Effect of whole-body vibration training on bone mass in adolescents with and without Down syndrome: a randomized controlled trial.

Abstract

Whole-body vibration training (WBV) attracts great interest as osteoporosis prevention strategy. Twenty-six adolescents with and without Down syndrome (DS) (13 DS; 12-18 years) performed 20 weeks of WBV. The results indicate that WBV seems to provoke a lesser response in adolescents with DS than in those without DS. This study aims to observe the differences between adolescents with and without DS in the effects of 20 weeks of WBV training, on bone mineral content (BMC) and density (BMD). Twenty-six adolescents (13 DS; 12-18 years) were measured with dual-energy X-ray absorptiometry before and after the intervention (3/week, 10 repetitions (30-60 s) and 1-min rest, frequency 25-30 Hz and peak-to-peak displacement of 2 mm (peak acceleration 2.5-3.6 g)). Both, an intention-to-treat (ITT) analysis designed to assess the effects on bone mass and a per-protocol analysis, designed to compare poor and high compliers, were performed. The ITT analysis revealed significant increases in all BMC and BMD parameters (dz = 0.66 to 1.64; all p < 0.05) in the non-DS group, whilst DS group improved whole-body, subtotal (whole-body less head), upper limbs (ULIMBS), pelvis, lower limbs (LLIMBS) and spine BMC (dz = 0.75 to 1.76; all p < 0.05) and subtotal, pelvis, LLIMBS and spine BMD (dz = 0.73 to 1.28; all p < 0.05). Significantly greater increases were evident in the absolute and percent changes of the non-DS group over DS group (d = 0.88 to 3.85; all p < 0.05). ULIMBS BMD showed a tendency towards an interaction (f = 0.41 and p = 0.086) with higher increase for non-DS group. When a per-protocol analysis was considered, high-complier adolescents had 8.1 versus 5.3 % of gains in the spine BMC over poor-complier adolescents (d = 0.93; p < 0.05). Twenty weeks of WBV training may improve BMC and BMD in clinically relevant skeletal sites in both groups. Nevertheless, this type of training seems to provoke a lesser response in adolescents with DS than in those without DS.