneficial to performance during the time trial.
Key practice applications: Ingestion of a 1,000 mg (1 g) dose of taurine two hours before running increased performance on a 3-km time trial in competitive athletes. Taurine supplementation did not affect respiratory parameters, heart rate, or blood lactate concentrations, therefore the mechanism by which taurine provides its effects are still unknown.
Limitations: The provision of an empty capsule as the placebo, versus one containing an inert filler (e.g., cellulose) is a limitation to the double-blinding of this study. Although the authors describe that both researchers and subjects “looked away” when the capsules were ingested, it seems probable that subjects could detect a difference between empty and full capsules. Thus, the potential for bias due to placebo effect could still exist.