Effects of physical activity and menopausal hormone replacement therapy onpostural stability in postmenopausal women - a cross-sectional study

Objectives: Poor postural stability and muscular strength in postmenopausal women are associated with increased risk of falls and fractures. This stud y examined whether these risk factors for falls differed according to habit ual physical activity and menopausal hormone replacement therapy (HRT) use. Methods: subjects were 117 post menopausal women (mean age 65.3 +/- 6.0 ye ars); of whom 70 had taken HRT for at least 5 years (42 tibolone and 28 tra nsdermal oestradiol), whilst 47 had not received HRT. Duration of physical activity was assessed with monitors worn on a waist belt. subjects were gro uped into low (LPA: less than or equal to 15 min day(-1)) or high (HPA: > 1 5 min day(-1)) physical activity. Postural stability was assessed using a s waymeter which measured displacement at the waist. Maximal isometric streng th of knee flexors was determined in 23 of the tibolone group, 26 of the oe strogen group and 12 of the no therapy group. Results: stature and body mas s did not differ according to physical activity participation or HRT use. a lthough the more active women were on average 1.5 years younger than the le ss active women. Body sway was lower in more physically active women in thr ee of the four measurement conditions (P < 0.05) and this effect persisted after inclusion of age as covariate. Body sway tended to be highest in the no therapy group. although not significantly so. Mean knee extensor strengt h was higher in women taking tibolone and oestrogen than in those not on th erapy (115.3 (5.2). 118.2 (7.2) and 97.6 (9.3) Nm. respectively), although again this difference was not statistically significant. Conclusions: The m ore physically active postmenopausal women had significantly better postura l stability than less active women. whilst HRT had no significant effect. P hysical activity might thus have a role in reducing the risk of fracture th rough reducing the risk of falling. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.