Aim: The present study was conducted to compare the effect of a course of corrective exercises on the electromyography activity of selected muscles in young men with the upper cross syndrome in preferred and non-preferred times based on chronotype.
method: To conduct this study, 24 men with upper cross syndrome were selected, who were placed in 2 evening exercise groups or the evening time group (non-preferred) (12 people) and the morning time group (preferred) (12 people). In this study, the angle of the forward head and forward shoulder was evaluated by the photographic method. Also, the amount of kyphosis of the flexible ruler was determined. Additionally, in this study, electromyography was used to determine the activity of the serratus anterior, upper, middle, and lower trapezius muscles. After the evaluation of the variables, the subjects of the two groups did the corrective exercise program for 4 weeks (3 sessions per week). After the end of the training period, the evaluations were done again. For statistical analysis, descriptive statistics were used to describe variables, and inferential statistics were used to evaluate hypotheses. The normal distribution of the data was determined by the Shapiro-Wilk test. After confirming the normality of the data distribution, paired t-test was used to compare the difference in the scores of each variable in the pre-test and post-test in each group, as well as the analysis of the ANCOVA test was used to examine the differences between groups. SPSS version 26 software was used to analyze the statistical part, and MATLAB software was used to convert EMS raw data.
Findings: The results of the research show the effect of both training programs on the variables of the forward head (p=0.001), forward shoulder (p=0.001), kyphosis (p=0.001), serratus anterior muscle activity (p=0.001), upper (p=0.001), middle (p=0.001) and lower (p=0.001) trapezoid. Also, in the comparison of the two training programs, there is a significant difference between the groups in the variables of serratus anterior muscle activity (p=0.04), upper trapezius (p=0.03), middle (p=0.04) and lower (p=0.03) was observed, but no significant difference was observed in the variables of forward head, forward shoulder, and kyphosis.
Conclusion: In general, the results of this study show the effect of corrective exercises in the morning and evening on the reduction of upper cruciate syndrome and the improvement of muscle activity in the serratus anterior, upper, middle, and lower trapezius muscles. Based on this, the use of training in both periods, especially the morning period, is suggested to trainers and activists in the field of corrective movements to correct the abnormality of upper cross syndrome