Cortical hemodynamics and inhibitory processing in preadolescent children with low and high physical activity

Background

Preadolescent children undergo developmental changes in inhibitory control. Maintenance of high levels of moderate-to-vigorous-intensity physical activity (MVPA) has been suggested to promote its maturation. We compared inhibitory control between children with low and high MVPA as well as their inhibitory processing stream and changes in cortical hemodynamics.

Method

109 participants aged 10 to 13 years wore accelerometers over 7 days. Those with MVPA levels of 30 min/d or less and 60 min/d or more further performed a computerized Stroop Color-Word task. Electroencephalography and functional near-infrared spectroscopy were used to record changes in inhibitory processing and cortical hemodynamics, respectively.

Results

An interaction of MVPA group and sex indicated better interference in highly-active boys, but the opposite pattern in girls. Independent from sex, the high compared to low MVPA group showed greater P300 and PSW amplitudes, whereas no group differences were found for N200, N450, and changes in cortical hemodynamics.

Conclusion

Children with high MVPA differ from their less-active peers by a distinct inhibitory processing profile, which is characterized by altered allocation of attentional resources and conflict resolution. However, these alterations do not necessarily translate into better performance, especially since MVPA is linked with higher inhibitory control in boys only.

Moderate-to-vigorous physical activity and reactivity to acute psychosocial stress in preadolescent children

OBJECTIVES

High reactivity to psychosocial stress during childhood increases the risk of future psychological and physiological disorders. The main objective of this study was to investigate associations between children's moderate-to-vigorous physical activity (MVPA) and physiological and psychological reactions to acute psychosocial stress.

DESIGN

Randomized cross-over study comparing two groups.

METHODS

After a 7-day accelerometer-based measurement of MVPA, 110 children aged 10-13 years (48 female) were categorized into a low (<30 min/d) or a high MVPA group (>60 min/d). On separate laboratory appointments, participants completed the Trier Social Stress Test for Children (TSST-C) and a non-stressful control task in randomized order. Stress reactivity was assessed from saliva cortisol, heart rate variability and self-reported anxiety.

RESULTS

In repeated measures analyses of variance, main effects of condition indicated higher stress reactivity in the TSST-C compared to control for cortisol and anxiety, with more pronounced effects in girls compared to boys. Differences in heart rate variability disappeared after controlling for confounding variables. No interactions with MVPA were found. A main effect of MVPA indicated generally lower cortisol reactivity in the high compared to the low MVPA group.

CONCLUSIONS

The TSST-C is suitable for induction of psychosocial stress in the laboratory, but sex-specific differences have to be considered. Children who met the WHO recommendations for MVPA exhibited generally lower endocrine reactivity to both laboratory tasks combined, underlining the potential role of regular physical activity in the regulation of the stress response in early developmental stages. Further studies are necessary to ascertain causal associations.

Does heart rate variability mediate the association between chronic stress, cardiorespiratory fitness, and working memory in young adults?

Young adulthood is a demanding development phase rendering individuals at risk for high levels of stress. While chronic stress may impair working memory maintenance, cardiorespiratory fitness is suggested to have a protective effect. Heart rate variability (HRV) contributes to this cognitive domain, but also retaliates to stress and aerobic exercise. Therefore, the present study investigated the mediating role of resting HRV on the association between chronic stress, cardiorespiratory fitness, and working memory maintenance in young healthy adults. Healthy participants (N = 115, 48% female) aged 18-35 years (M = 24.1, SD = 3.8) completed the Åstrand test on a bicycle ergometer to estimate maximal oxygen consumption [ V ̇ O 2 max $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\max } $$ (ml/min/kg)]. In addition, working memory maintenance was assessed using the modified Sternberg task with low (three items) and high cognitive load (six items). Using electrocardiography, HRV was recorded and the LF/HF ratio was extracted for mediation analyses. Path analysis revealed that cardiorespiratory fitness was significantly associated with accuracy on high cognitive load trials (β = 0.19, p = 0.035), but not on trials with low cognitive load. Perceived levels of chronic stress failed to show a significant association with working memory maintenance, independently of cognitive load. The pattern of results remained unchanged after introduction of HRV as a mediator (β = 0.18, p = 0.045). In conclusion, higher cardiorespiratory fitness is associated with better maintenance of verbal information in working memory. However, this association cannot be explained by vagal influences on memory processing driven by the autonomic nervous system.