The Effect of an Acute Bout of Exercise on Pain Sensitivity and Clinical Pain in Adults With Knee Osteoarthritis

Osteoarthritis (OA) has been defined as losing the function of cartilage which causes inflammation and pain. OA is one of the most common joint diseases affecting both men and women worldwide, with women being more affected than men. A previous report estimated that that OA affects approximately 240 million people globally. Furthermore, the 2016 Global Burden of Disease Study estimated that the global incidence of hip and knee OA is 199 cases per 100,000, with incidence rates varying by region and ethnicity. The economic impact of osteoarthritis is significant, and it continues to increase as the population ages and obesity increases.

The knee OA has more clinical symptoms than any other form of OA. Knee OA results not only in pain, but also causes loss of function, and decreased quality of life. The typical clinical presentation of Knee OA is knee pain, brief morning stiffness (less than 30 minutes), crepitus, bony tenderness, and enlargement without palpable warmth, muscles weakness. Furthermore, people diagnosed with OA commonly report psychological problems such as anxiety and fear of movement. These problems might prevent people from participation in exercise and social events, leading to further physical and social isolation. The prevalence of knee OA is estimated to be about 33% and it is one of the five causes of disability among people, especially in the elderly individuals.

Alleviating pain is critical to improve the lives of people with Knee OA. Exercise training is a fundamental treatment modality for chronic low back pain, knee osteoarthritis OA and fibromyalgia. However, pain intensity, kinesiophobia and low self-efficacy are barriers to initiating and adhering to an exercise training program. Therefore, an effective strategy to reduce pain intensity, kinesiophobia and increase self-efficacy to facilitate participation in an exercise training program for people with chronic musculoskeletal pain conditions is important. A single acute bout of exercise can produce a consistent reduction in pain sensitivity, termed exercise induced hypoalgesia, in pain-free populations. Although, the hypoalgesia response is likely dependent on the exercise mode or prescription variables applied. In chronic pain populations, exercise induced hypoalgesia is not always consistent, the optimal exercise dose is largely unknown and there are few studies in people with chronic low back pain, fibromyalgia and knee OA. It is not clear whether a single bout of exercise results in a clinically meaningful reduction in pain sensitivity or clinical pain intensity in these population groups. Pilot data from our lab showed adults with chronic low back pain (n=21) reduced pain sensitivity (via pain pressure threshold) globally (Cohen's d=0.5; medium effect), local to the site of pain (low back; d=0.5; medium effect) and distal to the site of pain (leg; d=0.8; large effect) following a single wall squat (100° knee angle) for three minutes or until volitional fatigue. Given these promising results, exploring the utility of this approach in a controlled clinical setting across a range of common chronic pain conditions is warranted to establish efficacy.

Methods Ethics The trial protocol was approved for the study protocol by the General Administration for Research and Studies of the Directorate of Health Affairs, Makkah, Saudi Arabia (H-02-K-076-0722-770). This study will follow the Declarations of Helsinki. Consents will be obtained from the patients before participating in the study.

Study design: