1 Department of Health, Kinesiology and Applied Physiology, Concordia University, Montreal, Quebec, Canada.
2 École de kinésiologie et des sciences de l'activité physique (EKSAP), Faculté de médecine, Université de Montréal, Montreal, Quebec, Canada.
3 Centre de recherche de l'Institut universitaire de gériatrie de Montréal (CRIUGM), Montreal, Quebec, Canada.
4 Département de médecine, Université de Montréal, Montréal, Québec, Canada.
5 Centre de Recherche, Institut de Cardiologie de Montréal, Montreal, Quebec, CanadaCentre de Recherche, Institut de Cardiologie de Montréal, Montreal, Quebec, Canada.
6 Centre interdisciplinaire de recherche sur le cerveau et l'apprentissage (CIRCA), Montreal, Quebec, Canada.
7 School of Health, Concordia University, Montreal, Quebec, Canada.
8 Alan Edwards Centre for Research on Pain (AECRP), McGill University, Montreal, Quebec, Canada.
9 Department of Anesthesiology, McGill University, Montreal, Quebec, Canada.

Background: Multimodal exercise programs do not specifically target lumbar paraspinal musculature, but incorporate aspects of different exercises to have an overall benefit.

Objective: To investigate the effect of a multimodal exercise program on paraspinal muscle volume and composition, and patient outcomes in individuals with chronic low back pain (CLBP).

Methods: Thirty-four participants with CLBP either completed a 14-week high-intensity training program (n = 8) including cardiorespiratory and resistance exercises 3 sessions per week or were waitlisted (n = 26). Participants underwent magnetic resonance imaging at baseline and post-intervention to assess paraspinal muscle volume (cm3) and fatty infiltration (% FI) at L3-L4, L4-L5, and L5-S1. Pain, disability, quality of life, pain-related fear (catastrophizing and Kinesiophobia), and anxiety were assessed via validated self-reported questionnaires.

Results: Mixed-design ANOVA revealed no significant time × group interactions for paraspinal muscle volume and %FI. An exploratory analysis revealed a significant increase in multifidus %FI in the control group at L3-L4, L4-L5, and L5-S1, with a concomitant increase in multifidus volume at L3-L4 and L5-S1. The exercise group had a significant increase in multifidus %FI and volume at L5-S1. Significant time × group interactions for pain, disability, catastrophizing and kinesiophobia, and a main effect of group in physical and mental health were found. Significant correlations were found between changes in patient-reported and functional outcomes with paraspinal muscle morphology.

Conclusion: Multimodal exercise programs may help prevent LBP-related paraspinal muscle atrophy and %FI, and lead to concomitant improvements in pain, disability and pain-related fear in individuals with CLBP.