Muscle outlines from Body Muscles by Ivan Vulović, Apache 2.0 — regrouped and recoloured for Muscle Train.
Stand tall with your feet hip-width apart. Bend one knee backward and grab that foot with your opposite hand. Lower your body by bending your supporting leg. Once your back knee lightly touches the floor, push yourself back up to the starting position. Switch sides and repeat for the desired number of sets and reps.
Hold on to a wall or a door frame at first until you find your balance. Keep your chest up and lean forward slightly as you go down. Keep the heel of your supporting foot on the floor and push through the whole foot to stand up. Put a folded towel under your back knee so it touches down softly. Do the same number of reps on each leg.
Muscle Train is actively being built. If something looks broken, or you have a suggestion, let us know — it really helps shape the app.