Aging effects on single- leg standing balance performance strategies

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Introduction: The majority of studies that investigated effects of biological aging on balance performance included adults and seniors. Children were rarely considered. Ankle muscle coordination can rely on modulation of agonists’ activation and co- activation of opposed muscles. While increasing active joint stiffness by higher co -activation constrains postural deviations (Warnica et al., 2014) , a small amount of sway is accepted through muscle activation modulation. Thus, the present study aimed at examining aging effects on postural strategies during standing balance in healthy and acti ve children, adults and seniors . Methods: Seventy -eight volun tarily participating children (10 boys, 9 girls, age: 9- 10 years), adults (20 males, 10 females, age: 20 -25 years) and seniors (16 males, 13 females, age: 53- 79 years) were recruited. Standing balance was measured via 30 s of single -leg sta nce at the domin ant leg while standing on a force plate (GK -1000, Mittweida). The best trial (lowest total center of pressure (COP) path length displacement) was considered for further analyses. The v elocity (COPv) of COP displacements served as an outcome measure of stan ding balance performance. Corresponding Surface EMG (Imago, Freiburg) data of the selected trials were used to characterize tibialis anterior (TA) and soleus (SO) muscle activation and co -activation (Talis et al., 2008) . Muscle activation is expressed as the coefficient of variation (sd/mean ×100) of the EMG envelope. Age -group effects on outcome variables were verified using a multivariate analysis of variance (MANOVA) . To estimate practical relevance , effect sizes (partial eta squared, η p ²) were calculated. Tukey -HSD post hoc tests were carried out to verify group differences. Results: The initial MANOVA revealed a large effect ( F = 8.6 , p < 0.001, η p 2 = 0.32 ) of age - group on the four outcome variabl es. Subsequent univariate F tests found the effects to be significant for COPv ( F = 19.5 , p < 0.001, η p 2 = 0.34 ), TA ( F = 9.8 , p < 0.001, η p 2 = 0.21), SO ( F = 6.4 , p < 0.0 1, η p 2 = 0.15 ) and for TA over SO ( F = 15.7 , p < 0.00 1, η p 2 = 0.30). Follow -up post h oc comparisons indicated significant differences between children (12 mm/s (3), mean (SD)) and adults (9 mm/s (2)) , adults and seniors ( 15 mm/s (5) ) as well as seniors and children ( p < 0.02). For TA over SO , both children and seniors differed from lower adults’ levels ( p < 0.001 ). TA modulation was significantly higher in children and adults as compared with seniors ( p < 0.002) , whereas SO modulation revealed lowest values in adults which differed from children only ( p = 0.002). Discussion: P repubescent children’ s neuromuscular capacities, among others, are not fully developed. In contrast, aging is known to affect neuromuscular performance in seniors . Our age -related results of postural steadiness (COPv) and ankle muscle co -activation confirm this u -shaped association. Children and adults use mainly activation modulation of TA to correct postural deviations, whereas seniors’ TA capacity is diminished . Increased postural sway is compensated by children through a more flexible neuromuscular system. Aging was mainly characterized via reduced TA modulation in seniors . Thus seniors presum ably use higher total activity of shank muscles and/or proximal strategies to realize difficult postural tasks like single -leg stance .
Titel8th SGS Annual Meeting : Book of Abstracts
Herausgeber/inSportwissenschaftliche Gesellschaft der Schweiz
PublikationsstatusVeröffentlicht - 18.02.2016
VeranstaltungJahrestagung der Sportwissenschaftlichen Gesellschaft der Schweiz (SGS) - Bern, Schweiz
Dauer: 18.02.201619.02.2016
Konferenznummer: 8

ID: 3425255

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