Lie on your back with one leg (the left) raised (knee bent at about 90°), whilst the other (right) leg remains either straight or resting loosely. Lift your upper body slightly (into a crunch position, but do not sit up fully), and place one hand on the raised knee. Actively press the knee against the hand, and the hand against the knee. Hold this tension isometrically without moving. Keep the head and neck in a neutral position (do not strain).
Attention:
Do not pull with your neck; instead, engage your core. If your knees or hands bear the load, movement occurs – this is not true isometric tension. Do not lift your upper body too high (as this puts too much strain on your hip flexors). Avoid arching your lower back, and ensure your shoulders remain relaxed.
Lighten:
Lift your upper body only slightly (mini-crunch); press your hand only lightly against your knee (no maximum pressure – focus on control rather than strength); keep your head on the floor and press only isometrically.
Harden:
Apply more pressure (maximum isometric tension); angle the leg further outwards or higher (greater leverage).
