Functional fitness and bone mineral density in the elderly

Bone quality has been associated with genetic factors and several environmental influences. This study suggests that although functional fitness should be considered in clinical assessments of bone health, body composition appears to have a higher relevance in the explanation of bone health/strength in older people.

This study aims to describe the association between functional fitness (FF), other constitutive factors, and bone health/strength in a large community-dwelling sample of elderly active Portuguese.

This cross-sectional study included 401 males and 401 females aged 60-79 years old. Bone mineral density (BMD) of the total body, lumbar spine (LS), and hip region was determined by dual-energy X-ray absorptiometry (DXA). In addition, femur strength index (FSI) was determined. FF was assessed using the Senior Fitness Test. Demographic information and a health history were obtained by telephone interview through questionnaire.

Aerobic endurance and body strength were positively related with hip BMD region in males (0.10 < r < 0.16; p < 0.01-0.05) and females (0.13 < r < 0.28; p < 0.01). No significant correlation was found between any FF test and LS BMD, except for upper-body strength in females. After controlling for other constitutive predictors (sex, age, height, body mass (BM), total fat mass (TFM), and total lean tissue mass (TLTM)), FF had a minor contribution only in prediction of BMD at multisites and FSI. The total explained variance for all determinants was moderate (R² = 0.35 for femoral neck (FN) BMD, R² = 0.27 for LS BMD, R² = 0.49 total body BMD, and R² = 0.22 for FSI).

Sex, age, height, BM, TLTM, and TFM entered as the most significant contributors for BMD and FSI. Although FF parameters are typically considered in clinical assessments of bone health/strength in older people, body composition appears to have a higher relevance in the explanation of BMD and strength.