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VIBRATION EXERCISE AND RESISTANCE TRAINING PREVENT BONE MINERAL LOSS DURING STRICT BED REST IN HEALTHY MEN

Seattle (Oct. 1, 2004)—Vibration exercise (VbX) combined with progressive resistance training effectively prevents bone mineral loss and the wasting or loss of muscle tissue in the lower body during prolonged bed rest. This type of training could be an especially useful countermeasure for astronauts on prolonged space flights, as well, said researchers at the 26th Annual Meeting of the American Society for Bone and Mineral Research (ASBMR).

The research team, headed by Dieter Felsenberg and Jörn Rittweger, randomly assigned 20 healthy young men to either a control group or an exercise group; both groups underwent eight weeks of strict bed rest under videotaped surveillance. For the exercise group, the researchers (based at the Institute for Biophysical and Clinical Research into Human Movement at Manchester University, Manchester, United Kingdom, and the Center for Muscle and Bone Research Charite, University Medicine Berlin, Germany) designed a regimen of resistance leg exercises combined with vibration.

Bone mineral content (BMC) and muscle cross-sectional area (mCSA) were measured at baseline and after bed rest by quantitative computed tomography in the calf and forearm. Leg muscle volume was measured by MRI. Jumping height and power, peak reflex muscle contraction in knee extension, and ability to stretch the foot upward and downward also were assessed.

Half of the subjects exercised while on bed rest on a prototype of a commercially available training device (called Galileo Space, made by Novotec in Pforzheim, Germany) for four one-minute sets twice a day, six days a week, while they lay on their backs. Vibration frequency was 19 Hz to 23 Hz and peak measurements of force during squat exercises were around 2,000 Newtons.

The exercise group had significantly lower bone mineral loss and muscle tissue wasting or loss than the control group. The control group lost significant amounts of bone mineral from their tibias. The loss near the ankle averaged 3.5 percent. In addition, there was a 17 percent decrease in calf muscle cross section and an 18 percent decrease in calf muscle force in the control group. The exercise group showed no significant bone mineral loss in the tibia, no calf muscle force change, and only an 8 percent decrease in calf muscle cross section.

Bed rest studies are considered models for the conditions of space flight because the skeletal and muscular effects of weightlessness match those of clinically immobilized patients. The authors conclude that just 12 minutes of resistive vibration exercise per day might completely prevent significant bone loss during prolonged bed rest (or space flight), and said their regimen is the first effective countermeasure for bone loss in patients on strict bed rest found to date.

For more information on this study, visit www.asbmr.org.

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