Association between moderate physical activity, spinal motion and back muscle strength in postmenopausal women with and without osteoporosis.

Abstract

The purpose of this study was to determine whether physical activity levels of postmenopausal women were associated with their bone mineral density (BMD), back extensor strength (BES), severity of thoracic kyphosis and range of spinal motion. This study adopted a cross-sectional design. 189 female subjects from 50 to 80 years of age were divided into moderately active (n=63) and sedentary (n=126) groups according to their physical activity level, which is measured by the physical activity score. BMD (lumbar spine and hip), BES, severity of thoracic kyphosis and range of spinal motion in the sagittal and frontal plane were measured in each subject. The groups differed significantly in the range of spinal motion in the sagittal plane (p = 0.01) (moderately active: 26.9 +/- 10.8; sedentary: 23.0 +/- 10.2), as well as in the right frontal plane (p < 0.001) (moderately active: 27.1 +/- 6.4; sedentary: 23.4 +/- 7.5) and left frontal plane (p < 0.001) (moderately active: 27.6 +/- 6.5; sedentary 23.7 +/- 7.4). There were no significant differences in BMD (active: 0.88 +/- 0.18 g/cm2; sedentary: 0.98 +/- 0.15 g/cm2), severity of thoracic kyphosis (active: 52.9 +/- 12.4; sedentary: 51.9 +/- 11.8) or BES (active: 49.0 N +/- 14.6; sedentary: 46.6 N +/- 15.1). This study demonstrates that active women had better range of spinal motion than sedentary women, but they did not differ significantly in severity of thoracic kyphosis, BES and BMD.