Journal of Preventive Medicine

Introduction
Proper body alignment has negative effects on athletic performance. In fact, maintaining proper body alignment allows an athlete to focus on the proper movement and performance. The presence of a healthy motor control system, in addition to improving performance, can prevent injuries during heavy sports activities. The lower crossed syndrome (LCS) is characterized by tightness or shortness of hip flexors and lumbar extensors and the weakness of the abdominal, gluteal, and hamstring muscles. Such imbalance can have harmful effects on static and dynamic balance, especially when walking. 
This syndrome causes anterior tilt of the pelvis, increased lumbar lordosis, and slight flexion of the hip joint. Studies have shown that, compared to the normal posture, lordotic postures can increase the compressive loading on the posterior spinal structures and increase the stress on the intervertebral disc. Also, the increase in the concentration of force on a relatively small part of the facet joints can cause more stress to be concentrated on the tissue of the facet joints. The lack of muscle stability in the lumbar-pelvic area can affect the position of the pelvis and subsequently change the angle of the lumbar arch, leading to postural abnormalities in this area, including hyperlordosis. One of the factors that play an important role in lumbopelvic stability and spinal deviations is the function of core muscles (abdominal mucles, multiceps, pelvic floor muscles, diaphragm). The main role of these muscles is to help stabilize the spine, pelvis, and trunk in basic and functional movements.
 Therefore, their strengthening can improve the neuromuscular system and support the spine, especially in the lumbopelvic area. According to the results of numerous studies on the effects of sports exercises on balance and improving performance and, on the other hand, the useful and accessible benefits of TRX exercises, and given that we found no study in Iran or other countries on the effect of TRX exercises on the performance of the upper and lower extremities in middle-aged women with LCS, this study aims to examine whether six weeks of TRX exercises have an effect on upper and lower extremity function of middle-aged women with LCS in Iran.

Methods
This is a quasi-experimental study with a pre-test/post-test design. The study population includes all non-athlete middle-aged women with LCS in Marivan county, Iran. Of these, 30 were purposefully selected based on the inclusion and exclusion criteria. The criteria for entering the study were the absence of pregnancy, age 30-40 years, general mental health, suffering from LCS (having a hyperlordosis angle above 52.35), and consent to participate. Exclusion criteria were a history of surgery in the past year, any lower limb injury in the past 6 months, neurological or central nervous system deficits, and irregular participation in the exercise sessions. After selection, samples were randomly divided into two control and TRX groups. Their height was evaluated by tape measure and their weight was measured by a scale (model BPS-9370). Then, their upper extremity function was measured by the Y balance test and Davis test, and lower extremity function was measured by the side hop test and the square hop test. Then, 6 weeks of TRX exercises were performed as a training protocol. After 6 weeks, the subjects were tested again under the same conditions.

Results
Paired t-test results for intra-group comparison of upper and lower extremity function variables in TRX and control groups in the pre- and post-test stages showed that all variables in the TRX group were significantly different except for the scores of square hop test (p=0.188) and side hop test (p=0.463). In the analysis of covariance for the variables after the intervention, the p for all variables was less than 0.05. Therefore, the effect of TRX exercises on upper and lower extremity performance was significant.

Discussion
The results of this study showed the significant effect of six weeks of TRX exercises on upper and lower extremity performance of non-athlete middle-aged women with LCS. This can be caused by increasing the strength and efficiency of the core muscles. Due to the novelty of its method, TRX can improve the intensity of core stability exercises simply by changing the lumbar angle or by including balance exercises. On the other hand, during TRX exercises, a coordinated and integrated system is used for neuromuscular coordination. Considering that these exercises require a sense of balance to stabilize the body on an unstable surface, they can cause coordination and bilateral activation of the neuromuscular system.

Ethical Considerations
Compliance with ethical guidelines
This study has ethical approval from the ethics committee of the Sports Sciences Research Center (Code: IR.SSRC.REC.1400.125). All participants signed an informed consent form..

Funding
This article was extracted from the master’s thesis of Mojdeh Fattahi registered by Islamic Azad University, Science and Research branch. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Authors' contributions
Conceptualization: Mojdeh Fattahi, Mohammad Rahimi and Shahin Akhdar; Methodology: Mojdeh Fattahi, Mohammad Rahimi and Aynollah Naderi; Investigation and Writing – Original Draft: Mojdeh Fattahi and Shahin Akhdar; Writing–Review and Editing: All Authors. 

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgements
The authors would like to thank all the women participated in this study for their cooperation.


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