Which principle suggests that gradual increases in exercise intensity will lead to improvements in fitness?

The principle that suggests gradual increases in exercise intensity will lead to improvements in fitness is known as the overload principle. This principle posits that to improve physical fitness, the body must be subjected to stress beyond what it is accustomed to. By systematically increasing the demands placed on the body through higher intensity or volume of exercise, adaptations occur, resulting in improved strength, endurance, and overall fitness.

The overload principle emphasizes the importance of progressive overload, meaning that fitness gains are achieved through incremental increases in workout intensity, duration, or frequency. For example, a person who regularly lifts weights may increase the amount of weight lifted or the number of repetitions performed to continue to challenge their muscles and stimulate growth.

In contrast, other principles like specificity focus on training specific muscles or energy systems to obtain particular outcomes, while variation involves changing workout routines to avoid plateaus or boredom. The recovery principle highlights the importance of rest and recuperation for improved performance but does not directly address improvements through increasing intensity. Thus, the overload principle is integral to achieving fitness improvements through progressively challenging workouts.