Background and Aims: The spine has an important role in the body alignment and its position has a big role in power production (1), therefore, changes in its curves can affect the resistance of the spine (2). Exaggeration of the the normal curves of the spine in the thoracic and lumbar spine is called kypholordotic posture (3). In this deformity, muscles of the abdomen are weakened .It is possible that affect the resistance and function of the flexor trunk by reducing the kyphosis angle. However, there arent any evidence about the beneficial effect of kyphosis corrective exercise on female students with kypholordotic posture. Therefore, the aim of this study is to evaluate the effects of kyphosis corrective exercises on the trunk flexor strengh in female students with kypholordotic posture.
Methods: This is a quasi-experimental and comparative study with control group and pretest posttest design. 30 Female Students, aged 18-25 years old with kypholordotic posture (kyphosis angle was more than 42 degrees and lordosis angle was more than 54 degrees) participated in this study. They were randomly divided into two groups of training and control group (15 per group). The training group performed the kyphosis corrective exercise for for eight weeks, three sessions per week. The kyphosis curve and the trunk flexor strengh assessed before and after training, using flexible ruler and sit up with a 6 kg weight, respectively. Independent t-test at p≤0.05 was used to compare variables between groups, After approving the normality of data by Kolmogorov-Smirnov test.
Results: The results of the independent t-test showed that there is significant difference between groups in the kyphosis angle (P=0.01) and trunk flexor strengh (P=0.01).

Conclusion: According to the results of the present study, in addition to reducing the kyphosis angle, kyphosis correction exercises had a significant effect on the strength of trunk flexor strength in students with kypholordotic deformity One of the main reasons for kypholordotic abnormality is the imbalance of agonist and antagonist muscle strength. For this reason, it can be said that by establishing the lateral alignment of the spine by strengh trainings, the strength of the trunk flexor muscles, which were weakened, can be increased.