Eight-week neuromuscular electrical stimulation training produces muscle strength gains and hypertrophy, and partial muscle quality improvement in the knee extensors

Ryota Akagi, Yusuke Miyokawa, Daigo Shiozaki, Yoshinari Yajima, Koki Yamada, Kosuke Kano, Yuto Hashimoto, Takanobu Okamoto, Soichi Ando

Research output: Contribution to journalArticlepeer-review

Abstract

This study investigated the effect of an 8-week neuromuscular electrical stimulation (NMES) training programme (3 days/week) on muscle quantity and quality and single-joint performance in the knee extensors. Thirty-nine untrained young male participants were randomly assigned to NMES training (n = 21) and control (n = 18) groups. The 8-week NMES training induced significant increase in the isometric maximal voluntary contraction (MVC) torque of the knee extensors (≈9.3%), muscle volume of the individual and entire quadriceps muscles determined by magnetic resonance imaging (≈3.3%–6.4%), and a significant decrease in the ultrasound echo intensity of the vastus lateralis (≈−4.0%); however, hypertrophy of the vastus intermedius (i.e., the deep muscle) was limited (≈3.3%). In the NMES training group, the repeated measures correlations of the isometric MVC torque with the muscle volume of the entire quadriceps muscle and each quadriceps muscle were significant (rrm (20) = 0.551–0.776), whereas that of the isometric MVC torque with the ultrasound echo intensity of the vastus lateralis was not significant. These findings suggest that NMES training produces muscle strength gains, muscle hypertrophy, and partial muscle quality improvement and that the NMES training-induced muscle strength gains is caused by muscle hypertrophy in the knee extensors.

Original languageEnglish
Pages (from-to)2209-2228
Number of pages20
JournalJournal of Sports Sciences
Volume41
Issue number24
DOIs
Publication statusPublished - 2023

Keywords

  • Isometric torque
  • echo intensity
  • isotonic power
  • muscle volume
  • shear modulus

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Fingerprint

Dive into the research topics of 'Eight-week neuromuscular electrical stimulation training produces muscle strength gains and hypertrophy, and partial muscle quality improvement in the knee extensors'. Together they form a unique fingerprint.

Cite this