Exercise alters pain sensitivity in Gulf War veterans with chronic musculoskeletal pain

Since returning from the Persian Gulf, nearly 100,000 veterans of the first Gulf War (GVs) have reported numerous symptoms with no apparent medical explanation. A primary complaint of these individuals is chronic musculoskeletal pain (CMP). CMP symptoms in GVs are similar to those reported by patients with fibromyalgia (FM), but have not received equivalent scientific attention. Exercise research in CMP patients suggests that acute exercise may exacerbate pain while chronic exercise can reduce pain and improve other symptoms. However, the influence of exercise on GVs with CMP is largely unexplored. This study examined the impact of an acute bout of exercise on pain sensitivity in GVs with CMP. Thirty-two GVs (CMP, n = 15; Control, n = 17) were recruited to complete a series of psychophysical assessments to determine pain sensitivity to heat and pressure stimuli before and after exercise. In response to heat-pain stimuli, GVs with CMP reported higher pain intensity and affect ratings than healthy GVs and exhibited a significant increase in ratings following exercise. GVs with CMP rated exercise as more painful and effortful and were generally more sensitive to heat-pain stimuli than healthy GVs. These results are similar to what has been reported for acute exercise in patients with FM.

Gulf War veterans with CMP perceive exercise as more painful and effortful than healthy GVs and experience increased pain sensitivity following exercise. These results suggest that similar abnormalities in central nervous system processing of nociceptive information documented in FM may also be occurring in GVs with CMP.