Bone Estrogen Strength Training
Condition: Osteoporosis
MeSH terms: Osteoporosis
Study type: Interventional
Phase: Phase 2

Summary: 
      We started the Bone, Estrogen, Strength Training (BEST) study in the fall of 1995 at the
      University of Arizona, Tucson, Arizona. The BEST study is the largest of its kind. It looks
      at the effects of hormone replacement therapy and strength training exercise on bone mineral
      density. (Bone mineral density affects bone strength and the risk of osteoporosis.) Six
      groups of about 300 women each participated in this osteoporosis prevention study. In 1998,
      the BEST study received additional funding to examine for another 2 years the long-term
      effects of strength training on bone mineral density. By 2001 we will have finished analyzing
      the results for all study groups on the 1-year effects of exercise on bone, as well as
      additional analyses on the effects of 2, 3, and 4 years of strength training and
      weight-bearing exercise on bone.
    

Detailed description: 
      Osteoporotic fractures associated with low bone mineral density (BMD) are a significant
      public health problem for women, resulting in over 1 million fractures per year. The
      increasing incidence of fractures will make an already major health problem an even greater
      one in the future. Estimates of medical costs for the treatment of osteoporotic fractures are
      expected to increase from $14.8 billion in 1995 to $60 billion by 2020. Although the Women's
      Health Initiative is investigating dietary and hormonal factors in relation to bone density,
      it is not investigating the effects of exercise on reducing bone mineral loss in
      postmenopausal women.

      This study includes completion of a large, partially randomized clinical trial evaluating the
      effect of a 1-year exercise intervention on total body and regional BMD in two populations
      (hormone replacement therapy [HRT] versus no HRT) of postmenopausal women with a previous
      history of physical inactivity. A major hypothesis is that, compared to the no-exercise
      group, the exercise intervention will be an effective alternative to reduce the risk of
      osteoporosis and the exercise effects will be larger in the cohort of women on HRT than those
      not on HRT.

      The exercise program includes progressive resistance exercises using free weights and weight
      resistance machines and weight-bearing aerobic exercises. We carefully supervise and monitor
      the exercise compliance by keeping records of the amount of exercise completed at each of
      three weekly exercise sessions and by measuring strength gains of selected muscle groups. We
      will measure biochemical markers of bone formation and resorption and hormonal correlates of
      bone mineral density changes including sex steroids at baseline, 6 months, and 1 year.

      We have obtained duplicate blood collections, made one week apart, for all cohorts at each of
      the three measurement periods. We have also collected duplicate dual energy x-ray
      absorptiometry (DXA) scans at each time period to follow changes in axial and appendicular
      BMD and total and regional soft tissue body composition as a result of the intervention. We
      collected extensive dietary intake records during the first year of intervention; we will
      monitor dietary intake in a 2-year followup using food frequency questionnaires. We will also
      measure followup BMD, soft tissue, and lean and fat body composition for 2 years in all women
      who complete the first-year intervention program.

      Two-hundred sixty-six women have completed the first year of the intervention. The study has
      a retention rate of 92 percent in the first year for the first four cohorts.

      Because of the paucity of information regarding long-term effects of exercise, and because of
      the increased emphasis in the scientific community on evaluating the long-term efficacy of
      exercise interventions for osteoporosis prevention, this comprehensive 1-year clinical trial
      and 2-year followup will make an important contribution to determining the future role of
      combining progressive resistance and weight bearing aerobic exercise in the prevention of
      osteoporosis in two populations (HRT vs. no HRT) of postmenopausal women.
    

Intervention name(s): Hormone replacement therapy; Strength training
Intervention type(s): Drug; Procedure
Intervention MeSH terms: Hormones
Allocation: Randomized
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Estrogen; Hormone therapy; Strength training; Exercise; Postmenopause; Disorder prevention; Osteoporosis; Bone mineral density; Bone mass; Cholesterol; Body composition