Motor learning moves from conscious attention to make certain movements through to movements that are basically over-learned or automatic. There are considerable differences in how a beginning learner carries out a movement from the way an accomplished or proficient person carries out the same movement – think about how we first learned to drive a car (complete with tongue poking out and bunnyhops!) through to the relatively automatic way we drive to and from work today! Motor learning is specific – so if we want to get good at typing, we need to actually type rather than lift weights. This has important implications when we look at how to recruit muscles, for example when learning to contract the transvers abdominis. Often the first step in learning this is to carry it out in lying – but as Lederman indicates, there is no guarantee that this practice leads to active recruitment while carrying out other activities in other positions.
A good example I had to giggle at was the effect of training to sit on a swiss ball – while participants learned how to sit well on a swiss ball, this training didn’t carry over into running. It’s important to remember that training to use certain muscles needs to be specific to the movements that those muscles are used in. (I’m not sure about the grammar of that sentence! but what I mean is if you want to get effective stability while bending to make a bed, the best way to learn to use the ‘core’ muscles is to – oh no! – make the bed!)
Lederman reviews the adaptation to core stability training that asks people to ‘think about their core’ while doing functional activities. There are problems with this – while it might be helpful when initially learning what it feels like to activate those muscles, it’s cognitively demanding and actually detracts from performance when the activity is more automatic. I can think of times when I’ve been playing the piano – when I’m thinking hard about technique, my playing deteriorates. When I simply think about the music, my performance improves. Lederman describes studies that suggest focusing on getting the job done (external focus) is more effective and improves performance more than focusing on working specific muscles (internal focus).
He goes on to discuss economy of movement – when we’re moving efficiently, there is a wonderful interplay of contraction and release of muscles to create a smooth and effective performance. When we’re learning, or focusing on moving in specific ways, we tend to co-contract or use more muscle contraction than required. This is both effortful and less efficient – and while the intention is to help people learn what it feels like to use their muscles, and eventually not need to focus on the feelings, what it seems to do instead is make the movements much more difficult. And when you’re sore, fatigued and maybe not enjoying movements, it’s less likely that you’ll persist with movements until they become automatic.
Prevention – core stability exercise has been suggested as a strategy to prevent back pain. A couple of studies cited by Lederman found that there were no significant differences between people who received core stability training and those who didn’t in terms of reporting of back pain episodes – and what was interesting in one of the studies was that these people had weak abdominal muscles and no back pain!
Treatment – I suppose my biggest reservation for core stability training is the way that it has been promoted as a treatment for low back pain. I think the premise originally derived from simply not understanding the difference between correlation and causation. Remember the original finding was that people with low back pain appeared to have delays in recruiting TrA. However, adding to this are studies that initially looked promising: improvements in low back pain when people were given core stability training in comparison with ‘other forms of therapy’. Those forms of therapy were – general practitioner care, but not other forms of physical therapy (not that these other forms are specified in this paper). As Lederman indicates, although these studies suggested that core stability was the key difference, in fact, ‘participants in the studies weren’t identified by timing or control issues of core stability, there was no attempt to evaluate how well the participants learned core stability movements, or whether they were able to maintain that throughout the study. And to add to the problem – there was no attempt to evaluate if there is a correlation between improvement in back pain and improved ‘stabilisation’.’ In other words, the active ingredient in these studies could well have been ‘placebo’ or ‘exercise’ or something else, not simply core stability.
Last but not least, Lederman looks at the aetiology of low back pain. Now despite some of my colleagues firmly believing that ‘most people with low back pain have undiagnosed nociception’, it is well established that psychological and psychosocial risk factors play an important role in recurrent back pain and in transitioning from acute low back pain to ongoing disability. Localised, peripheral and structural changes such as assymmetry have become less important along with other biomechanical factors. It would be hard to refute the finding that back pain is really a multifactorial problem – so it is just as difficult to believe that one single factor or treatment such as one single nerve block or ablation can actually ‘fix’ the problem, just as it is difficult to believe that core stability can do the same.
Is it really so difficult to think that back problems can be caused by – using the back in ways that involve very high, probably excessive loads, or having some sudden forceful event such as a trip or fall or even hurtling along a rugby field? Will improving core stability make an incredible difference in these situations? And what of the ‘other’ factors that have been shown to strongly influence recovery?
As Lederman concludes, maybe we need to encourage people to focus on getting the activities done rather than excessive focus on how to get movements done. Maybe once again, we need to help people think less about their back and muscles – and much more about living well and doing things as naturally as possible.
Lederman, E. (2009). The myth of core stability Journal of Bodywork and Movement Therapies DOI: 10.1016/j.jbmt.2009.08.001