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The Many Dimensions of Pain

by Anthony Carey, MA on Jan 13, 2016

To help clients reach their pain-free movement goals, fitness professionals must understand the biological, psychological and social ramifications of pain.

Pain is very personal and subjective. Science no longer views pain as a sensation , but sees it rather as an experience that results from a conglomerate of physical, psychological, emotional and social inputs. As a fitness professional, you have no doubt trained or taught clients and participants who were dealing with the effects of pain. You yourself may have a relationship with pain that has affected your life and career.

The International Association for the Study of Pain (2014) defines pain as “an unpleasant and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.” The word “potential” is significant in this definition because it signifies that pain can be experienced even in the absence of tissue damage. According to the American Academy of Pain Medicine (2015), pain affects more people in the United States (an estimated 100 million) than diabetes, heart disease and cancer combined.

Pain is generally defined as acute or chronic. As an indicator of the state of the tissue or imminent danger to the organism, acute pain is a valuable evolutionary characteristic that alerts us to take action (withdraw, rest or avoid). This initial information is a result of a noxious stimulus (mechanical, thermal or chemical) detected by our nociceptors , sensory neurons that respond to potentially damaging stimuli by sending signals to the spinal cord and brain (Garland 2012).

There is currently no universally accepted definition for chronic pain , but experts generally agree that it persists beyond the time in which tissue would normally heal (typically 12 weeks/3 months) (Merskey & Bogduk 1994). Some authors also define pain as chronic if it recurs for 6 months or more (Falla et al. 2014). Chronic pain in later life is a worldwide problem.

In one nationwide survey of older adults ( n = 7,601) in the United States, 52.8% reported experiencing bothersome pain in the preceding month (NIH 2015).

As a fitness professional, you are highly likely to work with clients who have chronic and/or recurring pain. These clients need to be cleared for exercise by their physician. When they come to you, they will probably have completed or be currently involved with treatment from a licensed medical provider such as a physical therapist or chiropractor. You must remain within your scope of practice at all times and avoid any attempts to treat or diagnose pathological conditions or to provide medical advice.

The Bio-Psycho-Social Paradigm

Understanding the many events that contribute to the pain experience—what Canadian psychologist Ronald Melzack (2001) calls the neuromatrix —will help you design safe and productive programs and environments for your clients. The neuromatrix is an aspect of the bio-psycho-social (BPS) model of modern pain science that researchers and clinicians have structured to better understand and treat chronic pain.

  • “Bio” represents biology or biomedical interventions, the way chronic pain has historically been treated—by purely seeking disease, dysfunction or damage and designing interventions that find and “fix” it.
  • “Pyscho” denotes the current psychological characteristics of the person who is suffering from chronic pain. These characteristics include the individual’s beliefs about the situation; historical references related to past pain experiences; anxiety and/or depression; and expectations about the future.
  • “Social” refers to the social implications of the pain experience. Social stressors relate to an absence of support and the sufferer’s feelings that peers, friends and family don’t believe the pain is real. Additional stressors may include missing important social events, being unable to travel and having to withdraw from employment.

The growing body of evidence regarding pain science is changing the way medical professionals approach treatment. To best assist clients who are experiencing chronic pain, you need to understand the bio-psycho-social paradigm and what that means in relation to program design, communication and expectations. The following research roundup explores this 
paradigm from different angles and offers important take-
home messages.

Pain Research

Visual References

Chronic pain is complex, resulting from many inputs processed through the nervous system and the brain. Visual references are one type of input the brain relies on to determine a potential threat to the organism. For example, a bruise may not hurt until you notice it is there.

For those suffering from chronic neck pain, vision provides a great deal of feedback about cervical range of motion. The endpoint a person sees when turning his or her head and experiencing pain combines with a cluster of other information occurring at the same time to form the neuro-representation of the pain experience in the brain, or what Melzack (2001) calls a “neuro-signature.”

To investigate the role of visual feedback on neck pain, Harvie et al. (2015) used a virtual-reality apparatus to alter the visual proprioceptive feedback that subjects received during cervical rotation. Subjects were seated with their torsos fixed to avoid contributing motion from the thoracic spine during cervical rotation. Twenty-four subjects with chronic neck pain were assessed for the onset of pain during cervical rotation to the left and right. They were asked to stop when they felt pain and to rate it on a scale of 0–10 at the point in the rotation where pain occurred. Each subjects was then fitted with a virtual-reality headset that provided six different visual scenes for six trials.

Researchers manipulated the virtual-reality scenes so that the visual cues did not match the actual cervical-rotation distance that subjects achieved on all trials. The virtual rotation provided by the headsets was either 20% more than the actual rotation, the same as the actual rotation or 20% less than the actual rotation. The bogus visual feedback of plus or minus 20% made the subjects perceive that they were rotating their cervical spines 20% more or less than they actually were.

