Poster Presentation 51st International Society for the Study of the Lumbar Spine Annual Meeting 2025

Isometric lumbar extension strength in individuals without back pain - A large multicenter cross-sectional study on normative values for clinical application and influencing factors (#202)

Christoph Spang 1 2 , Ruth Hendrix 3 , Stefan Penther 4 , Bernd Sigl 5 6 , Bernhard Dregger 7 , Zoran Stojanovic 3 , Sebastian Färber 8 , Bruno Domokos 1 2 , Ralf Jung 9 , Frank Horlbeck 10 11 , Florian Alfen 1
  1. Private Orthopaedic Spine Center, Würzburg, Bavaria, Germany
  2. Institute for Sports Science, University of Würzburg, Würzburg, Bavaria, Germany
  3. MedAix Spine Center, Aachen, Germany
  4. Penther & Partners - Practice for Spinal Rehabilitation and Physiotherapy, Ingolstadt, Germany
  5. Atos Clinic, Munich, Germany
  6. Rehabilitation, ATOS clinic , Munich, Germany
  7. Practice for Physical and Rehabilitative Medicine, Bonn, Germany
  8. Powerspine, Würzburg, Germany
  9. Center of Competence for Muscular Rehabilitation Dr. Ralf Jung , Nuremberg, Germany
  10. Practice for Physical and Rehabilitative Medicine, Chemnitz, Germany
  11. Kieser Training, Chemnitz, Germany

Introduction:

Chronic pain in the lower back region is known to be associated with pronounced atrophy and increase of fat infiltration in the paraspinal extensor muscles, especially in the m. multifidus. Heavy load isolated lumbar extension resistance exercise (ILEX) using a device including fixation through pelvic restraint and semi-sitting position has shown promising outcomes in plenty of clinical studies (Steele et al. 2015a; Golonka et al. 2021; Fortin et al., 2023). Interestingly, clinical improvements correlate with an increase of maximal isometric lumbar extension strength (MILES) highlighting the need for appropriate measurement of this parameter (Steele et al., 2018). However, there is a lack of robust normative values of MILES in individuals without back pain. However, this is essential for proper diagnosis and also for monitoring and evaluating therapy outcomes.

 

Methods:

This study was initiated by the German Society for Medical Strengthening Therapy (GMKT). Individuals were included when they had no pain in the lumber spine region during the last 6 months and exhibited no other exclusion criteria (e.g. previous spine surgeries, fractures, osteoporosis, cancer and clinical conditions related to the cardiovascular system). 701 individuals (363 men, 338 women; mean age 40 years, range 14-79 years) were tested between the years 2012-2022 in one of the participating certified spine centers using the same standardised protocol. Maximal isometric lumbar extension strength (in NM torque) was measured at seven different angles (72°, 60°, 48°, 36°, 24°, 12°, 0°) using a device with pelvic restraint and semi-sitting position (Steele et al., 2015b). The assessment was repeated after one week. Anthropometric data and information on sports activity were taken by a questionnaire.

 

Results:

The measured MILES was highest at 72° and declined towards extension (means in NM (angle): 318.6 (72°), 302.5 (60°), 280.2 (48°), 261.4 (36°), 240.2 (24°), 213.3 (12°), 167,1 (0°). There was a weak negative correlation of age with MILES for both men and women. Men exhibited no significant differences in age until the fifth decade followed by a decline of MILES afterwards. For women the decrease started earlier in life but was less strong along the course. Men had higher values than women at any time point and at any age (p<0.001). Furthermore, there was a moderate to strong positive correlation between MILES and body weight. Height correlated moderately with MILES for men but not women. Individuals that were active in sports exhibited higher MILES at any angle (p<0.01) than those who were not active in sports. Results concerning the influence of certain types of sports activity were unclear.

 

Disucssion:

This study provides important information on normative values of MILES in individuals without back pain. These are necessary for making proper diagnosis before ILEX based rehabilitation programs and can help to assess improvements through the rehabilitation process. The results also show that age and weight significantly influence MILES values. Therefore, a correction for these two parameters is necessary for clinical application and interpretation of therapy outcomes.

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  3. Steele J, Fisher J, Perrin C, Conway R, Bruce-Low S, Smith D. Does change in isolated lumbar extensor muscle function correlate with good clinical outcome? A secondary analysis of data on change in isolated lumbar extension strength, pain, and disability in chronic low back pain. Disabil Rehabil. 2019;41(11):1287-1295.
  4. Golonka W, Raschka C, Harandi VM, Domokos B, Alfredson H, Alfen FM, Spang C. Isolated Lumbar Extension Resistance Exercise in Limited Range of Motion for Patients with Lumbar Radiculopathy and Disk Herniation-Clinical Outcome and Influencing Factors. J Clin Med. 2021;10(11):2430.
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