Abstract
BACKGROUND: γ-aminobutyric acid (GABA), a common ingredient in sports supplements and other health products, regulates body temperature in the preoptic area and anterior hypothalamus (PO/AH). To date, no study has examined the effect of GABA on thermoregulation during exercise in humans in a cold temperature environment (11 ± 0.3°C, 45% ± 2% relative humidity). METHODS: We performed a randomized, double-blind study. Ten trained male athletes consumed either a drink (3 ml/kg weight) containing GABA (1,000 mg, trial G) or an equivalent amount of placebo drink (trial C) before exercise. They rested for 20 min and then cycled at 60% of maximum output power for 40 min, pedaling at 60 rpm, and recovered for 20 min. Core temperature (T(c)), skin temperature (upper arm, chest, thigh, calf), and heart rate (HR) were monitored at rest (T(0)), exercise begins (T(20)), 20 min of exercise (T(40)), the exercise ends (T(60)), and at recovery (T(80)). RESULTS: Compared to T(0), T(c) decreased significantly at T(20) and increased significantly at T(40), T(60) and T(80) (p < 0.01). From 35-80 min, the T(c) was higher in trial G (peaked at 37.96 ± 0.25°C) than in trial C (37.89 ± 0.37°C), but it failed to reach significant difference (p > 0.05); T(sk) continued to increase during exercise and was significantly higher than T(0) at T(40) (p < 0.05), T(60) and T(80) (p < 0.01). There was no significant difference in T(sk) between the two trials (p > 0.05). CONCLUSION: Our findings provide initial evidence that oral administration of GABA does not affect thermoregulation and has no adverse effects on the body as an ergogenic exercise supplement during exercise in cold environments.