Acute upregulation of PGC-1α mRNA correlates with training-induced increases in SDH activity in human skeletal muscle

The purpose of the present study was to determine if acute responses in PGC-1 alpha, VEGFA, SDHA, and GPD1-2 mRNA expression predict their associated chronic skeletal muscle molecular (SDH-GPD activity and substrate storage) and morphological (fibre-type composition and capillary density) adaptations following training. Skeletal muscle biopsies were collected from 14 recreationally active men ( age: 22.0 +/- 2.4 years) before (PRE) and 3 h after (3HR) the completion of an acute bout of sprint interval training ( SIT) ( eight 20-s intervals at similar to 170% peak oxygen uptake work rate separated by 10 s of recovery). Participants then completed 6 weeks of SIT 4 times per week with additional biopsies after 2 ( MID) and 6 ( POST) weeks of training. Acute increases in PGC-1 alpha mRNA strongly predicted increases in SDH activity ( a marker of oxidative capacity) from PRE and MID to POST (PRE-POST: r = 0.81, r(2) = 0.65, p < 0.01; MID-POST: r = 0.79, r(2) = 0.62, p < 0.01) and glycogen content from MID to POST ( r = 0.60, r(2) = 0.36, p < 0.05). No other significant relationships were found between acute responses in PGC-1 alpha, VEGFA, SDHA, and GPD1-2 mRNA expression and chronic adaptations to training. These results suggest that acute upregulation of PGC-1 alpha mRNA relates to the magnitude of subsequent training-induced increases in oxidative capacity, but not other molecular and morphological chronic skeletal muscle adaptations. Additionally, acute mRNA responses in PGC-1 alpha correlated with VEGFA, but not SDHA, suggesting a coordinated upregulation between PGC-1 alpha and only some of its proposed targets in human skeletal muscle.