Development and Validation of a Self-Determination Theory-Based Measure of Motivation to Exercise and Diet in Children

Objective: To develop and test the factorial structure of a new self-determination theory–based measure of behavioral regulation in children. Methods: Five hundred ninety 590 (F = 51.7%) children aged 7 to 11 years completed the Motivation to Exercise and Diet (MED-C) questionnaire, which comprises 16 items (eight for exercise and eight for diet) grouped into eight factors (five motivations and three needs). Psychometric testing included confirmatory factor analysis and internal consistency. Measurement invariance analyses were also performed to evaluate whether the factorial structure of the MED-C was equivalent for gender (male vs. female), age (>9 vs.