BACKGROUND It has been reported that boys' and girls' physical activity (PA) levels decline throughout adolescence. Boys are at risk of physical inactivity during adolescence; however, in intervention research, they are an under-represented group relative to girls. It is suggested that the school environment may be central to developing interventions that support adolescents in meeting the current PA guidelines. The aim of this systematic review and meta-analysis was to investigate the efficacy of school-based physical activity interventions for improving muscular fitness (MF) in adolescent males. METHODS This systematic review and meta-analysis followed the preferred reporting systems for meta-analyses guidelines and was registered on PROSPERO (Registration number: CRD42018091023). Eligible studies were published in English within peer-reviewed articles. Searches were conducted in three databases, with an additional grey literature search in Google Scholar. Studies investigating MF outcomes were included. RESULTS There were 43 data sets identified across 11 studies, from seven countries. Overall methodological quality of the studies was moderate-to-strong. Interventions targeting MF evidenced a small-to-medium effect (g = 0.32, CI 0.17, 0.48, p < 0.00). Subgroup analyses of MF delivery method resulted in small-to-medium effects: upper limb MF measures (g = 0.28, 95% CI - 0.02, 0.58, p = 0.07), lower limb MF measures (g = 0.28, 95% CI 0.09, 0.68, p = 0.03), combined MF activities (g = 0.24, 95% CI - 0.04 to 0.49, p = 0.05), plyometric activities (g = 0.39, 95% CI 0.09, 0.68, p = 0.01), body weight (g = 0.27, 95% CI - 0.10, 0.65, p = 0.15), and traditional MF methods (g = 0.43, 95% CI 0.09, 0.78, p = 0.01). CONCLUSIONS School-based interventions which aimed to increase MF outcomes in adolescent boys demonstrated small-to-moderate effects. Traditional and plyometric methods of resistance training appear to be the most effective form of PA delivery in adolescent males. More quality research is required to assess the impact of MF delivered in the school environment to inform future intervention design.

中文翻译：

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以学校为基础的干预措施对改善青春期男孩肌肉健康结果的功效：系统评价和荟萃分析。

背景 据报道，男孩和女孩的体力活动（PA）水平在整个青春期都会下降。男孩在青春期面临缺乏身体活动的风险；然而，在干预研究中，相对于女孩而言，她们是代表性不足的群体。有人建议，学校环境可能是制定支持青少年满足现行 PA 指南的干预措施的核心。本系统评价和荟萃分析的目的是调查以学校为基础的身体活动干预措施对改善青春期男性肌肉健康（MF）的效果。方法 本系统评价和荟萃分析遵循荟萃分析指南的首选报告系统，并在 PROSPERO 上注册（注册号：CRD42018091023）。符合条件的研究以英文发表在同行评审的文章中。搜索在三个数据库中进行，并在谷歌学术中进行了额外的灰色文献搜索。调查 MF 结果的研究也被纳入其中。结果 来自 7 个国家的 11 项研究确定了 43 个数据集。研究的总体方法学质量为中等到强。针对 MF 的干预措施显示出中小效果（g = 0.32，CI 0.17、0.48，p < 0.00）。MF 输送方法的亚组分析产生了中小效应：上肢 MF 测量值（g = 0.28，95% CI - 0.02、0.58，p = 0.07），下肢 MF 测量值（g = 0.28，95% CI 0.09） , 0.68, p = 0.03), 综合 MF 活动 (g = 0.24, 95% CI - 0.04 至 0.49, p = 0.05), 增强式活动 (g = 0.39, 95% CI 0.09, 0.68, p = 0.01), 体重（g = 0.27，95% CI - 0.10、0.65，p = 0.15）和传统 MF 方法（g = 0.43，95% CI 0.09、0.78，p = 0.01）。结论 旨在提高青春期男孩 MF 结局的学校干预措施显示出小到中度的效果。传统的增强式阻力训练方法似乎是青春期男性最有效的 PA 传递形式。需要更多高质量的研究来评估 MF 在学校环境中的影响，为未来的干预设计提供信息。