It is unclear whether the athletes had developed an efficient respiratory system after several years of practice, whether the training stimulus was not high enough to bring about measurable changes, or whether there was an inability in the testing methods to detect changes resulting from training and competition. Athletes in physically demanding sports show a different response to that of technical athletes. In-season training and competition may result in either increased or unchanged maximal respiratory parameters. Aerobic fitness is only maintained or stimulated by activity. It is used extensively for predicting aerobic performance.
ANThreshold adaptation is stimulated by a certain amount of work.
To assess aspects of anaerobic fitness, all-out cycle ergometer tests, standing broad jumps and vertical jumps are examples of evaluation tools commonly used. Components of anaerobic fitness show little seasonal variation in men and women of different competitive abilities. It is suspected that most tests currently used to evaluate anaerobic fitness do not appear to be sensitive enough to detect seasonal variations. With lower level athletes, off-season training that includes a considerable amount of strength training usually provokes an increase in muscular strength. Even in elite competitors, the trend to fail to maintain the gains made in off-season strength work during the competitive season is evident.