Correlation of Back Extensor Strength With Thoracic Kyphosis and Lumbar Lordosis in Estrogen-Deficient Women1

Abstract

Aging and osteoporosis have been associated with skeletal changes. Back extensor strengthening exercises are highly recommended for management of back pain, especially back pain related to osteoporosis. To our knowledge, the correlation of thoracic kyphosis, lumbar lordosis, and sacral inclination with back extensor strength, physical activity, and bone mineral density has not been critically studied in healthy, active, estrogen-deficient women. In a study of 65 such women (ages 48-65 yr), back extensor strength, bone mineral density, and physical activity score were evaluated and measured. These factors were then correlated with radiographic factors: (1) vertebral body ratios (anterior/posterior height) calculated for each vertebra from T-4 through L-5; (2) kyphosis index determined by adding the anterior heights of each vertebral body, T-4 through T-12, and then dividing the total by the corresponding sum of the posterior heights of each vertebral body; (3) thoracic kyphosis; (4) lumbar lordosis; and (5) sacral inclination. Back extensor strength had a significant negative correlation with thoracic kyphosis (r = -0.30, P = 0.019) and a positive correlation with lumbar lordosis (r = 0.26, P = 0.048) and sacral inclination (r = 0.34, P = 0.009). However, bone mineral density and physical activity score did not show any significant correlations with the radiographic factors. The results indicate that the stronger the back extensor, the smaller the thoracic kyphosis and the larger the lumbar lordosis and sacral inclination. We conclude that back extensor strength is an important determinant of posture in healthy women. However, prescribing back extensor strengthening exercises alone may also increase lumbar lordosis, which is not desirable.

Back muscle strength and spinal mobility are predictors of quality of life in middle-aged and elderly males

“…Some reports have shown a decrease in ADL and QOL in association with compression fracture and spinal deformity in osteoporosis patients [25][26][27][28][29][30][31]. Recently, Miyakoshi et al [13,32,33] investigated spinal ROM in postmenopausal patients with osteoporosis aged 50 years or older and found that a decrease in spinal ROM had negative effects on QOL, and that deterioration of back muscle strength was the most important factor decreasing spinal ROM, indicating that maintenance of back muscle strength and lumbar ROM are important for QOL.…”

How do anterior/posterior translations of the thoracic cage affect the sagittal lumbar spine, pelvic tilt, and thoracic kyphosis?

“…Likewise, thoracic cage flexion and extension are the primary movements thought to increase or decrease the thoracic kyphosis [32,34,39]. As such, pelvic tilt and/or thoracic cage flexion/extension are the primary movements utilized in today's clinical and surgical management for the correction/reduction of sagittal plane deformities [13,18,19,32,34,39]. However, "fixed" sagittal plane translations of the thoracic cage have been overlooked as main motions in range of motion, spinal coupling, and in X-ray projection studies [8,9,29,30,31].…”

Lumbar lordosis in osteoporosis and in osteoarthritis

“…In a subsequent study [5], curviscope measurements were not correlated with BMD in 20 women with vertebral compression fractures. Sinaki et al [33] also found no correlation between lumbar angles and BMD in a sample of postmenopausal women. However, lordosis was defined as ''the angle of intersection between the inferior border of the interference vertebra and the superior border of the sacrum''.…”