Unilateral Strength Training Leads to Muscle-Specific Sparing Effects During Opposite Homologous Limb Immobilization

Jeffrey Wilson — Tue, 09 Oct 2018 19:43:16 +0000

Date Added:

October 9, 2018

Journal/Publication:

Journal of Applied Physiology

Publisher:

American Physiological Society

Publication Date:

April 1, 2018

Issue:

Volume:

124

Pages:

866-876

URL:

Unilateral Strength Training Leads to Muscle-Specific Sparing Effects During Opposite Homologous Limb Immobilization

Type:

Clinical Research Results

Format:

Article

DOI (1):

10.1152/japplphysiol.00971.2017

Keywords

strength training

resistance training

PMID (1):

29357520

MeSH

resistance training

wrist

forearm

This study suggests that for people in casts, contralateral strengthening exercises to preserve strength and reduce atrophy in the immobilized extremity.

Free full text

Cross education (CE) occurs after unilateral training whereby performance of the untrained contralateral limb is enhanced. A few studies have shown that CE can preserve or “spare” strength and size of an opposite immobilized limb, but the specificity (i.e., trained homologous muscle and contraction type) of these effects is unknown. The purpose was to investigate specificity of CE “sparing” effects with immobilization. The nondominant forearm of 16 participants was immobilized with a cast, and participants were randomly assigned to a resistance training (eccentric wrist flexion, 3 times/week) or control group for 4 weeks. Pre- and posttesting involved wrist flexors and extensors eccentric, concentric and isometric maximal voluntary contractions (via dynamometer), muscle thickness (via ultrasound), and forearm muscle cross-sectional area (MCSA; via peripheral quantitative computed tomography). Only the training group showed strength preservation across all contractions in the wrist flexors of the immobilized limb (training: −2.4% vs. control: −21.6%; P = 0.04), and increased wrist flexors strength of the nonimmobilized limb (training: 30.8% vs. control: −7.4%; P = 0.04). Immobilized arm MCSA was preserved for the training group only (training: 1.3% vs. control: −2.3%; P = 0.01). Muscle thickness differed between groups for the immobilized (training: 2.8% vs. control: −3.2%; P = 0.01) and nonimmobilized wrist flexors (training: 7.1% vs. control: −3.7%; P = 0.02). Strength preservation was nonspecific to contraction type (P = 0.69, ηp2 = 0.03) yet specific to the trained flexors muscle. These findings suggest that eccentric training of the nonimmobilized limb can preserve size of the immobilized contralateral homologous muscle and strength across multiple contraction types.

NEW & NOTEWORTHY Unilateral strength training preserves strength, muscle thickness, and muscle cross-sectional area in an opposite immobilized limb. The preservation of size and strength was confined to the trained homologous muscle group. However, strength was preserved across multiple contraction types.

Author/s:

Andrushko, Justin W., Lanovaz, Joel L., Björkman, Kelsey M., Kontulainen, Saija A., Farthing, Jonathan P.