Prescription opioid analgesics and non-steroidal anti-inflammatory drugs are frontline treatments for chronic pain. However, inconsistent therapeutic effects and/or side effects limit their use. Development of better analgesics requires predictive and reliable preclinical models for pain. Although pain is typically associated with pain-evoked behaviors (e.g. withdrawal responses), and pain-suppressed behaviors (e.g. decreases in normally adaptive behaviors like feeding, locomotion, exercise), current preclinical pain models rely almost exclusively on pain-evoked behaviors. This approach has at least two limitations. First, although assays of pain-evoked behavior are thought to be predictive of many acute pain states, they may not be adequate models of clinical chronic pain (e.g., sustained inflammatory and/or neuropathic pain states). Second, drugs may decrease pain-evoked behaviors not only by reducing the sensory experience of pain (true analgesia), but also by producing motor impairment, which results in "false positive" effects. We have previously shown that locomotor activity can be reliably suppressed by a standard sub-acute noxious stimulus (i.p. injection of acetic acid), and pain-suppressed locomotor activity can be selectively restored by a prototype analgesic drug (morphine). The present study extended these findings by assessing the degree to which a chronic pain manipulation (MIA-induced osteoarthritis) suppressed exercise activity (wheel running) in rats. Rats had 24hr voluntary access to running wheels. Once high and stable baseline levels of wheel running were established, rats were administered a range of doses of infrapatellar MIA (0.32-3.2mg) into the left knee. Wheel activity was monitored for 28 consecutive days following MIA administration. MIA produced concentration-dependent decreases in total distance traveled and average speed. The effects of analgesic and non-analgesic drugs on MIA-suppressed wheel running are currently being evaluated. The successful development and validation of the proposed model will facilitate the discovery of more effective drugs for osteoarthritis.