Affiliations: [a] Département des sciences fondamentales, Université du Québec à Chicoutimi, Saguenay, Québec, Canada
| [b] Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux du Saguenay–Lac-St-Jean, Saguenay, Québec, Canada
| [c]
Centre de recherche Charles-Le Moyne – Saguenay–Lac-Saint-Jean sur les innovations en santé, Saguenay, Québec, Canada
| [d]
Centre interdisciplinaire de recherche en réadaptation et intégration sociale (CIRRIS), Québec, Québec, Canada
| [e] Départements de réadaptation et de radiologie-médecine nucléaire, Faculté de médecine, Université Laval, Québec, Québec, Canada
| [f] Département des sciences de la santé, Université du Québec à Chicoutimi, Saguenay, Québec, Canada
Correspondence:
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Correspondence to: Elise Duchesne, pht, Ph.D, Unité d’enseignement en physiothérapie, Département des sciences de la santé, Université du Québec à Chicoutimi, 555, boul. de l’Université Chicoutimi, Québec, Canada G7H 2B1. Tel.: +1 418 545 5011 (#6148); Fax: +1 418 545 5012; E-mail: elise1_duchesne@uqac.ca.
Abstract: Background:Myotonic dystrophy type 1 (DM1) is the most prevalent degenerative neuromuscular disease in adults. Knee extensor (KE) maximal strength loss is a strong indicator of physical limitations in DM1. A reliable, precise and accessible maximal strength evaluation method needs to be validated for this slowly progressive disease. Objective:This paper aims to assess the intra-rater reliability, the standard error of measurement (SEM), the minimal detectable change (MDC), and the concurrent validity of quantified muscle testing (QMT) using a handheld dynamometer with a gold standard: the Biodex isokinetic device. Methods:Nineteen men with the adult form of DM1 participated in this study by attending 2 visits spaced by one week. The evaluation of KE muscle strength with QMT was completed on the first visit and the same QMT evaluation in addition to the maximal muscle strength evaluation using an isokinetic device were performed on the second visit. Results:The intra-rater reliability was excellent with an intraclass correlation coefficient (ICC) of 0.98 (0.96–0.99 : 95% confidence interval). SEM and MDC values were 1.05 Nm and 2.92 Nm, respectively. Concurrent validity of QMT of KE muscle group with the Biodex was also excellent with a Spearman’s correlation of ρ= 0.98. Conclusions:The excellent concurrent validity and intra-rater reliability, and the small SEM and MDC of the QMT make this test a method of choice, in either a clinical or research setting, to precisely evaluate muscle strength impairments of the KE in men with DM1.
