1. The Effects of Aerobic
Exercise Training
on Brain Function in
Chronic Low Back Pain
Molly Roepke
Elise Umbarger
Faculty Advisor: Neena Sharma, PhD, PT, CMPT
Collaborators: Zaid, Mansour, PT, PhD student
Laura Martin, PhD
Rebecca Lepping, PhD
2. Abstract
Purpose: The purpose of this pilot study was to determine if moderate aerobic
exercise reduces activation in pain related areas of the brain in patients with
chronic low back pain. It is assumed that less blood flow to these areas would
result in the perception of less low back pain. Therefore, we hypothesized that
chronic low back pain subjects that perform a progressive aerobic exercise
training program would have decreased blood flow to pain related areas of the
brain compared to control subjects in the treadmill walking group.
Method: Five subjects with chronic low back pain for greater than six months
were randomized into a control and an experimental group. The control group
performed self-paced treadmill walking, while the experimental group
participated in a progressive aerobic training program of moderate intensity.
Subjects performed 12 weeks of exercise training within their respective groups
three times per week for 50-minute sessions. Blood pressure and heart rate
were monitored throughout exercise sessions. Functional MRI scans of the
brain were taken pre and post intervention and evaluated using AFNI software
to analyze blood flow (BOLD signal) in the brain while undergoing mechanical
pressure stimulation to the low back.
Results: Preliminary testing has shown mixed results of brain activation during
fMRI. Subjects from both groups have demonstrated varied results of no
change or decreased brain activation. At this time, no subjects have shown an
increase in brain activation. Due to the small sample size, the study is currently
underpowered and statistical conclusions cannot be made at this time.
Conclusion: This is an ongoing study. However, based on preliminary findings
there is a trend of decreased global brain activation after both treadmill walking
and aerobic exercise interventions. Based on the current findings, all intensities
of aerobic exercise appear to elicit either no change or a decrease in brain
activation during low back pressure stimulation.
3. Introduction
Low back pain is one of the most common reasons patients
visit their primary care physician, affecting 70% to 80% of the population.
Typical physical therapy treatment for a patient with chronic low back pain
(CLBP) would include correcting musculoskeletal imbalances and
focusing on core strengthening. However, a recent systematic review has
shown central processing may play a larger role for these patients than
objective musculoskeletal improvements as studies have shown they are
uncorrelated to perceived CLBP. (3)
Previous studies have used functional magnetic resonance
imaging (fMRI) to show brain changes in patients with CLBP. Changes
include a decrease in gray matter volume of the thalamus and prefrontal
cortex, an increased activation to pain, and decreased blood flow in the
contralateral thalamus. (1) The periaqueductal gray (PAG) and
subthalamic nucleus are highly involved in both the cardiovascular
response to exercise as well as the opioid-dependent pain modulation,
therefore implementing an aerobic exercise program could improve
central pain processing for a patient with CLBP. (3) When using the BOLD
signal to assess brain activity in chronic pain patients, it is assumed that
decreased activation in the pain related regions is correlated to decreased
perception of pain. Previous research has shown positive trends of fMRI
BOLD signal response following 12 weeks of low intensity aerobic
exercise in patients with chronic pain, however the intensity and number
of sessions may have been too low to show significant changes. (2)
Therefore, the aim of this study is to determine if a moderate
intensity aerobic exercise program will change brain activity in pain
regions suggesting functional changes and correlation with improvement
in pain intensity.
