J Korean Phys Ther.  2020 Dec;32(6):325-328. 10.18857/jkpt.2020.32.6.325.

Influence of Head-Neck Rotation on Elbow Flexor and Extensor Muscle Activity and Strength in Normal Adults

• Nam SM
• Kim SG

• KMID: 2520097
• DOI: http://doi.org/10.18857/jkpt.2020.32.6.325

Abstract

Purpose
This study examined the effects of the directions of neck rotation position on the muscle activity and strength of the elbow flexor and extensor muscle.
Methods
Forty-one healthy adults participated in this study. The subjects were asked to their elbow 90° flexion in three different neck rotations (neutral, ipsilateral, and contralateral) in the sitting position. The muscle activities of the biceps and triceps brachii muscle were measured using surface electromyography. And the muscle strength of the elbow flexor was measured using dynamometer. One way repeated measures ANOVA was used to compare the muscle activity and strength of the elbow flexor and extensor depending on the different neck turning directions.
Results
There were significant differences between contralateral neck rotation and ipsilateral neck rotation, contralateral neck rotation and neutral position. But, there was no significant difference in the triceps brachii muscle activity in comparison with the neck rotation. There were significant differences between contralateral neck rotation and ipsilateral neck rotation, contralateral neck rotation and neutral position.
Conclusion
To summarize this study, the elbow flexor and extensor muscle activity and strength was highest in the contralateral neck rotation position. In other words, it was possible to confirm the effect of Asymmetrical Tonic Neck Reflex in healthy adults whose primitive reflexes were inhibition, and head and neck positions should be considered during clinical evaluation and treatment.

Keyword

Head neck rotation; Biceps brachii; Triceps brachii; Muscle activity; Muscle strength