Children with Developmental Coordination Disorder (DCD) have poorer fitness and greater internalizing/externalizing problems compared with typically developing (TD) children. The purpose of this study was to examine the potential mediating role of internalizing/externalizing problems on the relationship between children at risk for DCD (DCDr) and physical fitness. Participants (N = 589) included 288 children with DCDr (Mage = 4.9, 67% male) and 301 TD children (Mage = 5.0, 48% male). Motor skills were assessed using the Movement Assessment Battery for Children-2nd edition (DCDr: at or below the 16th percentile, TD: >16th percentile). Parent-reported internalizing/externalizing problems were measured using the Child Behaviour Checklist. Physical fitness was measured using the Bruce protocol maximal treadmill test and a 30-second Wingate test. Tests for indirect (mediation) effects were assessed using the PROCESS v3.5 software macro. Children with DCDr had higher internalizing and externalizing problems (p < 0.001, d = 0.35-0.46) and poorer fitness levels (p < 0.001, ηp2 = 0.05-0.09). Internalizing problems mediated fitness performance on both the treadmill and Wingate test; however, externalizing problems showed no mediating effects. Thus, interventions targeting internalizing problems may contribute to improving performance on fitness-based tasks among children with DCDr. Novelty: Children at risk for DCD have poorer fitness when compared with TD children. Children at risk for DCD experience greater internalizing/externalizing problems. Internalizing problems were found to mediate the DCD-physical fitness relationship.
Keywords: autorégulation; condition physique; coordination motrice; executive functioning; fonctionnement exécutif; motor coordination; physical fitness; self-regulation.