Author(s): ISHIKAWA, M., NOBUE, A., Institution: OSAKA UNIVERSITY OF HEALTH AND SPORT SCIENCES, Country: JAPAN, Abstract-ID: 1127

INTRODUCTION:
The peripheral nerve conduction velocity (NCV) has specificity depending on the sports activities. Unlike reports from animal studies, in which muscle growth and nerve enlargement increase NCV, the mechanics of plasticity of peripheral nerve function in humans remain unclear. This study examined relationships between upper and lower limb morphology, nerve size, and NCV in sports athletes with characteristic upper and lower limb movements. If the plasticity of NCV is related to functional stress, NCV specificity exists in athletes characterized by upper and lower limb training status. However, NCV specificity does not exist in the lower limb because of the habitual stress of bipedalism.
METHODS:
The subjects were recruited from a group of athletes with well-trained upper limbs (UP group: n=21) and a group of athletes with well-trained lower limbs (LOW group: n=28). Musculoskeletal ultrasonography was used to measure the cross-sectional area (nCSA) of the nerve trunks of the ulnar nerve in both arms and that of the tibial nerve in both legs. NCV was measured by evoked electromyography. Limb circumference was measured using a measuring tape.
RESULTS:
In both arms, ulnar NCV was higher in UP than in LOW groups, but tibial NCV did not show any differences between LOW and UP groups. Unlike the upper limb, NCV of the lower limb cannot show lateral dominance. In addition, there were no significant differences in nCSA between the two groups in the upper and lower limbs, respectively. No relationship was found between nCSA and NCV in the upper and lower limbs, respectively. Lateral dominance was also found in the circumferences of the upper and lower limbs, respectively.
CONCLUSION:
In humans, the lower limbs unique functionality may result in less plasticity of peripheral nerve morphology and function. The differences in NCV and nCSA between the upper and lower limbs and between the left and right limbs were not simply related to the differences in the limb circumference but specific plasticity in neuromuscular morphology and function.