# Effects of Core Stabilization Exercise Programs on Changes in
## 4 Discussion and Limitation
However, there was a significant post-exercise increase in other variables, including maximum and relative extensor muscle strength at an angular velocity of 60\({}^{\circ}\)/s and 90\({}^{\circ}\)/s. Moreover, there was a significant decrease in the muscle ratio (ratio of the flexor and extensor muscles of the trunk) at an angular velocity of 60\({}^{\circ}\)/s and 90\({}^{\circ}\)/s. Our findings demonstrated that the core stabilization exercise program strengthens core muscles, which improves the balanced development of flexor and extensor muscles, as well as enhances the isokinetic muscle functions of the trunk, including muscle strength and endurance. Accordingly, core stabilization exercises could effectively increase muscle strength in the trunk and improve neuromuscular imbalance. Moreover, a 12-week core stabilization exercise program was found to improve the strength of the lumbar flexor and extensor muscles in primary school students with scoliosis [53]. Additionally, an 8-week core stabilization exercise program was found to significantly increase flexor and extensor muscle strength at an angular velocity of 60\({}^{\circ}\)/s and 90\({}^{\circ}\)/s in women with a sedentary lifestyle [54]. Furthermore, [PERSON] et al. [30] reported a 12-week lumbar stabilization exercise program improved isokinetic muscle function of the trunk in patients with non-specific chronic low-back pain. As aforementioned, most studies have demonstrated that core stabilization exercise enhances core muscle strength. In addition, core stabilization exercise increases lumbar stability by strengthening the core flexor and extensor muscles, as well as the contractile and neuromuscular control functions [55]. Consistent with these previous findings, we observed a significant post-exercise decrease in the muscle strength ratio, which was effective for the balanced development of core muscles. The core muscles represent the anatomical and functional center of the body and play a corset-like role in stabilizing the body and spine [56]. Weakened lumbar muscles cause deterioration of the spinal stabilization function, which can be a primary cause of low-back pain [12; 13]. Conversely, strengthening core muscles enhances core stability and is crucially involved in performing activities of daily living or various other activities, as well as maintaining posture and balance [57; 58]. Our core stabilization exercise program enhanced lumbar muscle function and strength, which can enhance core stability and prevent musculoskeletal disorders caused by a lengthy sedentary lifestyle. This study suggests that the core stabilization exercise program may have a positive effect on muscle stiffness and contraction rates in the group with long-term sedentary lifestyles. In addition, tensiomyography can be used to clinically evaluate muscle contraction characteristics. Limitations of this study were that there was no control group and only healthy subjects were recruited. In future studies, it is necessary to further study the effect of the core stabilization exercise program by composing a control group and a low-back-pain group.