principle of progressive overload
According to this basic training principle, training must include overload and progression to be successful. The body must be overloaded so that it has to work harder than normal. As the body adapts to a particular workload, the person should progress to a higher work level. For example, to gain strength, the muscles must be loaded beyond the point at which they are normally loaded. As the muscles become stronger, the load has to be increased to stimulate further strength increases. The load should be increased gradually over a long period of training. If the load is too high, there is a risk of overtraining and overuse injuries.