Knee strength measurement: Can we switch between isokinetic dynamometers?

Article type: Research Article

Authors: Paulus, Julien^{a; b; *} | Pauls, Jerome^c | Radizzi, Laurent^c | Krecke, Laurent^c | Bury, Thierry^a | Goff, Caroline Le^e | Laly, Arnaud^d | Schwartz, Cédric^b | Forthomme, Bénédicte^{a; b; e} | Kaux, Jean-François^e | Croisier, Jean-Louis^{a; b; e}

Affiliations: [a] Department of Motricity Sciences and Physical Therapy and Rehabilitation, University of Liege, Liege, Belgium | [b] Laboratory of Human Motion Analysis, Clinical University of Liege, Liege, Belgium | [c] Medical Luxembourg Olympic Centre, Clinical Centre of Sport and Orthopaedic, Luxemburg, Duchy of Luxemburg | [d] Training Centre of the Ligue Belge Francophone de Rugby, Liege, Belgium | [e] Multidisciplinary Medical and Sports Traumatology Service (SPORTS2), CHU, Liege, Belgium

Correspondence: [*] Corresponding author: Julien Paulus, Laboratoire d’Analyse du Mouvement Humain and Centre d’Aide à la Performance Sportive, Université de Liège, Quartier Polytech, Allée de la Découverte 9, B52/3, 4000 Liège, Belgium. Tel.: +32 499 600 904; E-mail: julien.paulus@uliege.be.

Abstract: BACKGROUND: Isokinetic evaluation is considered the gold standard in muscle strength measurement due to its sensitivity, intra-dynamometer reproducibility and usefulness in the injury prevention screening and follow up of subjects with musculoskeletal pathologies, neurological disease or after surgical operation. However, can one switch among different isokinetic dynamometers for the purpose of knee muscles evaluation? OBJECTIVES: To comprehensively evaluate the compatibility of the isokinetic short concentric and eccentric strength evaluation protocol and of the fatigability resistance evaluation between three different isokinetic devices. METHODS: Eighteen recreationally active men underwent three isokinetic knee testing sessions on three different isokinetic devices with 7–10 days of rest between each session. Relative (Pearson’s r product-moment correlation coefficient – PCC) and absolute (standard error of measurement – SEM, Cohen effect sizes (d) and probabilistic inferences – MBI) parameters of reproducibility were determined to assess the inter-dynamometer agreement. RESULTS: For the short concentric and eccentric strength evaluation protocol, the extensors in concentric mode and the flexors in eccentric mode can be compared (eventually with transposition formulas provided) between Biodex, Con-Trex and Cybex (almost all PCC ⩾ 0.80). The DCR could be compared between Con-Trex and Cybex and between Biodex and Cybex pairs (eventually with transposition formula provided). For the fatigability resistance evaluation protocol, the total sum can be compared for extensors (eventually with transposition formulas provided) for PM for all dynamometer pairs considered and, in the case of MW, only for Biodex and Con-Trex (PCC ⩾ 0.80). CONCLUSIONS: Only some of the parameters derived either from the short concentric and eccentric strength evaluation protocol or the fatigability resistance evaluation protocol may be interchangeable providing transposition formulas are applied. Otherwise, isokinetic findings are largely system-dependent save some specific instances.

Keywords: Compatibility, reproducibility, Biodex, ConTrex, Cybex, inter-dynamometers, strength profile, fatigability, fatigability resistance evaluation protocol, transposition formulas

DOI: 10.3233/IES-193193

Journal: Isokinetics and Exercise Science, vol. 29, no. 3, pp. 247-268, 2021