How Early-Life Physical Activity Affects Bone Strength Later

In this podcast, Ahmed Elhakeem, MPH, PhD, talks about how time spent in various physical activity levels throughout adolescence impacts peak bone strength and osteoporosis risk later in life. 

Additional Resource: 

• Elhakeem A, Heron J, Tobias JH, Lawlor DA. Physical activity throughout adolescence and peak hip strength in young adults. JAMA Netw Open. 2020;3(8). doi:10.1001/jamanetworkopen.2020.13463

Ahmed Elhakeem, MPH, PhD, is a senior research associate in epidemiology at Bristol Medical School. 

TRANSCRIPT:

Consultant360:  Hi, everyone. Welcome to another installment of "Podcast360," your go‑to resource for medical news and clinical updates. I'm Michael Potts, Managing Digital Editor at the Consultant360 Specialty Network.

Peak bone strength, which occurs in early adulthood, has been shown to be a marker for later risk of osteoporosis. However, the effects of various levels of physical activity in early life on this measure of bone strength are not well understood. Here with us today to speak about his research on the topic is Dr. Ahmed Elhakeem, who's a Senior Research Associate in Epidemiology at Bristol Medical School.

Thank you for joining us today, Dr. Elhakeem. Let's dive into your study. Can you tell us a little about how your study came about and how you decided on the topic?

Ahmed Elhakeem, MD:  We know that bone strength increases as you get older throughout childhood, and this tends to peak around early adulthood, young adulthood. It's also thought that peak bone strength in early adulthood is a marker of the future risk of fractures and osteoporosis, so this is an aging‑related disease that's characterized by bone loss.

Hip fractures make up a big proportion of the osteoporosis disease burden. Therefore, it's important to identify modifiable early‑life factors that might influence the attainment of peak hip strength. There's data out there that suggests that high‑intensity physical activity is important for bone strength, but a lot of that is based on a single time‑point assessment of physical activity.

What we wanted to do is to explore the role of long‑term patterns of physical activity in bone strength. That's pretty much how the study came about.

C360:  Why did you choose to measure physical activity with accelerometers rather than self‑reported activity as previous studies have?

AE:  Both types of data collection have strengths and limitations. Self‑reports are not ideal for capturing light‑intensity activity, whereas accelerometers can give you a direct measure of the time spent at different intensities. Self‑reports are also more susceptible to errors.

For example, it's difficult to remember exactly how much activity or what type of activity you did over the past week, whereas, again, with the accelerometer, you've got a more direct measure of this. That's why we went for the accelerometers over self‑reports.

C360:  Overall, you found that more time spent in physical activity in adolescence was associated with significant differences in bone health markers at age 25 years. Were there any notable differences observed in the effects of early physical activity on bone mineral density between girls and boys?

AE:  What we did was, we tried to look for groups of patterns of activity over long term in both the males and the females. We did these analyses separately in males and females. This was a data‑driven approach so you'd see what groups the data bring you out. We got different groups between males and females.

For example, in the males, we had most of them assigned to a low adolescent, moderate to vigorous activity group, with only about 6% that had high early adolescent and 9%, high mid‑adolescent MVPA.

In the females, the groups are a bit different. We had most females in a low adolescent and low adult, moderate to vigorous activity group. Then we had a small proportion who stayed low through adolescence but increased their moderate to vigorous activity in adulthood, and another group who had high moderate to vigorous activity throughout adolescence.

These were the different activity groups between males and females. The results overall between them are fairly consistent although it's difficult to compare. For the males, we found that compared to those with low adolescent, moderate to vigorous activity, the two other groups, so the high early adolescent and high mid‑adolescent, both had, on average, greater bone density at age 25.

Within the females, we found that compared to the group with low moderate to vigorous activity throughout follow‑up, those that had higher levels in adolescence had greater bone density, whereas the group who also had low levels in adolescence but increased the levels of moderate to vigorous activity in adulthood, there wasn't any noticeable differences in bone density.

C360:  How do you think that your findings will impact clinical practice?

AE:  The results highlight adolescence as a potentially important period for bone developments through high‑intensity exercise and that this could benefit future bone health and potentially prevent osteoporosis in later life. It's important for clinicians to be aware of the value of high‑intensity activity in this time period and in this age group.

We've also confirmed previous studies which showed that the levels of high intensity activity decline with age and throughout adolescence. It's important to support young people to remain active at this age.

C360:  What knowledge gaps still exist in this area and what should future studies focus on?

AE:  Important to replicate our results in other independent studies and see if you can get the same findings. That would make you more confident in the value of the results. The same time we did a small exploratory analysis as part of the study where we looked at different measures of activity.

Rather than focusing on intensity, we looked at the level of impact of activity. There was a suggestion there that, in addition to high‑intensity activity, high‑impact activity is also likely to be important for bone strength. This was a quite a small sample, so it will be nice to see bigger studies that look at this specific measurement of activity.

C360:  Thank you for joining us today, Dr. Elhakeem.