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Laterality of Accuracy of Grip and Elbow Flexion Force Exertions and Their Differences

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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