Truncated splice variant PGC-1α4 is not associated with exercise-induced human muscle hypertrophy

Introduction A truncated PGC‐1α splice variant (PGC‐1α4) has been implicated in the regulation of resistance exercise (RE)‐induced muscle hypertrophy, and basal expression levels said to be augmented in response to concurrent aerobic (AE) and RE training. Aim The current study investigated human muscle truncated and non‐truncated PGC‐1α transcripts in response to both acute and chronic RE, and with or without preceding AE (AE+RE). Methods Ten men performed 5 weeks of unilateral AE+RE and RE training. Before (untrained) and after (trained) this intervention, PGC‐1α transcripts were assessed in vastus lateralis muscle biopsies obtained before and 3 h after acute RE, with or without preceding AE. Additionally, samples were collected 72 h after the last exercise bout of the training programme. Results The truncated splice variant increased (P 0.05). Conclusion Our results do not support the view that truncated PGC‐1α coordinates exercise‐induced hypertrophy in human skeletal muscle. Rather, all PGC‐1α isoforms appear to be regulated transiently in response to acute exercise and regardless of mode.