4. Methods
Inclusion Criteria:
1) are male or female between the ages of 25 and 60 years
2) diagnosed with chronic low back pain (LBP) due to degenerative disc or joint
disease, discogenic pain, spinal instability, and/or muscular dysfunction (postural
issues, muscle strain or sprain, etc…)
3) CLBP of >6 months of continuous or recurrent episodes, which is described as
having pain every day or almost every day (4); LBP with or without referred pain
(pain localized to lumbosacral region or radiating into buttocks, thigh or below the
knee joint),
4) pain intensity at least ≥3 on 0 – 10 pain scale, where 0=no pain, 10=worse pain
imagined
5) ability to read and understand English
6) able to walk without assistive device
Exclusion Criteria:
1) constant or persistent severe pain defined as > 8 on 0-10 pain scale most of the
time
2) severe structural spinal deformity or severe spinal instability
3) spinal cord compression, tumor or infection
4) previous back surgery within one year
5) regular participation in moderate or vigorous aerobic exercises
6) head trauma, psychiatric, or cardiovascular disease
7) psychiatric disease reported by subjects
8) use of drug or alcohol abuse
9) known neurological compromise resulting in current nerve root entrapment
10) known neurological, neuromuscular or severe orthopedic problems
11) known injuries or arthiritis to hips, knees or ankle joints that may prevent
subjects from particiating in the exercise training
12) pregnency
13) MRI exclusion: metallic objects not compatible to MR scan, epilepsy,
pregnancy, claustrophobia etc…
5. Methods
Intervention—2 Groups:
1) Control Group self-paced treadmill walking
3 subjects
*Control subjects kept HR within +/- 10 bpm determined
by 5 minute self-paced walking
2) Experimental Group progressive aerobic training
program
2 subjects
*All subjects received pre and post intervention fMRI with
mechanical stimulation to analyze BOLD signal in the
brain
*All subjects performed clinical tests including self reported
standardized questionnaires and objective tests
*All subjects performed the NuStep submaximal exercise
test
Aerobic Ex group (50 min)
Wk 1-2 50% of Max HR
Wk 2-4 60% of Max HR
Wk 4-6 70% of Max HR
Wk 7-12 75% of Max HR
Plastic balls
Inflatable
plastic device
Air pressure
connection to wall
Control Group (50 min)
Wk 1-12 Self-paced walking
6. Subject Group Age Sex Pre
Pain
Post
Pain
Duration of
pain (yrs)
1 C 60 F 3 4 6
2 C 31 F 7 4 7
3 C 46 M 1 1 7
4 I 28 F 3 3 9
5 I 37 M 3 3 2
Results
Subject Pre VO2 Max
(ml*kg-1*min-1)
Post VO2 Max
(ml*kg-1*min-1)
1 21.8 21.8
2 No data No data
3 26 24
4 36 40
5 39 No data
7. Subject 1: Control Group
PostPre
Scale key:
Red = increased blood flow
Blue = decreased blood flow
9. Results
Subject 4: Experimental Group
Subject 5: Experimental Group
PostPrePostPre
This is an ongoing study, with the aim to recruit 30 total
subjects. Currently, this study is underpowered to draw
statistical conclusions, however the overall trend is a global
decrease in brain activation in both the control and
experimental groups.
10. Discussion
The cause of decreased global brain activation
demonstrated in the subjects in this study is likely
multifactorial. Until more subjects are recruited in to this
study, we can only speculate reasons for changes in brain
activation. We have reason to believe that changes in
subject’s VO2 max, BMI, strength and endurance, due to an
aerobic exercise program, as well as central processing
plays a role in the perception of CLBP. Specifically, we
believe the exercise-induced opioid release in the brain as
well as the decreased global activation in pain related
centers after completing an aerobic exercise program of
either intensity contributes to the decreased subject’s
perception of LBP. As this study continues, more data will be
collected to gather more substantial conclusions. Future
studies would benefit from analyzing BOLD signal in specific
pain related areas of the brain as opposed to global
activation as was done in this study.
11. Acknowledgements
References
1. Yoshitaka, K., et. al., (2009). Augmented Cerebral
Activation by Lumbar Mechanical Stimulus in Chronic Low
Back Pain Patients, an fMRI Study. Spine, 34(22): 2431-
2436.
2. Micalos, P.S., et. al., (2014). Cerebral responses to
innocuous somatic pressure stimulation following aerobic
exercise rehabilitation in chronic pain patients: a functional
magnetic resonance imaging study. International Journal of
General Medicine, 7: 425-432.
3. Jensen K.B., et. al., (2012). The use of functional
neuroimaging to evaluate psychological and other non-
pharmacological treatments for clinical pain. Neuroscience
Letters, 520: 156-164.
4. Weiner, DK, Rudy TE, Morrow L, Slaboda J, Lieber S. The
relationship between pain, neuropsychological performance,
and physical function in community-dwelling older adults with
chronic low back pain. Pain Medicine; 2006, (1).
KUMC School of Health Professionals Pilot Funding
Hogland Brain Imaging Center for fMRI scanning
REACH Lab (Dr. Billinger) for letting us use lab space
PhD Students: Viswa Gangeddula, PT, Sevana Haghverdian,
Anna Mattlage
DPT Student: Christian Busch
