Pain Perception and Modulation of Triathletes under Normal and Stress Conditions

Background: Triathletes engage in an extremely intense sport that involves pain, as well as psychological stress, every day during training and competitions. We were interested in the interactions between the pain and the stress systems among athletes.

The aim of the first study was to examine triathletes` baseline pain perception. In the second study we aimed to test triathletes` pain perception under an acute, controlled stress manipulation.

Methods: In the first study, 19 triathletes and 17 non-athlete controls underwent the measurements of pain threshold, pain tolerance, suprathreshold perceived pain intensity, and conditioned pain modulation (CPM). In the second study, 25 triathletes and 31 non-athlete controls underwent the aforementioned pain measurements prior to and following a psychosocial stress manipulation. Stress levels were evaluated with perceived stress and anxiety, autonomic variables and salivary cortisol.

Results: Triathletes exhibited greater pain tolerance, lower pain ratings and more efficient pain modulation than controls at baseline, underlying, perhaps, their perseverance in extreme efforts. However, CPM negatively correlated with retrospective reports of stress during training and competitions suggesting that stress may weaken pain modulation capabilities. Acute stress manipulation induced a decrease in pain threshold and in pain inhibition among both groups, a phenomenon termed stress-induced hyperalgesia (SIH). However, whereas controls who were high stress-responders had stronger SIH, triathletes who were high stress-responders had weaker SIH.

Conclusions: It appears that triathletes lose their advantageous pain modulation under acute psychosocial stress and that the magnitude of SIH is affected by the level of activity.