Influence of brief carbon dioxide inhalation on acute exercise performance and recovery: A pilot study

Source: PubMed Central Open Access, NCBI / U.S. National Library of Medicine

Abstract Brief inhalation of carbon dioxide (CO) has been proposed to counteract transient hypocapnia by enhancing oxygen unloading, vasodilation, and sympathetic modulation. Despite these potential ergogenic mechanisms, COhas rarely been investigated in the exercise context. The present study investigated whether brief COinhalation (iCO) 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% COor 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. During the first interval, iCOincreased exercise duration and VO. At matched exercise time, perceived exertion and dyspnea were lower with iCO. During recovery, systolic blood pressure was lower and heart rate was higher following iCO. Brief iCOimproved first‐interval performance, altered cardiovascular recovery, and reduced perceptual strain but did not extend overall exercise duration. These findings suggest iCOmay transiently modulate tolerance and autonomic‐vascular responses during high‐intensity interval exercise.