Unilateral strength training leads to muscle-specific sparing effects during opposite homologous limb immobilization

Abstract

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, [Formula: see text] = 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.

Massage as a mechanotherapy promotes skeletal muscle protein and ribosomal turnover but does not mitigate muscle atrophy during disuse in adult rats

“…The cross‐over effect from mechanical stimuli such as unilateral resistance exercise is well documented in terms of transferring muscle strength, but only few studies have reported an effect on muscle mass during disuse as recently reported in a study and a review from the same group . Importantly, to the best of our knowledge, our recent work and this study provide the only cross‐over effects reported on dynamic protein turnover induced by mechanical stimulation.…”

Cross-education does not accelerate the rehabilitation of neuromuscular functions after ACL reconstruction: a randomized controlled clinical trial

“…We have chosen for the isometric testing mode, because ACL patients would be able to perform this test with the reconstructed leg at 5 weeks post-surgery (Harput et al 2015 ). In addition, recent evidence shows that training of the non-immobilized wrist flexors in one mode results in strength preservation across all contraction modes in the non-trained wrist flexors following 4 weeks of immobilization (Andrushko et al 2017 ). Altogether, it is unlikely that we would have found a cross-education effect for strength if we had tested the quadriceps in the concentric mode.…”

“…Cross-education in addition to standard care has been shown to improve rehabilitation outcomes in patients with different orthopaedic injuries (Magnus et al 2013 ; Papandreou et al 2009 , 2013 ). To illustrate, ACL reconstructed patients had less quadriceps weakness 8 weeks after surgery (Papandreou et al 2013 ), healthy subjects revealed attenuated strength loss and atrophy of the upper extremity muscles following 3 weeks of immobilization (Andrushko et al 2017 ; Farthing et al 2009 ), and wrist fracture patients exhibited increased strength and range of motion at 12 weeks post-fracture (Magnus et al 2013 ). However, it is unknown whether cross-education of muscle force following an orthopaedic injury can improve voluntary muscle activation, postural stability, and force control—typical deficits present in the leg recovering from an ACL surgery (Nagelli and Hewett 2017 ; Telianidis et al 2014 ).…”

Contralateral effects of eccentric resistance training on immobilized arm

“…Pearce et al 6 reported that resistance training consisting of concentric-/eccentric-coupled contractions at 50%-70% of one repetition maximum (1-RM) increased maximal voluntary isometric contraction (MVIC) strength (5.8%) as well as dynamic (concentric 1-RM) strength (13.9%) of the elbow flexors in the trained arm, and maintained the MVIC and 1-RM strength of the contralateral non-trained arm after 3 weeks of sling immobilization. Andrushko et al 10 showed that contralateral maximal isokinetic eccentric training of the wrist flexors during 4 weeks of immobilization induced 33% increase in MVIC strength in the trained arm and preserved MVIC strength in the immobilized homologous muscles. Thus, it appears that dynamic resistance training of the contralateral limb is a good strategy to minimize the deleterious effects of immobilization.…”