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

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2023-12
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Language
en
Pages
10
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SCANDINAVIAN JOURNAL OF MEDICINE AND SCIENCE IN SPORTS
Abstract
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°; flexed: +45°; extended: −45°) affects maximal handgrip strength (HGSmax) and the motor evoked potentials (MEP) amplitudes during rest and active muscle contractions. HGSmax was higher at 0° (133%) than at −45° (93.6%; p < 0.001) and +45° (73.9%; p < 0.001). MEP amplitudes were higher for the FCR at +45° (83.6%) than at −45° (45.2%; p = 0.019) and at +45° (156%; p < 0.001) and 0° (146%; p = 0.014) than at −45° (106%) at rest and active condition, respectively. Regarding the ECR, the MEP amplitudes were higher at −45° (113%) than at +45° (60.8%; p < 0.001) and 0° (72.6%; p = 0.008), and at −45° (138%) than +45° (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.
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Funding Information: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior ‐ Brasil (CAPES) ‐ Finance Code 001. VHS received funding from the Jane and Aatos Erkko Foundation, the Academy of Finland (decision #349985), and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement #810377). BR was funded by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) (grant #2022/00582‐9) and by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (grant #141723/2015‐7). RHM was funded by CNPq (grant #141056/2018‐5) and FAPESP (grant #2022/14526‐3). This research was supported by CNPq (grant #310397/2021), Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) (CNE #202.785/2018 and E‐26/010.002418/2019), and Financiadora de Estudos e Projetos (FINEP); PROINFRA HOSPITALAR grant #18.569‐8. This research is also part of the activities of FAPESP's Research, Innovation and Dissemination Center for Neuromathematics‐NeuroMat (FAPESP grant #2013/07699‐0). | openaire: EC/H2020/810377/EU//ConnectToBrain
Keywords
handgrip strength, motor evoked potentials, transcranial magnetic stimulation, wrist joint
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Citation
Moraes , V H , Vargas , C D , Ramalho , B L , Matsuda , R H , Souza , V H , Imbiriba , L A & Garcia , M A C 2023 , ' Effect of muscle length in a handgrip task on corticomotor excitability of extrinsic and intrinsic hand muscles under resting and submaximal contraction conditions ' , SCANDINAVIAN JOURNAL OF MEDICINE AND SCIENCE IN SPORTS , vol. 33 , no. 12 , pp. 2524-2533 . https://doi.org/10.1111/sms.14477