Participants and Inclusion Criteria
The sampling method chosen was the selection of extreme cases, recommended when trying to compare cases or extreme groups (Sampieri, 2018). The initial sample, based on non-probability and convenience sampling (Battaglia, 2008), included 233 children (120 boys and 113 girls) from 10 natural groups of Early Childhood Education (M age = 5.03, SD = 1.21) of eight public schools in a Spanish province.
Once the Movement Assessment Battery for Children was administered, two groups were considered: group A, 57 children (66.7% boys and 33.3% girls, M age = 4.96, SD = 0.56) with low MC, i.e., below the 15th percentile, according to the battery classification system (Henderson & Sugden, 1992); and group B, 40 children (51.1% boys and 48.9% girls, M age = 5.10, SD = 0.52) with typical development or high MC group (TD or HMC), those above the 75th percentile.
Instruments
Assessment of Primary Reflexes. MR, TLR, ATNR and STNR reflexes were selected due to their major influence on motor development (Goddard, 2005; McPhillips & Sheehy, 2004). The assessment protocols described by Goddard (2015) were followed. It was performed using a five-point scale (Table 1). The lower the score obtained, the higher the reflex inhibition.
—————————————-Table 1—————————————–
Every child was individually evaluated according to the protocol of every reflex measured and under a specialist’s supervision (Master of Science in Physical Activity and Sport and specialist in Blomberg Rhythmic Movement Training and Primitive Reflexes).
Movement Assessment Battery for Children (Mabc-2, Henderson & Sugden, 1992) adapted to Spanish by Ruiz & Graupera-Sanz (Ruiz & Graupera-Sanz, 2012). It is a standardized, individually-administered test to assess children with motor difficulties. It is designed for children aged four to 16, divided into three age ranges (3–6; 7­–10; 11–16 years). The battery consists of eight subtests divided into three dimensions: manual dexterity, aiming and catching, and balance. It provides a classification system based on the scores obtained in every dimension and the age range. Children scoring below the 5th percentile meet diagnostic criterion A for Developmental Coordination Disorder (American Psychiatric Association, 2013). Children between the 5th and 15th percentiles (63–69 points) are at risk of having movement problems, while children above the 15th percentile (> 69 points) do not present movement problems.
Ad-hoc parent questionnaire consisted in a dichotomous question to ask parents whether their children had developed the crawling pattern (1) or not (0).