79010100065p

George A. Kelley, DAKristi S. Kelley, MEdZung Vu Tran, PhD Research Series Article
Clinical Investigation, MGH Instituteof Health Professions (GAK, KSK),Boston, Massachusetts; and theDepartment of Preventive Medicineand Biometrics, University ofColorado Health Sciences Center(ZVT), Denver, Colorado.
Resistance Training and Bone
Mineral Density in Women
All correspondence and requests forreprints should be addressed to George A. Kelley, DA, AssociateProfessor, Graduate Program inClinical Investigation, Director, Meta-Analytic Research Group, MGH ABSTRACT
Institute of Health Professions, 101Merrimac Street, Room 1059B, Kelley GA, Kelley KS, Tran ZV: Resistance training and bone mineral density in women: a meta-analysis of controlled trials. Am J Phys MedRehabil 2001;80:65–77.
The purpose of this study was to use meta-analysis to examine the effects of resistance training on bone mineral density at the femur, Department of Defense, Army MedicalResearch and Material Command lumbar spine, and radius in pre- and postmenopausal women. Resis- tance training had a positive effect on bone mineral density at thelumbar spine of all women and at the femur and radius sites for post- menopausal women. It was concluded that resistance training has a American Journal of PhysicalMedicine & Rehabilitation positive effect on bone mineral density in women.
Copyright 2001 by LippincottWilliams & Wilkins Key Words:
Osteopenia and osteoporosis are major public health problems in the
United States, affecting primarily lean, white, postmenopausal women.1 Cur-rently approximately 26.2 million white, postmenopausal women in the UnitedStates have either osteopenia or osteoporosis.1 More specifically, osteopenia,defined as bone density that is 1 to 2.5 SD below the young adult referencerange, affects an estimated 16.8 million (54%) of postmenopausal white wo-men in the United States, whereas osteoporosis, defined as bone density Ͼ2.5SD below the young adult reference range, affects another 9.4 million(30%) women.1, 2 Low-bone density increases the risk for fractures, particularly atthe hip, spine, and distal forearm. Currently, the estimated lifetime risk forfracture in 50-yr-old white women in the United States is 17.5% at the hip,15.6% at the vertebrae, and 16.0% at the distal forearm.1 In terms of themortality rate, the survival rate at 5-yr follow-up relative to those of like ageand gender is 0.83 for those who have experienced a hip fracture, 0.82 forvertebral fractures, and 1.00 for fractures of the forearm.3 In the United States, Resistance Training and Bone Mineral Density crease substantially in future years.
may have a positive effect on BMD, ercise does have a positive effect.
criteria was included in our analysis.
Am. J. Phys. Med. Rehabil. ● Vol. 80, No. 1 significant effect of exercise on BMD.
tion and interpretation of findings.
heterogeneous (P Ͻ 0.05), whereas a trained at a higher intensity vs. one tau statistic (␶).67 A statistically signif- icant result (P Ͻ 0.05) was considered to be suggestive of publication bias.
tity and institutional affiliation of the interrater agreement, r ϭ 0.77, 95% Subgroup Analyses. For categorical
Primary Outcomes. The primary out-
Resistance Training and Bone Mineral Density TABLE 1
Study characteristics
Study
addition of ankle and wristbands (1–2 kg) Am. J. Phys. Med. Rehabil. ● Vol. 80, No. 1 TABLE 1
Continued
training (10 of the 13completed the training alongwith an additional five subjects) performed jumping exerciseswith a weighted vest.
Resistance Training and Bone Mineral Density TABLE 1
Continued
to either a resistance training (n to either a resistance training (n Snow-Harter et al.49 RCT that included 20 to either a resistance training (n to either a resistance training (n RCT, randomized controlled trial; CT, controlled trial; subjects; ages reported as mean Ϯ SD; number of subjects listed includes only those who completed the study; BMD, bone mineral density; 1 RM, one repetition maximum; DEXA, dual-energyx-ray absorptiometry; DPA, dual photon absorptiometry; SPA, single photon absorptiometry; QCT, quantitative computed tomography.
differences. If statistically significant isted (P Ͻ 0.05), a random-effects tertrochanter, and Ward’s triangle.
