Also emphasized when near exhaustion in order to further exhaust the muscle or muscles exercised: doing static holds for periods of time, and negative reps (lowering the weight). This will stimulate further growth and strength because muscles are weakest in positive/contracting movements (sometimes referred to as first stage failure of a muscle). Although you may not be able to lift a weight for another rep you will almost certainly be able to hold it statically for a further period (second stage of failure) and finally lower a weight at a slow controlled speed (third stage of failure). Until all three (lifting, holding and lowering) parts of an exercise can no longer be completed in a controlled manner a muscle cannot be considered thoroughly exhausted/exercised .