PILATES study aims are to assess the main characteristics related to food habits, diet behaviors, and nutrition knowledge and how and where gym-goers get information on dietary supplementation. We present evidence for the reliability, feasibility, and construct validity of the PILATES questionnaire. Cohen's kappa statistic (k) for dichotomous variables was used to assess the agreement between the two administrations (interrater agreement). The nutrient composition and energy of food were derived from the Food Composition Database for Epidemiological Studies in Italy (Banca Dati di Composizione degli Alimenti per Studi Epidemiologici in Italia - BDA). Because of energy intake, waist circumference and weight are continuous variables; we calculate the agreement between the two interviews using Spearman's rho coefficient (nonparametric measure of rank correlation). An Italian 21-item self-administered questionnaire was designed and pretested on 28 students in food science and human nutrition at the University of Perugia who were enrolled on a voluntary basis. After verifying the feasibility of the questionnaire, pretest evaluation showed a generally high concordance with an 87.32% of agreement and k value = 0.71 ± 0.23. In addition, weight, daily energy intake, and waist circumference confirmed a statistically significant agreement (p <.001, Spearman rho coefficient). PILATES questionnaire is a valid tool to estimate dietary intakes in a fairly simple, cost-effective, and timesaving manner.
Keywords: food frequency; gym-goers; physical activity; questionnaire; supplementation; validation process.