What Have You Done for Your Bones Lately?

Image of human skeleton, bones.
The many bones in a human. Bone density measurements are typically taken of hip, lower spine and wrist. Photo By Sklmsta, licensed under CC0.

How is your work from home (WFH) exercise routine going? Have you been able to maintain some semblance of a normal exercise routine? Many of us are staying home to avoid potential SARS-CoV-2 infection.

That’s very important. But after six or so months into the pandemic, one starts to consider the impact of not getting more strenuous and varied forms of physical exercise. We frequently think of exercise and it’s effect on muscle tone and heart and lung fitness. But it goes deeper than that. Our bone health is also at risk from lack of exercise.

Bones: Your Newest Tissue
It’s no secret that our bones are tough, made of minerals like calcium and phosphorous. They help us keep upright, supporting a considerable amount of weight against the force of gravity. Bone also protects organs.

Until recently, little attention has been paid to how metabolically active bone is. Research is now revealing that bone is not simply mineralized scaffolding surrounding bone marrow. Bone is actually a tissue, with vasculature and cells with cilia and dendrites that reach through the bony scaffolding, signaling to other cells. This cellular network, influenced by hormones and other compounds produces new bone, and sometimes reabsorbs existing bone, depending on individual needs and state of health.

Bone Health Basics from the NIH
The National Institutes of Health (NIH) has good information on bone density and how it can change throughout life. While you should always discuss concerns about your bone health with your physician, the NIH provides some great basic information, such as:
• High bone density = strength; The stronger our bones, the less likely they are to fracture.
• Bone is an active tissue, constantly either creating new bone or breaking down (reabsorbing) old bone.
• Bone density generally peaks in our 20s, for both men and women.
• Women are at greater risk for bone density loss than men, and the greatest bone loss for women generally happens in early menopause. Estrogen supports bone, and as estrogen declines during menopause, so does bone density.
• Exercise is great for building and maintaining bone health.
• Smoking, drinking too much alcohol, diabetes and undiagnosed celiac disease can all contribute to bone density loss.

The take-home is that good health habits—regular exercise, moderate alcohol consumption and not smoking, as well as knowing your other health risks, are important to good bone health.

Taking Bone Health Seriously
Ok, so exercise can affect our bone strength. It’s September, and many of us been COVID-avoiding by staying at home since March, six months now. It may have occurred to you that an important bone health factor from the list above has been ignored during this time.

Exercise.

Running clubs, swimming pools and gyms were closed much of the early summer, here in Wisconsin. Using weights and treadmills at home is good exercise, but the lack of companionship gained from working out at a fitness center can make keeping the routine difficult.

Serious about working out, you’ve bought stretchy straps, and a few weights and have a bike at home. And you’re using all this equipment. So you’re set, right? Your bones are in great shape?

What Kind of Exercise Do Bones Need?
Our scaffolding, as it turns out, thrives on particular types of exercise. The American Academy of Orthopaedic Surgeons (AAOS) describes these exercises:

Weight-bearing exercise: Just as it sounds, these are activities performed while on our feet, where bones are supporting our weight against gravity. Walking, jogging, dancing, climbing stairs, tennis, pickleball, soccer, basketball are all good weight-bearing exercises. The recommendation is 30-minutes of weight-bearing exercise, 4 days a week. The good news is that if you’re busy or new to/just getting back to exercising, the exercise benefit can be gained from 3 x 10-minute sessions daily, instead of one 30-minute session!

Strength-training exercise: The AAOS describes strength training this way: “Although resistance exercises focus on increasing muscle mass, they also put stress on bones and have bone-building capacity.” Strength-training exercises can include the use of weight machines, free weights and exercises like push-ups and squats, that use body weight. Elastic bands are also good for resistance training. The AAOS recommends that we “exercise each major muscle group at least twice a week. Be sure to rest for a full day between strength sessions.”

Other forms of exercise: Of course healthy exercise is not only about bone strengthening. The AAOS says that activities like yoga and tai chi, while not as effective for bone strengthening, provide important flexibility and balance benefits. Swimming, biking and chair exercises don’t increase bone density, but provide significant benefits to muscles, heart and lungs. The AAOS notes that if you have a health condition like arthritis, that makes weight-bearing activities impossible, nonimpact exercises are good alternatives.

Can We Still Add Bone After 30?
Many experts believe that bone loss after age 30 is inevitable, and that we can, at best, slow bone loss. While researching this blog I found some intriguing research from Watson et al., High-Intensity Resistance and Impact Training Improves Bone Mineral Density and Physical Function in Postmenopausal Women With Osteopenia and Osteoporosis: The LIFTMOR Randomized Controlled Trial on the potential to not only stop bone loss in aging, but potentially to increase bone mass.

This group studied high intensity resistance and impact training in post-menopausal women, and showed that over 8 months of twice-weekly, supervised training, resistance exercises, including deadlift, overhead press and back squat, could enhance bone at clinically relevant sites (hip, spine and wrist) in post-menopausal women with low to very low bone mass. This study is the first to publish results using high-intensity training, previously considered not suitable for women with low bone mass.

The Take-Away
Keep at those heart-, muscle- and lung-challenging exercises, and include some walking, jogging, jump roping and/or stair climbing (basketball, soccer, tennis, etc.). Aim for 30 minutes a day, 4 days a week for the gravity-challenging, weight-bearing activities.

And if you’re of a certain age, it might be worthwhile to find a strength coach and learn some high intensity resistance and impact training. Here’s hoping that the results from Watson et al. soon translate to fitness centers and become on-trend for adults that had not previously exercised with high intensity resistance and impact exercises.

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Kari Kenefick

Kari has been a science writer/editor for Promega since 1996. Prior to that she enjoyed working in veterinary microbiology/immunology, and has an M.S. in Bacteriology, U of WI-Madison. Favorite topics include infectious disease, inflammation, aging, exercise, nutrition and personality traits. When not writing, she enjoys training her dogs in agility and obedience. About the practice of writing, as we say for cell-based assays, "add-mix-measure".

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