Test-Retest Reliability and the Learning Effect on Isokinetic Fatigue in Female Master’s Cyclists

Abstract

Background: Isokinetic exercise is commonly used as a benchmark for strength and performance. Objective: The purpose of this investigation was to establish isokinetic fatigue test-retest reliability and examine the learning effect when testing without familiarization. Methods: 22 masters-aged [53±5 years), competitive female cyclists completed 3 separate 50-repetition knee flexion/extension tests on a Biodex, separated by one-week with no familiarization. Test-retest reliability [intra-class correlation [ICC]), 95% confidence intervals [CI), technical error of measurement [TEM) were calculated. Results: ICCs between trials exhibited excellent reliability during extension [.93–.97) and flexion [.93–.97) for all variables except time to peak torque [ICC=.35 and.45 for extension and flexion, respectively) and fatigue index [ICC=.47 for flexion). Relative TEM was minimal for extension between trial 1 and trial 2 [0.27%–0.97%) and between trial 2 and trial 3 [0.27%–1.45%) for all variables. Similar results were observed for flexion between trial 1 and trial 2 [0.87%–2.45%) and between trial 2 and trial 3 [0.54%–1.10%). No differences [Wilks Λ>.05) existed between trials, indicating no learning effect associated with the tests. Conclusions: There was strong test-retest reliability in masters-aged, female athletes and no learning effect was associated with the Biodex during a knee extension/flexion fatigue protocol.