Muscle outlines from Body Muscles by Ivan Vulović, Apache 2.0 — regrouped and recoloured for Muscle Train.
Start on all fours, hands under shoulders, knees under hips. Tuck toes and lift knees, maintaining a 90-degree bend. Engage your core, flatten your back, and hold, breathing steadily.
Maintain a tight core to prevent back arching. Align shoulders over wrists. Gaze forward to avoid neck strain. If lower back pain occurs, re-engage your core. Start with shorter holds, increasing duration as strength improves.
MuscleTrain is actively being built. If something looks broken, or you have a suggestion, let us know — it really helps shape the app.