Intra-rater reliability of hallux flexor strength measures using the Nintendo Wii Balance Board

Functional assessments of foot strength: a comparative and repeatability study

Background

Evaluating the strength of the small muscles of the foot may be useful in a variety of clinical applications but is challenging from a methodology standpoint. Previous efforts have focused primarily on the functional movement of toe flexion, but clear methodology guidelines are lacking. A novel foot doming test has also been proposed, but not fully evaluated. The purposes of the present study were to assess the repeatability and comparability of several functional foot strength assessment techniques.

Methods

Forty healthy volunteers were evaluated across two testing days, with a two-week doming motion practice period between them. Seven different measurements were taken using a custom toe flexion dynamometer (seated), custom doming dynamometer (standing), and a pressure mat (standing). Measurements from the doming dynamometer were evaluated for reliability (ICCs) and a learning effect (paired t-tests), while measurements from the toe flexion dynamometer and pressure mat were evaluated for reliability and comparability (correlations). Electromyography was also used to descriptively assess the extent of muscle isolation in all measurements.

Results

Doming showed excellent within-session reliability (ICCs > 0.944), but a clear learning effect was present, with strength (p < 0.001) and muscle activity increasing between sessions. Both intrinsic and extrinsic muscles were engaged during this test. All toe flexion tests also showed excellent reliability (ICCs > 0.945). Seated toe flexion tests using the dynamometer were moderately correlated to standing toe flexion tests on a pressure mat (r > 0.54); however, there were some differences in muscle activity. The former may better isolate the toe flexors, while the latter appeared to be more functional for many pathologies. On the pressure mat, reciprocal motion appeared to display slightly greater forces and reliability than isolated toe flexion.

Conclusions

This study further refines potential methodology for foot strength testing. These devices and protocols can be duplicated in the clinic to evaluate and monitor rehabilitation progress in clinical populations associated with foot muscle weakness.

An exploratory study examining factors underpinning postural instability in older adults with idiopathic neck pain

There is limited understanding of potential mechanisms underpinning postural control deficits in people with neck pain. This study examined several characteristics that might explain impaired postural stability in a group of older adults with neck pain, and compared the results in this cohort with that of asymptomatic controls. In this cross-sectional study we compared physical activity, lower limb motor and sensory function, vestibular and visual function, falls efficacy and dizziness handicap in 84 older adults with (n=35, age 69.6±6.3) and without (n=49, age 69.4±4.7) idiopathic neck-pain. Additionally, dynamic balance was assessed using the dynamic gait index (DGI) and standard and wavelet analysis of static balance was computed after data capture. Physical activity levels, lower limb motor and sensory function, vestibular function and visual contrast sensitivity were not different between groups (p>0.05). The neck-pain group demonstrated higher falls efficacy (p=0.01), greater levels of dizziness handicap (p<0.01), and higher CoP velocity measures in the moderate (1.56-6.25Hz) and low (0.39-1.56Hz) frequency bandwidths. Our results suggest that neck-pain induced postural control deficits in older adults may not be associated with the physical activity levels, lower limb motor and sensory function, or vestibular and visual function. Inferring from wavelet analysis results, we speculated that sensory re-weighting may have occurred to compensate for the deficits in neck proprioception. Further research is warranted to determine neck specific mechanisms underpinning postural control dysfunction in neck pain.

Reliability of doming and toe flexion testing to quantify foot muscle strength

Background

Quantifying the strength of the intrinsic foot muscles has been a challenge for clinicians and researchers. The reliable measurement of this strength is important in order to assess weakness, which may contribute to a variety of functional issues in the foot and lower leg, including plantar fasciitis and hallux valgus. This study reports 3 novel methods for measuring foot strength – doming (previously unmeasured), hallux flexion, and flexion of the lesser toes.

Methods

Twenty-one healthy volunteers performed the strength tests during two testing sessions which occurred one to five days apart. Each participant performed each series of strength tests (doming, hallux flexion, and lesser toe flexion) four times during the first testing session (twice with each of two raters) and two times during the second testing session (once with each rater). Intra-class correlation coefficients were calculated to test for reliability for the following comparisons: between raters during the same testing session on the same day (inter-rater, intra-day, intra-session), between raters on different days (inter-rater, inter-day, inter-session), between days for the same rater (intra-rater, inter-day, inter-session), and between sessions on the same day by the same rater (intra-rater, intra-day, inter-session).

Results

ICCs showed good to excellent reliability for all tests between days, raters, and sessions. Average doming strength was 99.96 ± 47.04 N. Average hallux flexion strength was 65.66 ± 24.5 N. Average lateral toe flexion was 50.96 ± 22.54 N.

Conclusions

These simple tests using relatively low cost equipment can be used for research or clinical purposes. If repeated testing will be conducted on the same participant, it is suggested that the same researcher or clinician perform the testing each time for optimal reliability.

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

BACKGROUND

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.

AIM

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).

METHOD

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).

RESULTS

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.

CONCLUSION

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.