Psychobiological exercise response: A pilot investigation of a laboratory exercise assessment paradigm among young women with eating disorders

Objective: Compulsive exercise is a common feature of eating disorders (EDs) but understanding of factors that drive this symptom remain limited. This pilot trial evaluated psychobiological response to in-laboratory exercise among females (16-22y) with and without restrictive EDs. We aimed to demonstrate feasibility of two exercise assessment protocols and to evaluate acute effects of exercise on affect, body image, and circulating blood-based biomarkers (brain-derived neurotrophic factor [BDNF], cortisol, N-arachodonoylethanolamine [AEA], 2-arachidonoylglycerol [2-AG], leptin). Method: Twenty females with restrictive EDs and 20 healthy controls completed three study visits, including two bouts of stationary cycling (30-minutes prescribed pace vs. ≤ 30-minutes self-paced) and two complementary periods of rest. During visits, participants also consumed a milkshake, self-reported state affect and body image, and participated in pre- and post-exercise blood draws. Results: Per established thresholds, both tasks were determined feasible and safe, with initial evidence of validity in eliciting affective, behavioral, and biomarker change. In both exercise conditions, the group with EDs experienced more positive (Cohen’s d = 0.10 – 0.61) and less negative affect (Cohen’s d = -0.72 – -0.22) compared to controls, along with greater positive body image shifts (Cohen’s d = 0.20 – 0.66). Body image shifts correlated with higher muscularity drive and lower BMI. Those with EDs demonstrated increases in BDNF (Cohen’s d = 0.39) and AEA (Cohen’s d = 0.71). Discussion: Findings suggest perceived effects of exercise on body weight/shape may reinforce exercise maintenance in the context of EDs.