Bed rest and resistive vibration exercise unveil novel links between skeletal muscle mitochondrial function and insulin resistance

ims/hypothesis Physical inactivity has broad implications for human disease including insulin resistance, sarcopenia and obesity. The present study tested the hypothesis that (1) impaired mitochondrial respiration is linked with blunted insulin sensitivity and loss of muscle mass in healthy young men, and (2) resistive vibration exercise (RVE) would mitigate the negative metabolic effects of bed rest. Methods Participants ( n = 9) were maintained in energy balance during 21 days of bed rest with RVE and without (CON) in a crossover study. Mitochondrial respiration was determined by high-resolution respirometry in permeabilised fibre bundles from biopsies of the vastus lateralis. A hyperinsulinaemic–euglycaemic clamp was used to determine insulin sensitivity, and body composition was assessed by dual-energy x-ray absorptiometry (DEXA). Results Body mass (−3.2 ± 0.5 kg vs −2.8 ± 0.4 kg for CON and RVE, respectively, p < 0.05), fat-free mass (−2.9 ± 0.5 kg vs −2.7 ± 0.5 kg, p < 0.05) and peak oxygen consumption ( ·VO_2peak ) (10–15