Magnitude of spinal muscle damage is not statistically associated with exercise-induced low back pain intensity.

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BACKGROUND CONTEXT: Findings on imaging of noncontractile anatomic abnormalities and the intensity of low back pain have weak associations because of false-positive rates among asymptomatic individuals. This association might be stronger for contractile tissues. PURPOSE: The purpose of this study was to examine the relationship between location and reports of pain intensity in the low back and exercise-induced muscle damage to the lumbar paraspinal muscles. STUDY DESIGN: Nondiagnostic observational study in a laboratory setting. METHODS: Delayed onset muscle soreness was induced in the low back of healthy pain-free volunteers. Measures of pain intensity (100-mm visual analog scale [VAS]) and location (area on the pain diagram) were taken before and 48 hours after exercise. Muscle damage was quantified using mechanical pain thresholds, motor performance deficits, and transverse relaxation time (T2)-weighted magnetic resonance imaging (MRI). Changes pre- to postexercise in signal intensity on T2-weighted imaging within the erector spinae, pain intensity, pain area, mechanical pain threshold, and isometric torque were assessed using paired t tests. Bivariate correlations were conducted to assess associations among muscle damage, pain intensity, and pain drawing area. RESULTS: Twenty participants volunteered (11 women; average age, 22.3 years; average body mass index, 23.5) for study participation. Reports of pain intensity at 48 hours ranged from 0 to 59 mm on the VAS. Muscle damage was confirmed by reductions in mechanical threshold (p=.011) and motor performance (p<.001) and by changes in T2-weighted MRI (p=.007). This study was powered to find an association of at least r=0.5 to be statistically significant. Correlations of continuous variables revealed no significant correlations between pain intensity and measures of muscle damage (ranging between -0.075 and 0.151). There was a significant association between the remaining torque deficit at 48 hours and pain area. CONCLUSIONS: The results of this study indicate that there was no association between the magnitude of muscle damage in the lumbar erector spinae and reported pain intensity in the low back. In future studies, larger cohorts may report statistically significant associations, but our data suggest that there will be low magnitude potentially indicating limited clinical relevance.





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Bishop, Mark D, Maggie E Horn, Donovan J Lott, Ishu Arpan and Steven Z George (2011). Magnitude of spinal muscle damage is not statistically associated with exercise-induced low back pain intensity. Spine J, 11(12). pp. 1135–1142. 10.1016/j.spinee.2011.11.005 Retrieved from

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Maggie Elizabeth Horn

Assistant Professor in Orthopaedic Surgery

Steven Zachary George

Laszlo Ormandy Distinguished Professor of Orthopaedic Surgery

Dr. George’s primary interest is research involving biopsychosocial models for the prevention and treatment of chronic musculoskeletal pain disorders.  His long term goals are to 1) improve accuracy for predicting who is going to develop chronic pain; and 2) identify non-pharmacological treatment options that limit the development of chronic pain conditions.  Dr. George is an active member of the American Physical Therapy Association, United States Association of the Study of Pain, and International Association for the Study of Pain. 

Dr. George’s research projects have been supported by the National Institutes of Health, Department of Defense, and Orthopaedic Academy of the American Physical Therapy Association.  Dr. George and his collaborators have authored over 330 peer-reviewed publications in leading medical, orthopaedic surgery, physical therapy, rehabilitation, and pain research journals.  He currently serves as Editor-in-Chief for the Physical Therapy & Rehabilitation Journal. Dr. George has also been involved with clinical practice guideline development for the Academy of Orthopaedic Physical Therapy and the American Psychological Association. 

Dr. George has been recognized with prestigious research awards from the American Physical Therapy Association, American Pain Society, and International Association for the Study of Pain. For example from the American Physical Therapy Association: he was named the  21st John H.P. Maley Lecturer, recognized as a Catherine Worthingham Fellow in 2017, and selected for the Marian Williams Award for Research in Physical Therapy in 2022.    

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