Programa de Pós-Graduação em Ciências da Reabilitação e Desempenho Físico-Funcional, Faculdade de Fisioterapia, Universidade Federal de Juiz de Fora, Juiz de Fora, MG, Brazil.
Grupo de Estudos em Neuro Biomecânica, Faculdade de Fisioterapia, Universidade Federal de Juiz de Fora, Juiz de Fora, MG, Brazil.
J Appl Biomech. 2024 Jun 26;40(4):316-322. doi: 10.1123/jab.2022-0314. Print 2024 Aug 1.
Different forearm postures can modulate corticospinal excitability. However, there is no consensus on whether handedness plays a role in such a mechanism. This study investigated the effects of 3 forearm postures (pronation, neutral, and supination) on the corticospinal excitability of muscles from the dominant and nondominant upper limbs. Surface electromyography was recorded from the abductor digiti minimi, flexor pollicis brevis, and flexor carpi radialis from both sides of 12 right-handed volunteers. Transcranial magnetic stimulation pulses were applied to each muscle's hotspot in both cerebral hemispheres. Motor-evoked potential peak-to-peak amplitude and latency and resting motor threshold were measured. The data were evaluated by analysis of variance. The level of significance was set at 5%. The resting motor threshold was similar for the 3 muscles and both sides. Motor-evoked potential peak-to-peak amplitude from flexor pollicis brevis was lower during supination, and the dominant upper limb latency was longer. The flexor carpi radialis presented lower motor-evoked potential peak-to-peak amplitudes for neutral and shorter latencies during supination. Abductor digiti minimi seemed not to be affected by posture or side. Different muscles from dominant and nondominant sides may undergo corticospinal modulation, even distally localized from a particular joint and under rest.
不同的前臂姿势可以调节皮质脊髓兴奋性。然而，对于利手是否在这种机制中起作用，尚无共识。本研究调查了 3 种前臂姿势（旋前、中立和旋后）对优势侧和非优势侧上肢肌肉的皮质脊髓兴奋性的影响。12 名右利手志愿者的双侧小指展肌、拇指短展肌和桡侧腕屈肌记录表面肌电图。在每个肌肉的大脑半球热点应用经颅磁刺激脉冲。测量运动诱发电位峰峰值幅度和潜伏期以及静息运动阈值。数据通过方差分析进行评估。显著性水平设为 5%。3 种肌肉和两侧的静息运动阈值相似。旋后时，拇指短展肌的运动诱发电位峰峰值幅度较低，优势上肢潜伏期较长。桡侧腕屈肌在中立位时运动诱发电位峰峰值幅度较低，而旋后时潜伏期较短。小指展肌似乎不受姿势或侧别的影响。来自优势侧和非优势侧的不同肌肉可能会发生皮质脊髓调节，即使是特定关节的远端且处于休息状态。
