Clinimetric evaluation of five clinically feasible measures of the leg extensor muscle strength in neurological rehabilitation settings

Abstract

A gold-standard clinical measure of leg muscle strength has not been established. Therefore, the aim of this study was to evaluate clinimetric properties of five clinically feasible measures of lower-limb extensor muscle strength in neurological rehabilitation settings. This was a cross-sectional observational study of 36 participants with leg weakness as a result of a neurological condition/injury. Participants were recruited across a range of walking abilities, from non- to independently ambulant. Each was assessed using each of the following five measures: manual muscle test (MMT), hand-held dynamometry (HHD), seated single leg press one repetition maximum (1RM), functional sit-to-stand (STS) test and seated single leg press measured with a load cell. Each clinical measure was evaluated for its discriminative ability, floor/ceiling effects, test-retest reliability and clinical utility. The load cell and HHD were the most discriminative of the tests and were also resistant to floor/ceiling effects; however, the load cell was superior to the HHD when compared for its clinical utility. The MMT/STS tests received perfect scores for clinical utility, although similar to the 1RM test, they were susceptible to floor and ceiling effects. The load cell leg press test was the only measure of lower limb strength to satisfy all four clinimetric properties. Implications for clinical practice include, firstly, that strength tests available to clinicians vary in their clinimetric properties. Secondly, the functional status of the person will determine selection of the best clinical strength test. And lastly, load cell device technology should be considered for clinical strength assessments.