Effects Of Mitochondria-targeted Antioxidant Supplementation On The Transcriptional Response To Exercise And Cycling Performance

Abstract

Oral supplementation with general antioxidants has little impact on performance and, in some cases, interferes with training-induced adaptations that improve performance. This may be attributed to the non-specific nature of most antioxidant supplements. Mitochondria-targeted antioxidants are becoming popular amongst active individuals as they are specifically designed to accumulate within the mitochondria to provide more targeted protection against oxidative damage. The aim of this research was to investigate the effect of MitoQ on 1) the transcriptional response to high intensity interval exercise (HIIE) and HII training (HIIT) -induced changes in performance and 2) cycling performance in trained cyclists. To understand how MitoQ supplementation during training affects the transcriptional response to HIIE and HIIT-induced changes in performance, twenty-three untrained middle-aged (age 44.6 ± 8 years) men were randomised to receive MitoQ (20 mg/d) or a placebo before completing HIIE (cycle ergometer, 10 x 60s at VO2 peak workload with 75s rest) and HIIT (3 x wk for 3 wk). Mitochondrial and antioxidant gene expression were measured in muscle biopsies collected before, immediately and 3 hr after HIIE and VO2 peak and 20 km time trial performance were measured before and after HIIT. To further elucidate where MitoQ could be an ergogenic aid, twenty trained (VO2 peak 55.1 ± 13.2 ml.kg.min-1), middle-aged (age 44 ± 3 years) male cyclists were randomly assigned to the order in which they received MitoQ (20 mg/d) and the placebo for 6 weeks before completing a performance test (cycling at 70% VO2 peak for 45 min followed by an 8 km time trial). In untrained men, expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α) was increased 3 hr after HIIE and this effect was increased by MitoQ (Cohen’s d = 0.89). While VO2 peak and 20 km time trial performance improved similarly in the MitoQ and placebo group after HIIT, the improvement in peak power output (PPO) achieved during the VO2 peak test was greater in the MitoQ group (by 5.8%, p=0.03). MitoQ also significantly improved 8 km time trial performance in trained cyclists. These results suggest that MitoQ may augment exercise-induced increases in PGC1α expression and improve cycling performance when taken during exercise training.