Altheyab Abdulmajeed, Alqurashi Helal, England Timothy J, Phillips Bethan E, Piasecki Mathew
Centre of Metabolism, Ageing and Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research & National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, University of Nottingham, Derby, UK.
Faculty of College of Applied Medical Sciences, King Saud bin Abdulaziz University for Health Science, Riyadh, Saudi Arabia.
Exp Physiol. 2024 Sep 5. doi: 10.1113/EP091881.
Cross-education describes the training of one limb that leads to performance enhancements in the contralateral untrained limb, driven by neural changes rather than muscle adaptation. In this systematic review and meta-analysis, we aimed to evaluate the efficacy of cross-education (vs. a control group) via resistance exercise training (RET) for improving muscle strength in the untrained lower limb of healthy males and females. A literature search from inception to September 2023 was conducted using MEDLINE (via PubMed), the Cochrane Library (CENTRAL), Web of Science (Core Database), Scopus, EBSCO-host, and Ovid-EMBASE. Independent screening, data extraction and quality assessment were conducted. The measured outcomes were change in one-repetition maximum (1-RM) load, maximum voluntary contraction (MVC), and concentric, eccentric and isometric peak torque. Change in muscle structure (pennation angle and muscle thickness) was also analysed. A total of 29 studies were included. The pooled effect size from the random-effects model shows that cross-education significantly increased 1-RM compared to the control group (standardised mean difference (SMD): 0.59, 95% CI: 0.22-0.97; P = 0.002). Cross-education also significantly improved MVC (SMD: 0.55, 95% CI: 0.16-0.94; P = 0.006), concentric (SMD: 0.61, 95% CI: 0.39-0.84; P < 0.00001), eccentric (SMD: 0.39, 95% CI: 0.13-0.64; P = 0.003) and isometric (SMD: 0.45, 95% CI: 0.26-0.64; P < 0.00001) peak torque, each compared to the control group. When RET was categorised as eccentric or concentric, subgroup analysis showed that only eccentric training was associated with significantly increased isometric peak torque via cross-education (SMD: 0.37, 95% CI: 0.13-0.61; P = 0.003) (concentric, SMD: 0.33, 95% CI: -0.09 to 0.74; P = 0.12). This systematic review and meta-analysis emphasise the potency of cross-education for improving lower limb muscle strength. These findings have potential implications for clinical situations of impaired unilateral limb function (e.g., limb-casting or stroke). Future work exploring the mechanisms facilitating these enhancements will help to develop optimised rehabilitation protocols.
交叉训练是指对一侧肢体进行训练，从而使对侧未经训练的肢体的表现得到提升，这是由神经变化而非肌肉适应驱动的。在这项系统评价和荟萃分析中，我们旨在评估通过抗阻运动训练（RET）进行交叉训练（与对照组相比）对提高健康男性和女性未经训练的下肢肌肉力量的效果。我们使用MEDLINE（通过PubMed）、Cochrane图书馆（CENTRAL）、科学网（核心数据库）、Scopus、EBSCO主机和Ovid-EMBASE对从创刊到2023年9月的文献进行了检索。进行了独立筛选、数据提取和质量评估。测量的结果包括一次重复最大值（1-RM）负荷的变化、最大自主收缩（MVC）以及向心、离心和等长峰值扭矩。还分析了肌肉结构（羽状角和肌肉厚度）的变化。总共纳入了29项研究。随机效应模型的合并效应量表明，与对照组相比，交叉训练显著增加了1-RM（标准化均数差（SMD）：0.59，95%可信区间：0.22-0.97；P = 0.002）。交叉训练还显著改善了MVC（SMD：0.55，95%可信区间：0.16-0.94；P = 0.006）、向心（SMD：0.61，95%可信区间：0.39-0.84；P < 0.00001）、离心（SMD：0.39，95%可信区间：0.13-0.64；P = 0.003）和等长（SMD：0.45，95%可信区间：0.26-0.64；P < 0.00001）峰值扭矩，每项均与对照组相比。当将RET分为离心或向心时，亚组分析表明，只有离心训练通过交叉训练与等长峰值扭矩显著增加相关（SMD：0.37，95%可信区间：0.13-0.61；P = 0.003）（向心，SMD：0.33，95%可信区间：-0.09至0.74；P = 0.12）。这项系统评价和荟萃分析强调了交叉训练对提高下肢肌肉力量的有效性。这些发现对单侧肢体功能受损的临床情况（如肢体固定或中风）具有潜在意义。未来探索促进这些增强效果的机制的工作将有助于制定优化的康复方案。
