Smoking attenuates regular aerobic exercise benefits to episodic free recall immediately following strenuous physical activity

Abstract

The present study was designed to evaluate the extent to which free recall performance is influenced by competing demands on physiological resources dependent on blood-oxygen levels. Fifty-six healthy young adults (mean age=20 years) were allocated to groups (n1-4=14) according to their level of exercise (more than 6 h aerobic exercise per wk, or sedentary[Note 1][Here sedentary refers to individuals with no regular exercise routines].) and smoking (more than 10 cigarettes per day, or none) behaviour. Participants performed two free recall tasks, one under normal physically inactive conditions and the other immediately following strenuous physical exertion (a step-up test for 2 min). We predicted that recall would suffer following strenuous physical activity among smoking aerobic exercisers. We reasoned this would be due to the oxygen-carrying capacity of the blood being compromised in this group by higher levels of smoking-related carbon monoxide in the blood stream. The results supported this prediction. We interpret our findings according to a resource model of cognitive function, mediated by physiological mechanisms.