Effect of muscle length in a handgrip task on corticomotor excitability of extrinsic and intrinsic hand muscles under resting and submaximal contraction conditions

Autor(es)

Moraes, Victor Hugo ; Vargas, Claudia D. ; Ramalho, Bia L. ; Matsuda, Renan H. ; Souza, Victor H. ; Imbiriba, Luis Aureliano ; Garcia, Marco Antonio C.

• Tipo de documento: Artigo Científico
• Fonte: SCANDINAVIAN JOURNAL OF MEDICINE & SCIENCE IN SPORTS; v. N/A, p. 10-pg., 2023-08-29.

Resumo

The neurophysiological mechanisms underlying muscle force control for different wrist postures still need to be better understood. To further elucidate these mechanisms, the present study aimed to investigate the effects of wrist posture on the corticospinal excitability by transcranial magnetic stimulation (TMS) of extrinsic (flexor [FCR] and extensor carpi radialis [ECR]) and intrinsic (flexor pollicis brevis (FPB)) muscles at rest and during a submaximal handgrip strength task. Fourteen subjects (24.06 +/- 2.28 years) without neurological or motor disorders were included. We assessed how the wrist posture (neutral: 0 degrees; flexed: +45 degrees; extended: -45 degrees) affects maximal handgrip strength (HGS(max)) and the motor evoked potentials (MEP) amplitudes during rest and active muscle contractions. HGS(max) was higher at 0 degrees (133%) than at -45 degrees (93.6%; p < 0.001) and +45 degrees (73.9%; p < 0.001). MEP amplitudes were higher for the FCR at +45 degrees (83.6%) than at -45 degrees (45.2%; p = 0.019) and at +45 degrees (156%; p < 0.001) and 0 degrees (146%; p = 0.014) than at -45 degrees (106%) at rest and active condition, respectively. Regarding the ECR, the MEP amplitudes were higher at -45 degrees (113%) than at +45 degrees (60.8%; p < 0.001) and 0 degrees (72.6%; p = 0.008), and at -45 degrees (138%) than +45 degrees (96.7%; p = 0.007) also at rest and active conditions, respectively. In contrast, the FPB did not reveal any difference among wrist postures and conditions. Although extrinsic and intrinsic hand muscles exhibit overlapping cortical representations and partially share the same innervation, they can be modulated differently depending on the biomechanical constraints. (AU)

• Processo FAPESP: 22/00582-9 - Recuperando modelos de árvore de contexto produzidos por sequências estruturadas de pulsos de TMS aplicadas no córtex motor primário.
• Beneficiário: Bia Ramalho dos Santos Lima
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 13/07699-0 - Centro de Pesquisa, Inovação e Difusão em Neuromatemática - NeuroMat
• Beneficiário: Oswaldo Baffa Filho
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs
• Processo FAPESP: 22/14526-3 - Um modelo de árvore de contexto pode prever a excitabilidade do córtex motor primário? Um estudo de estimulação magnética transcraniana robotizada navegada por eletromiografia e eletroencefalografia.
• Beneficiário: Renan Hiroshi Matsuda
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado