The acute effects of mitochondrial targeted antioxidant on maximal oxygen uptake mechanics
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Abstract
Purpose: To determine the acute effects of a mitochondrial targeting antioxidant (MitoQ) on cardiac output and maximal oxygen uptake during maximal exercise. We hypothesized that MitoQ would blunt maximal oxygen uptake independent of changes in cardiac output. Methods: Eight (N=8) apparently healthy adults (age 25±2.8 years and BMI 25.0±3.8 kg/m2) performed two trials (Placebo and MitoQ) in a double-blind randomized cross-over design. In both trials, participants performed 2 submaximal workloads on a cycle ergometer consisting of 3-minute stages immediately followed by an incremental exercise protocol until volitional exhaustion. Participants received either a Placebo or MitoQ (80mg) one hour prior to beginning the exercise protocol. Indirect calorimetry, blood pressure, heart rate, stroke volume, cardiac output, RPE, and oxygen saturation were collected throughout the duration of the exercise bout. Results: Maximal absolute, relative, and relative to lean mass VO2 was higher (p<0.05) during Placebo (2.85±0.56 L/min, 36.4±6.2 mL/kg/min, 49.7±5.6 mL/kg/min) compared to MitoQ (2.68±0.63 L/min, 34.7±5.7 mL/kg/min, 46.5±6.3 mL/kg/min). Cycling work efficiency was higher (p<0.01) during MitoQ demonstrated by a lower peak VO2 per watt during MitoQ (10.5±0.7 mL/min/watt) compared to Placebo (11.4±0.6 mL/min/watt). The acute MitoQ had no effect on submaximal or maximal VCO2, ventilation, tidal volume, respiratory frequency, VE/VCO2, RER, workload, heart rate, stroke volume, or cardiac output (p>0.05). Conclusion: Consistent with our previous work, an acute dose of a mitochondrial targeted antioxidant blunted maximal absolute, relative, and relative to lean mass VO2. The reduction in VO2max does not appear to be related to blunted cardiac output, suggesting peripheral mechanisms underlie the lower oxygen utilization. Further, MitoQ improved work efficiency (VO2 per watt) at maximal exercise levels regardless of blunted oxygen uptake. Further research is warranted to examine the peripheral mechanism by which VO2 is blunted, and oxygen uptake efficiency is improved during maximal exercise.