Title

Are repeated single-limb heel raises and the manual muscle test associated with peak plantar flexion force in people with inclusion body myositis?

ORCiD

Davenport: 0000-0001-5772-7727

Document Type

Article

Publication Title

Physical Therapy

ISSN

0031-9023

Volume

94

Issue

4

DOI

10.2522/ptj.20130100

First Page

543

Last Page

552

Publication Date

4-1-2014

Abstract

Background. Repeated heel raises have been proposed as a method of ankle plantar-flexor strength testing that circumvents the limitations of manual muscle testing (MMT). Objective. The study objective was to examine the relationships among ankle plantar-flexion isometric maximum voluntary contraction (MVC), repeated single-limb heel raises (SLHRs), and MMT in people with myositis. Design. This was a cross-sectional study with a between-group design. The ability to complete 1 SLHR determined group assignment (SLHR group, n=24; no-SLHR group, n=19). Methods. Forty-three participants with myositis (13 women; median age=64.9 years) participated. Outcome measures included MVC, predicted MVC, Kendall MMT, and Daniels-Worthingham MMT. Results. The Kendall MMT was unable to detect significant ankle plantar-flexor weakness established by quantitative methods and was unable to discriminate between participants who could and those who could not perform the SLHR task. Ankle plantar-flexion MVC was not associated with the number of heel-raise repetitions in the SLHR group (pseudo R2=.13). No significant relationship was observed between MVC values and MMT grades in the SLHR and no-SLHR groups. However, a moderate relationship between MVC values and MMT grades was evident in a combined-group analysis (ρ=.50 -.67). Limitations. The lower half of both MMT grading scales was not represented in the study despite the profound weakness of the participants. Conclusions. Both Kendall MMT and Daniels-Worthingham MMT had limited utility in the assessment of ankle plantar-flexor strength. Repeated SLHRs should not be used as a proxy measure of ankle plantar-flexion MVC in people with myositis.