Influence of brief carbon dioxide inhalation on acute exercise performance and recovery: A pilot study
Dongwook Yeo, Jesse C. Schwartz, Bruce D. Johnson, Chul‐Ho KimAbstract
Brief inhalation of carbon dioxide (CO 2 ) has been proposed to counteract transient hypocapnia by enhancing oxygen unloading, vasodilation, and sympathetic modulation. Despite these potential ergogenic mechanisms, CO 2 has rarely been investigated in the exercise context. The present study investigated whether brief CO 2 inhalation (iCO 2 ) influences performance and recovery during high‐intensity interval exercise. Nine healthy adults completed two randomized, single‐blinded crossover trials of repeated cycling intervals at 85% peak work rate until volitional exhaustion or cadence dropped below 60 rpm, with a minimum 2‐min interval duration required and 3‐min active recovery between bouts. Participants inhaled 5% CO 2 or room air (15 breaths) before and after each exercise bout. Gas exchange, cardiovascular responses, and perceived exertion were assessed. Total exercise time was similar between trials; however, participants completed more intervals with iCO 2 . During the first interval, iCO 2 increased exercise duration and VO 2 . At matched exercise time, perceived exertion and dyspnea were lower with iCO 2 . During recovery, systolic blood pressure was lower and heart rate was higher following iCO 2 . Brief iCO 2 improved first‐interval performance, altered cardiovascular recovery, and reduced perceptual strain but did not extend overall exercise duration. These findings suggest iCO 2 may transiently modulate tolerance and autonomic‐vascular responses during high‐intensity interval exercise.