Robinson, Matthew M

We assessed the effects of 12 wk of supervised high-intensity interval training (HIIT), resistance training, and combined training (CT) on skeletal muscle mitochondrial abundance and markers of fission and fusion. HIIT increased mitochondrial area and size and promoted protein changes indicative of increased mitochondrial fusion, whereas lessor effects were observed after CT and no changes were observed after RT. Furthermore, increased mitochondrial area and size after HIIT associated with improved mitochondrial respiration, cardiorespiratory fitness, and insulin sensitivity.

Maximal aerobic exercise capacity [maximal oxygen consumption (V̇o 2max )] is one of the strongest predictors of morbidity and mortality. Aerobic exercise training can increase V̇o 2max , but inter-individual variability is marked and unexplained physiologically. The mechanisms underlying this variability have major clinical implications for extending human healthspan. Here, we report a novel transcriptome signature related to ΔV̇o 2max with exercise training detected in whole blood RNA. We used RNA-Seq to characterize transcriptomic signatures of ΔV̇o 2max in healthy women who completed a 16-wk randomized controlled trial comparing supervised, higher versus lower aerobic exercise training volume and intensity (4 training groups, fully crossed). We found significant baseline gene expression differences in subjects who responded to aerobic exercise training with robust versus little/no ΔV̇o 2max , and differentially expressed genes/transcripts were mostly related to inflammatory signaling and mitochondrial function/protein translation. Baseline gene expression signatures associated with robust versus little/no ΔV̇o 2max were also modulated by exercise training in a dose-dependent manner, and they predicted ΔV̇o 2max in this and a separate dataset. Collectively, our data demonstrate the potential utility of using whole blood transcriptomics to study the biology of inter-individual variability in responsiveness to the same exercise training stimulus.