The Impact of Whole-Body Vibration Training on Lower-Extremity Muscle Function in Older Adults: A Systematic Review and Meta-Analysis

This review aimed to analyze the impact of whole-body-vibration (WBV) training on strength, power, muscle endurance, functional lower-extremity flexibility (FLEF), and functional lower-extremity strength (FLES) in older adults and to evaluate the effectiveness of different WBV training periods. Electronic searches were conducted using four databases. The methodological quality and level of evidence of the selected articles were assessed by two reviewers. Standardized mean differences (SMD) and 95% confidence intervals (CIs) were calculated. Nineteen studies were included (474 participants; mean age 74.27 years). Strength was measured by isokinetic, isometric, or isotonic contraction using an isokinetic dynamometer or weight-training machines. Power was measured by an assessment task that required maximal force in a short period of time. Endurance was evaluated by maximal repetition of tasks, FLEF by chair stand-and-reach and functional reach tests, and FLES by the sit-to-stand test. Meta-analysis showed that WBV training had significant effects on strength (SMD = .54; CIs = .40, .67), power (SMD = .58; CIs = .28, .89), muscle endurance (SMD = .82; CIs = .36, 1.29), FLEF (SMD = .31; CIs = .06, .55), and FLES (SMD = -.75; CIs = -1.18, -.33). Our findings suggest that 1) WBV training improves overall lower-extremity muscle function in older adults, especially muscle endurance; 2) a minimum of 8 weeks of WBV training is recommended to improve strength, muscular endurance, and power; and 3) a longer period of the WBV training is more effective at improving muscle endurance, power, and strength but not FLEF and FLES. Therefore, WBV training is strongly recommended to improve various muscle function parameters in older adults.