Gym, upper body
Curl the weight up with your elbow pinned to your side, then lower it slowly.
Best on camera: a slow, steady move with your joints in clear view.
Phone at hip height, about 3 metres away, filming you from the side.
Your head, arms and hips need to be in the picture. The coach will remind you if it can't see you.
Elbow swinging forward
Pin your elbow to your side; only your forearm moves.
Half reps
Curl all the way up to your shoulder.