Sports Medicine ( IF 9.3 ) Pub Date : 2024-07-06 , DOI: 10.1007/s40279-024-02069-2
Zac P Robinson 1 , Joshua C Pelland 1 , Jacob F Remmert 1 , Martin C Refalo 2 , Ivan Jukic 3 , James Steele 4 , Michael C Zourdos 1
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Background
The proximity to failure in which sets are terminated has gained attention in the scientific literature as a potentially key resistance training variable. Multiple meta-analyses have directly (i.e., failure versus not to failure) or indirectly (e.g., velocity loss, alternative set structures) evaluated the effect of proximity to failure on strength and muscle hypertrophy outcomes categorically; however, the dose–response effects of proximity to failure have not been analyzed collectively in a continuous manner.
Objective
To meta-analyze the aforementioned areas of relevant research, proximity to failure was quantified as the number of repetitions in reserve (RIR). Importantly, the RIR associated with each effect in the analysis was estimated on the basis of the available descriptions of the training interventions in each study. Data were extracted and a series of exploratory multilevel meta-regressions were performed for outcomes related to both strength and muscle hypertrophy. A range of sensitivity analyses were also performed. All models were adjusted for the effects of load, method of volume equating, duration of intervention, and training status.
Results
The best fit models for both strength and muscle hypertrophy outcomes demonstrated modest quality of overall fit. In all of the best-fit models for strength, the confidence intervals of the marginal slopes for estimated RIR contained a null point estimate, indicating a negligible relationship with strength gains. However, in all of the best-fit models for muscle hypertrophy, the marginal slopes for estimated RIR were negative and their confidence intervals did not contain a null point estimate, indicating that changes in muscle size increased as sets were terminated closer to failure.
Conclusions
The dose–response relationship between proximity to failure and strength gain appears to differ from the relationship with muscle hypertrophy, with only the latter being meaningfully influenced by RIR. Strength gains were similar across a wide range of RIR, while muscle hypertrophy improves as sets are terminated closer to failure. Considering the RIR estimation procedures used, however, the exact relationship between RIR and muscle hypertrophy and strength remains unclear. Researchers and practitioners should be aware that optimal proximity to failure may differ between strength and muscle hypertrophy outcomes, but caution is warranted when interpreting the present analysis due to its exploratory nature. Future studies deliberately designed to explore the continuous nature of the dose–response effects of proximity to failure in large samples should be considered.
中文翻译:

探索估计的阻力训练接近失败、力量增加和肌肉肥大之间的剂量-反应关系:一系列元回归
背景
集合终止的接近失败程度在科学文献中作为潜在的关键阻力训练变量而受到关注。多项荟萃分析直接 (即,失败与不失败) 或间接 (例如,速度损失、替代集合结构) 分类评估了接近失败对力量和肌肉肥大结局的影响;然而,尚未以连续的方式集体分析接近失败的剂量反应效应。
目的
为了对上述相关研究领域进行荟萃分析,将接近失败量化为储备中的重复次数 (RIR)。重要的是,与分析中每种效应相关的 RIR 是根据每项研究中训练干预的可用描述来估计的。提取数据,并针对与力量和肌肉肥大相关的结局进行一系列探索性多水平 meta 回归。还进行了一系列敏感性分析。所有模型都根据负荷、容量等同方法、干预持续时间和训练状态的影响进行了调整。
结果
力量和肌肉肥大结局的最佳拟合模型显示出中等的整体拟合质量。在所有强度的最佳拟合模型中,估计 RIR 的边际斜率的置信区间都包含零点估计,表明与强度增益的关系可以忽略不计。然而,在所有肌肉肥大的最佳拟合模型中,估计 RIR 的边际斜率为负,并且它们的置信区间不包含零点估计,这表明肌肉大小的变化随着组在更接近失败时终止而增加。
结论
接近失败和力量增加之间的剂量-反应关系似乎与与肌肉肥大的关系不同,只有后者受到 RIR 的有意义影响。在广泛的 RIR 范围内,力量增加是相似的,而肌肉肥大随着组在接近失败时终止而改善。然而,考虑到所使用的 RIR 估计程序,RIR 与肌肉肥大和力量之间的确切关系仍不清楚。研究人员和从业者应该意识到,力量和肌肉肥大结果之间的最佳失败接近度可能有所不同,但由于其探索性,在解释当前分析时需要谨慎。应考虑专门设计的未来研究,以探索大样本中接近失败的剂量反应效应的连续性。