Isotonic exercise is the type of exercise that improves both muscular strength and muscular endurance. Isotonic exercises involve movement and include activities like lifting weights or performing bodyweight exercises, where the muscle changes length while contracting. These exercises promote both strength (through heavier loads) and endurance (through increased repetitions or reduced rest time).
In contrast, isometric exercises involve muscle contraction without movement, isokinetic exercises involve variable resistance at a constant speed, and aerobic exercises primarily improve cardiovascular endurance rather than muscular strength.