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Cognitive Demand Decreases Steadiness and Dexterity with Aging: 2263 Board #10 May 29, 9

Authors:
Cognitive Demand Decreases Steadiness and
Dexterity with Aging: 2263 Board #10 May
29, 9: 30 AM - 11: 00 AM
Pereira, Hugo M.; Esser, Tyler J.; Schlinder-Delap, Bonnie; Senefeld, Jonathon; Sundberg,
Christopher W.; Deering, Rita; Hunter, Sandra K. FACSM
Medicine & Science in Sports & Exercise: May 2015 - Volume 47 - Issue 5S - p 601
doi: 10.1249/01.mss.0000478351.48030.72
E-23 Free Communication/Poster - Aging Gracefully Friday, May 29, 2015, 7:30 AM - 12:30
PM Room: Exhibit Hall F
Author Information
Aging is associated with reduced steadiness during low-force static contractions and poor
dexterity. Cognitive demand imposed during a contraction will further decrease steadiness in old
adults. It is not known, however, if functional motor performance such as a dexterity task is
reduced when cognitive demand is imposed and whether it is associated with steadiness during
an isometric tasks.
PURPOSE: To (1) compare dexterity of the upper limb with and without imposition of cognitive
demand in young and old adults, and (2) determine the association between steadiness and
dexterity of the upper limb performed with and without cognitive demand.
METHODS: 46 young (21.8 ± 2.8 years, 22 men) and 32 old (67.9 ± 6 years, 15 men) adults
performed a steadiness task (i) and a dexterity task (ii) in the presence and absence of cognitive
demand (continuous subtraction by 13 or 7):(i) an isometric contraction with elbow flexor
muscles at 5% of maximum voluntary contraction for 40 seconds (steadiness task), and (ii) the
Minnesota Dexterity Test (one hand-turning and placing). Steadiness (force fluctuations) was
quantified as the coefficient of variation of force (CV = SD/mean × 100) and dexterity as the
time to manipulate 60 cylinders on a board.
RESULTS: Compared with the control task, old adults had poorer performance in the dexterity
task (longer times) when cognitive demand was imposed (98 ± 14 s vs. 147 ± 51 s) compared
with young adults (79 ± 8 s vs. 102 ± 48 s, session × age: P = 0.02). Old adults also had greater
differences in steadiness between the control and cognitive demand task (3.4 ± 2.4% vs. 6.4 ±
5.9%, respectively) compared with young adults (2.1 ± 0.8% vs. 3.2 ± 1.4%, session × age: P =
0.04). Steadiness was associated with dexterity for the control tasks (r = 0.40, P < 0.001) and for
the cognitive demand tasks (r=0.42; P<0.001) so that a larger CV was associated with poor
dexterity (longer times). Further, differences in steadiness between the control and cognitive
demand task was associated with the difference in dexterity between control and cognitive
demand (r = 0.25, P = 0.03).
CONCLUSIONS: Both steadiness and dexterity of the upper limb decreased when cognitive
demand was imposed but more so in the old than young adults. Associations between decreased
steadiness and dexterity when cognitive demand was imposed suggest a common mechanism for
the decrease in motor performance.
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