Exercise and calcium supplementation improve bone mineral density

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Exercise, Calcium Supplementation May Improve BMD in Postmenopausal

Women CME/CE

News Author: Laurie Barclay, MD

CME Author: Désirée Lie, MD, MSEd

Disclosures

To earn CME credit, read the news brief along with the CME

information that follows and answer the test questions.

Release Date: December 28, 2005

Dec. 28, 2005 — Exercise and calcium supplementation improve bone

mineral density (BMD) in postmenopausal women, according to the

results of a 4-year study reported in the December issue of

Osteoporosis International.

" The good news is these long-term data confirmed the potent

combination of improved nutrition and increased physical activity to

prevent bone loss, " principal investigator Lohman, PhD, from

the University of Arizona in Tucson, said in a news release. " The

extended use of calcium supplementation and exercise counteracted

the typical loss of BMD in women at this age, in a regimen that

women really can stick with. This is quite significant for younger

women as well, as these exercises and calcium supplementation can

help build peak BMD which may prevent health problems and

osteoporosis in the future. "

In the Bone, Estrogen, Strength Training (BEST) study, 167

postmenopausal, calcium-supplemented (800 mg/day) sedentary women

were randomized to a progressive strength training exercise program

or to a control group and were followed up for 4 years. Mean age was

56.1 ± 4.5 years, and 54% of the women were using hormone therapy

(HT) at baseline. At 1 year, women in the control group were

permitted to crossover to the exercise program. The final sample

consisted of 23 controls, 55 crossovers, and 89 randomized

exercisers.

The prescribed exercise program was 2 sets of 6 to 8 repetitions of

exercises at 70% to 80% of 1 repetition maximum, 3 times weekly.

" What sets this regimen apart is the six specific exercises that

help build bone in the wrist, hip and spine — three key fracture

sites, " says BEST Study coinvestigator Lauve Metcalfe, MS, also from

the University of Arizona in Tucson. " This type of weight-bearing

exercise now is proven to be beneficial and represents a shift in

prior bone health recommendations. It previously was thought that

any type of exercise was helpful, but now we understand that

resistance and weight-bearing exercise are essential. "

Dual-energy x-ray absorptiometry (DEXA) was used to measure BMD at

baseline and annually thereafter. Average 4-year percentage exercise

frequency (ExFreq) was 26.8% ± 20.1% for crossovers (including the

first year at 0%) and 50.4% ± 26.7% for exercisers. Average 4-year

total confidence interval (CI) was 1,635 ± 367 mg/day, and

supplemental calcium intake was 711 ± 174 mg/day.

Adjusted multiple linear regression models revealed that ExFreq was

positively and significantly related to changes in femur trochanter

(FT) and neck (FN), lumbar spine (LS), and total body (TB) BMD. For

women receiving HT, FT BMD increased 1.5%, and the FN and LS BMD

increased 1.2% (P < .01) for each SD of percentage ExFreq (29.5% or

0.9 days per week). Women not using HT gained 1.9% and 2.3% BMD at

FT and FN, respectively, for every SD of CI (P < .05).

" The significant, positive, association between BMD change and

ExFreq supports the long-term usefulness of strength training

exercise for the prevention of osteoporosis in postmenopausal women,

especially HT users, " the authors write. " The positive relationship

of CI to change in BMD among postmenopausal women not using HT has

clinical implications in light of recent evidence of an increased

health risk associated with HT. "

Study limitations include allowing controls to cross over to the

exercise group of the study after the first year of intervention;

potential training time discrepancies between exercisers and

crossovers; questionable accuracy of self-reports of exercise; and

dropout rates.

" This study supports the long-term benefits of strength training

exercise and calcium intake for the prevention of osteoporosis in

postmenopausal women, " the authors conclude. " Combined with

exercise, women may choose to continue HT or increase total calcium

intake to around 1,700 mg/day to help prevent osteoporosis. "

The National Institute for Arthritis and Musculoskeletal and Skin

Diseases of the National Institutes of Health funded the BEST Study.

Mission Pharmacal Co supplied calcium citrate (Citracal) for the

study.

