Physical Activity Is Needed to Treat Pain

“Physical activity is an important component of treatments for pain conditions, yet some patients with persistent pain have different responses to physical activity,” lead author Dr. Leemans told PPM.

“The hypoalgesic effects in response to physical activity typically seen in healthy individuals are reduced in some patients with chronic pain,” she said. “While several studies highlight the importance of movement-evoked pain (MEP), there is debate about how to measure it. Measuring movement-evoked pain in clinical practice can help identify patients with dysfunctional pain responses to physical activity and help clinicians and patients decide how best to manage movement-evoked pain,” she explained.

Systematic Review and Analysis of Exercise vs No Exercise

In the review, Dr. Leemans and colleagues analyzed data from 38 trials that included 60 different interventions. The size of the studies ranged from 30 to 301 participants for a total sample of 3,172 individuals with musculoskeletal pain.¹

The primary outcome was the mean change in musculoskeletal pain following a given intervention. Interventions included:

  • exercise therapy vs no therapy
  • taping vs a sham treatment
  • transcutaneous electrical nerve stimulation vs sham
  • transcutaneous electrical nerve stimulation vs no treatment
  • ultrasound vs sham treatment

Overall, the six studies that compared exercise therapy to no therapy yielded significant improvement with exercise compared to no therapy based on changes in NRS and VAS scores, with moderate-certainty evidence. The standardized mean difference (SMD) was -0.65 (< 0.001).

In these studies, “resistance training, proprioceptive exercises, active mobilizations, and stretching exercises were most effective in reducing movement-evoked pain in patients suffering from chronic spinal pain,” but little evidence supported the superiority of one exercise modality over another, the researchers wrote in their discussion of the findings. Exercise therapy appears to provide pain relief both centrally, by activating dysfunctional descending nociceptive inhibitory pathways, and peripherally, by releasing anti-inflammatory cytokines and endogenous analgesic substances.¹

The team also found benefit in the use of transcutaneous electrical nerve stimulation (TENS) compared to no treatment, but with low certainty evidence (SMD −0.46, P = 0.0004). There was no determined benefit of transcutaneous electrical nerve stimulation when compared to sham transcutaneous electrical nerve stimulation (SMD −0.28, P = 0.09).

The findings were limited by several factors, including the possible exclusion of studies based on varying definitions of movement-evoked pain, the researchers noted. Other limitations included the inability to draw firm conclusions about effectiveness from interventions such as TENS, taping, and ultrasound because of inadequately powered studies, and the true effects for these interventions are likely different than those reported.

Overall, the findings supported the value of exercise therapy as a first-choice treatment for movement-evoked pain in the clinical practice setting, the researchers concluded.

Exercise Should Be First-Choice Pain Treatment

“This systematic review provided moderate-certainty evidence that physical activity reduces movement-evoked pain,” Dr. Leemans told PPM. “These findings were not surprising, yet emphasize that the dysfunctional activation of descending nociceptive inhibitory pathways in these patients suffering from movement-evoked pain should not contradict the clinical benefits of exercise therapy.”

“A recent model for studying movement-evoked pain proposed the integration OF sensory, psychological, and motor factors, and suggested that both too little and too much movement are undesirable,” as seen in practical examples involving. pain neuroscience education (PNE) and behavioral graded activity (BGA), said Dr. Leemans. “Since previous research suggested a link between movement-evoked pain and central sensitization and psychological constructs, investigating whether similar, or even enhanced, treatment effects would manifest seems an interesting path worth exploring.”

“Logically, MEP is a predictor of decreased movement and physical activity because, if it hurts to move, most humans will move less,” Corey B. Simon, DPT, PhD, assistant professor of orthopedic surgery at Duke University, told PPM. However, human health is linked to movement, and less movement means increased risk for morbidity and mortality, he said.

Movement-evoked pain is relatively new to the field of pain research, “and our understanding about exercise effects are based on resting or recalled pain measures,” Dr. Simon noted. Dr. Leemans’ review is timely and valuable to systematically appraise exercise effects and other therapeutic interventions on MEP, he added.

