Knee extension with towel support

Extend the knee progressively and control the resistance on the way back. Keep the pelvis supported and avoid using torso momentum. Use a steady tempo: control the return phase in particular and avoid relying on momentum. Exhale through the hardest part and inhale as you recover the starting position.

Check that the movement stays stable in both directions and that the torso is not compensating. The goal is controlled loading of quadriceps; match resistance and range to a beginner level and never force a painful repetition.