There are three mechanisms of hypertrophy: mechanical tension, metabolic stress, and muscle damage. If you neglect any one of them, you're leaving a lot of growth on the table. Mechanical tension equates to muscular force. There's a "sweet spot" shy of the 1RM where mechanical tension is at its highest. For optimal metabolic stress ("the pump"), maintain constant tension on the muscles by reversing directions just short of lockout or just before bottoming out.
