Mindfulness physical therapy, pain management, rehabilitation

Progressive Muscle Relaxation and Pain Inhibition

In a randomized controlled study examining the effect of Progressive Muscle Relaxation (PMR) on the modulation of spinal nociceptive transmission, measures of the nociceptive flexor reflex (NFR) reflected an increase in nociceptive inhibition in individuals who practiced PMR.1 NFR is a polysynaptic spinal reflex indicative of spinal cord nociceptive processing. NFR is recorded via EMG of the hamstring muscle in response to electrical stimulation of the sural nerve. Compared to healthy controls, NFR thresholds are significantly lower in subjects with fibromyalgia, whiplash, primary headache and knee pain.2

In this study, 29 healthy men and 29 healthy women underwent NFR threshold assessments and completed questionnaires evaluating pain and stress. They were then randomly assigned to either a 25 minute recorded PMR practice or a no treatment control. Following the brief intervention, NFR threshold was again measured and questionnaires completed. Participants in the PMR condition experienced a significant increase in NFR threshold while those in the control group experienced no change. Pain ratings did not change in either group, however the PMR group reported decreased stress following the PMR intervention. Authors conclude that PMR can immediately influence central nervous system nociceptive processing via inhibitory pathways within the spinal cord. Further research that examines the NFR response to PMR in persistent pain populations is needed.

Clinically, I observe the benefits of PMR in many of my patients. I often guide a 10-minute PMR exercise in the first or second office visit. Most patients experience an increase in overall relaxation and many report reduced pain. Some report no change.  I summarize the results of this study in language understandable to a lay person and discuss the benefits of a regular relaxation and/or meditation practice with patients.  I highly recommend PMR as a simple and accessible exercise that can help patients build body awareness, learn to relax and self-manage their pain condition.

1 Emery CF, France CR, Harris J, et al. Effects of progressive muscle relaxation training on nocicpetive flexion reflex threshold in healthy young adults: A randomized trial. Pain 2008; 138(2):375-9.

2 Lim EC, Sterling M, Stoen A, et al. Central hyperexcitability as measured with nociceptive flexor reflex threshold in chronic musculoskeletal pain: a systematic review. Pain 2011; 152(8):1811-20.