High-intensity physical activity through adolescence helps prevent osteoporosis
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.”