NEW YORK (Reuters Health) - Teenage boys who perform heavy farm work may have stiffer bones than other boys their age, a study suggests.
Exactly what the difference means is not yet clear, researchers say, but stiffer bones could indicate a greater risk of arthritis down the road.
The findings, published in the Journal of Agromedicine, are based on bone measurements taken from 36 boys between the ages of 12 and 19.
Half had no farm experience, while the other half had regularly worked on a family farm, performing activities like feeding livestock, stacking hay and shoveling manure.
Researchers found that while bone mass was similar in the two groups, the boys who had done farm work showed lower bone "damping" levels -- the ability of the leg bones to absorb shock each time a person takes a step.
This implies that these boys had generally "stiffer" bones, explained lead researcher Dr. Amit Bhattacharya, of the University of Cincinnati College of Medicine.
It's possible that this increased stiffness reflects stronger bones. However, Bhattacharya told Reuters Health, the decreased bone damping seen in these boys was comparable to what's been found in osteoarthritis patients -- which, he said, is "concerning."
Some exercise is necessary for healthy bone development, Bhattacharya pointed out. But excessive weight-bearing activity during critical periods of bone growth may cause "microdamage" to bone tissue that could be detrimental later in life.
However, he said, long-term studies are needed to see whether the decreased bone damping seen in this study is reversible, and whether these boys are in fact at heightened risk of degenerative bone disorders later in life.
For now, Bhattacharya advised, "physical activity in moderation" is the best prescription for kids' bones.
SOURCE: Journal of Agromedicine, June 2008.
