Original articleStronger back muscles reduce the incidence of vertebral fractures: a prospective 10 year follow-up of postmenopausal women
Introduction
Reduction in the biomechanical competence of the axial skeleton can result from the parallel decline in bone and muscle mass with aging. Inactivity also may contribute to this decline.18 Participation in a strength training program can decrease the risk of falls and fractures of the lower extremities.21
One study of the effect of strengthening exercises for back extensor muscles in healthy postmenopausal women demonstrated a significant increase in back extensor muscle strength and improvement of posture, but not bone mineral density (BMD).10 However, results of previous studies have been inconsistent; some have demonstrated improvement in muscle strength with exercise but not in BMD,3, 8, 13, 15, 23, 28 whereas others depicted improvement in muscle strength and BMD of the lumbar spine in estrogen-deficient women.14, 22
Subject compliance with prescribed exercise interventions presents a challenge. In one 3 year controlled, randomized study of healthy premenopausal women, the dropout rate was 34% in the exercise group and 22% in the control group.27 Even in studies of shorter duration (i.e., 2 year trial of brisk walking in postmenopausal women), 41% attrition was noted in both areas of the study.6 Subjects who are not self-motivated may not continue with prescribed exercise programs.20 However, compliance with a short-term exercise program has been more satisfactory.12
We hypothesized that: (1) stronger back muscles could reduce the risk of vertebral compression fractures; and (2) some of the muscle strength achieved through strengthening exercises may persist even several years after cessation.
The objective of this prospective study was to determine the long-term protective effect of stronger back muscles on the spine. In this controlled trial, 8 years after cessation of a 2 year course of back-strengthening exercises, we investigated whether increased muscle strength had any effect on the development of age-related changes such as muscle strength, BMD, or development of vertebral compression fractures.
Section snippets
Study population
Of 100 volunteers, 68 met the inclusion criteria.28 Later in the process of evaluation and enrollment, one subject withdrew because she was moving from the area, one withdrew for lack of interest, and one was hospitalized for hemorrhagic duodenal ulcer. Thus, 65 healthy white, postmenopausal, nonsmoking women were randomized and enrolled into a 2 year controlled, intensive, progressive back-exercise study (approved by our institutional review board). The average age of the subjects at the time
Results
Data for both study groups are summarized in Table 1. There were no dropouts from either group in the first 2 years of the study, and 77% of the subjects were available for follow-up at 10 years (27 of 34 BE subjects [79%] and 23 of 31 C subjects [74%]). On review of the subjects’ medical records and histories, none had had a hip fracture. All were nonsmokers with minimal or no alcohol intake. Although some of the subjects had been prescribed estrogen during the 8 year poststudy period, none
Discussion
In this study, we evaluated the long-term effect of stronger back muscles on the spine in estrogen-deficient women. The data showed that although vertebral bone loss was comparable in both groups, the BE group had fewer than half as many vertebral fractures as the control group, even 8 years after cessation of the back-strengthening exercises. The difference in BMD between the groups was not statistically significant at baseline nor at 2 year follow-up. However, at 10 year follow-up, even
Acknowledgments
This study was supported in part by Grant RR 00585 from the National Institutes of Health, a grant from the Retirement Research Foundation, and a grant from Donaldson Charitable Trust. The authors thank Sandy Fitzgerald for her efforts in contacting and scheduling the subjects for follow-up and for secretarial support.
References (31)
- et al.
Effect of back-strengthening exercise on posture in healthy women 49 to 65 years of age
Mayo Clin Proc
(1994) - et al.
Downturn in hip fracture incidence
Public Health Rep
(1996) Influence of training and of inactivity on muscle strength
Arch Phys Med Rehabil
(1970)- et al.
Efficacy of nonloading exercises in prevention of vertebral bone loss in postmenopausal womenA controlled trial
Mayo Clin Proc
(1989) - et al.
Long-term recreational gymnastics, estrogen use, and selected risk factors for osteoporotic fractures
J Bone Miner Res
(1999) Metabolic calculations. Guidelines for exercise testing and prescription
(1995)Exercise testing and training of individuals with heart disease or at high risk for its developmentA handbook for physicians
(1975)- et al.
Pre- and postmenopausal women have different bone mineral density responses to the same high-impact exercise
J Bone Miner Res
(1998) - et al.
Decline of height with age in adults in a general population sampleEstimating maximum height and distinguishing birth cohort effects from actual loss of stature with aging
Hum Biol
(1989) - et al.
Weight-bearing exercise training and lumbar bone mineral content in postmenopausal women
Ann Intern Med
(1988)
Randomized placebo-controlled trial of brisk walking in the prevention of postmenopausal osteoporosis
Age Ageing
Strength conditioning in older men: Skeletal muscle hypertrophy and improved function
J Appl Physiol
Effects of weight lifting on bone mineral density in premenopausal women
J Bone Miner Res
Roentgenographic analysis of posture in spinal osteoporotics
Spine
High bone mineral density induced by weight lifting, returns to normal after cessation of training career
Trans Annu Meet Orthop Res Soc
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