CORRELATION OF BACK EXTENSOR STRENGTH WITH THORACIC KYPHOSIS AND LUMBAR LORDOSIS IN ESTROGEN-DEFICIENT WOMEN

Aging and osteoporosis have been associated with skeletal changes. Bac k extensor strengthening exercises are highly recommended for manageme nt 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, acti ve, estrogen-deficient women. In a study of 65 such women (ages 48-65 yr), back extensor strength, bone mineral density, and physical activi ty score were evaluated and measured. These factors were then correlat ed with radiographic factors: (1) vertebral body ratios (anterior/post erior height) calculated for each vertebra from T-4 through L-5; (2) k yphosis index determined by adding the anterior heights of each verteb ral body, T-4 through T-12, and then dividing the total by the corresp onding sum of the posterior heights of each vertebral body; (3) thorac ic kyphosis; (4) lumbar lordosis; and (5) sacral inclination. Back ext ensor strength had a significant negative correlation with thoracic ky phosis (r = -0.30, P = 0.019) and a positive correlation with lumbar l ordosis (r = 0.26, P = 0.048) and sacral inclination (r = 0.34, P = 0. 009). However, bone mineral density and physical activity score did no t show any significant correlations with the radiographic factors. The results indicate that the stronger the back extensor, the smatter the thoracic kyphosis and the larger the lumbar lordosis and sacral incli nation, We conclude that back extensor strength is an important determ inant of posture in healthy women, However, prescribing back extensor strengthening exercises alone may also increase lumbar lordosis, which is not desirable.