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Exercise Appears to Improve Bone Structure, Not Density

10/22/2021 | Health News

“Postmenopausal women with low bone mass should obtain adequate calcium and vitamin D and participate in bone-loading exercises,” researchers summarize in a recent study published in Osteoporosis International.

“Additional use of bisphosphonates will increase bone mineral density (BMD), especially at the spine,” Nancy Waltman, PhD, College of Nursing, University of Nebraska Medical Center, Omaha, and colleagues conclude.

The findings are partial results from the Heartland Osteoporosis Prevention Study (HOPS), which randomized women who had entered menopause within the previous 6 months and had osteopenia (low bone mass, T score –1.0 to –2.49) to receive one of three treatments for 12 months:

Bone-loading and resistance exercise plus calcium and vitamin D supplements
Risedronate plus calcium and vitamin D supplements
Calcium and vitamin D supplements alone (control)

At 1 year, “risedronate significantly increased BMD at the spine, compared to exercise and control, and serum biomarkers of bone turnover also significantly reduced in the risedronate group,” Laura Bilek, PT, PhD, summarized during an oral presentation of the research at the American Society of Bone and Mineral Research (ASBMR) 2021 Annual Meeting.

However, the results also showed that, importantly, “in postmenopausal women, exercise appears to improve strength at the hip through changes in structure, not BMD,” Bilek, from the College of Allied Health Professionals, University of Nebraska Medical Center, stressed.

Bone Health Is About More Than Just Bone Mineral Density

“The key takeaway for clinicians is that bone health is about more than just density!” she emphasized in an email to Medscape Medical News.

Current guidelines don’t recommend prescribing risedronate until a woman has overt osteoporosis, she noted.

On the other hand, many studies have shown that, to be most effective, bone-loading exercises should be a lifelong habit and women should begin to do them at least during menopause and not wait until bone loss occurs.

Other studies have shown that exercise changes bone structure (size or geometry), which improves bone strength. The current study supports both prior observations.

And exercise also improves muscle strength and decreases the risk of falls and fractures, Bilek noted.

Invited to comment, Pauline M. Camacho, MD, co-chair of the task force for the American Association of Clinical Endocrinologists (AACE) guidelines for osteoporosis, noted that all three measures — pharmacotherapy, exercise, and calcium/vitamin D — are important in the successful management of osteoporosis.

This study showed that risedronate is superior to calcium/vitamin D supplementation as well as exercise for BMD and for bone turnover in these women with osteopenia, said Camacho, professor of medicine and director of the Osteoporosis and Metabolic Bone Disease Center, Loyola University Medical Center, Chicago, Illinois.

“Most women with osteopenia do not receive pharmacologic therapy,” she noted, and only receive it “if there is a history of fractures or they have other features that change that diagnosis to osteoporosis.”

“There is no downside to exercise, and this needs to be advised to all patients,” she agreed. “The other aspect of exercise that was not assessed in this study is its effect on balance. Patients who exercise will have improved balance, which should translate into fewer falls, and thus fewer fractures.”

How Can Women With Osteopenia Maintain Bone Health?

In their article, Waltman and colleagues say the Lifting Intervention for Training Muscle and Osteoporosis Rehabilitation (LIFTMOR) clinical trial is one of the first to address clinician concerns about the safety and effectiveness of exercise to improve bone health.

In that trial of 101 postmenopausal women with low bone mass, 8 months of 30-minute, twice-weekly, supervised high-intensity resistance and impact training was safe and BMD increased by 2.9% at the lumbar spine and 0.3% at the femoral neck.

“Our [HOPS] study,” Waltman and colleagues explain, “builds on the LIFTMOR clinical trial and adds further data to inform whether postmenopausal women with low bone mass can effectively maintain or even improve BMD with bone-loading exercises prior to prescriptions for medication.”

“Our long-term goal is to contribute to the development of clinical practice guidelines for the prevention of fractures in postmenopausal women with low bone mass,” they say.

They randomized 276 postmenopausal women who were a mean age of 54 (range, 44-63); most were White (78%) or Hispanic (6%).

Women were excluded from the study if they had a diagnosis of osteoporosis (T-score < −2.5); had an increased risk of a major fracture or hip fracture; had been on bisphosphonates within the last 6 months; were currently on estrogen, tamoxifen, or aromatase inhibitors; had a serum vitamin D level < 10 mg/mL or > 100 mg/mL; had any conditions that prohibited prescriptions for calcium and vitamin D supplements, risedronate, or exercise; or weighed more than 300 lbs.

All women received 1200 mg/day of calcium (from supplements or diet) and 1000-3000 IU/day of vitamin D supplements, based on their serum 25(OH) vitamin D levels.

The exercise program consisted of visiting a gym three times a week for 45 minutes of bone-loading exercise — jogging with a weighted vest — and resistance exercises, which were supervised by a trainer for the first 2 weeks.

Women in the risedronate group received a 150-mg tablet of risedronate every 4 weeks.

At baseline, 6 months, and 12 months, the women had DXA scans to determine BMD and hip structure, and had blood tests to determine levels of serum markers for bone formation (bone specific alkaline phosphatase [Alkphase B]) and bone resorption (N-terminal telopeptide [NTx]).

Compared with baseline, at 12 months, the women had the following changes in BMD at the following sites:

Spine: +1.9%, +0.9%, and –0.4%, in the risedronate, exercise, and control groups
Total hip: +0.9%, +0.5%, and +0.5%, in the risedronate, exercise, and control groups
Femoral neck: +0.09%, –0.4%, and –0.5%, in the risedronate, exercise, and control groups

These improvements in BMD were significantly greater in the risedronate group than in the exercise or control groups (P < .01 for both).

The decreases in serum levels of NtX and Alkphase B were also greater with risedronate than in the exercise or control groups (P < .01 for all).

The most frequent adverse effect with the calcium supplement was constipation (n = 4). Some women taking risedronate had gastrointestinal disturbances (n = 4), muscle or joint pain (n = 11), or chest pain and dizziness (n = 2). None of the women had adverse effects from vitamin D. A few women had muscle soreness from exercise that went away after the exercises were adapted. None of the women had a serious injury or fracture from exercise.

More women in the exercise group withdrew from the study (n = 20), with most citing lack of time as the reason; 13 women withdrew from the risedronate group, and 16 withdrew from the control group.

Of the 276 participants who completed the 12-month study, treatment adherence was 92% for calcium, 94% for vitamin D, 75% for risedronate, and 59% for exercise.

Exercise was associated with positive changes in intertrochanter hip structural analysis measures, which will be described in an upcoming study, Bilek said.

The study was funded by the National Institute of Nursing Research of the National Institutes of Health. The researchers have reported no relevant financial relationships.