Study points to best bone health for kids

Children need 1.5 hours of moderate to physical exercise a day, such as sports or play.
Children need 1.5 hours of moderate to physical exercise a day, such as sports or play.

Childhood bone health is best supported with 90 minutes of exercise each day along with more than three hours of other light physical activity, a new study has found.

The University of South Australia research, involving children aged 11 to 13, has also pointed to the need for adequate sleep.

Lead researcher Dot Dumuid says the findings provide valuable insights for parents, caregivers and clinicians.

"Children's activities throughout the whole 24-hour day are important for their bone health but until now we haven't known the perfect combination of exercise, sleep and sedentary time," Dr Dumuid said.

"Higher levels of physical activity are known to be good for children's bone health, yet we can't just increase children's exercise without impacting their other activities.

"In this study, we looked at the interrelating factors of physical activity sedentary time and sleep, finding an ideal combination that delivers the best daily balance."

The study looked at 804 children and found that the best balance of daily activity to be 1.5 hours of moderate to physical exercise, such as sports or play, 3.4 hours of light physical activity, such as walking or chores, 8.2 hours of sedentary time, including studying and reading and 10.9 hours of sleep.

It used self-recorded logs and body worn accelerometers to map the activity of participants and scans to check on bone densities.

Dr Dumuid said up to 90 per cent of peak bone mass was achieved by age 20 which made development during childhood particularly important.

"Optimising bone health in children is a key protector against osteoporosis, the leading preventable cause of fracture in adults and a major public health problem with considerable economic and societal costs," she said.

The study also found boys needed an extra 2.4 hours sleep each night than girls to ensure best bone health.

"We always talk about getting enough exercise to help build bones but for children, it's vital that they also get enough sleep," Dr Dumuid said.

Australian Associated Press