Role of exercise and nutrition status on bone mineral density in cystic fibrosis.

BACKGROUND

Exercise has been shown to maintain or increase bone mineral density (BMD) in non-CF populations.

OBJECTIVES

The purpose of our study was to elucidate the relationship between exercise, body composition and dietary intake with BMD in an adult CF population with heterogeneous disease severity.

DESIGN

We measured spinal (L1-4) and femoral (femoral neck) BMD by dual energy X-ray absorptiometry (DEXA) in 68 CF adults (24 female, 44 male) with a mean age 30.8(1.7) and 27.4(1.3) (range 18-55) years. We used the average BMD Z score for spine and femoral neck for analyses. Differences in disease severity, exercise capacity, physical activity level, dietary intake, body composition, body mass index (BMI), glucocorticoid use were correlated with BMD scores. Exercise capacity was defined as the maximal amount of oxygen consumed by muscles during maximal exercise (Vo2max). Vertebral and non-vertebral fracture rate were also recorded.

RESULTS

Fifty-seven patients were identified with low BMD (Z score < -1). Multiple linear regression identified exercise capacity and BMI as significant predictors of BMD. Later diagnosis of CF was also associated with low adult BMD.

CONCLUSIONS

Low BMD is common in adult CF patients. Exercise capacity and BMI are predictors of low BMD.