The results showed that when rotation was understated (subjects perceived their rotation was less than it actually was), pain-free range of motion increased by 6%. When rotation was overstated (subjects perceived their rotation was more than it actually was), pain-free range of motion decreased by 7%.

Take-Home Message

This study provides additional evidence to support the findings that pain is not generated solely from tissue damage. Vision is one of many inputs that the brain processes when assessing a threat to the body, and vision therefore contributes to the production of pain. The association of a specific neck range of motion identified visually, coupled with information from the motor system and proprioceptive system, creates a confirmed reference for past pain experiences.

It is plausible that visual input can also influence pain in other areas. For example, if a client has lower-back pain, forward flexion of the spine will bring her eyes closer to the floor, possibly presenting a painful or pain-free experience, depending on the client. When designing a program for such a client, you could vary the visual field to minimize the visual association related to painful movements. One suggestion: Have the client visually follow her hand out to the side of the body by rotating the head as she flexes the spine.

Pain Anticipation

In a study of 20 healthy undergraduate students, researchers (Vanden Bulcke et al. 2013) investigated whether the anticipation of a painful stimulus made subjects more aware of an innocuous tactile stimulation to a body part compared with no anticipation of pain. In an elaborate experimental setup, the students placed both forearms on a table and their hands were fitted with instrumentation that measured tactile sensitivity, an instrument that delivered innocuous tactile stimuli and an instrument that delivered painful electrocutaneous stimuli. A video monitor informed the subjects immediately prior to each trial if a painful stimulus would possibly be delivered.

The stimuli were delivered to both hands at irregular intervals. In the threat trials, a colored warning designated a specific hand and alerted the students to the possibility of a painful stimulus (on the designated hand only); sometimes that painful stimulus actually followed, and sometimes it did not (it was the innocuous tactile stimulus instead). During the control trials, a color alerted the subjects that a specific hand would be affected, but the signal indicated (accurately) that no painful stimulus would be administered, only the tactile stimulus.

Each hand received one of the two stimuli in every trial, with an actual painful stimulus delivered to one hand 10% of the time. Subjects were required to report which hand felt the stimulus first each time. Results showed that when pain was expected, innocuous tactile stimuli were perceived sooner on the threatened hand than they were on the “neutral” hand. These findings demonstrate that the anticipation of pain resulted in the prioritization of somatosensory sensations at the location of possible threat. This would indicate that the brain was biased toward the threatened body part.

Take-Home Message

It’s common for someone who is dealing with chronic pain to be hypervigilant or overprotective of the affected area. However, this often leads to increased sensitivity and perceptions of threat from innocuous or neutral sensations. For example, a client may expect that a simple or safe exercise or movement will be damaging because he feels sensations in the protected region of the body. This may negatively affect functional outcomes at work, at home or in the gym. Acknowledge and validate a client’s concerns when they arise in instances such as this. Modify exercises or even substitute a move until the client can be gradually and safely exposed to the movement or similar movements.

The Relationship Between 
Diagnostic Imaging and Pain

Do degenerative changes automatically lead to pain? Guermazi et al. (2012) used magnetic resonance imaging (MRI) to look for osteoarthritic (OA) changes in knees. Radiographic imaging (X-rays) of the same knees showed no pathology. OA is generally diagnosed through examination and X-ray. X-rays can identify bony changes to the joint but can’t identify soft-tissue pathologies. Using the more sensitive MRI would make it 
 possible to detect structural lesions associated with OA and its relationship to age, sex and obesity. The subjects were 50 or older (mean age 62.3 years). Out of the 710 subjects, 206 (29%) complained about knee pain.

Overall, 631 (89%) of the subjects showed some knee abnormality. The three most common findings were osteophytes, cartilage damage and bone marrow lesions. These abnormalities increased with age. The study concluded that 91% of those who had knee pain also had abnormal MRIs, leaving 9% of those with painful knees with normal MRIs. Eighty-eight percent of those with no knee pain showed abnormalities in the MRIs. The authors noted that those with the most abnormalities identified as having mild pain, not moderate or severe pain.

Another study, published in the European Spine Journal (Kato et al. 2012), looked at the cervical spine MRIs of 1,211 asymptomatic volunteers. The subjects were Japanese men and women equally representing each decade of life from the 20s to the 70s. All of the subjects had an MRI and underwent a neurological exam administered by a spinal surgeon. > >

The findings showed spinal cord compression, spinal cord signal changes and disk compression. Increased signals on an MRI are associated with abnormal tissue, such as scarring or inflammation. For a disk bulge to be considered pathological it had to measure more than 1 millimeter from the vertebral body.

Of the 1,211 asymptomatic subjects studied, 64 (5.3%) showed spinal cord compression. High-intensity signal changes were seen in 28 (2.3%) subjects, and 1,061 (87.6%) presented with bulging disks. The prevalence of symptoms was significantly higher in people over 40 years of age.

