Background

The reactive strength index (RSI) is meaningfully associated with independent markers of athletic (e.g., linear sprint speed) and neuromuscular performance [e.g., stretch–shortening cycle (SSC)]. Plyometric jump training (PJT) is particularly suitable to improve the RSI due to exercises performed in the SSC. However, no literature review has attempted to meta-analyse the large number of studies regarding the potential effects of PJT on the RSI in healthy individuals across the lifespan.

Objective

The aim of this systematic review with meta-analysis was to examine the effects of PJT on the RSI of healthy individuals across the lifespan compared with active/specific-active controls.

Methods

Three electronic databases (PubMed, Scopus, Web of Science) were searched up to May 2022. According to the PICOS approach, the eligibility criteria were: (1) healthy participants, (2) PJT interventions of ≥ 3 weeks, (3) active (e.g., athletes involved in standard training) and specific-active (e.g., individuals using heavy resistance training) control group(s), (4) a measure of jump-based RSI pre-post training, and (5) controlled studies with multi-groups in randomised and non-randomised designs. The Physiotherapy Evidence Database (PEDro) scale was used to assess the risk of bias. The random-effects model was used to compute the meta-analyses, reporting Hedges’ g effect sizes (ES) with 95% confidence intervals (95% CIs). Statistical significance was set at p ≤ 0.05. Subgroup analyses were performed (chronological age; PJT duration, frequency, number of sessions, total number of jumps; randomization). A meta-regression was conducted to verify if PJT frequency, duration, and total number of sessions predicted the effects of PJT on the RSI. Certainty or confidence in the body of evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Potential adverse health effects derived from PJT were researched and reported.

Results

Sixty-one articles were meta-analysed, with a median PEDro score of 6.0, a low risk of bias and good methodological quality, comprising 2576 participants with an age range of 8.1–73.1 years (males, ~ 78%; aged under 18 years, ~ 60%); 42 studies included participants with a sport background (e.g., soccer, runners). The PJT duration ranged from 4 to 96 weeks, with one to three weekly exercise sessions. The RSI testing protocols involved the use of contact mats (n = 42) and force platforms (n = 19). Most studies reported RSI as mm/ms (n = 25 studies) from drop jump analysis (n = 47 studies). In general, PJT groups improved RSI compared to controls: ES = 0.54, 95% CI 0.46–0.62, p < 0.001. Training-induced RSI changes were greater (p = 0.023) for adults [i.e., age ≥ 18 years (group mean)] compared with youth. PJT was more effective with a duration of > 7 weeks versus ≤ 7 weeks, > 14 total PJT sessions versus ≤ 14 sessions, and three weekly sessions versus < three sessions (p = 0.027–0.060). Similar RSI improvements were noted after ≤ 1080 versus > 1080 total jumps, and for non-randomised versus randomised studies. Heterogeneity (I²) was low (0.0–22.2%) in nine analyses and moderate in three analyses (29.1–58.1%). According to the meta-regression, none of the analysed training variables explained the effects of PJT on RSI (p = 0.714–0.984, R² = 0.0). The certainty of the evidence was moderate for the main analysis, and low-to-moderate across the moderator analyses. Most studies did not report soreness, pain, injury or related adverse effects related to PJT.

Conclusions

The effects of PJT on the RSI were greater compared with active/specific-active controls, including traditional sport-specific training as well as alternative training interventions (e.g., high-load slow-speed resistance training). This conclusion is derived from 61 articles with low risk of bias (good methodological quality), low heterogeneity, and moderate certainty of evidence, comprising 2576 participants. PJT-related improvements on RSI were greater for adults versus youths, after > 7 training weeks versus ≤ 7 weeks, with > 14 total PJT versus ≤ 14 sessions, and with three versus < three weekly sessions.

