Antioxidant supplementation blunts the proteome response to three weeks of sprint interval training preferentially in human type 2 muscle fibres

Sprint interval training (SIT) is a time-efficient type of endurance training that involves large type 2 muscle fibre recruitment. Effiective antioxidant supplementation may mitigate positive training adaptations by limiting the oxidant challenge. Our aim was to test whether SIT affiects type 2 more than type 1 muscle fibres, and whether the training response is mitigated by antioxidant treatment. Young men performed three SIT sessions (6 × 30 s all-out cycling) per week for three weeks while treated with antioxidants (vitamin C, 1 g/day; vitamin E, 235 mg/day) or placebo. Vastus lateralis biopsies were taken to measure (i) activation of genes for reactive oxygen/nitrogen species (ROS) sensors and inflammatory mediators with quantitative RT PCR and (ii) fibre type-specific proteome adaptations using mass spectrometry-based proteomics. Vitamin treatment decreased the upregulation of genes for ROS sensors and inflammatory regulators during the first SIT session. The three weeks of SIT caused generally larger proteome adaptations in type 2 than in type 1 fibres, and this included larger increases in abundance of proteins involved in mitochondrial energy production. Vitamin treatment blunted the SIT-induced proteome adaptations, whereas it did not affiect the training-induced improvement in maximal cycling performance. In conclusion, (i) the large type 2 fibre recruitment and resulting proteome adaptations are instrumental to the effiectiveness of SIT, and (ii) antioxidant supplementation counteracts positive muscular adaptations to SIT, which would blunt any improvement in submaximal endurance performance, whereas it does not affiect the improvement in maximal cycling performance, where O2 delivery to muscle would be limiting.