High-intensity physical activity through adolescence helps prevent osteoporosis
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High-intensity physical activity throughout early life can help prevent osteoporosis and maximize peak hip strength later, according to data published in JAMA Network Open.
“Peak bone mass occurs in young adulthood and is considered to be a marker of the risk of fracture and osteoporosis in later life,” Ahmed Elhakeem, PhD, of the University of Bristol, in the United Kingdom, told Healio Rheumatology. “It is therefore important to identify modifiable early life factors that might influence peak bone strength.”
To examine the association between physical activity, of varying intensities, throughout adolescence with peak hip strength in adulthood, Elhakeem and colleagues analyzed data from the Avon Longitudinal Study of Parents and Children. According to the researchers, this prospective birth cohort study initially enrolled 15,454 pregnant individuals living within the catchment area — three health authorities in southwest England — with an expected delivery date between April 1, 1991, and Dec. 31, 1992. From this cohort, a total of 15,589 infants were delivered, of whom 14,901 were alive at age 1 year.
For their own analysis, Elhakeem and colleagues included 2,569 healthy children with valid physical activity measurements, recorded during clinical assessment, for at least one age — either 12, 14, 16 or 25 years — as well as up to four repeated accelerometer assessments. Trajectories obtained through accelerometer assessments allowed the researchers to measure time spent in moderate-to-vigorous- and light-intensity physical activity, measured in minutes per day. The main outcome was femur neck bone mineral density at age 25 years, assessed using dual-energy radiography absorptiometry scans of the hip.
According to the researchers, male participants spent more time in moderate-to-vigorous-intensity activity at each age and had greater adult femur neck bone mineral density than female participants, who made up 62% of the overall included cohort.
For both boys and girls, the researchers identified three moderate-to-vigorous-intensity trajectory subgroups, and three light-intensity trajectory subgroups. Regarding the moderate-to-vigorous-intensity trajectories, 85% of male participants were in the low adolescent subgroup, with only 6% and 9% in the high early-adolescent and high mid-adolescent subgroups, respectively. Meanwhile, for moderate-to-vigorous-intensity trajectories among female participants 73% were in the low-adolescent/low-adult subgroup, 8% were in the low-adolescent/high-adult subgroup, and 19% were classified as high adolescent.
The researchers classified light-intensity physical activity trajectories into either low nonlinear, moderate decreasing and high decreasing subgroups for males and females.
Femur neck bone mineral density in male participants was greater in the high early-adolescent subgroup (BMD = 0.38 g/cm2; 95% CI, 0.11-0.66) and the high mid-adolescent subgroup (BMD = 0.33 g/cm2; 95% CI, 0.07-0.6), compared with the low adolescent subgroup. Femur neck bone mineral density among female participants was greater in the high adolescent subgroup (BMD = 0.28 g/cm2; 95% CI, 0.15-0.41), but not in the low adolescent-high adult subgroup (BMD = –0.12 g/cm2; 95% CI, –0.44 to 0.2), compared with the low-adolescent/low-adult subgroup.
In addition, a sensitivity analysis using a negative-outcome control variable, to examine unmeasured confounding, support these findings, the researchers wrote. Light-intensity trajectories were not associated with femur neck bone mineral density. For example, differences in density between the high decreasing and low nonlinear subgroups were 0.16 g/cm2 (95% CI, –0.08 to 0.4) in male participants and 0.2 g/cm2 (95% CI, –0.05 to 0.44) in female participants.
“The results highlight adolescence as a potentially important period for bone development through high intensity exercise, which could benefit future bone health and prevent osteoporosis in later life,” Elhakeem said. “We have also confirmed other studies showing that levels of MVPA decline through adolescence. Our findings show it is really important to support young people to remain active at this age.”
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We are always telling our older osteoporosis patients to exercise to help increase their bone strength. Do you ever think about why we see less men than women in our osteoporosis clinics? A highly informative study by Dr. Elhakeem and his team may give some insight into this subject.
In their study of the amount/intensity of exercise in a cohort of males and females aged 12, 14, 16, 25 years and its effects on bone mineral density, the researchers determined that the male participants spent more time at moderate to vigorous intense activity at all age and points and had greater adult femoral neck BMD than female participants. Other relevant findings included moderate to intense physical activity from age 12 and even higher magnitude of gravitational force at age 18 was associated with greater hip strength at age 25.
This study gives us some insight that early exercise can help us jumpstart our bone health through early vigorous activity; however, further studies need to replicate these results.
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David A. McLain, MD, FACP, FACR
Exercise is a good thing — this has been shown in multiple studies. Even for patients with osteoarthritis of the knee, physical exercise has been shown to be beneficial. This study shows that physical activity as a child reaps benefits into adulthood.
I was talking with a patient recently about how, as kids, we would ride our bikes all over the neighborhood and told to be home by the time the streetlights came on. This does not seem to be the case any longer. There are several reasons for this. One is safety, with parents fearing for their children’s wellbeing in a dangerous world. Another is the replacement of physical exercise with video games. Instead of shooting baskets outdoors, you can shoot baskets on a video screen.
In a 2006 national survey, the School Health Policies and Programs Study found that while 69.3% of elementary schools, 83.9% of middle schools, and 95.2% of high schools required physical education, only 3.8% of elementary schools, 7.9% of middle schools, and 2.1% of high schools provided daily physical education, and only 13.7% of elementary schools, 15.2% of middle schools, and 3.0% of high schools provided physical education at least 3 days per week.
The emphasis on physical activity in schools is down from my era. There are students involved in community sports but the emphasis on exercise appears to be down in general. We need to encourage our patients and their families to “keep moving”.
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