Final answer:
The principle of progressive overload states that as the body adapts to physical stress, the workload must be increased to continue seeing improvements in muscle mass and strength. It involves making the weights lifted increasingly heavier to challenge the muscles and promote growth.
Step-by-step explanation:
The principle that states you must increase workload to maintain overload as the body adapts is known as progressive overload, which is fundamental to effective strength training. It implies that in order to enhance muscle mass and strength, one must continually challenge the muscles by increasing the weight or resistance. The concept of progressive overload is based on the idea that when the body is exposed to higher levels of physical stress, it will adapt by becoming stronger to withstand the stress. However, to achieve further improvements, the load must be increased as muscles adapt and require a heavier load to continue progressing.
For example, lifting the same amount of weight over a prolonged period will not contribute to increased muscle size or strength, because the muscles have adapted to easily handle that weight. Therefore, the weights lifted must become increasingly heavier, which challenges the muscles further and stimulates growth and strength gains. This is a key part of why athletes and individuals engaged in a fitness routine must continue to adjust their workout intensity to match their evolving bodies' capabilities.