In a joint research with Professor Hiroshi Akima of Nagoya University and others, skeletal muscle mass is maintained by strength training performed while the bed is resting, and fat that accumulates in the muscle in a marbling manner. It was revealed that (intramuscular fat) was reduced.
Generally, skeletal muscle mass decreases with decreased physical activity and increases with strength training.On the other hand, intramuscular fat increases with aging and obesity.So far, the effects of reduced physical activity and strength training in combination with skeletal muscle and intramuscular fat have been unclear.In this study, we investigated the effects of strength training during 8-week bed rest on thigh skeletal muscle mass, subcutaneous fat mass, and intramuscular fat mass.
Healthy young men were divided into a muscle training group in which strength training (squats, heel raises, toe raises, etc.) was performed three times a week during bed rest for 8 weeks, and a control group in which only bed rest was performed.In both groups, the skeletal muscle mass, intramuscular fat mass, and subcutaneous fat mass of the thigh were measured by magnetic resonance imaging before and after the experiment.As a result, the skeletal muscle mass in the muscle training group was maintained, and in the control group, the mass decreased after the experiment.The intramuscular fat mass in both groups decreased after the experiment, but the subcutaneous fat mass in the control group increased and was maintained in the muscle training group.Furthermore, a significant correlation was found between the quantitative changes in skeletal muscle and intramuscular fat in the muscle training group.
This time, it was shown that the decrease in physical activity and the adaptation of fat by strength training differ depending on the accumulation site, and that there is an interrelationship between the quantitative changes in skeletal muscle and intramuscular fat caused by strength training.Changes similar to the adaptation of skeletal muscle and fat observed in this study will lead to the establishment of methods for maintaining and improving health in bedridden elderly people and long-term stays in space.
