Effects of bedrest and hypoxia on human skeletal muscle miRNA expression

The present study concerns the effects of 21 days of sustained recumbence (bedrest) and hypoxia, alone and in combination, on skeletal muscle microRNA expression. 14 male subjects participated in 3 experimental campaigns in a counterbalanced fashion: normoxic bedrest (NBR), hypoxic bedrest (HBR) and hypoxic ambulatory confinement (HAMB), both hypoxic conditions with FO2 = 0.141 and PIO2 = 90 ± 0.4 mmHg, equivalent to an altitude of ≈ 4000 m). Each intervention (bedrest or ambulatory confinement) lasted 21 days, and the interventions were separated by a 4-month wash-out/recovery period. The order in which each subject undertook the interventions is denoted 'Intervention_order' Throughout both bedrest interventions, each subject remained in a horizontal position at all times. He was allowed one pillow for the head and to occasionally lean on an elbow while eating or being transferred to a gurney. Muscular exercise was prohibited. During the HAMB confinement, each subject was allowed to move freely within the hypoxic area. To mimic a normal level of physical activity subjects performed 30 minutes of low-to-moderate-intensity exercise twice daily. Muscle samples from Vastus lateralis. Biospy material sufficient for anlaysis was avialable for 72 observations, another 4 were excluded due to technical problems with the array hybridisation, leaving in total 68 observations.