Exercise and Pain
The American Pain Society and the American College of Physicians (Chou &
Huffman 2007) endorse exercise as a treatment intervention for chronic
lower-back pain (LBP). Many in the fitness community, the medical
profession and the general public believe that core training (including
core strength and/or core stability) is the solution for LBP.
Wang et al. (2012) performed a meta-analysis (a statistical technique
for combining results from independent studies) on the effectiveness of
core stability exercise versus general exercise. They looked at five
studies that included 414 patients and compared core stability to
general exercise for LBP. The subjects all had chronic LBP ( > 3 months).
The results of the analysis showed that core stability exercise was
better than general exercise for short-term pain relief. However, in
long-term follow-ups at 6 and 12 months, there was no difference between
core stability exercise and general exercise. The analysis also showed
that in the short term, functional status improved with core stability
exercises.
The authors acknowledged some limitations associated with this
meta-analysis, noting that the results were based on relatively
low-quality data with a high risk of bias. For example, neither the
subjects nor the clinicians were blinded to the interventions or the
outcomes. The total number of subjects (414) was too small to enable
researchers to identify differences between the two exercise
interventions. And the types of core stability exercises were not
specified, nor were examples provided.
In a study by Falla et al. (2014) the authors looked not at an exercise
intervention but rather at relevant muscular responses to the exercise
environment. The study examined the lumbar erector activity of patients
with chronic LBP versus healthy controls. Multiple prior studies had
shown that people with chronic LBP displayed biomechanical disturbances
in trunk, spinal and lumbopelvic motion.
Using electromyography (EMG), Falla and colleagues observed muscle
activity during a repetitive lifting task of 25 cycles in 200 seconds.
The load lifted was consistent for all subjects, and researchers
controlled the rate of movement with a metronome. They measured pain
thresholds while lifting and 3 minutes after the test and then compared
those numbers with baseline pain levels for the LBP subjects.
Results showed that healthy controls used a more variable movement
strategy and changed the distribution of lumbar erector activity during
the repetitive lifting task. This muscle activation variability in
different regions of the erector spinae in healthy subjects may be a
preferential movement strategy for maintaining motor output and avoiding
overload on one region. Conversely, the LBP group performed the task
with the same group of lumbar erectors throughout the task. This lack of
variability and muscle activity coincided with reduced lumbar movement
and higher levels of LBP. The LBP group also showed a reduction in mean
EMG frequency. Over time, a reduction in EMG frequency can occur due to
an accumulation of metabolic byproducts, which may then lead to
increased nociception stimulation and fatigue.
Take-Home Message
When selecting exercises for clients who have chronic pain, be specific
and consider the entire bio-psycho-social perspective. Some
clients—particularly those who report back instability—may respond well
to core stability exercises. But others may already be overusing a
bracing/stability strategy that is counterproductive to long-term
function and movement confidence. For a client in this group, isometric
core stabilization exercises such as planks may reinforce the lack of
variable motion in the lower-back region and perpetuate the
limited-movement strategy that has been shown to increase their pain.
For this client, consider beginning with more remedial corrective
exercises in postures or positions that do not immediately encourage
bracing; for example, exercises that are done prone, supine, in
quadruped position, kneeling or half-kneeling. Help the client focus on
external cues to remove his attention from his internal focus on
stabilizing.
Movement variability is key to healthy motion and dissipates mechanical
stress to soft tissue and joint structures, thereby avoiding localized
fatigue and developing alternative movement strategies.
To read more about how physical activity can reduce the risk of nearly three dozen harmful conditions and life-threatening diseases, please see “The Many Dimensions of Pain” in the online IDEA Library or in the February 2016 print issue of IDEA Fitness Journal. If you cannot access the full article and would like to, please contact the IDEA Inspired Service Team at (800) 999-4332, ext. 7.