中文翻译：

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增强式跳跃训练对整个生命周期健康个体反应强度指数的影响：荟萃分析的系统评价

背景

反应强度指数 (RSI) 与运动（例如，线性冲刺速度）和神经肌肉性能 [例如，拉伸-缩短循环 (SSC)] 的独立标志物有意义相关。由于在 SSC 中进行的练习，增强式跳跃训练 (PJT) 特别适合改善 RSI。然而，没有文献综述试图对大量关于 PJT 对健康个体 RSI 的潜在影响的研究进行荟萃分析。

客观的

这项采用荟萃分析的系统评价的目的是检查 PJT 与活性/特异性活性对照相比，对健康个体整个生命周期的 RSI 的影响。

方法

搜索了截至 2022 年 5 月的三个电子数据库（PubMed、Scopus、Web of Science）。根据 PICOS 方法，资格标准为：(1) 健康参与者，(2) PJT 干预≥ 3 周，(3) 活跃（例如，参与标准训练的运动员）和特定活动（例如，使用重阻力训练的个人）控制组，(4) 测量基于跳跃的 RSI 前后训练，以及 (5) 对照研究随机和非随机设计中的多组。物理治疗证据数据库 (PEDro) 量表用于评估偏倚风险。随机效应模型用于计算荟萃分析，报告 Hedges 的g效应量 (ES) 和 95% 置信区间 (95% CI)。统计显着性设定为p ≤ 0.05。进行了亚组分析（实际年龄；PJT 持续时间、频率、会话次数、跳跃总数；随机化）。进行元回归以验证 PJT 频率、持续时间和会话总数是否预测了 PJT 对 RSI 的影响。使用建议评估、制定和评估的分级 (GRADE) 评估了对证据体的确定性或置信度。研究和报告了 PJT 对健康的潜在不利影响。

结果

对 61 篇文章进行了荟萃分析，PEDro 评分中位数为 6.0，偏倚风险低且方法学质量良好，包括 2576 名年龄在 8.1-73.1 岁之间的参与者（男性，约 78%；年龄在 18 岁以下） , ~ 60%); 42 项研究包括具有运动背景（例如，足球、跑步）的参与者。PJT 持续时间从 4 到 96 周不等，每周进行一到三次锻炼。RSI 测试协议涉及使用接触垫 ( n  = 42) 和力平台 ( n  = 19)。大多数研究将 RSI 报告为 mm/ms（n  = 25 项研究），来自跌落跳跃分析（n  = 47 项研究）。一般而言，与对照组相比，PJT 组改善了 RSI：ES = 0.54，95% CI 0.46–0.62，p < 0.001。 与青年人相比，成人 [即年龄≥ 18 岁（组平均值）] 的训练引起的 RSI 变化更大 ( p = 0.023)。PJT 持续时间 > 7 周与 ≤ 7 周、> 14 次总 PJT 疗程与 ≤ 14 次疗程以及每周 3 次疗程与 < 3 次疗程相比更有效 (p = 0.027–0.060 )  。在 ≤ 1080 次与 > 1080 次总跳跃后以及非随机研究与随机研究中，观察到类似的 RSI 改善。异质性 ( I ² ) 在九项分析中较低 (0.0–22.2%)，在三项分析中为中等 (29.1–58.1%)。根据元回归，分析的训练变量均未解释 PJT 对 RSI 的影响（p  = 0.714–0.984，R ² = 0.0）。主要分析的证据质量为中等，而调节分析的证据质量为低至中等。大多数研究没有报告与 PJT 相关的酸痛、疼痛、损伤或相关不良反应。

结论

与主动/特定-主动控制相比，PJT 对 RSI 的影响更大，包括传统的特定运动训练以及替代训练干预（例如，高负荷慢速阻力训练）。这一结论来自 61 篇具有低偏倚风险（良好的方法学质量）、低异质性和中等确定性证据的文章，包括 2576 名参与者。PJT 相关的 RSI 改善在成年人和青少年中更大，在 > 7 周训练后对比 ≤ 7 周，> 14 次总 PJT 对比 ≤ 14 次训练，每周训练 3 次对比 < 3 次训练。