EFFECT OF BACK-STRENGTHENING EXERCISE ON POSTURE IN HEALTHY WOMEN 49 TO 65 YEARS OF AGE

Objective: To evaluate the effect of back-strengthening exercise on po sture in 60 healthy estrogen-deficient women. Design: The 60 study sub jects were randomly assigned to either an exercise or a control group, and various factors were assessed at time of enrollment in the study and at 2-year follow-up. Material and Methods: The 32 women in the exe rcise group were instructed in progressive back-strengthening exercise s, whereas the 28 women in the control group had no exercise prescript ion and were asked to continue their usual physical and dietary activi ties. At baseline and 2-year follow-up examinations, back extensor str ength was measured with a strain-gauge dynamometer, and lateral roentg enograms of the thoracic and lumbar areas of the spine were obtained t o measure the angles of thoracic kyphosis, lumbar lordosis, and sacral inclination. The changes in radiographic measurements and back extens or strength were analyzed statistically. Results: Back extensor streng th increased significantly in both the exercise and the control groups , but no radiographic measurements were significantly different betwee n these groups. The significant increase in back extensor strength in both groups of healthy women suggested that the original grouping did not accurately reflect the amount of exercise. Thus, the 60 subjects w ere reclassified for comparison on the basis of increase in back exten sor strength-27 with more than or equal to the mean increase of 21.1 k g and 33 with less than 21.1 kg. Furthermore, each of these groups of subjects was subdivided on the basis of degree of thoracic kyphosis. A mong the subjects with substantial thoracic kyphosis, those with a sig nificant increase in back extensor strength had a significant decrease in thoracic kyphosis (-2.8 +/- 4.2 degrees; P = 0.041), whereas those with a small increase in strength had a nonsignificant increase in th oracic kyphosis (1.8 +/- 5.3 degrees). The increase in back extensor s trength did not seem to affect mild degrees of kyphosis. Conclusion: I ncreasing the back extensor strength in healthy estrogen-deficient wom en helps decrease thoracic kyphosis.