Leg extension backward supported on a stability ball

Extend the knee progressively and control the resistance on the way back. Keep the pelvis supported and avoid using torso momentum. Prioritize control over speed. Maintain useful tension through the range and deliberately reset the starting position before the next repetition.

Do not turn the final repetitions into fast or partial movements. Aim to load abdominals, shoulders and glutes and hip flexors without sacrificing position; at beginner level, progress control first and then add load, repetitions or complexity. On unstable surfaces, master the position with light resistance first; stability should limit difficulty before load does.