Laterality refers to the preference most
humans show for one side of their body over the other. It is particularly
noticeable in functions of fingers, such as in using a spoon or writing
letters, and is considered to occur from more preferential and frequent use of
one hand in daily activities.
Some studies have
shown that laterality in accuracy of force exertion differs even in the same
upper limbs. This is why agonist muscles contributing to the achievement of
each movement seem to differ. Agonist muscle is a muscle group in the fingers
and antebrachium for handgrip and in biceps brachii for elbow flexion. Hence,
laterality in accuracy of force exertion may differ between handgrip and elbow
flexion in spite of movement in the same upper limb. So this study aimed to
examine the accuracy of grip and elbow flexion force exertions for each demand
value and the difference between movements.
Participants were
22 right-armed healthy young males (mean age 22.5 ± 5.6 years old, mean height
170.9 ± 5.8 cm, mean weight 62.4 ± 9.4 kg). Demand values of 25%, 50%, and 75%
of maximum voluntary contraction (MVC) were selected. Using subjective
judgment, participants were requested to exert each arm’s handgrip and elbow
flexion forces for each demand value. Evaluation parameters were differences
(errors) between demand and exertion values and their total error.
Results of two-way
ANOVA (laterality and demand value) showed a significant interaction in grip
movement. In results of multiple comparisons, an error in 25% MVC was greater
than that in 50% MVC and 75% MVC in the non-dominant arm. For elbow flexion
movement, a significant difference was found in a demand value factor, and
results of multiple comparisons showed that error was greater in the order of
25% MVC, 50% MVC, and 75% MVC in the non-dominant arm; in the dominant arm,
error was greater in 25% MVC than in 50% MVC and 75% MVC. Total error showed significant
interaction and was greater in elbow flexion strength than in grip strength in
the non-dominant arm.
In conclusion, the
non-dominant arm had less error with greater demand values in grip and elbow
flexion strengths, and laterality was not found in either movement at each
demand value. Accuracy of force exertion in elbow flexion strength was inferior
to grip strength.
Article by Hiroki
Aoki and Shin-Ichi Demura, from Japan.
Full access: http://mrw.so/3Q8VhR
Image by bvstuber,
from Flickr-cc.
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