Available at: http://digitalcommons.calpoly.edu/theses/1807
Date of Award
MS in Kinesiology
Cory Jackson Greever
Purpose: Moderate-intensity aerobic exercise (MAE) has been shown to elicit improvements in cognition and subsequent academic performance among preadolescents. Aerobic exercise has also shown to increase cortisol release in response to increasing exercise intensity. However, it is unknown if increased cortisol levels following exercise are related to acute improvements in executive function following a bout of MAE in preadolescents. The purpose of this study was to examine the potential effects of increased cortisol release after acute MAE on attention and working memory among preadolescents. Methods: Eleven preadolescents [6 males, 5 females] volunteered to participate in this study (age=9.45±1.03). Participants were randomized in a counterbalanced fashion to 30 minutes of rest or 30 minutes of treadmill MAE (60-70% HR max). Immediately pre-post each condition, participants completed a cognitive battery consisting of tests of attention (Flanker Test) and working memory (List Sorting Working Memory Test), as well as salivary samples for the analysis of cortisol. Linear Regression models were used to assess significance of covariates. Generalized linear models were used to assess significance of changes in each dependent variable against time, condition, time*condition and change in cortisol. Tukey’s HSD post-hoc tests for multiple comparisons were used to assess the effect of condition on working memory, attention, and salivary cortisol. Results: There was a significant effect of condition on working memory (F=3.16, p =0.04), with no change from pre-post rest (p=0.93) and improving from pre-post exercise (p=0.04). There was no effect of condition on attention or salivary cortisol, most likely due to a small sample size. Multiple linear regression models showed a significant effect of age (p=0.03) and change in cortisol (p=0.007) on working memory. Conclusion: Exercise had a positive effect on working memory, however, we were unable to relate this improvement to changes in salivary cortisol due to a lack of statistical power. This study could provide insight into the physiological effects of increased cortisol release on cognition, specifically in regard to working memory. However, more data are needed to achieve sufficient statistical power to detect these relationships.