This study shows that infants who achieve their motor milestones later are physically less active and more sedentary when growing older. However, the effects are small. Although we found that infants reach their motor milestone later over the past decades, motor milestone achievement and BMI during childhood are largely independent. Instead of physical activity, aerobic fitness might have a stronger association with health outcomes during adolescence.
Higher aerobic fitness reduced cardiometabolic risk in adolescents even in those with higher BMI. Therefore, stimulating high intensive physical activities to increase aerobic fitness is advised. Physical activity during childhood could be stimulated by focusing on early motor milestone achievement and by involving parents as a role-model for PA.
For future studies, and comparability of studies, it would be good to have guidelines for the use and data processing of accelerometry data. Furthermore, we advise to combine accelerometry data with other measurements, like questionnaires to define the nature of the activities, and to measure aerobic fitness, because it may be more relevant for health outcomes than physical activity alone.
Interested in the article? Read: Motor milestones, physical activity, overweight and cardiometabolic risk: from birth to adolescence