Whole-Body-Vibration Training Effective in Older Women
News Author: Laurie Barclay, MD
CME Author: Désirée Lie, MD, MSEd
June 18, 2004 — Whole-body-vibration (WBV) training is as efficient as standard resistance (RES) training for improving strength and speed in older women, according to the results of a randomized trial published in the June issue of the Journal of the American Geriatric Society.
"Recently, WBV training has been promoted as an efficient alternative for resistance training," write Machteld Roelants, MS, from Katholieke Universiteit in Leuven, Belgium, and colleagues. "Even if performed to exhaustion, the increases in heart rate, blood pressure, and oxygen uptake during WBV are mild, so the cardiovascular risks of WBV in older adults are negligible."
In this controlled trial at the Exercise Physiology and Biomechanics Laboratory in Leuven, 89 postmenopausal women were randomized to WBV training, RES training, or to a control group that did not participate in any training. All women were not receiving hormone replacement therapy (HRT), and age range was 58 to 74 years.
Both active intervention groups trained three times a week for 24 weeks. The WBV group performed unloaded static and dynamic knee-extensor exercises on a vibration platform, which provokes reflexive muscle activity. The RES group performed dynamic leg-press and leg-extension exercises, increasing from low (20 repetitions maximum) to high (8 repetitions maximum) resistance, to train knee extensors.
A motor-driven dynamometer measured isometric strength and dynamic strength, speed of movement was measured using an external resistance equivalent to 1%, 20%, 40%, and 60% of isometric maximum, and countermovement jump performance was determined using a contact mat.
After 24 weeks of training, isometric and dynamic knee-extensor strength increased significantly in both groups (P < .001 vs. baseline), and the training effects were similar in both groups (P = .56). Isometric and dynamic knee-extensor strength were 15.0% ± 2.1% and 16.1% ± 3.1%, respectively, in the WBV group, and 18.4% ± 2.8% and 13.9% ± 2.7%, respectively, in the RES group.
After 24 weeks of training, speed of movement of knee extension significantly increased at low resistance (1% or 20% of isometric maximum) to 7.4% ± 1.8% and 6.3% ± 2.0%, respectively, in the WBV group only. There were no significant differences in training effect between the WBV and the RES groups (P = .39 and P = .14, respectively).
Countermovement jump height improved from baseline (P < .001) after 24 weeks of training in the WBV group (19.4% ± 2.8%) and the RES group (12.9% ± 2.9%). Most of the improvement in knee-extension strength, speed of movement, and in countermovement jump performance occurred after 12 weeks of training.
"WBV is a suitable training method and is as efficient as conventional resistance training to improve knee-extension strength and speed of movement and countermovement jump performance in older women," the authors write. "As previously shown in young women, it is suggested that the strength gain in older women is mainly due to the vibration stimulus and not only to the unloaded exercises performed on the WBV platform."
J Am Geriatr Soc. 2004;52:901-908
Age-related decrease in physical activity and reduction in sex hormones are linked to strength loss and muscle atrophy. The latter predispose elderly women to falls and fractures with subsequent morbidity and mortality. WBV consists of standing unloaded on a platform generating vertical sinusoidal vibration at a frequency of 2.5 to 40 Hz with amplitudes of 2.0 to 10.5 mm transmitted to the body to stimulate sensory receptors such as muscle spindles. Unloaded exercise is performed on the platform. Tonic vibration is believed to facilitate activation of high-threshold motor units affecting fast-twitch fibers, which play a role in muscle strength and power. The major part of the gain in strength is believed to be due to muscle activity provoked by vibration.
One study by Delecluse and colleagues published in the June 2003 issue of Medicine and Science in Sports and Exercise showed increased isometric and dynamic knee-extensor strength of 16.6% and 9.0%, respectively, in previously untrained young women. WBV has the potential to enhance muscular performance in older adults who are unwilling or unable to perform standard RES exercises.
This is the first randomized study to investigate long-term (24 weeks) effects of WBV training on muscle strength, measured as knee-extension isometric, dynamic strength and speed in postmenopausal women not receiving HRT and to compare these effects with similar standard RES training.