RANDOMIZED CONTROLLED TRIAL OF EFFECT OF HIGH-IMPACT EXERCISE ON SELECTED RISK-FACTORS FOR OSTEOPOROTIC FRACTURES

Background Osteoporotic fractures among the elderly are common, and wi thout preventive measures the burden of these fractures on health-care systems will increase further. The purpose of this randomised control led study was to evaluate, in premenopausal women, the effects of high -impact loading on several determinants of osteoporotic fractures. Met hods 98 healthy, sedentary female volunteers aged 35-45 years were ran domly assigned to either a training (n=49) or a control group (n=49). Progressive high-impact exercises were done three times per week for 1 8 months. We measured bone mineral density (BMD) in specific axial and lower-limb sites, by dual-energy X-ray absorptiometry, at baseline an d after 12 and 18 months. Maximum isometric strength, muscular and car diovascular performance, and dynamic balance were also assessed. Findi ngs BMD at the femoral neck, a weightbearing site, increased significa ntly more in the training group (mean 1 . 6% [95% CI 0 . 8-2 . 4]) tha n in the control group (0 . 6% [-0 . 2 to 1 . 4], p=0 . 006). By contr ast, at non-weightbearing sites, such as the distal radius, there was no significant difference between the training and control groups (-1 . 5% [-2 . 7 to -0 . 3] vs -0 . 7% [-1 . 9 to -0 . 5], p=0 . 60). In t he training group there was a significant improvement in vertical jump and predicted oxygen consumption per min at maximum exercise compared with controls. Interpretation High-impact exercises that load bones w ith a rapidly rising force profile in versatile movements improve inte grity, muscular performance, and dynamic in premenopausal women. If do ne on a regular basis, this type of exercise may help decrease the ris k of osteoporotic fractures in later life. Long-term studies are requi red to show whether these 18-month results can be translated into long -term benefit.