Maternal sociodemographic factors differentially affect the risk of behavioral problems in Brazilian and Italian preterm toddlers

The main aim of the present study was to examine differences in behavioral problems in toddlers born very preterm in Brazil and Italy. The sample comprised 154 toddlers (18–24 months of age) born very preterm, including 76 toddlers from Brazil and 78 toddlers from Italy. The Child Behavior Checklist was used to assess behavioral problems. Specific sociodemographic factors (i.e., maternal age at childbirth and maternal education) and neonatal factors (i.e., gestational age, sex, and length of hospitalization) were tested as potential mediators of country-related differences in behavioral problems. Brazilian toddlers presented more internalizing, externalizing, and total behavioral problems compared with their Italian counterparts. The effect of country on the toddlers’ internalizing and total behavioral problems was mediated by maternal age at childbirth and education. Independent effects of country, maternal age at childbirth, and maternal education emerged for externalizing behavioral problems. No significant effect emerged for neonatal variables. These findings suggest that sociodemographic factors, in addition to country-related differences, should be considered when assessing the risk of behavioral problems in preterm toddlers.     

Does parental autonomy support mediate the relation between parent and infant executive function? A study of mothers and fathers in the Netherlands and China

Parenting skills, such as Autonomy Support (AS), have been proposed as a potential mechanism explaining the intergenerational contiguity of Executive Function (EF). However, few studies have focused on mothers and fathers among non-Western families. The current study investigated the role of maternal and paternal AS in the relation between parental EF and infant EF at 14 months of age among 123 Dutch and 63 Chinese first-time mothers and fathers and their infants. Multiple-group structural equation models were built for mothers and fathers separately with country as a grouping variable. Results showed that parental AS did not mediate the relation between parent EF and infant EF at 14 months. Mean-level differences were found in parental AS, maternal EF, and infant inhibition across countries, while no country differences were found in the relation between parent EF, AS and infant EF. Our findings suggested that individual differences in early EF may not be stable enough to be reliably predicted from parental factors across the Netherlands and China.     

The effect of swinging the arms on muscle activation and production of leg force during ski skating at different skiing speeds

The study investigated the effects of arm swing during leg push-off in V2-alternate/G4 skating on neuromuscular activation and force production by the leg muscles. Nine skilled cross-country skiers performed V2-alternate skating without poles at moderate, high, and maximal speeds, both with free (SWING) and restricted arm swing (NOSWING). Maximal speed was 5% greater in SWING (P < 0.01), while neuromuscular activation and produced forces did not differ between techniques. At both moderate and high speed the maximal (2% and 5%, respectively) and average (both 5%) vertical force and associated impulse (10% and 14%) were greater with SWING (all P < 0.05). At high speed range of motion and angular velocity of knee flexion were 24% greater with SWING (both P < 0.05), while average EMG of m. biceps femoris was 31% lower (all P < 0.05) in SWING. In a similar manner, the average EMG of m. vastus medialis and m. biceps femoris were lower (17% and 32%, P < 0.05) during the following knee extension. Thus, swinging the arms while performing V2-alternate can enhance both maximal speed and skiing economy at moderate and, in particularly, high speeds.