Cardiovascular activity during mental stress following vigorous exercise in sportsmen and inactive men

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Abstract
Thirty-six competitive sportsmen and 36 inactive men participated in a two-session experiment. Session 1 involved exercise to exhaustion so as to assess maximal oxygen consumption (VO2 max). In Session 2, both groups were randomized into three experimental conditions: 20 min of exercise at high intensity (70% VO2max) or moderate intensity (50% VO2max) or a light exercise control. Following 30 min of recovery, all subjects performed mental arithmetic and public speech tasks in a counterbalanced order. Cardiovascular, electrodermal, respiratory, and subjective variables were recorded. Sportsmen had higher VO2max, lower body fat, and lower resting heart rate (HR) than inactive men. A postexercise hypotensive response was observed among subjects in the 70% and 50% VO2max conditions, accompanied by baroreceptor reflex inhibition in the 70% condition. Systolic pressure was lower during mental arithmetic and during recovery from the speech task in the high-intensity than in the control group. Diastolic pressure was lower following mental arithmetic in the high-intensity group. No differences in HR reactivity, electrodermal, or respiratory parameters were observed, but baroreceptor reflex sensitivity was inhibited during mental arithmetic. The results are discussed in relation to previous reports of suppressed cardiovascular reactivity to mental stress tests following vigorous exercise and the role of stress-related processes in the antihypertensive response to physical training.