Exercise strengthens bones even in kids with genetic risk

Exercise, particularly high- impact activity, builds stronger bones in children, even for those who are genetically predisposed to have bone weakness, a new study has found.
The findings underscore that genetics does not necessarily equate to destiny, and reinforce the importance of physical activity as a key factor to improve the bone health of children in the present and into later life, researchers said.
"While we have known for decades that physical activity during childhood builds up bone and confers lifelong benefits, we did not know whether the effects of activity depend on genetic risks for bone fragility," said Jonathan A Mitchell, a paediatric researcher at The Children's Hospital of Philadelphia (CHOP) in the US.

"This study was the first to show that physical activity can counteract the negative effects of genetic variants that associate with bone fragility in childhood," said Mitchell.
Researchers analysed a cohort of 918 children and adolescents, from 5 to 19 years old, all of European ancestry.
They used questionnaires in which study participants estimated their amount and type of physical activity during childhood.

The study team also measured the participants' bone density and genotyped their DNA for over 60 genetic variants known to be associated with bone density.
The researchers found that across the board, children had higher bone density scores if they had higher levels of physical activity.

This even applied to those with a higher genetic risk for bone fragility.
The benefits of activity were driven entirely by high-impact, weight-bearing activity, such as gymnastics and soccer, which involve sprinting, turning or jumping actions.
The researchers said that replication studies by other groups are going to be needed to follow up their study, and that other groups should investigate similar questions in populations other than the children of European ancestry.
The findings were published in the Journal of Bone and Mineral Research.