VALIDITY AND RELIABILITY OF METHODS FOR TESTING VERTICAL JUMPING PERFORMANCE

The validity and reliability of the jumping ergometer method for evalu ating performance in two-legged vertical countermovement and serial re bound jumps were investigated. The internal segmental and nonvertical energy flow components for drop jumps were also studied. The exact dyn amic equations governing the jumping motion in three dimensions were d erived and used together with the approximate relations of the jumping ergometer method to evaluate a total of 72 vertical jumps of differen t types executed by 22 subjects (15 males, 7 females), average age 24. 59 years. The forceplate method was selected as a reference procedure, to which the jumping egometer results were related. For countermoveme nt jumps, the relative error for jumping height was 3.55% (+/-2.92%), and for average power per kilogram body mass during the propulsion pha se it was 23.79% (+/-4.85%). For serial rebound jumps, the respective errors were 7.40% (+/-4.58%) and 5.09% (+/-4.48%). Internal and nonver tical energy flow components amounted to about 3% of the total. It was concluded that, because of a number of invalid assumptions, unpredict able errors, and contradictory performance requirements, the validity and reliability of the jumping ergometer method for evaluating certain aspects of athletic performance are highly questionable.