REGIONAL BONE MINERAL DENSITY PATTERN IN MARATHON RUNNERS

Abstract

1184 The effect of intense, chronic exercise on bone mineral density is unclear. To clarify the effects of marathon training on patterns of bone mineral density (BMD), we compared regional Z scores of 11 national class male marathon runners (best mean marathon time of 2 hours 35 (±8.7) min) using dual energy x-ray absorptiometry. Our subjects averaged 29.6 (±3.9) years, had a mean BMI of 20.1 (±1.2) kg/m2, a mean relative fat of 10.5% (±2.8), a mean VO2max (n=10) of 75.8 (±7.1) ml/kg/min, and had been running for 16.7 (±7.1) years, currently averaging 70 (±8) miles per week. The BMD was measured at the lumbar spine (L2-L4), femur, forearm, and total body. Mean Z scores were compared by paired t tests using SPSS with the following results: (Table)TableThe following differences were significant: arm BMD<trunk BMD<leg BMD (p<0.01) and radius 33%<L2-L4<total femur (p<0.03). In contrast to others' results, osteopenia was not found in these subjects at the lumbar spine or proximal femur; two subjects showed osteopenia at the radius 33% site (>1 SD below the mean). These results demonstrate that in highly trained marathon runners, BMD shows a distinct patterned response and is well above age and sex-matched values in skeletal sites experiencing the greatest loading during running.