It is well-known, at least amongst health-conscious people of a certain age, that exercise plays a role in the prevention of osteoporosis.

Furthermore, it’s generally considered that resistance training is the most beneficial, as putting weight on bones forces them to become stronger. This may seem like a dangerous endeavor, akin to “putting stress on this teacup will force it to become stronger”, which clearly has a false logic to it, but the fact is that (contrary to popular belief that they are a sort of inorganic mineral scaffold) our bones are a living, ever-changing part of our body. Yes, there’s a lot of inorganic mineral mass in there, but there are a lot of living cells too, and those cells are continuously breaking down our bones and rebuilding, bit by tiny bit.

So, exercise—and the stress that exercise puts on our bones—is part of what tells those cells how to go about doing their jobs.

For more about this process, see: Which Osteoporosis Medication, If Any, Is Right For You? ← this is because some of the meds work by slowing down the cells that break down cells, and other meds work by accelerating the bone-building process

And as for resistance training, see: Resistance Is Useful! (Especially As We Get Older)

But won’t exercise increase the risk of breaking already-weakened bones?

Yes, yes it will. Which creates a very unfortunate catch-22:

• don’t exercise and your bones will deteriorate more rapidly, which wouldn’t happen if you maintained them with exercise
• do exercise and you might fracture something while exercising, which wouldn’t have happened relaxing on your couch

However, this risk can be mitigated somewhat by being judicious about our choice of exercise. The trick is to engage in exercise that will involve resistance (and thus moderate physical stress, cueing the bones to get stronger), but won’t involve the kinds of movements that are most likely to result in a fracture (which include but are not limited to: heavy impacts and rapid changes of direction).

For more on this, see: Osteoporosis & Exercises: Which To Do (And Which To Avoid)

So, how about walking and other “light exercise”?

We’ll first mention some now-older research (published January 2024), that we wrote about back when it was new, and that yes, walking does help. The study by Dr. Tiina Savikangas et al. looked at 299 people in their 70s (just over half being women) and found that, over the course of a year, bone mineral density loss was inversely correlated with moderate exercise as recorded by an accelerometer (as found in most fitness-tracking wearables and smartphones).

In other words: those who got more minutes of exercise, kept more bone mineral density.

You can read more about that here: One More Resource Against Osteoporosis!

Now, that was about moderate exercise, as measured by an accelerometer (i.e. the participants each wore a smartwatch or similar accelerometer-based fitness tracker).

More recently, a new research review by the International Osteoporosis Foundation Rehabilitation Working Group looked at a huge amount of data from many studies, and found:

• Physical activity—especially weight-bearing and resistance training—improves bone mineral density and helps reduce fracture risk in both younger and older populations.
• Sedentary behavior—independent of overall activity levels—has harmful effects on bone health, increasing fracture risk, particularly in frail or pre-frail individuals.
• Light-intensity activity can yield measurable benefits when it replaces sedentary time, especially in older adults and postmenopausal women.
• Early and continuous promotion of physical activity, aligned with World Health Organization (WHO) guidelines, provides an effective strategy for maintaining skeletal health and preventing osteoporotic fractures.

You can find the paper itself here: The Impact of Sedentary Behavior and Physical Activity on Bone Health: A Narrative Review from the Rehabilitation Working Group of the International Osteoporosis Foundation

That second item is perhaps the most relevant to take into account, because it shows that while light activity will not yield the same results as moderate weight-bearing or resistance training exercise, it’s a world better than sedentary behavior, because sedentary behavior essentially tells your bones “we don’t need you”, and in many cases, especially resource-intensive biological processes (as bone turnover is), the body will not use valuable resources to maintain something that doesn’t seem to be needed.

So, it’s less about the light activity for its own sake, and more about not being sedentary.

You may be wondering: does this distinction matter? And the answer is, it might do; it depends on your lifestyle. For example, your writer here sits down for a total of about 1 hour per day (and lies in bed for about 8 hours, of which, about 7.5 hours sleeping). However, that does not mean that the remaining 15 hours per day are spent actively exercising. Indeed, a good many of the remaining hours are spent standing at my desk. Which is not enough to stress my bones even moderately, but is enough that my body is aware of the need to maintain a structure capable of maintaining a whole-body upright posture, and thus, my bones are maintained more than they would if I spent the same time sitting.

See also: Stand Up For Your Health (Or Don’t) ← this is about reducing the damage done by sitting, including if for whatever reason you have to spend a lot of time sitting, including if you physically cannot stand and/or cannot walk.

You can also build in not just “movement breaks”, but also active exercise in small, manageable chunks that add to to disproportionate benefits: How Useful Is “Exercise Snacking”, Really?

Want to learn more?

Here’s an excellent book we reviewed a little while back:

Yoga for Osteoporosis – by Dr. Loren Fishman ← the title makes it seem like any one of a thousand other “gentle exercise” books, but actually this one has an incredible wealth of science, clear explanations, and there’s far more going on in here than one could ever reasonably expect of book with this title, so if this topic (avoiding/reversing osteoporosis) is at all relevant to you personally, we very strongly recommend this specific book.

Take care!