Crew Bone & Muscle Loss Simulator

Long-duration spaceflight removes the constant mechanical loading that keeps bone and muscle in balance on Earth, and the body responds by shedding tissue it no longer needs to support — bone mineral density falls at roughly 1–1.5% per month and muscle mass declines even faster without intervention. This simulator advances a mission day by day, applying those measured deconditioning rates while crediting whatever daily resistance and aerobic exercise the crew performs as a countermeasure, exactly as ISS flight surgeons track it with pre- and post-flight DEXA scans. Switch exercise mode and daily minutes to see how close a well-executed combined protocol comes to fully offsetting a rate that, left unchecked, would leave a year-long crew measurably more fracture-prone on the day they step back onto solid ground.