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

Area of Science:

• Gerontology
• Biomechanics
• Rehabilitation Technology

Background:

• Lower limb weakness is a key indicator of fall risk and mortality in older adults.
• Assessing unilateral (one-sided) leg strength is crucial due to its impact on fall risk and clinical relevance in conditions affecting a single limb.

Purpose of the Study:

• To evaluate the intra-rater reproducibility of the Nintendo Wii Balance Board (WBB) for measuring unilateral lower limb strength.
• To compare the WBB's strength measurement capabilities against a stationary isometric muscle apparatus (SID).

Main Methods:

• A test-retest design was employed with a one-week interval between sessions.
• Thirty community-dwelling older adults (average age 69 years) participated, with strength measured in both dominant and non-dominant legs.
• Reproducibility was assessed using Intraclass Correlation Coefficient (ICC), Standard Error of Measurement (SEM), Limits of Agreement (LOA), and Smallest Real Difference (SRD). Concurrent validity was determined using Pearson Product-Moment Correlation Coefficient (PCC) against the SID.

Main Results:

• High relative reproducibility was found, with ICC values ranging from 0.919 to 0.950.
• Acceptable absolute reproducibility was indicated by SEM (2.9-4.1 kg), LOA (24.1-28.3 kg), and SRD (7.6-11.3 kg).
• Strong concurrent validity was observed, with PCC values of 0.755 for the dominant limb and 0.730 for the non-dominant limb when compared to the SID.

Conclusions:

• The Nintendo Wii Balance Board demonstrates high relative and acceptable absolute reproducibility for assessing unilateral lower limb strength in older adults.
• The WBB is a valid tool, showing strong correlation with a traditional stationary isometric muscle apparatus for this measurement.