Yoga has been practiced around the world for thousands of years and usually involves a series of integrated mind-body exercises – concentrating on stretching, breathing, balance, co-ordination and control. It also involves significant aspects of meditation and relaxation. These days in Western cultures, yoga is often practised within the context of fitness and general health, and it is also used in the context of rehabilitation and the treatment of chronic pain disorders.
Yoga has been associated with pain reduction in a vast number of groups – including fibromyalgia, chronic low back pain, chronic neck pain, osteoarthritis, carpel tunnel syndrome, delayed onset muscle soreness, migraine, headache, rheumatoid arthritis, labour pains and in haemodialysis patients (Sutar 2016). So, what is it about yoga that might lead to pain reduction in such a vast range of pain groups?
People who practise yoga have been found to have heightened ‘bodily awareness’ (Rani & Roa 1994). For anyone who has tried yoga, you might be able to understand why. There is a large focus on the precision of body positioning and movement and a strong awareness of bodily processes. A task of judging a body part as belonging to the left or right side of the body is one way of interrogating cortical proprioceptive body maps, such as those that might be used during yoga practise. When we judge an image of a hand as belonging to the left or right side, we recruit our cortical body maps and mentally rotate our virtual hand to match that of the image. Depending on the outcome, the matching is either confirmed or negated. Given this – we predicted that people who practise yoga regularly would have a more robust cortical proprioceptive body representation and perform better at a left/right judgement task.
We were wrong (Wallwork et al 2015). We analysed data from a large (1737 participants) online cross-sectional investigation of left/right neck rotation and left/right hand judgements and found that in 86 age and gender-matched pairs of yoga practitioners vs non-practising controls, performance was no better in the yoga group. That is, the response time and accuracy to complete the task did not differ.
Why? The literature suggests that yoga increases bodily awareness – however our findings suggest that this bodily awareness may be limited to interoception (the ability to consciously perceive bodily sensations) rather than proprioception, motor planning or spatial perception – which are more obviously targeted in motor imagery, such as the left/right judgement task. That is, the large relaxation and meditative component of yoga might contribute to an enhanced interoceptive body awareness, however because the left/right judgment task is predominantly a visuoproprioceptive task, it is unlikely to identify any differences in this type of ‘bodily awareness’. It’s also possible that yoga does enhance cortical proprioceptive maps, however our cross-sectional study design might have limited us in detecting any such differences. Another possibility is that the available literature is flawed and that yoga does not enhance body awareness at all.
Overall our findings indicate that yoga may not help people with pain by improving cortical proprioceptive maps. Many other possibilities exist as to why yoga might be associated with pain reduction, for example: effects on the hypothalamus-pituitary-adrenal axis, sympathetic or cardiorespiratory system mediated analgesia, improved strength and endurance, improved co-ordination, a calmed and focused mind, positive emotions, and optimism – however at this stage these things can only be speculative.
About Sarah Wallwork
Sarah is a Post-Doctoral Research Fellow at the University of Canberra (Research Institute for Sport and Exercise). In 2010 she completed a physiotherapy degree at the University of South Australia and after working clinically for a few years, she decided to undertake a PhD here at BiM and in collaboration with Giandomenico Iannetti at UCL. In 2016 she completed a Specialist Certificate in Clinical Neuroscience Research and Neuroimaging from the University of Melbourne. Her main research interests are in clinical pain neuroscience and neurophysiology – specifically looking at body representation, defensive peripersonal space, the influence of beliefs on pain perception, multisensory integration, left/right judgements and pain. These days she spends a lot of her time running around after her cheeky 1 year old, but still makes time to pursue her love for adventurous outdoor fun!
References
Rani NJ & Roa PC 1994 “Body awareness and yoga training” Perceptual Motor Skills, 79, 1103-6.
Sutar, R, Yadav, S & Desai, G 2016 “Yoga intervention and functional pain syndromes: a selective review”, International Review of Psychiatry, vol. 28 iss. 3.
Wallwork SB, Butler DS, Wilson, DJ & Moseley GL 2015, “Are people who do yoga any better at a motor imagery task than those who do not?” British Journal of Sports Medicine, 49, 123-127.