High intensity physical activity in early life might help maximise peak hip strength and prevent osteoporosis in later life, according to a study from researchers at the University of Bristol. The research, which analysed data from 2,569 participants of the Children of the 90s health study, found that more time spent doing moderate-to-vigorous intensity physical activity (MVPA) from age 12 years was associated with stronger hips at age 25 years, whereas time spent in light intensity activity was less clearly associated with adult hip strength.
Peak bone mass occurs in young adulthood and is considered to be a marker of the risk of fracture and osteoporosis in later life. Hip fractures make up a large proportion of the osteoporosis disease burden.
Researchers looked at data from healthy individuals who had physical activity measured up to 4 times using accelerometers worn as part of clinical assessments at age 12, 14, 16 and 25 years. This is a device that measures a person's movement for the whole time they wear it.
Researchers also found evidence to suggest that adolescent MVPA was more important than MVPA in adulthood, and that MVPA in early adolescence may be more important than in later adolescence. There was also some evidence that higher impact activity (consistent with jumping; assessed once in a subsample in late adolescence using custom accelerometer) was related to stronger hips at age 25.
Dr Ahmed Elhakeem, lead author and senior research associate in epidemiology, said: "The unique availability of repeated accelerometer assessments over many years beginning at age 12 within the Children of the 90s cohort, allowed us to describe the trajectory of time spent in different physical activity intensities through early life and to examine how this might relate to adult hip strength. 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. 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"
Francesca Thompson, clinical and operations director at the Royal Osteoporosis Society (ROS), said: "The ROS is working closely at the moment with Public Health England to review the importance of exercise for bone health in children. The findings from this study are welcome as they provide further evidence that children need to be doing moderate to vigorous intensity physical activity during their early adolescence to maximise bone strength in later life and reduce the risk of painful fractures. Supporting and encouraging young people to be more physically active needs to be a priority for bone as well as general health."
Abstract
Importance: Peak bone strength, which occurs in early adulthood, is an important marker of the future risk of osteoporosis. It is therefore important to identify modifiable early life factors that are associated with the attainment of peak hip strength.
Objective: To investigate the association of time spent in moderate to vigorous–intensity and light-intensity physical activity throughout adolescence with peak hip strength in adulthood.
Design, Setting, and Participants: The Avon Longitudinal Study of Parents and Children is a prospective birth cohort study that initially recruited all pregnant women residing within the catchment area of 3 health authorities in southwest England who had an expected delivery date between April 1, 1991, and December 31, 1992. In total, 15 454 eligible pregnant women were enrolled, and 15 589 infants were delivered. Of those, 14 901 infants were alive at age 1 year. The present analysis examined 2569 healthy offspring who had valid physical activity measurements obtained during a clinical assessment for at least 1 age (12, 14, 16, and/or 25 years), with up to 4 repeated accelerometer assessments performed (1 per age-associated clinical visit). Data were analyzed from June 2019 to June 2020.
Exposures: Trajectories of accelerometer-assessed time spent in moderate to vigorous–intensity and light-intensity physical activity at ages 12, 14, 16, and 25 years (measured in minutes per day) were identified using latent trajectory modeling. Moderate to vigorous–intensity and light-intensity physical activity were determined using established thresholds of acceleration counts per minute.
Main Outcomes and Measures: Femur neck bone mineral density (BMD; measured in g/cm2) at age 25 years assessed by dual-energy radiography absorptiometry scans of the hip.
Results: A total of 2569 participants (1588 female participants [62%]) were included in the analysis. Male participants spent more time in moderate to vigorous–intensity activity at each age and had greater adult femur neck BMD than female participants. For each sex, 3 moderate to vigorous–intensity trajectory subgroups and 3 light-intensity trajectory subgroups were identified. With regard to the moderate to vigorous–intensity trajectories, most male participants (85%) were in the low adolescent subgroup, with only 6% and 9% in the high early-adolescent and high mid-adolescent subgroups, respectively. Moderate to vigorous–intensity trajectories in female participants were divided into low adolescent-low adult (73%), low adolescent-high adult (8%), and high adolescent (19%) subgroups. Light-intensity physical activity trajectories were classified into low nonlinear, moderate decreasing, and high decreasing subgroups for both sexes. Femur neck BMD in male participants was greater in the high early-adolescent subgroup (0.38 g/cm2; 95% CI, 0.11-0.66 g/cm2) and the high mid-adolescent subgroup (0.33 g/cm2; 95% CI, 0.07-0.60 g/cm2) compared with the low adolescent (reference) subgroup. Femur neck BMD in female participants was greater in the high adolescent subgroup (0.28 g/cm2; 95% CI, 0.15-0.41 g/cm2) but not in the low adolescent-high adult subgroup (−0.12 g/cm2; 95% CI, −0.44 to 0.20 g/cm2) compared with the low adolescent-low adult (reference) subgroup. A sensitivity analysis using a negative-outcome control variable to explore unmeasured confounding supported these findings. The light-intensity trajectories were not associated with femur neck BMD; for example, differences in femur neck BMD between the high decreasing and low nonlinear subgroups were 0.16 g/cm2 (95% CI, −0.08 to 0.40 g/cm2) in male participants and 0.20 g/cm2 (95% CI, −0.05 to 0.44 g/cm2) in female participants.
Conclusions and Relevance: Supporting high-intensity physical activity throughout early life may help to maximize peak hip strength and prevent osteoporosis in later life. Replication of our findings in independent studies will be important.
Authors
Ahmed Elhakeem, Jon Heron, Jon H Tobias, Deborah A Lawlor
[link url="https://www.bristol.ac.uk/news/2020/august/hip-bone-strength-research.html"]University of Bristol material[/link]
[link url="https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2769317"]JAMA Network Open abstract[/link]