Aerobic exercise reduces anxiety and fear ratings to threat and increases circulating endocannabinoids in women with and without PTSD

Abstract

Reductions in state anxiety have been reported following an acute bout of aerobic exercise. However, less is known regarding anxiety and fear ratings to specific threatening stimuli following an acute bout of aerobic exercise in women with PTSD. Moreover, the mechanisms responsible for the anxiolytic effects of exercise are not fully understood, although recent studies suggest a role for the endocannabinoid (eCB) system. Thus, this study utilized a randomized, counterbalanced approach to examine anxiety and fear ratings to predictable or unpredictable electric shock administration and circulating concentrations of eCBs and mood states immediately following moderate-intensity aerobic exercise (30 min on treadmill at 70–75% maximum heart rate) and a quiet rest control condition in women with and without a history of trauma, and in women with PTSD (N = 42). Results revealed that anxiety and fear ratings to unpredictable and predictable threats were significantly (p < .05) lower following exercise compared to quiet rest, with correlational analyses indicating those with greater increases in circulating eCBs had greater reductions in anxiety and fear ratings to unpredictable and predictable threats following exercise. Also, there were significant (p < .05) reductions in fatigue, confusion, total mood disturbance, and increases in positive affect following exercise for the entire sample. Non-trauma controls and PTSD groups reported significant (p < .05) increases in vigor, with additional mood improvements following exercise for the PTSD group (i.e., decreases in state anxiety, negative affect, tension, anger, and depression). Results from this study suggest that aerobic exercise exerts psychological benefits in women with PTSD, potentially due to exercise-induced increases in circulating concentrations of eCBs.