What concept explains that athletes lose the benefits of training when they stop exercising?

The concept that explains why athletes lose the benefits of training when they stop exercising is known as reversibility. This principle highlights that gains in fitness, strength, endurance, and skill can diminish over time if an individual ceases to engage in regular exercise. Essentially, the physical adaptations that occur from training are not permanent; they require ongoing activity to be maintained.

When athletes stop exercising, their bodies gradually revert to pre-training states, which can involve a reduction in muscle mass, strength, endurance, and overall fitness levels. This is a crucial factor for athletes and individuals who are committed to maintaining their fitness or sports performance over time, as it emphasizes the importance of consistency in training regimes.

In contrast, the other options pertain to different aspects of exercise physiology. The overload principle relates to the necessity of increasing the demands on the body during training to continue making gains. Specificity refers to the idea that training should be relevant and appropriate to the sport or activity for which the individual is preparing. Progression involves the gradual increase of training intensity, duration, or difficulty to stimulate continued improvement. Therefore, while these concepts are integral to understanding effective training methods, it is the concept of reversibility that specifically addresses the loss of benefits due to cessation of exercise.