Short-term whole-body vibration in adolescents: A prospective single-arm study of diffusion tensor imaging-derived...

ObjectiveTo investigate short-term diffusion tensor imaging-derived changes in the knee physis after whole-body vibration and to assess postural stability in healthy adolescents.MethodsThis prospective, single-arm, within-subject exploratory study included 48 healthy adolescents (24 males and 24 females; mean age, 11.94 ± 2.31 years) who underwent a 1-week whole-body vibration protocol (15 Hz, 5 mm amplitude). Fractional anisotropy and apparent diffusion coefficient values of the distal femoral and proximal tibial physes were measured before and after whole-body vibration using knee diffusion tensor imaging. Postural stability was evaluated using force plate center-of-pressure parameters. Paired comparisons were performed for the overall cohort and sex-stratified subgroups, and age- and bone age-related trends were explored using quadratic regression models.ResultsIn the overall cohort, fractional anisotropy increased in both the distal femoral physis (0.472 ± 0.074 to 0.515 ± 0.070; mean change, 0.043; Cohen's dz = 0.737; p < 0.001) and the proximal tibial physis (0.486 ± 0.063 to 0.527 ± 0.067; mean change, 0.041; Cohen's dz = 0.897; p < 0.001). Apparent diffusion coefficient decreased in the distal femoral physis (1.171 ± 0.230 to 1.081 ± 0.160 × 10^-3 mm²/s; mean change, -0.090; Cohen's dz = -0.483; p = 0.002) and the proximal tibial physis (1.171 ± 0.211 to 1.100 ± 0.168 × 10^-3 mm²/s; mean change, -0.071; Cohen's dz = -0.584; p < 0.001). Sex-stratified analyses showed generally larger standardized changes in males, whereas apparent diffusion coefficient changes in females did not reach statistical significance. Exploratory scatter plots and quadratic regression models suggested that the magnitude of diffusion tensor imaging-derived changes varied with chronological age and bone age, with a trend toward larger changes within a bone age range of 12-14 years. Postural stability parameters increased transiently but remained within the "no-impact" safety threshold.ConclusionsA 1-week whole-body vibration protocol was associated with measurable diffusion tensor imaging-derived changes in the adolescent knee physis and transient changes in postural stability. These findings should be interpreted as preliminary, hypothesis-generating biophysical observations rather than direct evidence of improved physeal function, growth promotion, or beneficial structural effects. Larger sham-controlled longitudinal studies incorporating growth outcomes and complementary diffusion tensor imaging metrics are warranted.