THE EFFECT OF 18 MONTH HIGH-IMPACT EXERCISE ON LOWER LIMB BONE MINERAL DENSITY IN PREMENOPAUSAL WOMEN 785

Abstract

It was hypothesized that the rate of the mechanical strains developed in bone due to external loading is an important factor in the skeletal adaptive response to exercise. The purpose of this study was therefore to find out whether high-impact loading would affect beneficially the lower limb BMD in premenopausal women. A total of 98 clinically healthy and sedentary women volunteers (35-45 years) were randomly assigned to training (N=49) or control(N=49) group. The training consisted of supervised progressive high-impact exercises done an average 2.5 times/week for 18 months. The exercises were selected on the basis of a pilot study, which identified peak forces in 130 exercise movements. A total of 84 women completed the study (39 trainees and 45 controls). DXA measurements were made 3 times at 7 skeletal sites. Leg extensor power and the figure-of-8 running improved significantly (20% and-6%, respectively) as compared to control group (15% and -1%). The increases in the BMD at the loaded sites were 1.4 - 3.7% in the training group in contrast to changes of 0-1.8% in the control group. Intergroup differences of BMD are given in Table 1. This study showed that an 18 month high-impact training increased significantly the BMD of the loaded sites in premenopausal women. The results support the hypothesis that high strain rate loading of bones in versatile movements is potent in improving skeletal integrity.