Muscle outlines from Body Muscles by Ivan Vulović, Apache 2.0 — regrouped and recoloured for Muscle Train.
Stand with feet shoulder-width apart, holding a dumbbell in each hand with an overhand grip. Arms close to your body, palms facing thighs. Curl wrists upwards, contracting forearm extensors, keeping elbows stationary. Hold briefly at the top. Slowly lower to the starting position. Repeat.
Start with a light weight to maintain proper form. Isolate wrist movement; keep arms still. Control the motion throughout. Exhale on the curl, inhale on the lower. Grip firmly but avoid excessive tension.
MuscleTrain is actively being built. If something looks broken, or you have a suggestion, let us know — it really helps shape the app.