What type of exercise is best for producing muscle strength?

In accordance with the principle of specificity — which states that training adaptations are specific to the demands imposed on the body — heavy loads (≥ 80% of 1RM) are superior to lighter loads for increasing 1RM strength.^[1][2] Training to muscular failure (i.e., the point at which another concentric repetition cannot be completed with proper form) is not necessary to increase muscle strength.^[3] In fact, ending each set a few reps shy of failure appears to be superior to training to failure for maximizing gains in 1RM strength.^[4][5] Also, rest intervals between sets should be at least 3 minutes.^[6][7]