Sinus-like versus random vibration: Acute effects on elderly people with a high risk of falling.

Abstract

BACKGROUND: Whole-body vibration (WBV) could be an alternative training method for elderly with a high risk of falling. RESEARCH QUESTION: What acute effects of sinus-like and random WBV intervention occur in this risk group and how do they differ? METHODS: This prospective pilot study was performed on two days separated by a one-week wash-out phase. Twelve subjects (10 women and 2 men, age 77.7 +/- 5.3; 162.3 +/- 7.4 cm; 82.4 +/- 15.2 kg; BMI 31.2 +/- 5.1 kg/m(2)) undertook sinus-like WBV intervention. One week later random WBV were performed. This consisted of six intervals each lasting 60 s, with heart and respiratory rates monitored. Feasibility outcomes involved safety and compliance. The primary endpoint was postural control, measured by a static posturography before and after the first interval and complete intervention. Secondary outcomes measured before and after the intervention were a Timed-Up-and-Go-Test (TUGT) and an instrumental gait analysis. RESULTS: Random WBV intervention showed positive acute effect on postural control (Standard deviation (SD) Ellipse area p = 0.007; SD of the Center of force (CoF) independent from direction p = 0.017; SD of the CoF in the antero-posterior direction p = 0.011). There were no significant acute effects on TUGT or gait analysis (comparison between sinus-like and random WBV: Single Task: DeltaVelocity p = 0.373, DeltaStep time p = 0.077, DeltaStep length p = 0.369, DeltaStride length p = 0.408, DeltaDouble-support-time p = 0.492; Dual task: DeltaVelocity p = 0.580, DeltaStep-time p = 0.559, DeltaStep length p = 0.626, DeltaStride length p = 0.584, DeltaDouble-support-time p = 0.550). During sinus-like WBV, heart rate increased significantly from rest 69.7 +/- 20.9bpm to max.146.0 +/- 24.9bpm (p = 0.025). Respiratory rate increased significantly from 10.0 +/- 1.0 to max.32.0 +/- 6.0 (p = 0.011) during random WBV. No undesirable side effects were observed. SIGNIFICANCE: Findings demonstrate that random WBV improves acute functional ability of postural control, but not gait for elderly people with a high risk of falling. Intervention with WBV seems safe and well accepted by participants. Monitoring of heart and respiratory rate offers protection for subjects with heart disease.