Regression Analysis. For continuous
Am. J. Phys. Med. Rehabil. ● Vol. 80, No. 1 tions,26, 27, 32–37, 40, 42, 44, 46, 47, 51 were,25, 28, 30, 31, 39, 43, 45, 48 and one Secondary
Outcomes.
rettes,25, 31, 33, 36, 39, 40, 44–47 whereas in journals,25, 27–32, 34–38, 40, 42–50, 52 five smoked.28, 35, 48, 51 Two studies reported were dissertations,24, 26, 33, 39, 41 and States,24, 26–28, 33, 34, 36–39, 41–50 three ously active,25, 26, 29, 31, 33, 34, 36, 39, 40, 43 were,24, 28, 32, 35, 44, 48–50 and five re- ported that all were.30, 37, 46, 51, 52 Five tures,29, 39, 43, 46, 47 whereas three re- 551 subjects who served as controls.
are reported as mean Ϯ SD. The ␣ level for statistical significance was set at P tistical significance. Bonferroni adjust- reported that all of the subjects werewhite,26, 28, 33–36, 40, 43, 45–48 one study ria for inclusion.24–52, 59, 60 However, ments,33, 36–38, 43, 46, 48, 51 seven re- taking supple ments,24, 26–28, 34, 44, 49 Resistance Training and Bone Mineral Density TABLE 2
Initial physical characteristics of subjects
n, number of groups reporting data; BMI, body mass index.
Proximal Femur. Small and statisti-
bias was observed (r ϭ Ϫ0.08, P ϭ 0.27 Ϯ 0.36 (95% BCI, 0.14 – 0.41).
bias was observed (r ϭ 0.12, P ϭ statistically significant differences be- Femur. There was a trend for greater
Radius. Small and statistically signif-
bias was observed (r ϭ 0.17, P ϭ Lumbar Spine. Small but statistically
TABLE 3
Initial BMD values
BMD, bone mineral density; BMD data based on number of exercise and control values.
Am. J. Phys. Med. Rehabil. ● Vol. 80, No. 1 TABLE 4
BMD results
a Statistically significant.
BMD, bone mineral density; ES, effect size; BCI, Bootstrap Confidence Interval, Q (P), heterogeneity (probability for alpha).
Lumbar Spine. No statistically signifi-
0.23% increase in the control groups.
sufficient data were available to examine diet, and sites at which the lumbar spine Radius. There was a trend for greater
well as drugs that could affect BMD.
TABLE 5
Subgroup analyses
ES, effect size; BCI, Bootstrap Confidence Interval; Q , difference between groups.
a Trend for statistical significance when P ranges from Ն0.05 to Յ0.10; b Statistically significant when P Ͻ 0.05.
ES outcomes based on number of ESs.
Resistance Training and Bone Mineral Density DISCUSSION
Femur. The only significant predictor
(Q ϭ 6.67, P ϭ 0.03; Q ϭ 14.32, P ϭ 0.35). Larger ES changes in BMD study is the fact that the largest effect Radius. The only significant predic- (Q ϭ 6.76, P ϭ 0.009; Q ϭ 9.26, P vs. the lumbar spine and femur sites.
place greater stress on their bones.
Am. J. Phys. Med. Rehabil. ● Vol. 80, No. 1 been the case with our investigation.
“rigor,” we believe that it is critical, studies that yielded a statistically sig- Resistance Training and Bone Mineral Density al: Exercise therapy for osteoporosis. Os- teoporos Int 1993;Suppl 1:S166 –S168 of therapeutic intervention. Am J Phys 13. Sinaki M: Exercise and osteoporosis.
Arch Phys Med Rehabil 1989;70:220 –9 30. Heinonen A, Sievanen H, Kannus P,et al: Effects of unilateral strength train- bone mineral density, and osteoporosis.
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