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 remains limited. This pilot trial evaluated psychobiological response to in-laboratory exercise among females (14-22 years) with and without restrictive eating pathology. We aimed to demonstrate the feasibility of two exercise assessment protocols and provide initial estimates of acute exercise effects 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-min prescribed pace vs. ≤ 30-min 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 and body image change. In both exercise conditions, the ED group 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 in the ED group correlated with higher drive for muscularity and lower BMI.

Discussion: Findings suggest perceived effects of exercise on body weight/shape may reinforce exercise maintenance in the context of EDs.