METAANALYSIS OF THE EFFECTIVENESS OF PHYSICAL-ACTIVITY FOR THE PREVENTION OF BONE LOSS IN POSTMENOPAUSAL WOMEN

A meta-analysis was done to measure the effect of physical activity on the bone mass of healthy postmenopausal women. All studies published between 1966 and 1996, in French or English, were reviewed for inclusi on from Medline search, bibliographies of relevant studies, review art icles and books. Studies had to be prospective intervention trials, ra ndomized or not, evaluating the effectiveness of an exercise program o f any duration, frequency and intensity, with a control group. Studies had to measure bone parameters and involve healthy postmenopausal wom en over 50 years of age who were free of symptomatic osteoporosis at t he time of study entry. Effect sizes (ES) were calculated for each bon e parameter and site measured in every eligible study according to Hed ges and Olkin. DerSimonian and Laird's model was used to estimate over all effect sizes when combining studies. All analyses were bone parame ter and site specific. Of 217 papers extracted from the literature, 18 7 did not meet eligibility criteria and 12 others were rejected. The t wo main reasons for rejection were that both genders were combined in the analyses and no exercise group without drug interaction was presen t. Eighteen studies were included for metaanalysis. Taking into accoun t the frequency, duration, compliance rate and average age of the subj ects, the programs were judged of moderate intensity and focused on wa lking, running, physical conditioning and aerobics. A significant effe ct of physical activity was detected on the bone mineral density at th e L2-4 level of the lumbar column in studies published after 1991 (ES = 0.8745, p<0.05). No effect could be seen, however, on forearm and fe moral bone mass. Although applied to a small number of studies, this m eta-analysis suggests that exercise programs in a population of postme nopausal women over 50 years of age are effective for preventing spina l bone mineral density loss at the L2-4 level. However, such programs do not have any effect on the forearm or femoral bone mass.