Long-term Effect of Physical Inactivity on Thoracic and Lumbar Disc Degeneration-An MRI-based Analysis of 385 Individuals From the General Population

Spine J. 2020 Apr 30;S1529-9430(20)30166-2. doi: 10.1016/j.spinee.2020.04.016. Online ahead of print.

Abstract

Background context: The correlation between physical inactivity, thoracolumbar disc degeneration, and back pain remains unclear.

Purpose: This study investigated the relationship between short- and long-term physical inactivity and degenerative changes of the thoracic and lumbar spine in a southern German cohort from the general population over a time period of 14 years.

Study design/setting: This study was designed as a cross-sectional case-control study, nested in a prospective cohort from the "Cooperative Health Research in the Region of Augsburg/Kooperative Gesundheitsforschung in der Region Augsburg" (KORA) study.

Patient sample: All participants in the population-based KORA study were assessed using a physical activity questionnaire to establish a baseline in 1999-2001 (exam 1), within an initial follow up questionnaire in 2006-2008 (exam 2), and a second follow-up questionnaire between 2013 and 2014 (exam 3). A subsample of this group (400 subjects) underwent full body MR scan performed on a 3T magnetic resonance imaging scanner current with exam 3.

Outcome measure: Data regarding physical inactivity over a time period of 14 years and back pain, and quantification of thoracic and lumbar disc degeneration on magnetic resonance imaging.

Methods: Quantification of thoracic and lumbar disc degeneration was performed using the Pfirrmann score. Physical activity was grouped as no physical activity, irregularly for 1 hour, regularly for 1 hour, or regularly for ≥2 hours. This was used to calculate another variable "physical inactivity," with the options of irregular activity ≤1 hour per week or regularly ≥1 hour. Physical labor, walking, and cycling activity were additionally investigated. Correlations between physical inactivity measurements and thoracic and lumbar disc degeneration were analyzed via linear regression models adjusted for age, sex, BMI, hypertension, diabetes, and back pain.

Results: In total, 385 individuals (mean age: 56 years, SD ± 9.19; 58.2% male) were included in this study. Mean summed Pfirrmann score was 2.41 (SD ± 4.19) in the thoracic and 1.78 (SD ± 1.81) in the lumbar spine. The level of current exercise in our cohort varied with 113 (29.4%) subjects exercising regularly ≥2 hours per week, 118 (30.7%) regularly 1 hour per week, 57 (14%) irregularly for about 1 hour per week, and 97 (25.2%) stated not to exercise at exam 3. Disc degeneration was more apparent in those with irregular activity <1 hour compared to those with regular activity of ≥1 hour and more per week (p<.01) and in those with no activity compared to those with regular activity of ≥2 (p<.001) measured using exam 3. Less physical activity over a time period of 14 years correlated with an increase of disc degeneration of the thoracic and lumbar spine after adjustment for age, sex, BMI, hypertension and diabetes mellitus (p<.05). There was no statistically significant association between physical labor, walking activity, or cycling activity with disc degeneration. Additionally, no significant correlations between degree of disc degeneration (p=.990), degree of physical inactivity (p=.158), and back pain were observed.

Conclusion: Degree of physical inactivity as measured over a time period of 14 years demonstrated a strong correlation with disc degeneration of the thoracic and lumbar spine.

Keywords: Cohort studies; Intervertebral disc degeneration; Magnetic resonance imaging; Physical inactivity; Spine.