Painful truth about knee osteoarthritis: Why inactivity might be more complex than we think

Knee osteoarthritis (OA) is a common cause of pain and joint stiffness. And while physical activity is known to ease symptoms, only one in 10 people regularly exercise.

Understanding what contributes to patients' inactivity is the focus of a world first study from the University of South Australia's Persistent Pain Research Group at SAHMRI. Researchers have found that people with knee OA unconsciously believe that activity might be dangerous to their condition, despite medical advice telling them otherwise.

The study found that of those surveyed, 69% of people with knee pain had stronger implicit (unconscious) beliefs that exercise was dangerous than the average person without pain.

It’s an interesting finding that not only highlights the conflicted nature of pain and exercise, but also that what people say and what people think, deep down, may be entirely different things.

Lead researcher, and UniSA PhD candidate Brian Pulling says the research provides valuable insights for clinicians treating people with knee OA.

“Research shows that physical activity is good for people with knee OA, but most people with this condition do not move enough to support joint or general health,” he said.

“To understand why people with OA might not be active, research studies typically use questionnaires to assess fear of moving. But unfortunately, questionnaires are limited – what we feel deep down (and how our system naturally reacts to something that is threatening) may be different to what we report. And we still know that many people are avoiding exercise, so we wanted to know why.”

To assess this, the researchers developed a tool that can detect and evaluate people’s implicit beliefs about exercise; that is, whether they unconsciously think activity is dangerous for their condition.

“We found that that even among those who said they were not fearful about exercise, they held unconscious beliefs that movement was dangerous,” Mr Pulling said.

“Our research shows that people have complicated beliefs about exercise, and that they sometimes say one thing if asked directly yet hold a completely different implicit belief.

“People are not aware that what they say doesn’t match what they choose on the new task; they are not misrepresenting their beliefs.

“This research suggests that to fully understand how someone feels about an activity, we must go beyond just asking directly, because their implicit beliefs can sometimes be a better predictor of actual behaviour than what people report. That’s where our tool is useful.”

The online implicit association test presents a series of words and images to which a participant must quickly associate with being either safe or dangerous. The tool intentionally promotes instant responses to avoid deliberation and other influencing factors (such as responding how they think they should respond).

Persistent Pain Research Group Leader Associate Professor Tasha Stanton says the new tool has the potential to identify a group of people who might have challenges increasing their activity levels and undertaking exercise.

“What people say and what people do are often two different things," she said.

“Having access to more accurate and insightful information will help health professionals better support their patients to engage with activity and exercise. It may also open opportunities for pain science education, exposure-based therapy or cognitive functional therapy - things that would not usually be considered for someone who said that they were not scared to exercise.”

Researchers are now looking to see if implicit beliefs are directly associated with behaviour and are asking for people to complete the Implicit Association Test (takes seven minutes). At the end of the test participants are given their results in comparison to the rest of the population.