Osteoporos Int. 2005;16:2129-2141

Learning Objectives for This Educational Activity

Upon completion of this activity, participants will be able to:

Describe the benefits of exercise on BMD in postmenopausal women.

Identify the role of calcium supplementation in preserving BMD in

postmenopausal women.

Clinical Context

Women may lose 10% to 20% of BMD with aging, and according to the

authors, in the United States by 2020, 50% of the population older

than 50 years will be at risk for bone fracture. Progressive

strength training may improve BMD at critical fracture sites and,

according to the authors, one study has suggested that BMD increased

in women who were not receiving HT and were performing 1 hour of

loading exercises per week for 2 years. However, the role of

exercise in combination with calcium supplementation has not been

well studied.

The current study is a prospective 4-year block-randomized trial of

women enrolled in the BEST study, who continued a regimen of calcium

supplementation with or without exercise, to examine the effect of

regular progressive resistance exercises on BMD in early

postmenopausal women.

Study Highlights

Women who completed baseline and at least the fourth year of annual

testing were included in analysis.

Inclusion criteria were ages 40 to 65 years, surgical or natural

menopause, body mass index greater than 19 kg/m2 and less than 33

kg/m2, no weight gain or loss greater than 13.6 kg in the previous

year, free of cancer, nonsmoking, not using bone-altering

medications, dietary calcium intake of more than 300 mg daily, and

engaging in less than 120 minutes of low-intensity, low-impact

exercise weekly.

Those receiving HT were asked to continue the regimen as prescribed.

Most women took combination HT (80%), and the rest took estrogen

only (10%) or estrogen/protein by patch (10%).

54% of women were receiving HT in the study.

167 women were analyzed, of whom 23 remained controls for 4 years;

89 were in the randomized exercise group and 78 crossed over to

exercise from year 2.

Dietary calcium intake was estimated using 8 days of dietary records

and the scanned Arizona Food Frequency Questionnaire.

In years 1 and 2, all participants received 800 mg of elemental

calcium daily, and in years 3 and 4, they purchased calcium citrate

(Citracal) or a comparable supplement.

Primary outcomes were BMD measured by DEXA using total body

densitometer annually. The mean of 2 measurements was used for each

analysis. Percentage body fat was estimated.

Exercise consisted of 3 days a week of 60 to 75 minutes per session

in a community facility with a trainer and was composed of leg

press, military press, seated row, squats, back extension, and

lateral pull down. Participants did 2 sets of 6 to 8 repetitions

with 7 to 10 minutes of cardiovascular weight-bearing activity for

each session.

Mean age was 56 years, and mean years since menopause was 6 years.

In year 1, 92.8% of women were 80% compliant with the calcium

supplement protocol. By year 4, the compliance dropped to 65.1%.

Women gained an average of 0.9 kg during 4 years; mean daily calcium

dietary intake was 924 mg and supplemental calcium intake was 711

mg.

Mean calcium intake was higher in those with the ExFreq (P < .01).

Mean ExFreq averaged 26.8% for crossovers and 50.4% for exercisers.

The highest ExFreq was associated with less BMD loss for the TB vs

the lowest tertile of ExFreq.

ExFreq was positively, independently, and significantly associated

with change in FT, FN, LS, and TB BMD among HT users and associated

with change in LS BMD among nonusers (P < .05), controlling for age,

baseline BMD, and body weight.

Women who attended the most exercise sessions showed the largest

gains in BMD.

FT BMD increased by 1.5% and FN and LS BMD by 1.2% for every

increase of 29.5% or 0.9 days per week of exercise.

Mean total daily calcium was positively and significantly associated

with change in BMD at the FT and FN (P < .05) for women not using

HT.

Mean daily calcium intake was significantly and positively

associated with change in BMD at all sites and for the TB (P < .05)

for women not using HT.

Among women not using HT, those taking at least 800 mg of

supplemental calcium (for a total intake of at least 1,700 mg) daily

had a greater improvement in BMD.

Pearls for Practice

Strength training exercise for 4 years is associated with greater

protection of BMD compared with no exercise in postmenopausal women.

Intake of at least 1,700 mg of calcium daily is protective for BMD

among nonusers of HT.