Effects of Whole-Body Vibration Training on Muscle Strength and Flexibility: A Meta-Analysis with Subgroup Analyses Based on Population and Vibration Parameters

This study conducted a meta-analysis to systematically evaluate the effects of whole-body vibration training on muscle strength and flexibility in different athletic populations, as well as to examine the moderating effects of factors such as vibration frequency, training duration, amplitude, and population type on the outcomes, aiming to provide a basis for the scientific application of vibration training.Randomized controlled trials related to whole-body vibration training were retrieved from databases including PubMed, Web of Science, CNKI, VIP, Wanfang, EBSCO, and Cochrane. Literature was screened based on the PICOS principle, and Meta-analysis and subgroup analyses were conducted using Review Manager 5.4 to evaluate the overall effects of vibration training on strength and flexibility. A total of 15 studies involving 491 participants were included, encompassing healthy young adults, the elderly, athletes, special female populations, and special male populations.The meta-analysis results showed that the overall effect size of whole-body vibration training on strength was moderate (SMD=0.67, 95% CI [0.42, 0.93]), while the overall effect size on flexibility was small (SMD=0.20, 95% CI [-0.05, 0.45]).Subgroup analyses indicated that vibration training yielded the most pronounced strength improvement in special female populations, whereas its effect on healthy young adults was relatively limited (SMD=0.13). In terms of vibration parameters, medium frequency (20-40 Hz) and medium amplitude (2-4 mm) yielded optimal effects. Medium- to long-term training durations (8-16 weeks and >16 weeks) were superior to short-term interventions ([≤] 8 weeks). For flexibility, the overall effect remained non-significant (SMD=0.20).In conclusion, whole-body vibration training demonstrates a moderate effect on improving muscle strength, with particularly significant benefits observed in special female populations and the elderly. However, its effect on flexibility enhancement remains limited. Vibration frequency, amplitude, and training duration are key factors influencing the training outcomes. Future research should focus on further optimizing vibration parameters and conducting empirical studies on personalized training protocols.