Aerobic fitness, physical activity, and psychophysiological reactions to mental tasks.

The association between aerobic fitness, exercise, and psychophysiological reactivity was assessed in cross-sectional and prospective analyses. Seventy-five healthy but sedentary adults carried out a sub-maximal exercise test and easy and difficult problem solving tasks. Blood pressure, heart rate, skin conductance level, respiration rate, tidal volume, and oxygen consumption were monitored and additional heart rate was also computed. Differences between relatively fit and unfit individuals were found in respiration rate during tasks and in skin conductance level during post-task recovery periods, with a tendency toward diminished heart rate reactivity in fitter people. Subjects were subsequently allocated to four conditions: high intensity aerobic training, moderate intensity aerobic training, an undemanding strength and flexibility program (designed as an attention-placebo condition), and waiting list control. Training programs were conducted over a 10-week period, and were followed by a second laboratory session. Appropriate changes in aerobic performance over the training period were observed in the 12-min run/walk test. There were no important modifications in psychophysiological stress reactions associated with the different experimental conditions. These results are discussed in relation to the literature concerning the effects of fitness and physical activity on physiological response patterns.