Affiliations: [a] Department of Motricity Sciences and Physical Therapy and Rehabilitation, University of Liege, Liege, Belgium | [b] Faculty of Sport Sciences, University of Poitier, Poitiers, France | [c] Department of Physical Medicine and Sport Traumatology, University of Liege, Liege, Belgium | [d] Department Public Health Sciences, University of Liege, Liege, Belgium | [e] Pole Rehabilitation, University Hospital Center of Dijon, Dijon, France
Correspondence:
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Corresponding author: J. Paulus, Department of Motricity Sciences and Physical Therapy and Rehabilitation, Laboratory of Human Motion Analysis, University of Liege, Quartier Polytech, Allée de la découverte 9, B52/3 (+1/518), 4000 Liege, Belgium. Tel.: +32 499 600 904; E-mail: julien.paulus@uliege.be.
Abstract: BACKGROUND: Fatigability measured and derived parameters are commonly used in research and clinical contexts to characterize performance during isokinetic fatigue protocols. The fatigability measured parameters are the best repetition, the total and the partial sums while the fatigability derived parameters are ratios and formula-based parameters. OBJECTIVES: To comprehensively evaluate the reproducibility of fatigability measured and derived parameter and to determine which of these is/are sufficiently interpretable for assessment of knee muscles. METHODS: Eighteen sedentary men underwent three isokinetic knee fatigability testing sessions with 7–10 days of rest between each session. Peak moment (PM) and maximal work (MW) were computed for each repetition and analyzed to calculate 54 measured and derived parameters. Relative (Intra-class Correlation Coefficients – ICC) and absolute (Coefficient of Variation of Method Error – CVME%, standard error of measurement – SEM and minimum detectable change – MDC) parameters of reproducibility were determined to assess the inter-session agreement. RESULTS: All fatigability measured parameters (save one) were associated with a high relative and absolute reproducibility for knee extensors (ICC ⩾ 0.80; almost all SEM ⩽SD2; MDCs largely ranging 10–30%) and a high relative but weak absolute reproducibility for flexors (ICC ⩾ 0.70; SEM >SD2; MDCs ranging 35–95%). On the other hand, all knee extensor and flexor fatigability derived parameters were characterized by low relative and absolute reproducibility (ICCextensors< 0.70 and ICCflexors< 0.50; all SEM >SD2; MDCs largely ranging 30–100%). CONCLUSIONS: All fatigability measured parameters may be used for assessing knee extensors fatigue with either PM or MW; for assessing knee flexors, no measured parameters can be utilized. Above all, knee fatigability derived parameters, either PT- or MW-based, should not be used, for both the extensors and the flexors of the knee, due to clinically unacceptable reproducibility.
