Specific therapeutic exercise of the neck induces immediate local hypoalgesia. 2007

Abstract
This study compared the effect of 2 specific cervical flexor muscle exercise protocols on immediate pain relief in the cervical spine of people with chronic neck pain. In addition, the study evaluated whether these exercise protocols elicited any systemic effects by studying sympathetic nervous system (SNS) function and pain at a location distant from the cervical spine. Participants were randomly allocated into either a cranio-cervical flexion (CCF) coordination exercise group (n = 24) or a cervical flexion (CF) endurance exercise group (n = 24). Measures of pain and SNS function were recorded immediately before and after a single session of the exercise interventions. Pain measures included visual analogue scale (VAS) ratings ofneck pain at rest and during active cervical motion and pressure pain threshold (PPT) and thermal pain threshold (TPT) recordings over the cervical spine and at a remote site on the leg. Measures of SNS function consisted of blood flow, skin conductance, skin temperature, heart rate, and blood pressure. Immediately after 1 session of exercise, there was a reasonably sized increase of 21% (P < .001, d = 0.88) and 7.3% (P = .03, d = 0.47) in PPT locally at the neck for the CCF exercise and the CF exercise, respectively. There were no changes in local neck TPT with either exercise. Pressure pain threshold and TPT at the leg and SNS did not change after exercise. Only the CCF exercise demonstrated a small improvement in VAS ratings during active movement (change on 10-cm VAS: CCF, 0.42 cm (P = .04). This study shows that specific CCF therapeutic exercise is likely to provide immediate change in mechanical hyperalgesia local to the neck with translation into perceived pain relief on movement in patients with chronic neck pain.
PERSPECTIVE:
This study showed an immediate local mechanical hypoalgesic response to specific exercise of the cervical spine. Understanding the pain-relieving effects of exercise will assist the clinician in prescribing the most appropriate exercise protocols for patients with chronic neck pain.

My comments:
Hypoalgesia is a good five dollar word that means there was a decrease in pain and pain sensitivity immediately after the exercises performed in neck pain sufferers. It’s interesting seeing this put into a study. When I treat my physical therapy patients for neck pain with a largely exercise-based approach, they often report their pain levels decreasing from the beginning to the end of the workout. This decrease in pain happens before the application of EMS, which is my preferred modality for pain. This paper reviewed a number of others discussing “exercise induced hypoalgesia” which seems to be a hot area in research right now.

The exercises used were a supine neck flexion hold, where you lay on your back and hold your head no more than 2 cm off the table (which is an exercise I like). They did 3 sets of 10 reps, each rep with a 3 second hold and 2 second rest with 30 seconds between. Resistance was added to the forehead as needed. The other exercise was a supine (lying on your back) chin tuck, where you attempted to bring your chin toward the chest while keeping the back of your head flat on the mat. The chin tuck was held for 10 seconds with 10 seconds rest in between for 10 reps.

Both exercises worked to decrease pain, but the chin tuck exercise worked better. I imagine the difference might be due to the chin tuck increasing space for the spinal cord and nerves exiting the cervical spine, and perhaps it having a more immediate effect on improving posture once completed. The improved posture also increases space for the spinal cord and nerves exiting the cervical spine after the exercise so it’s win-win. The other exercise would do more to increase cervical flexor strength and endurance, which would likely lead to gains further down the road. However, it does not immediately lessen stresses on cervical structures in the same way the chin tuck does. So which exercise should be in your physical therapy or home exercise program for neck pain? Probably both, along with a number of others. This was a great study overall; I learned something.