Most athletes would agree that resistance training improves muscle strength and capacity to resist fatigue. Likewise, endurance training improves the ability to perform aerobic exercise at higher intensities and for longer periods. But if training is decreased or stopped, the physiological adaptations that caused those improvements in performance will be reversed.
Any gains achieved with training will eventually be lost. The principle of reversibility lends scientific support to the saying. “Use it or lose it.” A training program must include a maintenance plan. In other words, when the track season is over, one should not just sit in the couch and turn couch potato, one should continute training at a lesser intensity to maintain their gain.