Having a physical weakness seems to be the “core” focus for many sufferers and therapists involved in low back pain (sorry, I’ll try to avoid any cheap puns in the rest of this article). Perhaps like you, I’ve had my fair share of back pain over the years, and yet I’d regard myself as reasonably fit- having pretty good abdominal musculature since my teens (you’ll have to make-do with the picture of a model’s abs, as I thought it inappropriate to post my own impressive midriff).
So, what’s the real relationship between musculature and recurrent low back pain? Well, it turns out that a weak core is more likely due to low back pain (LBP) than it is likely to be the cause of it. This is the old chicken and egg problem. Researchers found that people with low back pain had poor “core stability” i.e. the ability to engage the deeper layers of abdominal muscles (particularly Transversus Abdominis). Some fitness professionals and clinicians (rather hastily it now seems) claimed that LBP was due to poor core strength. But this isn’t really backed up by any great evidence. It’s fair to say that people who have recurrent or long-term LBP often have poor core strength, but that’s not the same as cause and effect.
Here’s a scenario: let’s say you have had a severe episode of LBP – you tend to do less physical activity and tend to move your back less because otherwise it hurts. Remember the “use it or lose it rule”? Well, if you don’t use the muscles of your trunk as much, your nervous system starts to lose connections between the nerve cells that control these muscles, so gradually (or quite suddenly in some people) your muscles in this area become weaker – this is one of the downsides to neuroplasticity. And it tends to be selective; some muscles (Transversus Abdominis and the Multifidus and Rotatores muscles in the low back) seem to weaken faster than others. One effect of this is that your movements become less well coordinated and so you’re at more risk of hurting your lower back again. So, pain leads to less movement, more weakness, more injury, more pain, less movement etc..
If the pictured model has a history of LBP, I’ll bet his low back muscles aren’t nearly as impressive. It turns out that a more accurate muscle-related predictor of LBP is the ratio of low back endurance to abdominal muscle endurance. Next time you’re in, let’s test your ratio to see whether you need a bit more guidance on the types of exercise you should be doing.
This is the first part to “Why have I got a weak back?” – look out for the second part coming to a screen near you soon!
Meantime, I must get “back” to patients (sorry, couldn’t resist another) ;-)