Effect of exercise on bone mineral density and lean mass in postmenopausal women.
OBJECTIVE
To evaluate the effects of physical activity on bone mineral density, bone mineral content, and lean mass in postmenopausal, overweight/obese women.


METHODS
We conducted a 12-month randomized controlled aerobic exercise intervention versus control in 173 sedentary, overweight/obese, postmenopausal women, aged 50-75 yr. The exercise prescription consisted of >or=45 min of moderate-intensity aerobic exercise (60-75% of maximal heart rate), 5 d.wk for 12 months. Control participants attended 45-min stretching sessions once a week. Ninety-eight percent (N=170) completed the trial. Exercisers averaged 172 min.wk (SD=89) of exercise and expended 3828 kJ.wk (SD=2053). We assessed body fat, total lean mass, and total body bone mineral density and content using dual-energy x-ray absortiometry (DXA). We compared baseline with 12-month changes in exercisers versus controls.


RESULTS
Exercisers lost significantly more weight than stretchers (1.3-kg loss vs 0.1-kg gain, P=0.01). However, no differences between exercisers and controls in the change from baseline to 12 months were detected: exercisers' average bone mineral density increased by 0.005 g.cm and controls' by 0.003 g.cm (P=0.61). Similarly, no significant differences were detected for bone mineral content. Lean mass increased by 0.2 kg in both groups (P=0.84).


CONCLUSIONS
Overall, the results from this randomized controlled study suggest that a yearlong moderate-intensity aerobic exercise intervention does not affect total body bone mineral density, bone mineral content, or lean mass in overweight/obese postmenopausal women.
Chubak
Jessica
J
Fred Hutchinson Cancer Research Center, Cancer Prevention Research Program, and University of Washington, School of Public Health and Community Medicine, Department of Epidemiology, Seattle, WA 98109-1024, USA.
Ulrich
Cornelia M
CM
Tworoger
Shelley S
SS
Sorensen
Bess
B
Yasui
Yutaka
Y
Irwin
Melinda L
ML
Stanczyk
Frank Z
FZ
Potter
John D
JD
McTiernan
Anne
A
D000368:Aged; D015519:Bone Density / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D050177:Overweight; D017698:Postmenopause; D013851:Thinness; D014861:Washington