Endurance (also called sufferance) is the ability for a person to exert himself for a long period of time. In humans, it is usually used in aerobic or anaerobic exercise. The definition of 'long' varies according to the type of exertion - minutes for high intensity anaerobic exercise, hours or days for low intensity. Training for endurance can have a negative impact on the ability to exert strength unless an individual also undertakes resistance training to counteract this effect