Transcranial Direct Current Stimulation Enhances Muscle Strength of Non-dominant Knee in Healthy Young Males

Panpan Lu; Nicholas J. Hanson; Lin Wen; Feng Guo; Xiaoyu Tian

doi:10.3389/fphys.2021.788719

Frontiers in Physiology (Dec 2021)

Transcranial Direct Current Stimulation Enhances Muscle Strength of Non-dominant Knee in Healthy Young Males

Panpan Lu,
Nicholas J. Hanson,
Lin Wen,
Feng Guo,
Xiaoyu Tian

Affiliations

Panpan Lu: Department of Sports, Nanchang Institute of Technology, Nanchang, China
Nicholas J. Hanson: Department of Human Performance and Health Education, College of Human Development and Education, Western Michigan University, Kalamazoo, MI, United States
Lin Wen: Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
Feng Guo: College of Human Kinesiology, Shenyang Sport University, Shenyang, China
Xiaoyu Tian: School of Physical Education, Hainan Normal University, Haikou, China

DOI: https://doi.org/10.3389/fphys.2021.788719
Journal volume & issue: Vol. 12

Abstract

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Transcranial direct current stimulation (tDCS) has been applied in training and competition, but its effects on physical performance remain largely unknown. This study aimed to observe the effect of tDCS on muscular strength and knee activation. Nineteen healthy young men were subjected to 20 min of real stimulation (2 mA) and sham stimulation (0 mA) over the primary motor cortex (M1) bilaterally on different days. The maximal voluntary contraction (MVC) of the knee extensors and flexors, and surface electromyography (sEMG) of the rectus femoris (RF) and biceps femoris (BF) were recorded before, immediately after, and 30 min after stimulation. MVC, rate of force development (RFD), and sEMG activity were analyzed before and after each condition. MVC of the non-dominant leg extensor and flexor was significantly higher immediately after real stimulation and 30 min after stimulation than before, and MVC of the non-dominant leg flexor was significantly higher 30 min after real stimulation than that after sham stimulation (P < 0.05). The RFD of the non-dominant leg extensor and flexor immediately after real stimulation was significantly higher than before stimulation, and the RFD of the non-dominant leg extensor immediately after real stimulation and 30 min after stimulation was significantly higher than that of sham stimulation (P < 0.05). EMG analysis showed the root mean square amplitude and mean power frequency (MPF) of the non-dominant BF and RF were significantly higher immediately after real stimulation and 30 min after stimulation than before stimulation, and the MPF of the non-dominant BF EMG was significantly higher 30 min after real stimulation than that after sham stimulation (P < 0.05). Bilateral tDCS of the M1 can significantly improve the muscle strength and explosive force of the non-dominant knee extensor and flexor, which might result from increased recruitment of motor units. This effect can last until 30 min after stimulation, but there is no significant effect on the dominant knee.

Published in Frontiers in Physiology

ISSN: 1664-042X (Online)
Publisher: Frontiers Media S.A.
Country of publisher: Switzerland
LCC subjects: Science: Physiology
Website: https://www.frontiersin.org/journals/physiology

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