Simulation of oxygen uptake and leg joint reaction force during ergometer exercise under altered gravity.

Ergometers are safe devices for patients and elderly individuals, as the exercise intensity can be controlled. Moreover, ergometer exercises, which remove the load from body weight on the leg joint, would better reflect training conditions in locations where the force of gravity is lower than that on Earth, such as the International Space Station or on the surface of Mars. The purpose of this study was not only to validate an ergometer exercise model for measuring oxygen uptake and knee joint reaction force by comparison with experimental results, but also to consider a strategy for electrically stimulating leg joint muscles to modulate them under altered gravity.