The purpose of the study is to determine the effectiveness of combining exercise training (i.e. weight lifting and walking) and dietary supplementation with a soy-based nutritional supplement for increasing bone mineral density. We hypothesize that the exercise training and soy-based supplement will be additive for increasing bone mineral density.

Exercise training is effective for increasing bone mineral density and preventing osteoporosis, but the effects are small. When estrogen replacement is given to post-menopausal women the effectiveness of exercise training for improving bone mineral density is increased. Currently many women are concerned about the risks of taking hormone-replacement therapy and are seeking alternative therapies. The purpose of our study therefore is to use an estrogen-like dietary supplement derived from soy called a phytoestrogen (soy isoflavone) combined with exercise training for improving bone mineral density.

Comparisons: Four groups are being compared: 1) Exercise training (i.e. weight lifting 2 times per week and walking 4 times per week) plus soy isoflavone (90 mg aglycone equivalents per day); 2) Exercise training plus placebo; 3) Exercise placebo (flexibility exercises four times per week) plus soy isoflavone; 4) Exercise placebo plus placebo.

Inclusion Criteria:

• Post-menopausal women

Exclusion Criteria:

• Diagnosed osteoporotic
• Previous fragility fractures
• Previous breast cancer
• Previous endometrial cancer
• Taken bisphosphonates in past 12 months
• Taken hormone replacement therapy in past 12 months
• Taken selective estrogen receptor modulators in past 12 months
• Taken parathyroid hormone in past 12 months
• Taken calcitonin in past 12 months
• Currently taking corticosteroids
• Currently taking a thiazide diuretic
• Crohn's Disease
• Cushing Disease
• Allergy to soy
• Severe osteoarthritis
• Currently participating in vigorous exercise