Transmission of whole body vibration in children while standing.

BACKGROUND Whole body vibration has recently been used as a therapeutic intervention for the treatment of children with disabling conditions. Researchers of these studies observed encouraging results; however, children may not be capable of attenuating high vibration accelerations to the head because of low mass. The purpose of this study was to determine if children transmit vibration differently than adults while standing on a vibration platform. METHODS The experimental protocol required 11 children and 10 adults to stand on a commercially available vibration platform at progressively greater frequencies (28, 33, and 42 Hz). Transmissibility of vibration to various skeletal landmarks was assessed with a high speed motion analysis system. FINDINGS Transmissibility in children was 42% and 62% greater than adults for the ankle and hip, respectively (P=0.03; effect size=0.84-1.29). The values at the head were not different between groups (P=0.92) and remained 86% and 50% lower than values at the ankle and knee, respectively (effect size=4.75-19.1). INTERPRETATION Transmissibility of whole body vibration while standing is not markedly different between children and adults. In fact, the only differences are the transmissibility to the ankle and hip which are greater in children when the vibration platform is set at 33 Hz. More importantly, transmissibility to the head is not different between groups. These results do not suggest vibration therapy is safe as the biological response of children to acute or chronic acceleration impacts during whole body vibration is unknown.