Does Low Or High Intensity Exercise Strengthen Bones? This Study Has The Answer

Savers know that regular exercise reduces fracture risk. That's why it's a fundamental part of the Osteoporosis Reversal Program. Since that basic fact is established, scientists have begun seeking more precise answers about which type and duration of physical activity have the greatest benefit.

Today we'll look at the details of a recently-published study that examined the association of physical activity and fracture risk among postmenopausal women. Their findings are a useful tool for pursuing optimal bone health.

The Details Of The Study

“Is the amount and intensity of physical activity associated with total and site-specific fracture among postmenopausal women who participated in the Women’s Health Initiative study?”¹

That is the question posed by a team of researchers from across the United States in their study published recently in The Journal of the American Medical Association. The study followed 77,206 postmenopausal women aged 50 to 79 over an average of 14 years, using information they volunteered to the Women's Health Initiative study.

The researchers compiled data on the type, duration, and frequency (days-per-week) of exercise performed by each of those participants.

The varieties of physical activity (PA) were grouped into strenuous, moderate, or mild.

Strenuous PA was defined as exercise that elicited sweating and a fast heartbeat, including:¹

• Aerobics
• Aerobics dancing
• Jogging
• Tennis
• Swimming laps

Moderate PA included less exhausting activities such as:

• Biking outdoors
• Using an exercise machine
• Calisthenics
• Easy swimming
• Social dancing
• Folk dancing

Mild PA included activities such as:

• Slow dancing
• Bowling
• Golf

Walking was assessed as a seperate category. And data was also gathered on non-recreational activities such as heavy indoor household chores (like scrubbing floors or sweeping) and yard work (like raking, gardening or shoveling snow).

The researchers compared this detailed information about each participant's physical activity with their bone health records, considering total fractures and fractures at particular locations (hip, wrist, forearm, and vertebral). Once assembled, this massive set of information revealed trends about the relationship between different types and practice of physical activities and fracture outcomes.

Synopsis

Researchers gathered data from 77,206 postmenopausal women on their physical activity and fracture occurrence over the course of 14 years. They grouped physical activities into strenuous, moderate, and mild categories, and considered walking and non-recreational activities like household chores and yardwork.

The Results Of The Study

The study found that frequent intense physical activity generally reduces fracture risk, but may increase the chance of a wrist or forearm fracture. Less intense physical activities reduce fracture risk of all types, without increasing the chance of a wrist or forearm fracture.

This result was reinforced by data showing that sedentary time was positively associated with total fracture risk.

Perhaps the most important and novel finding was that lower intensity activities like walking and non-recreational activities like yard work have a measurable benefit on fracture risk at older ages.

The studies' findings include the following:¹

• Recreational and non-recreational PA was inversely associated with risks of hip, clinical vertebral, and total fractures (meaning more PA resulted in less fracture.)
• Women in the highest total PA tertile had an 18% lower risk of hip fracture.
• Total PA was positively associated with knee and elbow fracture when the most active group was compared to inactive participants.
• Mild-intensity PA was associated with lower risks of hip, vertebral, and total fracture, and moderate to vigorous PA was associated with lower risk of hip fracture but higher risk of wrist or forearm fracture.
• Yard work was inversely associated with hip and total fractures.
• Yard work was not associated with risks of clinical vertebral or wrist and forearm fractures.
• Energy expenditure from heavy chores was not associated with total or site-specific fractures.
• Mild PA and walking were associated with lower risk of hip fracture.

The study's discussion section included the following passage, which interprets the report's findings on the relationship between PA and fracture, including the surprising link between high-intensity PA and wrist or forearm fracture:

“Regular PA can help improve balance, range of motion, and muscle strength, thereby reducing falls, a major risk factor for fracture. Because hip and vertebral fractures occur frequently in older women, even a modest protective association with PA could account for a meaningful number of averted fracture cases and related complications within the population.

While ambulatory PA can mitigate age-related hip and spine bone loss, it may exert less stress on the wrist and forearm and minimally influence BMD at this site. The greater demands of MVPA (moderate to vigorous physical activity) might be assumed to increase the risk of falling.

However, recent results in a WHI (women's health initiative) substudy on women aged 63 to 99 years whose PA was directly measured using accelerometers showed that fall rates were elevated in women engaging in low but not moderate or higher levels of MVPA. Women capable of doing MVPA may be more functional and more likely to break a fall with outstretched hands, which could account for the higher prevalence of wrist and forearm fractures associated with MVPA in the present study.”¹

The last section shows how study data often presents only part of a complete picture. The researchers are suggesting that the increase of wrist and forearm fracture occurs because the most physically active women are coordinated and fit enough to catch themselves with their hands, instead of falling in a way that might fracture their hip, leg, or spine.

Synopsis

Overall PA was associated with reduced falls and fractures. In particular, hip and total fractures decreased as PA increased. The participants who did the most frequent and highest intensity PA were more likely to break a wrist or forearm than inactive participants, but this may be a sign that their physical coordination allowed them to break a fall with their hands. Yard work and walking both were associated with reduced fracture risk.

What This Means To You

The wrist or forearm fractures recorded in the participants engaging in high-intensity activities are an excellent reminder that you should always use caution, especially as you get older.

However, as the study found, you don't need to do high-intensity activities to reduce your overall fracture risk. If you'd like help putting together a safe and effective workout routine, trust the experts at SaveTrainer. With SaveTrainer you can customize your workout routines to match your fitness and comfort level, and ensure that you're not overextending yourself.

References

¹ https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2753526