Influence of acute non-invasive cranial electrostimulation using the scalp acupuncture technique on overflow-potentiated handgrip strength

• Grant number: 25/01398-5
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: July 01, 2025
• End date: February 28, 2029
• Field of knowledge: Health Sciences - Physiotherapy and Occupational Therapy
• Principal Investigator: João Eduardo de Araujo
• Grantee: Kelly Zhang
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Introduction: In musculoskeletal rehabilitation, different techniques are used to optimize motor control. The biological phenomenon that has significant implications for this goal is motor overflow. This phenomenon can be activated to enhance the motor response of contralateral homologous muscles during strength activities at an intensity of at least 70% of maximum voluntary isometric capacity (MVIC). In the context of motor rehabilitation, scalp acupuncture, a contemporary technique that integrates the concepts of Traditional Chinese Medicine, uses non-invasive electrical stimulation of the skull with current concepts of the anatomical and functional areas of the cerebral cortex. Objective: To analyze the influence of electrical stimulation through scalp acupuncture on the generation of handgrip strength with or without the induction of overflow, during an isometric activity of index finger flexion of healthy participants (Experiment 1) and post-stroke patients (Experiment 2). Material and Methods: The study will include 150 healthy subjects aged between 18 and 59 years (Experiment 1), and 150 ischemic post-stroke patients aged between 40 and 79 years (Experiment 2), of both sexes. In both experiments the participants will be divided into five groups: Control (C), Scalp Acupuncture (SA), Overflow (O), Sham Scalp Acupuncture with Overflow (SAsO) and Scalp Acupuncture with Overflow (SAO). Using a hand dynamometer, all groups will undergo a handgrip protocol consisting of 3 isometric handgrip contractions (6 seconds with a 9-second interval) on the right and, after 60 seconds, on the left, forming the baseline (BL). In C, after 20 minutes, the protocol that determined the BL will be repeated; in SA, in addition to the BL, electrical stimulation will be performed by inserting acupuncture needles in the middle ¿ of the primary motor area on the left, after 20 minutes, the needles will be removed and the handgrip protocol will be repeated. In the O group, after 20 minutes, the overflow protocol will be carried out concomitantly with the BL protocol, consisting of 3 index finger flexion contractions concomitantly with 3 handgrip contractions; in the SAsO and SAO groups, in addition to BL, electrical stimulation or sham stimulation will be carried out by inserting acupuncture needles in the middle ¿ of the left primary motor area, after 20 minutes, the needles will be removed and the overflow protocol will be carried out. In the overflow induction groups, 10 minutes after the conclusion of the respective protocols, the index finger flexion MIVC will be measured to compare with the MIVC obtained during the protocols. For statistical analysis, a multiple comparison analysis of variance (MANOVA) will be used (p<0.05).