Cardiovascular response of trained and untrained old men to mental challenge.

PURPOSE: The cardiovascular response to mental challenge of trained and untrained older men was examined. METHODS: Blood pressure, heart rate, stroke volume, cardiac output, total peripheral resistance (TPR), rate pressure product, and cardiac contractility of 10 aerobically trained (trained) and 10 untrained (untrained) older men during and recovering from the Stroop task were compared. Fitness was assessed by online, open-circuit spirometry using a bicycle ergometer. RESULTS: Trained compared with untrained men showed significantly lower absolute heart rate during and recovering from the Stroop and greater left ventricular ejection time recovering from Stroop. Delta TPR scores were greater for Trained during and recovering from the Stroop, whereas delta systolic blood pressure was greater recovering from Stroop. CONCLUSION: These results indicate that although aerobically trained men possessed lower absolute heart rate their change in TPR and systolic blood pressure during mental challenge was significantly greater than that of untrained older men. The greater vascular response of the trained to mental challenge may reflect greater sensitivity to alpha-adrenergic stimulation.

Heart period variability of trained and untrained men at rest and during mental challenge.

The effect of aerobic training on parasympathetic reactivity to mental stress is unclear. Thus, the parasympathetic response, as assessed by time series analysis of heart period variability (HPVts), of 10 trained male runners (trained group), 10 inherently low resting heart rate untrained men (low HR group), and 10 normal resting HR men (control group) at rest and to two mental stressors was examined. Participants completed a mental arithmetic and Stroop task. Resting HPVts at high and medium frequencies was significantly greater for the trained and the low HR groups than for the control group. Significantly greater decreases in HPVts at the medium frequency during arithmetic recovery were measured for the trained and low HR groups compared with the response of the control group. Significantly greater decreases in HPVts at both the the high and medium frequencies during the first two epochs of the Stroop occurred only for the trained and low HR groups. These results suggest that the greater HPVts at rest and decline in HPVts during and after mental challenge is influenced by both aerobic training and genetic inheritance.

Stroke volume response to cycle ergometry in trained and untrained older men.

UNLABELLED: The aims of this study were threefold: (1) to investigate the stroke volume (SV) response of trained older male cyclists [Cyclists: 65 (2.1) years, n = 10] during incremental cycle ergometry (20 W.min-1); (2) to determine the SV dynamics and total peripheral resistance response of untrained, but healthy and active older male controls [ CONTROLS: 66 (1.1) years; n = 10]; (3) to compare the maximum oxygen consumption (VO2max) and SV response of trained older male runners [Runners: 65 (3.4) years; n = 11] with that of age-matched Cyclists. Impedance cardiography was used to assess the response of cardiac output (CO), SV and total peripheral resistance to exercise involving cycle ergometry. The mean VO2max of the trained Cyclists [54 (1.6) ml.kg-1.min-1] was significantly higher (P < 0.05) than that of the Runner [48 (3.9) ml.kg-1.min-1], whereas both groups possessed a significantly higher VO2max than the CONTROLS [28 (1.3) ml.kg-1.min-1]. During exercise, at a heart rate of 90 beats.min-1, the SV of the Cyclists increased by 41%, that of the Runners increased by 47%, and that of the CONTROLS increased by 31%. However, the Cyclists' and Runners' SV response was significantly greater than that of the CONTROLS. The SV for cyclists and controls peaked at 30% of VO2max. This early increase in SV was a major factor underlying the increase in CO during exercise in both the trained and the untrained subjects. In addition, all three groups showed a significant decrease in total peripheral resistance throughout exercise. The finding that older male runners possessed a large exercise SV and high VO2max suggests that run training results in enhanced cardiovascular performance during cycle ergometry.

Autonomic nervous function at rest in aerobically trained and untrained older men.

The relationship between aerobic training, vagal influence on the heart and ageing was examined by assessing aerobic fitness and resting heart rate variability in trained and untrained older men. Subjects were 11 trained cyclists and runners (mean age = 66 +/- 1.6 years) and 11 untrained, age-matched men (mean age = 66 +/- 1.2 years). Heart rate variability testing involved subjects lying supine for 25 min during which subjects' breathing was paced and monitored (7.5 breaths min(-1)). Heart rate variability was assessed through time series analysis (HRV(ts)) of the interbeat interval. Results indicated that trained older men (355 +/- 0.21 1 min(-1)) had significantly (P < 0.05) greater VO2(max) than that of control subjects (2.35 +/- 0.15 1 min(-1)). Also, trained older men (52 +/- 1.8 beats min(-1)) had significantly (P < 0.05) lower supine resting heart rate than that of control subjects (65 +/- 4.2 beats min(-1)). HRV(ts) at high frequencies was greater for trained men (5.98 +/- 0.22) than for untrained men (5.23 +/- 0.32). These data suggest that regular aerobic exercise in older men is associated with greater levels of HRV(ts) at rest.