What must be exceeded to see improvements in fitness, according to training principles?

To see improvements in fitness, one must exceed the threshold of training. This concept is fundamental in exercise science, as it posits that to stimulate adaptations in the body—such as increased strength, endurance, or flexibility—an individual must engage in physical activity that surpasses their current fitness level. The threshold of training is essentially the minimum intensity or volume of exercise needed to elicit a positive response from the body.

When the training stimulus is adequate, the body reacts by becoming stronger or more efficient in the specific area being trained. Consistently working at or above this threshold will lead to improvements; however, consistently training below this threshold may result in no significant changes in fitness levels. This principle underscores the importance of progressively increasing the intensity or duration of workouts to continue making gains and avoid plateaus in performance.

The concept encompasses various training components, such as cardiovascular fitness, strength training, and flexibility, ensuring that improvement in these areas occurs only when adequate challenge is presented to the body.