Evaluating the reliability and validity of the proposed muscle dysmorphia criteria

Abstract

This study aimed to: (a) determine the inter-rater reliability of the proposed muscle dysmorphia criteria, (b) investigate if muscle dysmorphia (MD) represented a syndrome of frequently co-occurring symptoms, and (c) determine the level of correlation between the proposed MD criteria and the Muscle Appearance Satisfaction Scale. Men (N = 48) aged 18 years and older who were currently participating in resistance training were assessed using the Muscle Appearance Satisfaction Scale and a one-on-one interview. Two qualified psychologists assigned a diagnosis of MD to those participants who appeared to meet the proposed criteria for MD. Inter-rater reliability and the frequency of co-occurring symptoms in participants were assessed. The correlation between MD and the Muscle Appearance Satisfaction Scale was explored. The inter-rater reliability between the researchers was low (Cohen's kappa = .39; p ≤ .05). A Binomial test revealed that MD represented a syndrome of frequently co-occurring symptoms; there was a significant probability (>.70) of a participant with one diagnostic symptom of MD (criterion 2a or 3) to exhibit another symptom (criterion 1) of the disorder. Point-biserial correlation indicated that the proposed MD criteria, excluding criterion 2b, were significantly correlated with the total score of the Muscle Appearance Satisfaction Scale and its subscales, excluding Muscle Satisfaction. The study provides some evidence to question the acceptance of the proposed MD criteria.