[Musculoskeletal rehabilitation and bone. Musculoskeletal atrophy, and rehabilitation medicine].

: Weightless environments such as prolonged bed rest and spaceflight are associated with dramatic losses of muscle volume and bone mass that hinder patients' or astronauts' health and reintegration into daily life. It is important that the countermeasure is effective for slow twitch fiber, and adds mechanical stress to a bone. So, we developed the hybrid training method (HYB) as a countermeasure of this musculoskeletal atrophy, which uses the contraction produced in a muscle by electrical stimulation of antagonist to resist the volitional contraction of agonist. HYB has several features. These include ; 1) simple device, 2) simultaneous contractions both agonist and antagonist musculature, 3) volitional contraction of deep layers of muscle, 4) longitudinal bone force loads. Several studies reported that, this HYB was tested successfully for increasing muscles strength and hypertrophy in the upper and lower extremities. And, a wearable HYB apparatus with a virtual reality control system was developed. Now, we are developing the hybrid ergometer with virtual reality system, which training can play while playing a game at home.