Muscle contractile exercise through a belt electrode device prevents myofiber atrophy, muscle contracture, and muscular pain in immobilized rat gastrocnemius muscle

PLoS One. 2022 Sep 23;17(9):e0275175. doi: 10.1371/journal.pone.0275175. eCollection 2022.

Abstract

Purpose: Immobilization of skeletal muscles causes muscle atrophy, muscle contracture, and muscle pain, the mechanisms of which are related to macrophage accumulation. However, muscle contractile exercise through a belt electrode device may mitigate macrophage accumulation. We hypothesized that such exercise would be effective in preventing myofiber atrophy, muscle contracture, and muscular pain. This study tested this hypothesis in immobilized rat gastrocnemius muscle.

Materials and methods: A total of 32 rats were divided into the following control and experimental groups: immobilization (immobilized treatment only), low-frequency (LF; immobilized treatment and muscle contractile exercise with a 2 s (do) /6 s (rest) duty cycle), and high-frequency (HF; immobilized treatment and muscle contractile exercise with a 2 s (do)/2 s (rest) duty cycle). Electrical stimulation was performed at 50 Hz and 4.7 mA, and muscle contractile exercise was applied to the lower limb muscles for 15 or 20 min/session (once daily) for 2 weeks (6 times/week). After the behavioral tests, the bilateral gastrocnemius muscles were collected for analysis.

Results: The number of macrophages, the Atrogin-1 and MuRF-1 mRNA expression, and the hydroxyproline content in the HF group were lower than those in the immobilization and LF groups. The cross-sectional area (CSA) of type IIb myofibers in the superficial region, the PGC-1α mRNA expression, and the range of motion of dorsiflexion in the HF group were significantly higher than those in the immobilization and LF groups. The pressure pain thresholds in the LF and HF groups were significantly higher than that in the immobilization group, and the nerve growth factor (NGF) content in the LF and HF groups was significantly lower than that in the immobilization group.

Conclusion: Muscle contractile exercise through the belt electrode device may be effective in preventing immobilization-induced myofiber atrophy, muscle contracture, and muscular pain in the immobilized rat gastrocnemius muscle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Contracture* / etiology
  • Contracture* / prevention & control
  • Electrodes
  • Hydroxyproline / metabolism
  • Immobilization / adverse effects
  • Muscle, Skeletal* / metabolism
  • Muscle, Skeletal* / physiopathology
  • Muscular Atrophy* / etiology
  • Muscular Atrophy* / prevention & control
  • Myalgia* / etiology
  • Myalgia* / prevention & control
  • Nerve Growth Factor / metabolism
  • Physical Conditioning, Animal
  • RNA, Messenger / metabolism
  • Rats

Substances

  • RNA, Messenger
  • Nerve Growth Factor
  • Hydroxyproline

Grants and funding

No.1 ● Initials of the authors who received each award: YH ● Grant numbers awarded to each author: KAKENHI Grant No. 19K19795 ● The full name of each funder: Japan Society for the Promotion of Science ● URL of each funder website: https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/hokabunya/kenkyujigyou/index.html ● Did the sponsors or funders play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript?: The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript No.2 ● Initials of the authors who received each award: MO ● Grant numbers awarded to each author: KAKENHI Grant No. 20K20668 and 21H03291 ● The full name of each funder: Japan Society for the Promotion of Science ● URL of each funder website: https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/hokabunya/kenkyujigyou/index.html ● Did the sponsors or funders play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript?: The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript No.3 ● Initials of the authors who received each award: MO ● Grant numbers awarded to each author: research funding from ALCARE Co., Ltd. ● The full name of each funder: ALCARE Co., Ltd. ● URL of each funder website: https://www.alcare.co.jp/ ● Did the sponsors or funders play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript?: The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.