Habitual and low-impact activities are associated with better bone outcomes and lower body fat in older women

Abstract

The influence of habitual and low-impact physical activity (PA) on bone health and soft tissue including bone-free lean (BFL) and fat mass is less elucidated than the influence of high-impact activities. This study examines the interactive effects of PA and soft tissue on bone mineral density (BMD) and content (BMC) in healthy Caucasian women, aged 68.6 +/- 7.1 years, with body mass index (BMI) of 26.0 +/- 3.8 kg/m(2) evaluated at baseline and every 6 months for 3 years. Measurements/assessments included BMD/BMC and soft tissue (by dual-energy X-ray absorptiometry), anthropometrics, dietary intake, and PA. Activities assessed were past activity, present heavy housework, gardening, do-it-yourself activities, stair-climbing, walking, walking pace, sports/recreation, and total activity. Baseline analyses revealed significant positive associations between past activity, heavy housework, faster-paced walking, BFL, and BMD/BMC of various skeletal sites. Prospective analyses showed subjects with more walking hours/week had significantly higher BMD/BMC of several skeletal sites (P < 0.05). Stratification by cumulative (over 3 years) median for heavy housework, walking, sports/recreational, and total activities revealed higher BMD and BMC in the femur and spine (P = 0.01) in subjects with those activities above median. Multivariate analysis of covariance results revealed that weight had the strongest influence on BMD and BMC, followed by BFL. Various modes of PA were negatively associated with BMI and fat but not with BFL. In conclusion, heavy housework, walking (faster pace), sports/recreational activities, and overall total participation in low-impact PA were beneficial for bone and for achieving more favorable body weight and fat but were not associated with BFL. The results indicate that even habitual activities engaged in by older women could benefit their bone and diminish body fat.