Low-frequency vibratory exercise reduces the risk of bone fracture more than walking: a randomized controlled trial.
BACKGROUND
Whole-body vibration (WBV) is a new type of exercise that has been increasingly tested for the ability to prevent bone fractures and osteoporosis in frail people. There are two currently marketed vibrating plates: a) the whole plate oscillates up and down; b) reciprocating vertical displacements on the left and right side of a fulcrum, increasing the lateral accelerations. A few studies have shown recently the effectiveness of the up-and-down plate for increasing Bone Mineral Density (BMD) and balance; but the effectiveness of the reciprocating plate technique remains mainly unknown. The aim was to compare the effects of WBV using a reciprocating platform at frequencies lower than 20 Hz and a walking-based exercise programme on BMD and balance in post-menopausal women.


METHODS
Twenty-eight physically untrained post-menopausal women were assigned at random to a WBV group or a Walking group. Both experimental programmes consisted of 3 sessions per week for 8 months. Each vibratory session included 6 bouts of 1 min (12.6 Hz in frequency and 3 cm in amplitude with 60 degrees of knee flexion) with 1 min rest between bouts. Each walking session was 55 minutes of walking and 5 minutes of stretching. Hip and lumbar BMD (g.cm-2) were measured using dual-energy X-ray absorptiometry and balance was assessed by the blind flamingo test. ANOVA for repeated measurements was adjusted by baseline data, weight and age.


RESULTS
After 8 months, BMD at the femoral neck in the WBV group was increased by 4.3% (P = 0.011) compared to the Walking group. In contrast, the BMD at the lumbar spine was unaltered in both groups. Balance was improved in the WBV group (29%) but not in the Walking group.


CONCLUSIONS
The 8-month course of vibratory exercise using a reciprocating plate is feasible and is more effective than walking to improve two major determinants of bone fractures: hip BMD and balance.
Gusi
Narcís
N
Faculty of Sports Sciences, University of Extremadura, Cáceres, Spain. ngusi@unex.es
Raimundo
Armando
A
Leal
Alejo
A
D000367:Age Factors; D000368:Aged; D015519:Bone Density / Q000502:physiology; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D005269:Femur / Q000502:physiology; D050723:Fractures, Bone / Q000209:etiology / Q000517:prevention & control* / Q000628:therapy; D006801:Humans; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000150:complications / Q000517:prevention & control* / Q000628:therapy; D010809:Physical Fitness / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology; D012737:Sex Factors; D016896:Treatment Outcome; D014732:Vibration / Q000627:therapeutic use*; D016138:Walking / Q000502:physiology*