We often hear about the benefits of physical exercise in alleviating pain and improving our day-to-day life in general. In order to manage low back pain or other pain conditions, it is often recommended to remain active and to consult a physical therapist or occupational therapist that will create an activity-based treatment plan or teach us how to move better in order to decrease pain. However, while exercise can decrease pain, in some cases it can make pain worse. When we feel pain, it can be a barrier to continue to exercise and thus not help manage the pain.
Goal
Our sensitivity to physical activity (SPA), or the pain that we feel after a physical task can prevent individuals from continuing physical exercise. But can this sensitivity to exercise be measured in other ways than self-reporting it? Researchers wanted to investigate what are some objective, measurable biomarkers that we can use to determine if a person is likely to experience pain following a physical task and what happens to these biological characteristics once we experience pain after daily movements that evoke pain. Researchers wanted to investigate whether interleukin-6 (IL-6), a marker of inflammation and cortisol, a marker of stress could explain which people will experience pain and which will not.
Methodology
From June 2018 to May 2019, researchers from McGill University invited 27 people with chronic low back pain and 21 health controls (with no pain) to come into the lab, complete a series of questionnaires, perform standardized movements including lifting, stretching and other tasks that mimic activities of daily living (like sweeping or unpacking groceries) and rate their pain. The goal was to capture the total change in pain during the exercise session. Saliva samples were also collected in order to measure IL-6 and cortisol levels. Three days before the second testing session, participants had to collect their saliva every morning.
Main findings
People with greater levels of IL-6 in their saliva also had greater increases in pain after the physical activity tasks were performed. Since IL-6 has been shown to be a biological indicator of the body’s reaction (inflammation) to something bad happening, the sensitivity to physical activity (SPA) is associated with how much inflammation is in the body after exercise. Thus, reducing inflammation can be a way to decrease SPA and increase adherence to physical rehabilitation programs. Cortisol or stress levels were not associated with the changes in pain ratings before and after performing the physical exercise session.
Take home message
Having a biological marker that can be easily measured in saliva such as IL-6 will help clinicians to determine whether a person is more likely to experience pain after physical exercise can be useful to tailor treatment plan to individuals. Authors suggest investigating potential strategies such as enhancing positive emotions, improving sleep quality, associating exercise with anti-inflammatory medication like NSAIDS in order to lower inflammation, and thus IL-6. This way, people living with pain can still benefit from physical rehabilitation programs.
