Aerobic Exercise Effects on Cognition and Physiology

Multiple regression and correlation procedures were used to residualize the 6-month data from baseline to create change scores. Residualized cognitive measures were subjected to separate multivariate analyses of variance (MANOVA) by domain (ie, executive function, memory), with treatment group as the independent variable. Covariates statistically considered for inclusion in the model included age, education, baseline insulin sensitivity (glucose disposal), V̇o₂peak, and cognitive status (Mini-Mental State Examination). In light of reports suggesting a sex bias in cognitive response,2 (link),19 (link) sex was included as a predictor variable. Cardiorespiratory outcomes (V̇o₂peak, treadmill grade, treadmill time to exhaustion) and measures of glucose homeostasis (glucose disposal and an estimate of insulin sensitivity using the homeostasis model assessment49 (link)) were subjected to similarly structured MANOVAs. For significant MANOVAs, separate univariate ANOVAs were conducted. Pairwise comparisons were performed using t tests when appropriate. Secondary analyses examined aerobic exercise effects on adiposity (dual-energy x-ray absorptiometry–determined percentage of body fat), cardiovascular outcomes (lipids, blood pressures), hypothalamic-pituitary-adrenal (HPA) axis (plasma cortisol) and trophic (plasma IGF-I, BDNF) activity, and plasma β-amyloid levels using similarly structured ANOVAs. Exercise-related associations were examined using multiple regression and correlation for measures of cognition, cardiorespiratory fitness, insulin sensitivity, adiposity, cortisol, BDNF, IGF-I, and β-amyloid. Positively skewed distributions were log-transformed prior to analysis.