Changes in the normal characteristic pattern of abdominal muscle thickness in rowers with low back pain

Royal Hospital for Neuro-disability, London and Applied Biomedical Research Group, GKT School of Biomedical Sciences, King’s College London Background: The relationship between the size and therefore force-generating capacity of individual abdominal muscles is unknown and maybe influenced by various factors. The aim of this study was to investigate the normal relative contribution of individual muscles to total abdominal muscle thickness, and to examine the association with training and low back pain (LBP).Method: Three groups of male subjects (age range 18–30 years) were studied: elite rowers with (n = 10) or without (n = 20) current or previous LBP and age-matched controls (n = 18). Real-time ultrasound imaging was used to measure the external oblique (EO), internal oblique(IO), transversus abdominis (TA) and rectus abdominis (RA) bilaterally. The relative thickness of each muscle was expressed as a percentage of total abdominal muscle thickness.Results: The controls and rowers without LBP showed the same pattern of order of relative thickness. As a group the rowers with LBP were not significantly different from the other two groups. However, as each rower with LBP showed a different pattern and considerable individual variation, analysis of group means was therefore inappropriate. Fisher’s Exact Test classified the rowers with LBP as showing significantly abnormal patterns (p < 0.05). An example of a rower with LBP is shown in Figure 1.Discussion: A characteristic pattern of relative abdominal muscle thickness was found in controls and rowers without LBP. In rowers with LBP the pattern was altered; this could be a cause or effect of LBP.Conclusions: Ultrasound imaging can be used to aid assessment of abdominal muscle involvement in LBP. Specific abnormalities could be addressed by individual exercise programmes, the effects of which need to be evaluated to provide evidence for rehabilitation