Effects of Complex Training on Physical Performance: An Umbrella Review

Dan Xiang¹Chen Hu¹Zhiqiang Du^1*Shengxi He¹Miaoying Zhang¹Zhipeng Zhu²

• ¹College of Physical Education, China Three Gorges University, Yichang, China
• ²College of Physical Education, Shanxi University, Taiyuan, China

Background: In the past few decades, sports scientists have tried to form a variety of complex training through the combination of different exercises and the sequencing of different loads to form a new training method, and investigated the impact of complex training on the performance results of different populations. This study aims to systematically review and synthesize the findings of published meta-analyses on complex training's effects on physical performance, as well as to assess their methodological quality. Methods: This study employed a systematic umbrella review design to synthesize existing meta-analyses, utilizing a systematic literature search across PubMed, Scopus, SPORT Discus, Web of Science, and Google Scholar to identify relevant studies, with eligibility criteria restricted to meta-analyses investigating the effects of complex training on physical fitness outcomes across diverse populations. Results: The methodological quality of the 12 included meta-analyses was predominantly low. Among them, 10 meta-analyses involved comparisons with control groups, while 2 focused on pre-post effect sizes. A critical limitation identified in the current literature is the moderate to substantial overlap of primary studies across the meta-analyses. The certainty of evidence for physical fitness-related outcomes was mainly rated as very low to low. Conclusion: Current evidence suggests that complex training improves most relevant physical fitness parameters and athletic performance. However, it is important to note that the certainty of evidence in the majority of meta-analyses is low, and substantial overlap of primary studies across meta-analyses may introduce bias into the conclusions. Therefore, careful consideration should be given to the selection of evidence and the interpretation of results.