In-season training and competition may result in either increased or unchanged maximal respiratory parameters. Reductions are rarely, if ever, found. Aerobic fitness is only maintained or stimulated by activity. If that activity declines or ceases, then fitness will regress. It is used extensively for predicting aerobic performance.
ANThreshold adaptation is stimulated by a certain amount of work.
Extra work above that level will not result in any further adaptation and may even be harmful. 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. More sophisticated tests are usually able to detect changes from untrained to moderately trained states but are not sensitive to changes in higher levels of fitness.