Effects of Upper-Body Plyometric Training on Physical Fitness in Healthy Youth and Young Adult Participants: A Systematic Review with Meta-Analysis

BACKGROUND: Upper-body plyometric training (UBPT) is a commonly used training method, yet its effects on physical fitness are inconsistent and there is a lack of comprehensive reviews on the topic. OBJECTIVE: To examine the effects of UBPT on physical fitness in healthy youth and young adult participants compared to active, specific-active, and passive controls. METHODS: This systematic review followed PRISMA 2020 guidelines and utilized the PICOS framework. PubMed, WOS, and SCOPUS were searched. Studies were assessed for eligibility using the PICOS framework. The effects of UBPT on upper-body physical fitness were assessed, including maximal strength, medicine ball throw performance, sport-specific throwing performance, and upper limb muscle volume. The risk of bias was evaluated using the PEDro scale. Means and standard deviations were used to calculate effect sizes, and the I(2) statistic was used to assess heterogeneity. Publication bias was assessed using the extended Egger's test. Certainty of evidence was rated using the GRADE scale. Additional analyses included sensitivity analyses and adverse effects. RESULTS: Thirty-five studies were included in the systematic review and 30 studies in meta-analyses, involving 1412 male and female participants from various sport-fitness backgrounds. Training duration ranged from 4 to 16 weeks. Compared to controls, UBPT improved maximal strength (small ES = 0.39 95% CI = 0.15–0.63, p = 0.002, I(2) = 29.7%), medicine ball throw performance (moderate ES = 0.64, 95% CI = 0.43–0.85, p < 0.001, I(2) = 46.3%), sport-specific throwing performance (small ES = 0.55, 95% CI = 0.25–0.86, p < 0.001, I(2) = 36.8%), and upper limbs muscle volume (moderate ES = 0.64, 95% CI = 0.20–1.08, p = 0.005, I(2) = 0.0%). The GRADE analyses provided low or very low certainty for the recommendation of UBPT for improving physical fitness in healthy participants. One study reported one participant with an injury due to UBPT. The other 34 included studies provided no report measure for adverse effects linked to UBPT. CONCLUSIONS: UBPT interventions may enhance physical fitness in healthy youth and young adult individuals compared to control conditions. However, the certainty of evidence for these recommendations is low or very low. Further research is needed to establish the optimal dose of UBPT and to determine its effect on female participants and its transfer to other upper-body dominated sports. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40798-023-00631-2.