Physical Activity and Bone
Our physical activity and bone research is led by Prof Jon Tobias. In research projects funded by the Wellcome Trust, we have been examining the influence of physical activity on bone development in childhood using the ALSPAC cohort, in collaboration with Professor Andy Ness at the University of Bristol, and Professor Joern Rittweger at the Division Space Physiology, Institute of Aerospace Medicine, German Aerospace Center, Cologne. In our initial studies, we found that physical activity as assessed using Actigraph accelerometers worn by children at age 11 were positive related to total body bone mineral density . Important inter-relationships were also observed between exercise, bone and body composition, reflecting concurrent influences of fat mass on bone development.
In further investigations we explored relationships between physical activity as assessed using the same approach at age 15, and bone development as assessed by pQCT scans. Interestingly, whereas vigorous physical activity was positively related to bone development, relatively little relationship was seen for moderate activity . This suggests that whereas activities like running are effective at building up bones in children, less intense activities like walking may have little effect.
We have since examined the relationship physical activity, according to level of impact, and bone development at age 17. To do this, we used a different type of accelerometer developed by Newtest in Finland. This device records the number of movements within different levels of impact as defined by G-bands. As shown below, this can distinguish high impacts associated with activities like jumping. 
In further studies we examined the relationship between different G-bands and hip BMD. Interestingly, only those impacts in the top G-bands were positively related to hip BMD, suggesting that high impact activity is primarily responsible for building bone . We have also examined interactions between physical activity, gender and obesity, with the results suggesting that girls are less responsive to the stimulatory effect of high impact exercise on bone expansion.
A new Medical Research Council funded project called VIBE is currently underway to describe habitual levels of physical activity in older people in terms of impact loads and how this relates to bone and other systems.
- Tobias JH, Steer CD, Mattocks C, Riddoch C, Ness AR. Habitual levels of physical activity influence bone mass in 11 year-old children from the UK: findings from a large population-based cohort. J Bone Miner Res. 2007;22:101-109.
- Sayers A, Mattocks C, Deere K, Ness A, Riddoch C, Tobias JH. Habitual levels of vigorous, but not moderate or light, physical activity is positively related to cortical bone mass in adolescents J Clin Endocrinol Metab. 2011;In Press.
- Deere K, Sayers A, Davey Smith G, Rittweger J, Tobias JH. High impact activity is related to lean but not fat mass: findings from a population-based study in adolescents. Int J Epidemiol. May 9 2012.
- Deere K, Sayers A, Rittweger J, Tobias J. Habitual levels of high, but not moderate or low, impact activity are positively related to hip BMD and geometry: Results from a population-based study of adolescents. J Bone Miner Res. Apr 10 2012.