Dr. Simon said that he found the data in the review more reassuring than surprising. “We have a growing body of evidence to support MEP as a central component of musculoskeletal pain and high-impact chronic pain,” he explained. “Also, exercise is a primary intervention in musculoskeletal pain conditions. The limitation was that previous work used resting or recalled pain outcome measures, not MEP outcome measures, so we could only speculate that exercise would also work for MEP,” he said. “At the same time, MEP is a biopsychosocial phenomenon, and a large body of research shows exercise effects on biological, psychological, cognitive, and social factors. It made sense then that exercise would improve MEP,” he emphasized.

Movement-evoked pain is a central component of most musculoskeletal pain conditions, said Dr. Simon. “In addition to measuring MEP, clinicians should strongly consider the interventions found in this article to be effective, such as exercise in general and resistance training in particular.”

Encourage Resistance Training

Resistance training has long been considered a primary treatment for musculoskeletal pain, especially for middle-aged and older adults who comprise the largest population living with musculoskeletal pain conditions, Dr. Simon noted. “However, this study was the first to systematically endorse resistance training specifically for MEP,” he said.

Personalize Exercises for Patient Adherence

“Every patient with musculoskeletal MEP is different in their underlying mechanisms and life experiences that can be barriers to exercise adherence and effects,” said Dr. Simon. “Clinicians must acknowledge this and understand that exercise for MEP is not ‘one size fits all.’ While it is certainly indicated for MEP, a patient’s receptiveness and response to exercise is mediated by multiple factors, including their readiness to change, pain-related psychological distress, confidence (self-efficacy), social support, social roles, and time,” and these factors may need to be addressed during pain management, he explained.

Recommend the Right Amount

Another barrier to managing MEP is a clinician’s understanding and comfort with prescribing exercise for MEP, said Dr. Simon. “As the study reiterates, too little or too much exercise may be harmful to the patient,” although bedrest was once the first-line treatment for musculoskeletal pain, he said.

“Despite our new understanding, many clinicians still adhere to ceasing activity when a patient experiences musculoskeletal pain. Many clinicians also fear hurting their patient with exercise. At the same time, it’s also possible to overwork the patient and exacerbate their pain condition,” said Dr. Simon.

Lastly, Dr. Simon recommended the use of pain diaries, in which the patient keeps a journal of their pain at multiple times of the day, physical activity, and what exacerbates or alleviates pain, to inform treatment plans and changes.

Standardized Measures for Movement-Evoked Pain Still Needed

“A standardized MEP measure doesn’t currently exist, which is a problem because researchers and clinicians may all be using different MEP measures,” said Dr. Simon. “Everyone is speaking a different language.” Looking ahead, “A standardized MEP measure for specific pain populations, whether age-specific, disease-specific, or pain specific, is an important step in clinical research, he said.

What do you rely on most for musculoskeletal pain assessment? Respondents stated:

  • 5% imaging
  • 12% physical exam
  • 16% patient report
  • 67% all of the above

Meanwhile, Dr. Simon said, pain management clinicians can partially mitigate the lack of a standardized MEP measure with two simple rules:

  • Whichever MEP measure they implement at baseline should stay the same throughout the course of that patient’s treatment. This will allow clinicians to measure the extent to which their interventions change the MEP measure in relation to baseline
  • Clinicians should try and tailor the MEP measure to the activities which evoke pain in a patient’s home and community

Another crucial area for future research highlighted by Dr. Leemans’ study is the need to identify underlying mechanisms of MEP, said Dr. Simon. “Mechanistic research is the foundation for determining what causes MEP and also people who are susceptible to MEP and non-recovery,” he said. “MEP research specific to clinical phenotyping and precision medicine is in the infant stage. However, if we can determine modifiable mechanisms of MEP, such as those that have the capacity to change with treatments, we can better tailor treatments to a patient to improve effectiveness,” he added.