Positive physiologic and cognitive responses to aerobic exercise have resulted in a proposed cardiorespiratory (CR) fitness hypothesis in which fitness gains drive changes leading to cognitive benefit. The purpose of this study was to directly assess the CR fitness hypothesis. Using data from an aerobic exercise trial, we examined individuals who completed cardiopulmonary and cognitive testing at baseline and 26 weeks. Change in cognitive test performance was not related to CR fitness change (r 2 = .06, p = .06). However, in the subset of individuals who gave excellent effort during exercise testing, change in cognitive test performance was related to CR fitness change (r 2 = .33, p < .01). This was largely due to change in the cognitive domain of attention (r 2 = .36, p < .01). The magnitude of change was not explained by duration of exercise. Our findings support further investigation of the CR fitness hypothesis and mechanisms by which physiologic adaptation may drive cognitive change.
Sandra A. Billinger, Eric D. Vidoni, Jill K. Morris, John P. Thyfault and Jeffrey M. Burns
Eric D. Vidoni, Anna Mattlage, Jonathan Mahnken, Jeffrey M. Burns, Joe McDonough and Sandra A. Billinger
The purpose of this study was to determine the validity of a submaximal exercise test, the Step Test Exercise Prescription (STEP), in a broad age range and in individuals in the earliest stages of Alzheimer’s disease (AD). Individuals (n = 102) underwent treadmill-based maximal exercise testing and a STEP. The STEP failed to predict peak oxygen consumption (VO2peak), and was a biased estimate of VO2peak (p < .0001). Only 43% of subjects’ STEP results were within 3.5 ml · kg–1 · min–1 of VO2peak. When categorized into fitness levels these 2 measures demonstrated moderate agreement (kappa = .59). The validity of the STEP was not supported in our participants, including those with AD. The STEP may not be appropriate in the clinic as a basis for exercise recommendations in these groups, although it may continue to have utility in classifying fitness in research or community health screenings.