Weight training decreases vertebral bone density in premenopausal women: a prospective study.
The effect of exercise on bone mass is unclear. To determine the skeletal effect of weight-bearing exercise in premenopausal women, we prospectively evaluated the effects of a weight-training program on lumbar spine bone mass in 10 women (mean +/- SEM, 36.2 +/- 1.3 yr) and compared the results with those in 7 sedentary women (40.4 +/- 1.6 yr). None of the women had previously participated in a weight-training program, and all ingested a 500-mg calcium supplement each day throughout the study. Axial loading and balance of large muscle groups were emphasized. Individual strength increased by 57 +/- 8% over 9 months. Despite the increase in muscle strength, lumbar spine bone density in the exercising women decreased by 2.90% at 4.5 months and 3.96% at 9 months (P = 0.01). In contrast, there was no change in lumbar density in the controls over the 9-month period. We conclude that short term weight training at this frequency and intensity decreases vertebral bone mass in premenopausal women.
Department of Medicine, University of Massachusetts Medical Center, Worcester 01655.
J C
JC
Rockwell
A M
AM
Sorensen
S
S
Baker
D
D
Leahey
J L
JL
Stock
J
J
Michaels
D T
DT
Baran
D000328:Adult; D015992:Body Mass Index; D015519:Bone Density; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae; D010806:Physical Education and Training; D011446:Prospective Studies