The difficult reality of knee osteoarthritis: Understanding the complexity of inactivity

Knee osteoarthritis (OA) is a prevalent cause of pain and joint stiffness. Although physical activity can alleviate symptoms, only one in ten individuals with OA exercises regularly.

A groundbreaking study from the University of South Australia aims to understand why patients with knee OA remain inactive. Researchers discovered that many people with knee OA unconsciously believe that exercise could worsen their condition, contrary to medical advice.

The study revealed that 69% of individuals with knee pain harbored stronger implicit (unconscious) beliefs that exercise was dangerous compared to those without pain.

This finding underscores the conflicted relationship between pain and exercise, highlighting the disparity between what people say and what they truly believe.

Brian Pulling, lead researcher and UniSA PhD candidate at SAHMRI, explains that this research offers valuable insights for clinicians treating knee OA patients.

“Studies show that physical activity benefits people with knee OA, yet most do not engage in enough movement to support joint or general health,” Pulling says.

“Traditional questionnaires used to assess fear of movement are limited because they do not account for deep-seated, unconscious reactions. Many people still avoid exercise, and we wanted to understand why.”

To address this, researchers developed a tool to detect and evaluate people’s implicit beliefs about exercise, uncovering unconscious fears that movement might be harmful.

“We found that even those who claimed not to fear exercise held unconscious beliefs that it was dangerous,” Pulling notes.

“Our research indicates that people’s beliefs about exercise are complex. They may express one view directly but hold a different implicit belief.

“People are often unaware that their explicit statements do not match their implicit beliefs, which are not intentionally misrepresented.

“This suggests that to fully understand someone’s feelings about an activity, we must look beyond direct questioning, as implicit beliefs can better predict behavior. Our tool helps achieve this.”

The online implicit association test presents words and images that participants must quickly classify as either safe or dangerous, prompting instant responses free from deliberation or social desirability bias.

Associate Professor Tasha Stanton highlights the tool’s potential to identify individuals who may struggle with increasing their activity levels.

“What people say and what they do often differ,” Assoc Prof Stanton says.

“Access to more accurate and insightful information will help health professionals better support their patients in engaging with activity and exercise. It could also pave the way for interventions like pain science education, exposure-based therapy, or cognitive functional therapy, which might not be considered for someone who denies fear of exercise.”

Researchers are now investigating if implicit beliefs directly influence behavior and are inviting people to complete the seven-minute Implicit Association Test, which provides participants with their results compared to the general population.

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