Methods of physical training, which increase the capability of the musculoskeletal system and which are on a high level not only for astronauts of high interest. Also bedridden patients and the elderly could benefit from this special training. In recent years different vibration platforms have been developed (Galileo, Nemes). A short time of a few minutes per day promise significant amelioration in legs in matters of muscle mass and velocity on the one hand and bone strength on the other hand.Athletes show growing interest in an innovative training method, the so called vibration training. The athlete is standing on a motor-driven horizontally vibrating platform and performs exercises known from resistance training like squats. The underlying mechanisms are not yet understood.There is a strong need for adequate training methods in order to counteract muscle and bone loss in space. Therefore we investigated the effect of vibration training on the musculoskeletal system during simulated weightlessness in a bed rest study.
Effects of mechanical stimuli via vibration training on bone metabolism in immobilized healthy subjects
Absence of mechanical loading in weightlessness as well as in immobilization leads to substantial loss in bone and muscle mass. Reduction of mechanical stress on bone inhibits osteoblast-mediated bone formation and increases osteoclast-mediated bone resorption, and results in what has been called disuse osteoporosis. Recent research showed a positive effect of vibration training on bone metabolism in postmenopausal women. There is also a high potential that vibration training may also have positive effects on bone metabolism in immobilized subjects.
In our Vibration-Bedrest-Study (VBR) study we investigate whether vibration training at 20 Hz with amplitude of 3 mm may counteract bone loss during immobilization. 8 male subjects performed a 14 day bed-rest in -6° head-down-tilt. The study is designed as a cross-over design with two study phases. Subjects stood on the vibration plate with a knee flexion angle of ~ 30° for 5 x 1 minute twice a day. The standing position altered with a 1 Minute resting position while sitting on a chair. In the intervention phase the subjects are exposed to the whole body vibration while standing on the plate. The control just stands on the plate without vibration. The subjects receive a strictly controlled diet, tailored to their activity level, their age and body mass. To investigate the effects of vibration training on bone metabolism, bone formation markers and calcium metabolism had been analyzed. Our results show that the applied protocol of mere vibration training without any resistive exercise was not an effective countermeasure for disuse induced bone loss. Other vibration training protocols as well as methods of other training interventions need to be developed to counteract bone loss in immobilized people.