Muscle outlines from Body Muscles by Ivan Vulović, Apache 2.0 — regrouped and recoloured for Muscle Train.
Sit on a stable, stationary chair (avoid chairs with wheels) with your feet apart and hands clasped in front of your chest. Without using your hands for assistance, press through your feet to stand up completely and hold the position. Bend your knees and slowly lower yourself back into the chair with total control.
MuscleTrain is actively being built. If something looks broken, or you have a suggestion, let us know — it really helps shape the app.