Effects of exercise-induced mild dehydration on motor skills and cognitive performance in children

The effect of exercise on motor skill and cognitive performance is also sensitive to hydration status. It is hypothesised that brain function may be impaired due to dehydration and consequently lead to impairment in motor skill and cognitive performance. However, most of the research has been conducted on young healthy adults who usually exercise in the heat. The inconsistency of research results also prevents any conclusions from being drawn. Even if the findings are consistent, confounding variables such as fatigue and increased temperature prevent interpretation of these findings.Even if the findings are consistent, confounding variables such as fatigue and increased temperature prevent interpretation of these findings. In addition, very few studies have been conducted on children in this field. Therefore, the data are quite scarce and insufficient. In our study, we aimed to investigate the effects of exercise-induced mild dehydration on motor skills and cognitive performance in children with or without routine physical activity in daily life.Two groups of 112 children aged 12-13 years, one physically active (exercising more than 150 min per week) (n:57) and the other sedentary (n:55), were included in the study by random assignment. In the study, a counterbalanced design with repeated measures was applied to evaluate hydrated and mildly dehydrated children.A 12-hour hydration programme was applied to balance their hydration status. After the hydration measurements, mild dehydration was induced in the children by intermittent exercise of moderate intensity for approximately ninety minutes at normal room temperature (temperature: 21±0.5 °C; humidity: 45-50%).Hydration to determine dehydration status, urine colour was determined using a colour scale. Body weight changes were also used. In case of hydration and mild dehydration, Bruininks-Oseretsky Motor Competence Test (BOT-2) and d2 attention test were applied to the children.Repeated Measures ANOVA test was performed to determine the differences in the SPSS package programme and Bonferroni post-hoc test was performed as the second level when significant results were found.When the hydrated/ dehydrated groups were analysed separately, no significant difference was found in Fine Motor Skill Precision, Fine Motor Skill Integration, Hand dexterity and Bidirectional Coordination, Balance, Running speed and Agility, Hand arm coordination, Power and BOT-2 Total pre-posttest comparison (p>0.05).In terms of cognitive performance, significant decreases in Focused Attention, Processing Speed, Accuracy, Concentration Performance and Attention Span were detected in both groups (p<0.05). In conclusion, mild dehydration jeopardized the cognitive performance necessary for learning in children. However, motor skills were not affected by mild dehydration.