Arntz Fabian, Markov Adrian, Schoenfeld Brad J, Behrens Martin, Behm David G, Prieske Olaf, Negra Yassine, Chaabene Helmi
Department of Social- and Preventive Medicine, Research Focus Cognition Sciences, University of Potsdam, Am Neuen Palais 10, Building 12, 14469, Potsdam, Germany.
Faculty of Human Sciences, Division of Training and Movement Sciences, Research Focus Cognition Sciences, University of Potsdam, 14469, Potsdam, Germany.
Sports Med Open. 2024 Sep 28;10(1):106. doi: 10.1186/s40798-024-00772-y.
The chronic effect of static stretching (SS) on muscle hypertrophy is still unclear. This study aimed to examine the chronic effects of SS exercises on skeletal muscle hypertrophy in healthy individuals.
A systematic literature search was conducted in the PubMed, Web of Science, Cochrane Library, and SPORTDiscus databases up to July 2023. Included studies examined chronic effects of SS exercise compared to an active/passive control group or the contralateral leg (i.e., utilizing between- or within-study designs, respectively) and assessed at least one outcome of skeletal muscle hypertrophy in healthy individuals with no age restriction.
Twenty-five studies met the inclusion criteria. Overall, findings indicated an unclear effect of chronic SS exercises on skeletal muscle hypertrophy with a trivial point estimate (standardised mean difference [SMD] = 0.118 [95% prediction interval [95% PI] = - 0.233 to 0.469; p = 0.017]) and low heterogeneity (I = 24%). Subgroup analyses revealed that trained individuals (β = 0.424; 95% PI = 0.095 to 0.753) displayed larger effects compared to recreationally trained (β = 0.115; 95% PI = - 0.195 to 0.425) and sedentary individuals (β = - 0.081; 95% PI = - 0.399 to 0.236). Subanalysis suggested the potential for greater skeletal muscle hypertrophy in samples with higher percentages of females (β = 0.003, [95% confidence interval [95% CI] = - 0.000 to 0.005]). However, the practical significance of this finding is questionable. Furthermore, a greater variety of stretching exercises elicited larger increases in muscle hypertrophy (β = 0.069, [95% CI = 0.041 to 0.097]). Longer durations of single stretching exercises (β = 0.006, [95% CI = 0.002 to 0.010]), time under stretching per session (β = 0.006, [95% CI = 0.003 to 0.009]), per week (β = 0.001, [95% CI = 0.000 to 0.001]) and in total (β = 0.008, [95% CI = 0.003 to 0.013]) induced larger muscle hypertrophy. Regarding joint range of motion, there was a clear positive effect with a moderate point estimate (β = 0.698; 95% PI = 0.147 to 1.249; p < 0.001) and moderate heterogeneity (I = 43%). Moreover, findings indicated no significant association between the gains in joint range of motion and the increase in muscle hypertrophy (β = 0.036, [95% CI = - 0.123 to 0.196]; p = 0.638).
This study revealed an overall unclear chronic effect of SS on skeletal muscle hypertrophy, although interpretation across the range of PI suggests a potential modest beneficial effect. Subgroup analysis indicated larger stretching-induced muscle gains in trained individuals, a more varied selection of SS exercises, longer mean duration of single stretching exercise, increased time under SS per session, week, and in total, and possibly in samples with a higher proportion of females. From a practical perspective, it appears that SS exercises may not be highly effective in promoting skeletal muscle hypertrophy unless a higher duration of training is utilized. PROSPERO registration number: CRD42022331762.
静态拉伸（SS）对肌肉肥大的慢性影响仍不明确。本研究旨在探讨SS运动对健康个体骨骼肌肥大的慢性影响。
截至2023年7月，在PubMed、科学网、Cochrane图书馆和SPORTDiscus数据库中进行了系统的文献检索。纳入的研究考察了与主动/被动对照组或对侧腿相比，SS运动的慢性影响（即分别采用组间或组内研究设计），并评估了无年龄限制的健康个体骨骼肌肥大的至少一项结果。
25项研究符合纳入标准。总体而言，研究结果表明，慢性SS运动对骨骼肌肥大的影响不明确，点估计值微不足道（标准化均数差[SMD]=0.118[95%预测区间[95%PI]=-0.233至0.469；p=0.017]），异质性较低（I=24%）。亚组分析显示，与休闲训练者（β=0.115；95%PI=-0.195至0.425）和久坐不动者（β=-0.081；95%PI=-0.399至0.236）相比，训练有素的个体（β=0.424；95%PI=0.095至0.753）表现出更大的效果。亚分析表明，女性比例较高的样本中，骨骼肌肥大的可能性更大（β=0.003，[95%置信区间[95%CI]=-0.000至0.005]）。然而，这一发现的实际意义值得怀疑。此外，更多种类的拉伸运动能使肌肉肥大有更大程度的增加（β=0.069，[95%CI=0.041至0.097]）。单次拉伸运动持续时间更长（β=0.006，[95%CI=0.002至0.010]）、每次训练的拉伸时间（β=0.006，[95%CI=0.003至0.009]）、每周（β=0.001，[95%CI=0.000至0.001]）以及总的拉伸时间（β=0.008，[95%CI=0.003至0.013]）能诱导更大程度的肌肉肥大。关于关节活动范围，有明显的积极影响，点估计值为中等（β=0.698；95%PI=0.147至1.249；p<0.001），异质性为中等（I=43%）。此外，研究结果表明，关节活动范围的增加与肌肉肥大的增加之间无显著关联（β=0.036，[95%CI=-0.123至0.196]；p=0.638）。
本研究揭示了SS对骨骼肌肥大的总体慢性影响不明确，尽管在整个预测区间内的解释表明可能有适度的有益影响。亚组分析表明，训练有素的个体、更多种类的SS运动选择、单次拉伸运动的平均持续时间更长、每次训练、每周以及总的SS时间增加，以及可能在女性比例较高的样本中，拉伸诱导的肌肉增长更大。从实际角度来看，除非采用更长的训练时间，否则SS运动在促进骨骼肌肥大方面可能不太有效。PROSPERO注册号：CRD42022331762。
