Ibuprofen's Effect On Thermoregulatory Responses And Gastrointestinal Distress During Exercise In A Hot Environment

Ibuprofen is commonly used by athletes to alleviate pain and inflammation. Recently, it has been hypothesized that ibuprofen may mitigate exercise-induced core temperature (Tc) increases and improve heat tolerance during exercise in hot environments. However, ibuprofen may induce gastrointestinal (GI) symptoms during exercise associated with heat stress. PURPOSE: To investigate the effect of ibuprofen on thermoregulatory responses and the occurrence of GI symptoms during exercise in a hot environment. METHODS: In a double-blind, randomized, cross-over design, 12 recreationally endurance-trained males (n = 6) and females (n = 6) completed 60 minutes of treadmill running at vigorous intensity [65% of maximum oxygen consumption (VO2max) measured in a temperate environment] in a controlled hot environment (35 °C) on two separate occasions. Ibuprofen (1200 mg total) or placebo (PL) was administered by ingesting 600 mg at 12 hours and 60 minutes prior to each trial. Throughout the exercise trials, Tc, via rectal thermistor, and heart rate (HR), via chest strap, were recorded every 5 minutes. Ratings of perceived exertion (RPE), thermal sensation (Ts), and thermal comfort were recorded every 10 minutes of exercise. A GI symptoms questionnaire was administered pre-, at minute 30, immediately post-, and 1-hour post-exercise. RESULTS: No significant difference between PL and ibuprofen in peak Tc (39.05 ± 0.48 and 38.97 ± 0.54 °C, respectively) (p = 0.323) or peak HR (174 ± 14 and 171 ± 15 bpm, respectively) (p = 0.232) were found. There were no significant differences between PL and ibuprofen for peak RPE (15.7 ± 2.3 and 15.6 ± 1.7, respectively) (p = 0.391), maximum Ts (7.4 ± 0.5 and 7.3 ± 0.5, respectively) (p = 0.293), and maximum thermal comfort (3.3 ± 1.2 and 3.4 ± 0.9, respectively) (p = 0.397). There were no significant differences in upper (p = 0.127), lower (p = 0.536), or overall GI symptoms (p = 0.303) when comparing conditions and time points. No significant differences in nausea (p = 0.254), dizziness (p = 0.516), and abdominal stitch (p = 0.926) were found when comparing conditions and time points. CONCLUSION: Ibuprofen, when administered with the maximum over-the-counter dosage (1200 mg), does not have a detrimental effect on GI symptoms or thermoregulatory responses during exercise in hot conditions.