Original Article

Osteoporosis International

, Volume 16, Issue 12, pp 2129-2141

Exercise frequency and calcium intake predict 4-year bone changes in postmenopausal women

  • Ellen C. CusslerAffiliated withDepartment of Physiology, University of Arizona
  • , Scott B. GoingAffiliated withDepartment of Physiology, University of ArizonaDepartment of Nutritional Sciences, University of Arizona
  • , Linda B. HoutkooperAffiliated withDepartment of Nutritional Sciences, University of Arizona
  • , Vanessa A. StanfordAffiliated withDepartment of Nutritional Sciences, University of Arizona
  • , Robert M. BlewAffiliated withDepartment of Physiology, University of Arizona
  • , Hilary G. Flint-WagnerAffiliated withDepartment of Health and Nutritional Sciences, Kasiska College of Health Professions
  • , Lauve L. MetcalfeAffiliated withDepartment of Physiology, University of Arizona
  • , Ji-Eun ChoiAffiliated withDepartment of Physiology, University of Arizona
  • , Timothy G. LohmanAffiliated withDepartment of Physiology, University of ArizonaDepartment of Physiology, Ina Gittings Building, University of Arizona Email author 

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Abstract

The aim of this study was to examine the association of exercise frequency and calcium intake (CI) with change in regional and total bone mineral density (BMD) in a group of postmenopausal women completing 4 years of progressive strength training. One hundred sixty-seven calcium-supplemented (800 mg/day) sedentary women (56.1±4.5 years) randomized to a progressive strength training exercise program or to control were followed for 4 years. Fifty-four percent of the women were using hormone therapy (HT) at baseline. At 1 year, controls were permitted to begin the exercise program (crossovers). The final sample included 23 controls, 55 crossovers, and 89 randomized exercisers. Exercisers were instructed to complete two sets of six to eight repetitions of exercises at 70–80% of one repetition maximum, three times weekly. BMD was measured at baseline and thereafter annually using dual-energy X-ray absorptiometry. Four-year percentage exercise frequency (ExFreq) averaged 26.8%±20.1% for crossovers (including the first year at 0%), and 50.4%±26.7% for exercisers. Four-year total CI averaged 1,635±367 mg/day and supplemental calcium intake, 711±174 mg/day. In adjusted multiple linear regression models, ExFreq was positively and significantly related to changes in femur trochanter (FT) and neck (FN), lumbar spine (LS), and total body (TB) BMD. Among HT users, FT BMD increased 1.5%, and FN and LS BMD, 1.2% ( p <0.01) for each standard deviation (SD) of percentage ExFreq (29.5% or 0.9 days/week). HT non-users gained 1.9% and 2.3% BMD at FT and FN, respectively, ( p <0.05) for every SD of CI. The significant, positive, association between BMD change and ExFreq supports the long-term usefulness of strength training exercise for the prevention of osteoporosis in postmenopausal women, especially HT users. The positive relationship of CI to change in BMD among postmenopausal women not using HT has clinical implications in light of recent evidence of an increased health risk associated with HT.

Keywords

Dietary calcium Exercise Hormone therapy Menopause Osteoporosis Strength training BMD