Effects of 8 weeks of bed rest with or without resistance exercise intervention on the volume of the muscle tissue and the adipose tissues of the thigh.

The present study aims to investigate the effects of 8 weeks of bed rest, with or without resistance exercise intervention, on the volumes of muscle tissue and the intramuscular, intermuscular, and subcutaneous adipose tissues of the thigh. Twenty men were included, who were randomly assigned in three groups: resistance exercises group (RE group), resistance exercises with whole-body vibration group (VRE group), and nonexercise control group (CTR group). The RE and VRE groups performed resistance exercises during 8 weeks of bed rest (3 days per week). Additionally, consecutive axial magnetic resonance images were obtained before and after the bed rest. Using these images, the volumes of the muscle tissue and the intramuscular adipose tissue, intermuscular adipose tissue, and subcutaneous adipose tissue of the thigh were evaluated. No significant time-by-group interaction was observed the volumes of the muscle tissue and the intramuscular adipose tissue, intermuscular adipose tissue, and subcutaneous adipose tissue between the RE and VRE groups. Furthermore, the RE and VRE groups were pooled as the resistance exercise intervention group (TR group), wherein their thigh muscle tissue volume was observed to be maintained after the bed rest. However, that of the CTR group significantly decreased. Regarding the thigh intramuscular adipose tissue and intermuscular adipose tissue volumes, no significant difference was observed among the CTR and TR groups. Although subcutaneous adipose tissue volume in the CTR group significantly increased after the bed rest, no changes were observed in that of the TR group. Therefore, the results of the present study suggested that within the 8 weeks of bed rest, adipose tissue adaptation differs depending on the location.