Abstract
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
.
Originalsprache | Englisch |
---|---|
Titel | 8th SGS Annual Meeting : Book of Abstracts |
Seitenumfang | 1 |
Herausgeber (Verlag) | Sportwissenschaftliche Gesellschaft der Schweiz |
Erscheinungsdatum | 18.02.2016 |
Seiten | 68 |
Publikationsstatus | Veröffentlicht - 18.02.2016 |
Veranstaltung | Jahrestagung der Sportwissenschaftlichen Gesellschaft der Schweiz (SGS) - Bern, Schweiz Dauer: 18.02.2016 → 19.02.2016 Konferenznummer: 8 |