BACKGROUND Ischemic preconditioning (IPC) is purported to have beneficial effects on athletic performance, although findings are inconsistent, with some studies reporting placebo effects. The majority of studies have investigated IPC alongside a placebo condition, but without a control condition that was devoid of experimental manipulation, thereby limiting accurate determination of the IPC effects. Therefore, the aims of this study wereto assess the impact of the IPC intervention, compared to both placebo and no intervention, on exercise capacity and athletic performance. METHODS A systematic search of PubMed, Embase, SPORTDiscus, Cochrane Library, and Latin American and Caribbean Health Sciences Literature (LILACS) covering records from their inception until July 2023 was conducted. To qualify for inclusion, studies had to apply IPC as an acute intervention, comparing it with placebo and/or control conditions. Outcomes of interest were performance (force, number of repetitions, power, time to exhaustion, and time trial performance), physiological measurements (maximum oxygen consumption, and heart rate), or perceptual measurements (RPE). For each outcome measure, we conducted 3 independent meta-analyses (IPC vs. placebo, IPC vs. control, placebo vs. control) using an inverse-variance random-effects model. The between-treatment effects were quantified by the standardized mean difference (SMD), accompanied by their respective 95% confidence intervals. Additionally, we employed the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach to assess the level of certainty in the evidence. RESULTS Seventy-nine studies were included in the quantitative analysis. Overall, IPC demonstrates a comparable effect to the placebo condition (using a low-pressure tourniquet), irrespective of the subjects'training level (all outcomes presenting p > 0.05), except for the outcome of time to exhaustion, which exhibits a small magnitude effect (SMD = 0.37; p = 0.002). Additionally, the placebo exhibited effects notably greater than the control condition (outcome: number of repetitions; SMD=0.45; p = 0.03), suggesting a potential influence of participants' cognitive perception on the outcomes. However, the evidence is of moderate to low certainty, regardless of the comparison or outcome. CONCLUSION IPC has significant effects compared to the control intervention, but it did not surpass the placebo condition. Its administration might be influenced by the cognitive perception of the receiving subject, and the efficacy of IPC as an ergogenic strategy for enhancing exercise capacity and athletic performance remains questionable.

中文翻译：

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缺血预处理是否比安慰剂或不干预更能提高运动表现？荟萃分析的系统评价。


背景 缺血预处理 （IPC） 据称对运动表现有有益影响，尽管研究结果不一致，一些研究报告了安慰剂效应。大多数研究将 IPC 与安慰剂条件一起调查，但没有没有没有实验操作的对照条件，从而限制了 IPC 效应的准确确定。因此，本研究的目的是评估与安慰剂和无干预相比，IPC 干预对运动能力和运动表现的影响。方法 对 PubMed、Embase、SPORTDiscus、Cochrane 图书馆和拉丁美洲和加勒比健康科学文献 （LILACS） 进行了系统检索，涵盖了从建库到 2023 年 7 月的记录。为了符合纳入标准，研究必须将IPC作为急性干预，将其与安慰剂和/或对照条件进行比较。感兴趣的结局是性能（力量、重复次数、力量、疲惫时间和计时赛表现）、生理测量（最大耗氧量和心率）或感知测量 （RPE）。对于每个结局指标，我们使用逆方差随机效应模型进行了 3 项独立的荟萃分析（IPC 与安慰剂、IPC 与对照、安慰剂与对照）。治疗间效应通过标准化均数差 （SMD） 以及它们各自的 95% 置信区间进行量化。此外，我们采用建议分级、评估、开发和评价（Grading of Recommendations， Assessment， Development and Evaluation， GRADE）方法来评估证据的质量水平。结果 定量分析纳入 79 项研究。 总体而言，IPC 显示出与安慰剂条件（使用低压止血带）相当的效果，无论受试者的训练水平如何（所有结果均显示 p > 0.05），除了疲惫时间的结果，它表现出较小的幅度效应 （SMD = 0.37;p = 0.002）。此外，安慰剂表现出的效果明显大于对照条件（结果：重复次数;贴片=0.45;p = 0.03），表明参与者的认知感知对结果有潜在影响。然而，无论比较或结局如何，证据都是中等到低质量的。结论 与对照干预相比，IPC 具有显着效果，但未超过安慰剂条件。它的给药可能受到接收受试者认知感知的影响，并且 IPC 作为增强运动能力和运动表现的增效策略的有效性仍然值得怀疑。