When we think of all the important tissues in our body, things like brain tissue, heart tissue, and muscle tissue seem to top the list, but without our bones we'd just be a gelatinous blob with no structure. We can't have a conversation about preserving and improving health without discussing the critically important role of bone health: how we define it, what happens if it deteriorates, and most importantly how we improve it to optimize health as we age.
Defining Bone Health
Bone health is most commonly assessed by measuring Bone Mineral Density (BMD) using a machine called a DEXA scanner. This is a simple test that involves laying on a table for 10 to 30 minutes (in most cases). Common areas assessed are the spine, femur, and forearm, as these are the areas that can be susceptible to fracture from falls. There are two outputs from the test:
T-Scores: your BMD compared to the average value of a healthy young adult at peak bone mass.
Z-Scores: your BMD compared with individuals of the same age and sex.
Both of these scores are important, but the T-score is what classifies the true health of bone because it basically answers the question, how far has BMD declined from a healthy point? It is measured in standard deviations (SD) from that healthy point and this creates diagnostic cut points.
Interactive T-Score Explorer
Drag the slider to see how T-score classifications work.
Bone scans are typically recommended for women over 65 and men over 70. However, if your doctor suspects you're at risk for osteoporosis, they may opt for scans earlier in life depending on risk factors (more on those below). These earlier scans are where the Z-scores come in handy. Since it's unlikely you are even osteopenic yet, the Z-score allows your doctor to compare you to people of the same age and gender to see if there could be an issue brewing.
Risk Factors for Low Bone Density
Like with many health conditions, there are risk factors for low BMD that you can influence and others you can't.
Non-Modifiable (Can't Change)
Age
We lose BMD with age, making time our biggest non-modifiable factor.
Biological Sex
Women have lower BMD than men due to skeletal and hormonal differences.
Genetics
Individuals with a family history of low BMD are more susceptible to it.
Modifiable (You Can Influence)
Sedentary Lifestyle
Increasing activity increases BMD.
Low Lean Mass
Maintaining and increasing muscle mass can help improve BMD.
Inadequate Nutrition
Calorically adequate diets with good calcium sources improve BMD.
Tobacco & Alcohol
Avoiding tobacco and excessive alcohol can improve bone health.
Bone Biology 101
Bone is an extremely active tissue; it is always remodeling. Said another way, we're breaking down (resorption) and building up (formation) bone mineral all of the time. When formation exceeds resorption, BMD improves. When resorption exceeds formation, BMD reduces.
Most of us achieve peak BMD by our late teens to early 30s, and after that, the game shifts from building to maintaining and slowing decline. Our goal with BMD is as much maintenance as possible. Clinically, low BMD is just a deviation from what peak would be, so the more we maintain our BMD from this peak, the healthier our bones are.
Wolff's Law in Action
See how different stress levels affect bone density over time.
Like most tissues in our body, bone responds to stress. When we're talking about bone, this stress response is referred to as Wolff's Law, which states bone adapts to the forces placed upon it. Less force or less frequency equals greater breakdown and less buildup (lower BMD). Greater force and more frequency equals greater buildup according to Wolff's Law, and therefore higher BMD.
Gender Differences & Bone Health
Women are at a biological disadvantage for bone health. Their bones tend to be smaller in overall size, less dense, and because of that have a smaller cross-sectional area. You can think of this from an engineering perspective: a wider and denser beam resists bending more than a narrow, less dense beam. While the smaller skeletal structure of women contributes, hormones are the big culprit.
Women
BMD loss per year after menopause due to rapid estrogen decline
Men
More gradual estrogen decline, starting from higher baseline BMD
Estrogen is a big regulator of bone turnover. It helps suppress breakdown and supports buildup. When estrogen levels drop significantly after menopause, breakdown accelerates. This, combined with the structural differences, can cause BMD to reduce significantly. While men do experience estrogen decline, it is more gradual and they're normally starting from a point of higher BMD.
How to Improve Bone Health
Despite the non-modifiable risk factors mentioned above, the good news is there is a lot you can do to improve BMD as you age. As you'd probably expect (based on Wolff's Law), the more you load your bones, the healthier they will be.
Weight-Bearing Aerobic Exercise & Strength Training
This is one of the most effective ways to increase BMD. Weight-bearing aerobic exercise (such as walking, step aerobics, and jogging) physically loads bones, increasing bone formation when compared to non-weight-bearing forms of exercise (bike, elliptical trainer, water aerobics). If you're looking to double dip on heart and bone health, weight-bearing aerobic exercise is much more effective.
Strength training is even more effective for improving BMD for a few reasons. First, the loads you can place on your bones will be much greater with strength training. Second, you can load bones from a variety of different angles. Lastly, you can load your spine and bones in your upper body to a far greater degree with strength training. All of this results in greater BMD systemically.
BMD improvement possible with a properly designed strength training program
A little goes a long way with exercise to improve BMD. Even one day per week of weight-bearing aerobic exercise can result in improvements. Below is a starter workout routine for improving BMD (of course, consult your doctor first before beginning an exercise program).
Strength Training (1–2 days/week)
2–3 sets of 8–12 reps each. Last few reps should feel challenging but controlled.
Weight-Bearing Aerobic Exercise (1–2 days/week)
20–30 minutes with heart rate and breathing rate elevated.
Other Ways to Improve BMD
The exercise suggestions listed above are the most effective way to improve BMD. That said, there are certainly other ways to improve your BMD. Tap each item below for details:
Taking Control of Your Bone Health
The idea of reduced bone health leading to fractures is scary as people age. We know that the fear of falling and fracturing a bone reduces activity levels and makes people fearful of engaging in the activities they enjoy. It doesn't have to be that way.
Beyond the research, I've been privileged to see many of our members not only report the maintenance of BMD, but most impressively the improvement of BMD, through exercise. Some members have even reversed their osteoporosis (my mom included — great work, Mom)!
The good news is this article gives you all the tools you need to take back control of your bone health through exercise. That knowledge is power that can continue to strengthen your bones as you age, so you won't need to worry about bone health while you're experiencing all the great parts of your life.
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