Less Muscle Activity Tied to Poor Bone Health for CF Children

More physical activity for kids may improve bone health: study

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Among children with cystic fibrosis (CF), bone health tends to become worse with older age — and poor bone health in CF is linked to less activity of nearby muscle — a new study suggests.

The findings imply that promoting physical activity for children with CF could help to improve long-term bone health.

“Given [the] high fracture risk in this population from childhood onwards, development of interventions to improve bone health would be of substantial clinical value,” the researchers wrote.

The study, “Development of musculoskeletal deficits in children with cystic fibrosis in later childhood,” was published in the journal Bone.

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Muscle activity key for healthy bones

Bone-related health problems are common among people with CF, and often are present by young adulthood — studies suggest that more than half of CF patients have experienced a broken bone by the time they’re 25.

However, there has not been much research into how bone problems tend to develop over time in children with CF.

Now, a team led by scientists in the U.K. sought to learn more. They used an advanced imaging technique, called high-resolution peripheral quantitative computed tomography or HR-pQCT, to measure the bone health of 25 children with CF, who had a mean age of 11.3 years.

The scientists also assessed bone health in 147 children without CF, who served as controls.

Age and puberty status were similar in the CF patients and controls, though the controls were on average significantly taller and heavier.

From the HR-pQCT data, the researchers extracted various measures of bone health; then, they used statistical models to examine how bone health changed with increasing age in the CF patients and controls.

The results showed that age-related patterns of changes in bone health differed significantly between the two groups. In other words, abnormalities in the bones of children with CF appeared to become increasingly severe as children got older. These associations were significant for age, but not pubertal status or body size.

“Children with CF develop a characteristic pattern of bone deficits during later childhood. … These age-related trends are independent of pubertal development, and body size,” the researchers wrote.

“However,” they added, “it appears that differences in muscle function may mediate these developing deficits.”

That [bone] deficits appear to develop in later childhood suggests that interventions targeted at this age may be highly beneficial.

Bone health is closely tied to muscle activity — muscles are attached to bones, sending both mechanical and chemical signals that are critical for keeping bones healthy.

In additional analyses, the researchers found that the connection between poorer bone health and increasing age among the CF patients was weaker when they included data about muscle strength in the models. This implies that part of the reason that bone health becomes worse with increasing age in CF is that nearby muscles are not as active.

“It seems that differences in skeletal loading attributable to physical inactivity contributes to developing bone deficits in children with CF,” the researchers wrote, noting these connections were particularly strong in the areas along the shaft of long bones, known as diaphyseal regions.

Given that bone problems appear to develop in later childhood, and are linked to less physical activity, these findings imply that interventions aiming to promote activity in children with CF might help improve long-term bone health.

“That [bone] deficits appear to develop in later childhood suggests that interventions targeted at this age may be highly beneficial,” the researchers wrote, adding that new interventions encouraging more physical activity could be helpful for CF patients, “given the greatly increased fracture risk in this population across adult life.”

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