Effects of Whole-Body Vibration With Foot Core Exercises: A Randomized Controlled Trial

Overview

This randomized, single-blind clinical trial investigates whether adding whole-body vibration (WBV) to a supervised foot core exercise program improves ankle muscle strength, balance, and proprioception in overweight and obese young adults (BMI 25.0-39.9 kg/m²). Participants attended 24 face-to-face sessions over 8 weeks (3×/week) under physiotherapist supervision. Outcomes included isometric inversion/eversion strength (hand-held dynamometry) and instrumented balance/proprioception tests (Limits of Stability, mCTSIB, single-leg balance, single-leg proprioception) recorded by a computerized balance analysis system.

Design: randomized controlled, single-blind, parallel-group trial conducted at İstinye University Physiotherapy and Rehabilitation Practice \& Research Center. Eligible adults (18-35 years; BMI 25-39.9 kg/m²) able to stand barefoot ≥15 s single-leg and perform 5 repetitions of 60° knee-flexion squats without rest were enrolled. Stratified randomization (sex, BMI) with computer sequence (Research Randomizer) and sealed opaque envelopes allocated participants to: (1) Exercise Group (EG): progressive foot core exercises performed on a vibration platform with vibration OFF; (2) WBV-Combined Exercise Group (TEG): identical exercises WITH synchronous whole-body vibration (20-50 Hz; 15-60 s bouts) using a DKN Technology Xg-10 Pro device. Both groups completed 24 supervised sessions across 8 weeks (3×/week). A standardized warm-up/self-massage of the foot/ankle preceded exercises; progression targeted repetitions, active time, and (in TEG) vibration frequency. Assessments were performed pre- and post-intervention in fixed order with rest intervals. Ankle inversion/eversion strength was measured using a J-Tech Commander Echo digital handheld dynamometer (kg-force). Balance and proprioception were quantified on the PROKIN computerized system (Limits of Stability; mCTSIB; single-leg balance; single-leg proprioception metrics including trunk total standard deviation and mean tracking error). Statistical plan: normality by Shapiro-Wilk; parametric tests for normally distributed variables (paired t-test within groups; independent t-test between groups), Mann-Whitney U for non-normal age, chi-square for categorical variables; Cohen's d for effect size where within-group change was significant. Analyses in IBM SPSS 25.0. Sample size was estimated a priori for large effect (d=0.8), α=0.05, power=0.80 (planned n=26; 13/group). Post-hoc power for Limits of Stability change in TEG yielded d=0.96, power=0.87. No funding; no conflicts declared.