Human skeletal muscle transcriptome in response to high-intensity interval training

Skeletal muscle tissue is a highly adaptable tissue, responding to the specific demands it is subjected to. High-intensity interval training (HIIT) has been shown to generate similar, or even greater, molecular changes in skeletal muscle as that of constant load longer-lasting endurance-type training at moderate intensities. Despite shorter exposure times, the higher intensity provided by HIIT training leads to greater metabolic perturbations and thereby larger improvements in mitochondrial content and maximal oxygen uptake. During a period of regular exercise training, the performance improvements follow a non-linear pattern with a relatively faster pace initially and a gradual ‘plateauing-off’ after weeks and months. It is believed that this ‘plateau effect’ is due to a blunting of the molecular responses to acute exercise with exercise training. In the present study we utilised an explorative global transcriptomic approach to investigate the phenomenon of transcriptional-level blunting of the acute exercise response in human skeletal muscle over the course of a three-week HIIT intervention. We hypothesize that the blunting of transcription at this time-point is specific to certain pathways, including metabolic regulation and that these genes have communal transcriptional regulation. Eleven healthy men with mean age of 24.8 years and VO2peak of 51.9 ± 1.9 ml O2x kg-1 x min-1 performed nine sessions of HIIT (10 x 4 minutes of cycling at 91 % of HRmax) over three weeks. Before and 3 h after the 1st and 9th exercise bout, skeletal muscle biopsies were obtained, and RNA sequencing was performed.