NASHVILLE, TENN. — A school-based exercise program may be one way to head off osteoporosis later in life, according to results from a study presented at the annual meeting of the American Society for Bone and Mineral Research.
A school-based exercise program in early school years seems to be followed by a greater increase in bone mineral content (BMC) and bone size, said Christian Linden, M.D., of Malmö (Sweden) University Hospital.
The finding comes from the Pediatric Osteoporosis Prevention (POP) study, a prospective, controlled population-based study assessing the effects of daily exercise during early school years on the accrual of bone mineral.
A total of 121 children (73 boys and 48 girls) in grades 1 and 2 (average age 7.7 years) participated in 40 minutes of physical activity during each school day for 4 years. A control group of 100 age-, height-, and weight-matched children (52 boys and 48 girls) in nearby schools followed the standard Swedish physical education curriculum, consisting of 60–90 minutes of physical activity each week.
BMC was assessed using dual-energy x-ray absorptiometry measurements of the lumbar spine and the femoral neck at baseline and at yearly evaluations. The researchers also tracked duration of physical activity outside of school.
At baseline, there were no differences between the groups with regard to bone mass and size. At follow-up, the boys in the control group had a significantly higher Tanner stage on average; otherwise the children in the two groups were similar.
Boys who were in the intervention group had significantly greater BMC in the lumbar spine at follow-up after 4 years, compared with those in the control group (7.0 g vs. 6.2 g). Girls in the intervention group had significantly higher BMC at the lumbar spine (9.1 g vs. 7.1 g) and femora neck (0.39 g vs. 0.29 g) at follow-up than did those in the control group. The annual increase in femoral neck width was greater in the intervention group than in the control group for girls (1.23 mm vs. 1.07 mm) and boys (1.45 mm vs. 1.03 mm).
The findings support those from earlier studies suggesting that the best time to increase bone mineral accrual through exercise in is the prepubertal period. Approximately 30% of bone mass acquired over a lifetime can be influenced by nongenetic factors, such as exercise.
Exercise programs in early life show potential as a prevention strategy of osteoporosis, Dr. Linden concluded.