Task difficulty affects the association between childhood fitness and cognitive flexibility

In this chapter we provide additional insight into the association between aerobic fitness and cognitive flexibility in preadolescent children. We compared lower-fit and higher-fit children’s task performance during the Trail Making Test (TMT). The TMT consists of two parts. TMT-A requires participants to draw a line connecting 25 randomly positioned numbers in numerical order, while TMT-B asks them to draw a line connecting numbers and letters in an alternating order. That is, the TMT-B necessitates greater cognitive flexibility than the TMT-A. Analyses revealed that higher-fit children exhibited superior task performance relative to lower-fit children for the TMT-A, corroborating previous findings indicating the general nature of the relationship between fitness and cognition in preadolescent children. In contrast, task performance did not differ between the fitness groups for the TMT-B. Thus, the positive association between aerobic fitness and cognitive flexibility disappeared, likely because the cognitive task was too difficult for preadolescent children. This result indicates that task difficulty affects the association between fitness and cognitive control during childhood.