Handgrip force steadiness in young and older adults: a reproducibility study

Abstract

BackgroundForce steadiness is a quantitative measure of the ability to control muscle tonus. It is an independent predictor of functional performance and has shown to correlate well with different degrees of motor impairment following stroke. Despite being clinically relevant, few studies have assessed the validity of measuring force steadiness. The aim of this study was to explore the reproducibility of handgrip force steadiness, and to assess age difference in steadiness.MethodIntrarater reproducibility (the degree to which a rating gives consistent result on separate occasions) was investigated in a test-retest design with seven days between sessions. Ten young and thirty older adults were recruited and handgrip steadiness was tested at 5%, 10% and 25% of maximum voluntary contraction (MVC) using Nintendo Wii Balance Board (WBB). Coefficients of variation were calculated from the mean force produced (CVM) and the target force (CVT). Area between the force curve and the target force line (Area) was also calculated. For the older adults we explored reliability using intraclass correlation coefficient (ICC) and agreement using standard error of measurement (SEM), limits of agreement (LOA) and smallest real difference (SRD).ResultsA systematic improvement in handgrip steadiness was found between sessions for all measures (CVM, CVT, Area). CVM and CVT at 5% of MVC showed good to high reliability, while Area had poor reliability for all percentages of MVC. Averaged ICC for CVM, CVT and Area was 0.815, 0.806 and 0.464, respectively. Averaged ICC on 5%, 10%, and 25% of MVC was 0.751, 0.667 and 0.668, respectively. Measures of agreement showed similar trends with better results for CVM and CVT than for Area. Young adults had better handgrip steadiness than older adults across all measures.ConclusionThe CVM and CVT measures demonstrated good reproducibility at lower percentages of MVC using the WBB, and could become relevant measures in the clinical setting. The Area measure had poor reproducibility. Young adults have better handgrip steadiness than old adults.

Swallowing Pressure Variability as a Function of Pharyngeal Region, Bolus Volume, Age, and Sex

“…16 In pressure generation and modulation tasks, older adults have greater muscle force variability in both upper and lower extremities. 10,[17][18][19] As tasks become more complex and less automatic, movement variability also tends to increase. 12,20,21 Alternatively, as effort in applying pressure increases, variability tends to decrease.…”

“…12,20,21 Alternatively, as effort in applying pressure increases, variability tends to decrease. 11,17,19,22 Furthermore, movement variability systematically increases during motor learning and decreases as one tries new strategies and masters a skill. 18,23 Movement variability during swallowing is likely also affected by task differences (e.g., bolus volume) as well as individual differences (e.g., age).…”

“…Older individuals also show greater movement variability in upper extremity aiming tasks 14,15 and fine motor control 16 . In pressure generation and modulation tasks, older adults have greater muscle force variability in both upper and lower extremities 10,17–19 . As tasks become more complex and less automatic, movement variability also tends to increase 12,20,21 .…”

“…As tasks become more complex and less automatic, movement variability also tends to increase 12,20,21 . Alternatively, as effort in applying pressure increases, variability tends to decrease 11,17,19,22 . Furthermore, movement variability systematically increases during motor learning and decreases as one tries new strategies and masters a skill 18,23 …”

Reference data on hand grip and lower limb strength using the Nintendo Wii balance board: a cross-sectional study of 354 subjects from 20 to 99 years of age

“…The method has a good validity when compared against the reference standards for HGS and LS [20, 23, 27]. It has also been shown to be valid for testing reaction time [28, 29], muscle force steadiness [30], and postural balance in younger [31] and older adults [32, 33]. Hence, the WBB has the potential to provide accurate assessment of several physiological measures, previously unavailable in a community setting.…”