| Author: | Zhou, Fengming |
| Title: | Association between the mechanical properties of paraspinal muscles and chronic non-specific low back pain in athletes |
| Advisors: | Fu, Amy (RS) Yu, Clare (RS) |
| Degree: | Ph.D. |
| Year: | 2025 |
| Department: | Department of Rehabilitation Sciences |
| Pages: | 204 pages : color illustrations |
| Language: | English |
| Abstract: | Although alterations in lumbar muscle mechanics have been proposed as a cause of low back pain (LBP) in athletes, there is limited research on the diaphragm and psoas major (PM) muscles and their association with chronic LBP. Therefore, this thesis aimed to deepen our understanding of lumbar muscle mechanical dysfunctions in athletes with chronic LBP. Previous studies have identified a connection between the mechanical properties of the diaphragm, PM, lumbar multifidus (LM), and LBP. However, several knowledge gaps indicate the need for further exploration. First, it is unclear whether athletes with LBP exhibit inferior diaphragm mechanical properties. More essentially, how diaphragm mechanical properties are associated with sports performance and the severity of LBP are largely unknown. Second, a reliable method for quantifying PM muscle stiffness is needed, along with a comparison of stiffness between athletes with and without LBP. Finally, research is lacking on muscle stiffness, particularly the differential modulation of the deep (DLM) and superficial (SLM) layers of the LM muscle by LBP or specific sports activities, necessitating further investigation. The review (Study 1) aimed to identify a feasible and reliable method for quantifying diaphragm thickness and excursion at a sports centre, while the cross-sectional study (Study 2) assessed the test-retest reliability of using ultrasound shear wave elastography (SWE) to measure the stiffness of the PM. The findings from these studies indicated that ultrasonography provides sufficient reliability (ICC > 0.7) for assessing diaphragm thickness and excursion. The test-retest reliability of Young's modulus measurements was found to be good to excellent for the PM muscle (ICC: 0.79-0.92). These results supported the use of B-mode ultrasound for measuring diaphragm thickness, M-mode ultrasound for measuring diaphragm excursion, and SWE for quantifying the PM stiffness. Following confirming the measurement methods, three cross-sectional studies were conducted aiming to explore dysfunctions in the muscle mechanical properties of the diaphragm, PM, and LM in athletes with chronic LBP. We discovered that (1) weightlifters with chronic LBP exhibited significantly reduced diaphragmatic contractility, as evidenced by lower diaphragm thickening fractions and excursion. Also, greater inspiratory muscle strength (primary diaphragm) may enhance lifting performance (Study 3); (2) PM stiffness was significantly elevated in gymnastic and wushu athletes with chronic LBP; increased PM stiffness was associated with greater LBP severity (Study 4); and (3) athletes with LBP exhibited significantly greater stiffness in the DLM compared to their pain-free counterparts, while SLM stiffness was affected by type of sports (Study 5). In summary, this project has developed a reliable method for quantifying the stiffness of deep-seated lumbar stabilizing muscles. More importantly, it has provided evidence of dysfunction in muscle mechanical properties among athletes with chronic LBP, highlighting their association with pain severity and sports participation. These findings suggest that chronic LBP may be linked to multi-muscle dysfunctions in mechanical properties, with each muscle exhibiting distinct types of mechanical property impairments. This underscores the need for precise assessment and management strategies. Further longitudinal or interventional studies are recommended to evaluate the cause-effect relationship between muscle mechanical properties and the incidence of LBP. |
| Rights: | All rights reserved |
| Access: | open access |
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