Take-Home Message

Degenerative changes to the body are a normal part of aging and do not directly correlate with pain. The studies clearly demonstrate that an individual can have many abnormal findings in the neck and knees and yet have no pain. Clients who have had imaging studies done may experience stress or fear when learning of abnormalities in joints or soft tissue. If imaging reveals degenerative changes, medical professionals often consider these changes to be the sole source of the clients’ pain—and clients who have experienced pain in the past may themselves perceive this to be the case, even if they are not currently in pain.

A client who believes that known degenerative changes will lead to pain may act with self-limiting and guarded movements, in an effort to anticipate pain. This has the potential to decrease the client’s functional capacity and increase her anxiety about certain exercises or activities. Work closely with allied medical professionals to ensure that your program design will not provoke any symptoms, and help the client feel more confident that abnormal findings may not necessarily lead to the experience of pain. Also keep in mind that physicians may be overcautious when giving advice; for example, they may say, “Do not squat,” when this is an action we do every day. Help the client discern the difference between an activity that is truly contraindicated and one that is not.

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.

The Complexity of Pain

We can no longer view chronic pain as purely the result of biological origins. The current body of science has identified many factors that contribute to the human pain experience. Information from the peripheral and central nervous systems and cognitive functions all play a part in how a person experiences pain.

Pain is a complex issue, and it is neither helpful nor accurate to approach client communication and programming from an outdated paradigm that solely addresses the physical or somatic effects of pain. Broaden your awareness of the bio-psycho-social model and have a professional support system in place to help clients reach their pain-free movement goals.

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References

American Academy of Pain Medicine. 2015. AAPM facts and figures on pain. Accessed Jul. 10, 2015. www.painmed.org/patientcenter/facts-on-pain/.

Chou, R., & Huffman, L.H. 2007. Nonpharmacologic therapies for acute and chronic low back pain: A review of the evidence for an American Pain Society/American College of Physicians clinical practice guideline. Annals of Internal Medicine, 147, (7), 492–504.

Exercise is Medicine Australia. 2014. Chronic pain and exercise. Accessed Nov. 20, 2015. http://exerciseismedicine.org.au/wp-content/uploads/2014/05/2014-Chronic-Pain-FULL.pdf.

Falla, D., et al. 2014. Reduced task-induced variations in the distribution of activity across back muscle regions in individuals with low back pain. Pain. doi: 10.1016/j.pain.2014.01.027.

Garland, E. 2012. Pain processing in the human nervous system: A selective

review of nociceptive and biobehavioral pathways. Primary Care, 39 (3), 561–71.

Guermazi, A., et al. 2012. Prevalence of abnormalities in knees detected by MRI in adults without knee osteoarthritis: Population based observational study (Framingham Osteoarthritis Study). BMJ. doi: 10.1136/bmj.e5339.

Harvie, D.S., et al. 2015. Bogus visual feedback alters onset of movement-evoked pain in people with neck pain. Psychological Science. doi:10.1177/0956797614563339.

International Association for the Study of Pain. 2014. IASP taxonomy. Accessed Jul. 10, 2015.www.iasp-pain.org/Taxonomy.

Kato, F., et al. 2012. Normal morphology, age-related changes and abnormal findings of the cervical spine. Part II: Magnetic resonance imaging of over 1,200 asymptomatic subjects. European Spine Journal, 21 (8), 1499–1507.

Melzack, R. 2001. Pain and the neuromatrix in the brain. Journal of Dental Education, 65 (12), 1378–82.

Merskey, H., & Bogduk, N. 1994. Classification of Chronic Pain. Descriptions of Chronic Pain Syndromes and Definitions of Pain Terms Seattle: IASP Press.

NIH (National Institutes of Health). 2015. NIH analysis shows Americans are in pain. Accessed Aug. 12, 2015. www.nih.gov/news/helath/aug2015/nccih-ll.htm

Newton, B.J., et al. 2013. A narrative review of the impact of disbelief in chronic pain. Pain Management Nursing, 14 (3), 161–71.

Vanden Bulcke, C., et al. 2013. The anticipation oPain, 154, 1464–68.

Wang, X.-Q., et al. 2012. A meta-analysis of core stability exercise versus general exercise for chronic low back pain. PLOS One, 7 (12), e52082.

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About the Author

Anthony Carey, MA

Anthony Carey, MA IDEA Author/Presenter

Anthony Carey, MA, owns Function First in San Diego, California. He holds a master?s degree in biomechanics and athletic training, and is an internationally-recognized speaker on biomechanics, posture, motor control and musculoskeletal pain and function. As a best-selling author, his work has been featured in the New York Times and Time Magazine. Anthony is also the inventor of the Core-Tex.