Mitochondrial-targeted antioxidant ingestion acutely blunts VO2max in physically inactive females

Abstract

Purpose: To determine the acute effects of a mitochondrial targeting antioxidant (MitoQ) on the metabolic response during exercise.

Methods: Nine (n = 9) physically inactive females (age 47 ± 22 years) performed two trials (Placebo and MitoQ) in a double-blind randomized cross-over design. In both trials, participants performed an exercise protocol consisting of 3-min stages at submaximal workloads followed by a ramp protocol to volitional exhaustion. Participants received either Placebo or MitoQ (80 mg) 1 h prior to exercise. Indirect calorimetry and cardiovascular measurements were collected throughout the duration of the exercise bout.

Results: Submaximal metabolic and cardiovascular variables were not different between trials (p > 0.05). VO_2max was higher (p = 0.03) during Placebo (23.5 ± 5.7 mL kg min^-1 ) compared to MitoQ (21.0 ± 6.6 mL kg min^-1 ). Maximal ventilation was also higher (p = 0.02) in Placebo (82.4 ± 17.7 L/min) compared to MitoQ (75.0 ± 16.8 L/min). Maximal cardiovascular variables and blood lactate were not different between trials (p > 0.05).

Conclusion: An acute dose of MitoQ blunted VO_2max , which was primarily mediated by impairment of ventilatory function. These data suggest that the acute accumulation of exercise-induced mitochondrial reactive oxygen species (mtROS) are necessary for maximal aerobic capacity. Further research is warranted on mtROS-antioxidant cell signaling cascades, and how they relate to mitochondrial function during exercise.

Keywords: cardiorespiratory fitness; exercise; mitochondria.