Unilateral lower limb strength assessed using the Nintendo Wii Balance Board: a simple and reliable method

Lower limb weakness is an important risk factor for fall accidents and a predictor for all-cause mortality among older adults. Unilateral whole-lower limb strength may be a better measure of fall risk than the bilateral measure. In addition, a number of clinical conditions affect only one leg, and thus this type of assessment is relevant in clinical settings.

To explore the intra-rater reproducibility of the Nintendo Wii Balance Board (WBB) to measure unilateral whole-lower limb strength and to compare the method with stationary isometric muscle apparatus (SID).

Intra-rater test-retest design with 1 week between sessions. Thirty community-dwelling older adults (69 ± 4.2 years) were enrolled and examined for maximum lower limb strength in their dominant and non-dominant leg. Intraclass correlation coefficient (ICC) was calculated to describe relative reproducibility, while standard error of measurement (SEM), limits of agreement (LOA) and smallest real difference (SRD) were calculated to describe absolute reproducibility between test sessions. Concurrent validity with the SID was explored using the Pearson product-moment correlation coefficient (PCC).

No systematic difference was observed between test sessions. ICC was 0.919-0.950 and SEM, LOA and SRD was 2.9-4.1 kg, 24.1-28.3 kg and 7.6-11.3 kg, respectively. Further, the PCC was 0.755 and 0.730 for the dominant limb and the non-dominant limb, respectively.

A high relative and an acceptable absolute reproducibility was seen when using the Nintendo Wii Balance Board for testing unilateral lower limb strength in community-dwelling older adults. The WBB correlated strongly with the SID.