The Journal of Bodywork and Movement Therapies recently carried a study examining spinal mobility and the accuracy of the patient’s movement perception following HVLA (high-velocity, low-amplitude) manipulation to the area where the thoracic spine and the lumbar spine meet (thoracolumbar junction). While the study was looking at osteopathic techniques, it is highly applicable to chiropractic as HVLA spinal manipulation is also something that occurs frequently in the chiropractic scope of practice.
This study aimed to discover whether such spinal manipulation would increase spinal mobility (also called range of motion, or ROM), or change the way the participant perceived their movement (also called interoceptive accuracy, or IAc). Additionally, it looked into whether baseline IAc correlated with post-intervention ROM measurements or changes.
Lower back pain usually comes with a restricted range of motion (ROM). Typically, as pain intensifies, range of motion decreases. There are many studies that reveal the efficacy of spinal manipulation in reducing lower back pain, but they are usually centred around cervical, lumbar, spine, hip, and jaw areas. These studies also primarily investigate pain levels and there is less evidence for a change in ROM following manipulation.
That is one reason this study was particularly interesting. Now, there are a few factors that may play into changes in range of motion of perceptive (IAC) accuracy.
An increase in ROM may be because:
- The sensitivity of mechanoreceptors is reduced. Mechanoreceptors regulate muscle tension and stretch.
- HVLA (high-velocity low amplitude manipulation) is improves the inflow of sensory signals received from the body to the brain. This in turn may allow the joints to move further.
- Also HVLA may have stimulated the thoracic splanchnic (abdominal) nerves, which can activate the sympathetic section of the autonomic nervous system and the adrenal medullary system. This is an excitatory response and may have led to greater ROM.
Importance of Interoceptive Accuracy:
- Higher IAc levels have been related to a lower pain threshold, higher perceived pain, and higher levels of anxiety.
- Higher IAc would mean greater sensitivity and lower pain tolerance, which may reduce mobility (ROM)
This study took in 21 asymptomatic osteopathic students. On a surface level, this might seem like a bit of a convenient sample, thus potentially skewing the results. However, researchers were keen to ensure that participants weren’t chosen just because they were in close proximity to the researcher. The researcher sought first and second-year students with less knowledge about HVLA thrust and sham osteopathic techniques. This was an attempt to reduce bias caused by students being able to distinguish between an authentic and sham treatment.
The 21 participants were between ages 18-35, not experiencing any form of musculoskeletal complaint, or have received adjustment 3 days prior to any of the sessions. The study was actually a relatively rare triple-blind where neither the participants, the person administering treatment or the data analysts knew who was in the sham/placebo group and who was in the intervention group.
Participants were subject to three different interventions: control, sham, and HVLA manipulation. (repeated measures)
- Control: instructed to lie in a position for two minutes
- Sham: mimicked a technique but no therapeutic barrier was engaged
- HVLA manipulation
Two measures were being examined by this study
- Range of Motion (ROM): tolerable stretch. How far you can move your joints in different directions
- Interoceptive Accuracy (IAc): heartbeats were recorded for 30 seconds and participants were asked to guess how many heartbeats (perceived beats) there were. This is usually repeated 6 times. Actual beats vs perceived beats
Interestingly, the study found that the mean change in range of motion is larger for the HVLA group in comparison to the other group. This might not be surprising to practitioners of manual therapies (including chiropractors), but there were no significant changes in IAc for any of the participants.
The study found a negative relationship (negative association) between interoceptive accuracy and range of motion: i.e. when a patients awareness of their movement was higher, there was less of a change in range of motion following manipulation. This may be useful in future research to estimate the increase in spinal mobility following manipulation.
Importantly, the study was conducted on an asymptomatic population. This means that we aren’t “treating” any conditions that may augment the results of the study. We are simply getting a baseline to measure the effect. It could be much higher or much lower in a clinical population, and this would certainly be an interesting topic for future research.
It was a relatively small sample size so a much larger study may have rendered slightly different results, and thus we can’t generalise these findings to the wider population just yet.
In any case, it is interesting to see the interplay of range of motion and interoceptive accuracy with it comes to HVLA – a manipulation used very commonly in chiropractic care. We look forward to seeing what else comes from this line of investigation.
Make sure you check out the full paper at the reference below.
Griffiths. F., McSweeney. T., Edwards. D, (2019), Immediate effects and associations between interoceptive accuracy and range of motion after a HVLA thrust on the thoracolumbar junction: A randomised controlled trial, Journal of Bodywork & Movement Therapies, 23, 818-824, https://doi.org/10.1016/j.jbmt.2019.06.007