Changes in soft tissue composition are the primary predictors of 4-year bone mineral density changes in postmenopausal women.
Changes in body weight influence bone mineral density, but the role of body composition is not clear in postmenopausal women. Body weight and soft tissue composition predicted bone changes independent of calcium supplementation and exercise frequency, indicating that soft tissue composition should be measured in clinical trials.


BACKGROUND
The purpose of this study was to examine the relationship between changes in body weight and composition and changes in 4-year bone mineral density (BMD) after accounting for age, 4-year exercise frequency (EX), and 4-year calcium supplement intake (CA) in postmenopausal women with and without hormone therapy (HT).


METHODS
Postmenopausal women (aged 40-65 years) either using HT (for 1-3.9 years) or not using HT (for > or =1 year) were recruited to the study. EX and CA was monitored throughout the study and 167 women completed 4 years. BMD and soft tissue composition measurements were made using dual-energy X-ray absorptiometry. Regression was used to predict 4-year BMD changes from EX, CA, age, baseline and 4-year changes in body weight and composition. HT users (n = 115, 55.3 +/- 4.3 years) and non-users (n = 52, 57.5 +/- 4.7 years) were analyzed separately.


RESULTS
The models predicting regional BMD changes that included soft tissue composition changes explained the most variation compared with those with body weight or EX and CA alone. Larger amounts of variation in BMD changes were explained in the no HT group.


CONCLUSIONS
Body composition changes are important positive predictors of BMD changes independent of EX and CA supplementation, but their contribution varies according to bone site and with HT use.
Milliken
L A
LA
Department of Exercise and Health Sciences, University of Massachusetts Boston, MA 02125, USA. laurie.milliken@umb.edu
Cussler
E
E
Zeller
R A
RA
Choi
J-E
JE
Metcalfe
L
L
Going
S B
SB
Lohman
T G
TG
D015502:Absorptiometry, Photon; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology; D015519:Bone Density; D002136:Calcium, Dietary / Q000008:administration & dosage; D016022:Case-Control Studies; D019587:Dietary Supplements; D015914:Estrogen Replacement Therapy; D005081:Exercise Therapy / Q000379:methods; D005260:Female; D005269:Femur / Q000503:physiopathology; D005272:Femur Neck / Q000503:physiopathology; D005500:Follow-Up Studies; D006801:Humans; D008159:Lumbar Vertebrae / Q000503:physiopathology; D008875:Middle Aged; D017698:Postmenopause / Q000502:physiology*; D012044:Regression Analysis
D002136:Calcium, Dietary