Strength is the ability to carry out work against a resistance. The maximum force that can be generated depends on the size and number of muscles involved, the proportion of muscle fibers called into action, the coordination of the muscle groups, the physical condition of the muscles and the mechanical advantage of the levers involved. Due to this complexity and the variations in these properties for each muscle group, there is no single test for strength. Each strength test is specific to the action and muscle groups being tested.
Muscular strength endurance is the ability to repeat a series of muscle contractions without fatiguing. It is different from cardiovascular endurance because it involves the muscle fatiguing rather than a limitation in the amount of oxygen being supplied or utilized by the muscles.