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.
Rockwell
J C
JC
Department of Medicine, University of Massachusetts Medical Center, Worcester 01655.
Sorensen
A M
AM
Baker
S
S
Leahey
D
D
Stock
J L
JL
Michaels
J
J
Baran
D T
DT
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