Sympathetic nervous system and behavioral responses to stress following exercise training

This study tests the hypothesis that a short-term (16 weeks) exercise program modifies sympathetic nervous system (SNS) and selected behavioral responses to acute psychological stress. Twenty-four previously sedentary middle-aged men with maximal aerobic capacity (VmaxO2) values less than 40 ml.kg-1.min-1 were assigned to experimental (n = 12) and control (n = 12) groups. All subjects performed a modified Stroop test (18 min) at pre- and postexercise training during which intravenous blood samples were drawn at three time intervals for plasma catecholamine (CA) determination. Motor performance was continuously recorded for assessment of premotor (PMT) and motor (MOT) components of reactions time. A set of anagrams were administered immediately following the modified Stroop to determine the level of cognitive fatigue induced. At both pre- and postexercise intervention, the total group (n = 24) manifested significant (p less than or equal to 0.05) elevations in state anxiety, heart rate, and plasma norepinephrine. No significant changes occurred over time on PMT or MOT. There were significantly (p less than or equal to 0.01) lengthened anagram performance scores poststress compared to nonstress values. The experimental group exercise trained 3 days/week for 16 weeks, resulting in a 20% increase in VO2max. However, there were no group differences on the CA or behavioral responses to the modified Stroop at pre- or postintervention. These findings do not support the hypothesis that short-term aerobic training significantly alters SNS activity or behavioral measures of central processing in middle-aged men exposed to an acute psychological challenge.