Overview

The objective of the study is to explore the effects of arm exercise (UE, arm ergometer) vs. leg exercise (LE, cycling ergometer) on exercise-induced hypoalgesia (EIH), central pain mechanisms and knee pain in people with knee osteoarthritis (OA). Furthermore, we will explore relations of socioeconomic status, racial discrimination, acculturative stress, and autonomic function to exercise effects on EIH, central pain mechanisms, and knee pain. This will be a pilot randomized cross-over study where all participants undergo Day 1 (baseline assessments), Day 2 (UE or LE), and Day 3 (UE or LE).

Eligibility

Participants with knee OA (Target n=40)

Inclusion Criteria:

        We will recruit participants with knee OA, using the National Institute for Health and Care
        Excellence's clinical diagnostic criteria, which does not require radiographs. The clinical
        diagnostic criteria include:
          -  age ≥45
          -  activity-related knee pain
          -  either no morning joint-related stiffness or stiffness that lasts ≤ 30 minutes.
          -  knee pain at least 4 on a 0-10 pain scale
          -  knee pain as a chief complaint if having multiple pain
          -  understand English
        Exclusion Criteria:
          -  peripheral neuropathy or other sensation loss on the body sites for pain measurements
             (i.e., the wrist, knee, the forearm)
          -  use of medical devices electrically active (e.g., pacemaker)
          -  chronic use of opioids
          -  pregnant women
          -  serious and uncontrolled concomitant disease, including cardiovascular, nervous
             system, pulmonary, renal, hepatic, metabolic, hormonal, endocrine, gastrointestinal or
             epileptic disease
          -  rheumatoid arthritis, ankylosing spondylitis, and any neurological disorders that
             prevent the study procedure
          -  cognitive impairment
          -  history of a knee replacement surgery
          -  inability to perform exercise due to severe pain or other symptoms
          -  any intervention procedures for knee pain in the last 3 months
        Inclusion and exclusion criteria for pain-free controls (Target n = 20) Pain-free controls
        are not having a pain-related medical condition. They have to speak and understand English.
        Pain-free controls are excluded if they had experienced a pain episode, caused by
        musculoskeletal injury or otherwise in the previous 3 months.