Dose-response relationship of taurine on endurance cycling performance under hot and humid conditions

Purpose To investigate the effects of different doses of taurine on endurance exercise performance and physiological parameters under hot and humid conditions. Methods This study adopted a double-blind, randomized, placebo-controlled, cross-over design. Sixteen male university students majoring in physical education (age: 20.12 ± 1.12 years; training status: ≥3 endurance sessions/week) received 4 supplement conditions: (1) placebo (maltodextrin), (2) low-dose (1 g taurine), (3) medium-dose (4 g taurine), and (4) high-dose (6 g taurine). Participants performed a graded cycling test (initial 50 W, +50 W every 3 min at 70 rpm) until exhaustion in an environmental chamber (35 °C, 65% RH). Heart rate, core temperature, skin temperature, sweat rate, RPE, and thermal sensation were measured. Results Compared to placebo, time to exhaustion was significantly longer in the medium-dose group (p < 0.05), with no significant or trend-level effects in low- or high-dose groups. Blood lactate accumulation and sweating rate were higher in the medium-dose group (p < 0.05). Core temperature (9 min-End) was lower in the medium-dose group during the latter exercise phase (p < 0.05). Conclusion Under hot and humid conditions, acute 4 g taurine supplementation enhanced time to exhaustion during graded cycling by improving thermoregulatory responses, whereas 1 g and 6 g doses showed no ergogenic effects.