(485) Light physical activity behavior predicts pain modulatory function in healthy older adults

      Older compared to younger adults are characterized by greater endogenous pain facilitation and a reduced capacity to endogenously inhibit pain, potentially placing them at greater risk for chronic pain. Prior research suggests higher levels of self-reported physical activity (PA) are associated with more effective pain inhibition and less pain facilitation on psychophysical tests in healthy adults. However, no studies have directly tested the relationship between PA behavior and pain modulatory function in older adults. The current cross-sectional study examined whether objective measures of PA behavior predicted pain inhibitory function and pain facilitation on psychophysical tests in healthy older adults. Forty-seven adults (15 male, average age=67.35±5) wore a hip accelerometer for 7 days and completed the following psychophysical tests of pain modulation: conditioned pain modulation (CPM: test of pain inhibition) and temporal summation of heat pain (TS: test of pain facilitation) at 44oC, 46oC and 48oC. Indices of pain inhibition and facilitation were created from the CPM and TS tests, respectively. Measures of total energy expenditure, sedentary time (1-1.5 METs), light (1<3 METs), moderate (3-<6 METs, and vigorous (≥ 6 METs) PA were obtained from the accelerometer. Hierarchical linear regressions were conducted to determine the relationship of TS and CPM with levels of PA, while controlling for age, sex, and psychological variables. Results indicated total energy expenditure and light PA significantly predicted pain inhibitory function on the CPM test and pain facilitation on the TS test at 48oC. More light PA per day was associated with less pain facilitation and greater pain inhibition on the psychophysical tests. Results suggest high volume, low intensity PA may have beneficial effects on pain modulatory function in healthy older adults. This study was funded by the IUPUI School of Physical Education, Tourism, and Management Faculty Research Opportunity Grant.