The purpose of this study is to determine whether an acute bout of exercise may temporarily enhance cognitive function (such as memory or attention span) by measuring behavioral performance on cognitive tests, as well as expression of hormones in circulation associated with brain plasticity and stress.

This is a randomized experiment consisting of three visits for each participant. Participants are determined to be eligible beforehand during a phone screening, in which the various study inclusions and exclusions are determined and the Physical Activity Readiness Questionnaire for Everyone 2015 (PARQ) is administered. In the first visit, various anthropometric data are collected from participants, such as height, weight, and waist and hip circumference. The participants' blood pressure is also checked for hypertension. The participants are given Dual Energy X-Ray Absorptiometry (DEXA) scans to determine total body composition (bone, fat, and fat-free mass) If the participant is female, a urine analysis to determine pregnancy is required during the visit before the DEXA to ensure safety. Participants are given the Rapid Assessment of Physical Activity (RAPA) questionnaire to assess habitual activity levels. The participants' muscle strength is also measured using the Biodex System 3, an isokinetic dynamometer. The participants then undergo a maximal stress test on a treadmill integrated with a Cardinal Health Metabolic/ECG cart using a modified Balke protocol, beginning at 3 mph, 0% grade, and increasing 2.5% grade every 3 minutes. The ECG component of the metabolic cart will be used for continuous heart rate monitoring as part of the fitness assessment. Cardiorespiratory parameters (VO2, ventilation, respiratory rate) will also be measured throughout the test. Blood pressure is measured during the last 30 seconds of each exercise stage and the rating of perceived exertion (RPE) using the Borg 6 to 20 scale is obtained during each stage. Subjects are urged to give a maximal effort and are pushed until volitional fatigue. In the second visit, participants are first given a series of cognitive tests designed to quantify such cognitive faculties as visual short-term memory, selective attention, processing speed, and verbal fluency. These tests consist of seeing simple images on a computer screen, such as a series of colored shapes, and responding using a keypad. A blood sample is also collected from the participants to serve as a baseline. The subject is then randomized to one of three groups: the first group rests for 30 minutes; the second group walks on the treadmill at a mild intensity, defined as maintaining 60% of the heart rate observed during the max VO2 from the first visit; the last group walks on the treadmill at a hard intensity, defined as maintaining 80% of the heart rate observed during the max VO2 from the first visit. The subjects then undergo a second blood draw after cooling down, followed immediately by another round of the same cognitive tests. An hour after finishing the exercise intervention, the same procedure of blood draw followed by cognitive tests is repeated, and an hour after that it is repeated again. The third visit must be about 24 hours after the previous visit. Participants have blood drawn and one final round of cognitive tests.