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<p> The Wingate anaerobic test can be used in an exercise training program as a powerful training stimulus for producing metabolic and performance enhancements. Although the acute cardiovascular responses in terms of heart rate (HR), blood pressure (BP), stroke volume (SV), cardiac output (CO), and leg blood flow following a single Wingate have been characterized, the acute cardiovascular recovery pattern in response to multiple Wingate exercise bouts performed in an interval pattern have yet to be described. The purpose of the current investigation was to characterize that acute cardiovascular recovery period following multiple Wingate exercise. We observed the recovery patterns of HR, BP, SV, CO, and leg blood flow for 120 minutes immediately following multiple Wingate exercise. Ten recreationally active males aged 19.8 ± 1.2 years (mean± SD) years performed a single bout of Wingate exercise, and a session of multiple Wingate exercise in random order, on separate days. Cardiovascular measurements were conducted at rest and after two-minutes of recovery and then continued at 15-minute intervals until 120 minutes of recovery. HR was elevated immediately after exercise compared to rest, and declined towards resting values for the remainder of recovery, although HR failed to return to resting values after 120 minutes of recovery. SV was significantly decreased, compared to rest, immediately following exercise from 87.3 ± 5.7 to 60.0 ± 5.6 ml. CO was increased compared to rest at two minutes following multiple Wingate exercise, and continued to increase to a maximum recovery value of 8.1 ± 0.7 L/min at R15. Immediately following exercise systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were all elevated to 155 ± 3, 73 ± 2, and 100 ± 3 mmHg respectively. Although SBP and MAP returned to resting values 15-minutes after exercise, DBP continued to decrease, resulting in a period of hypotension observed from R15 and R30. Leg blood flow was elevated compared to rest following exercise. Common femoral artery (CFA) blood flow was higher after a single Wingate, than after multiple Wingate exercise (1264 ± 109 and 1036 ± 86 ml/min respectively). Superficial femoral artery (SFA) blood flow (616 ± 55 ml/min) immediately following multiple Wingate exercise was not different following a single Wingate, however the time to return to resting values was longer after multiple Wingate exercise. We attribute the sustained elevations in (SFA) blood flow to increased cutaneous flow for thermoregulation purposes following multiple Wingate exercise.</p> <p> The results of this investigation indicate that the general cardiovascular recovery time is longer after multiple Wingate exercise, than after a single Wingate bout. This type of supramaximal exercise temporarily reduces SV due to elevated SBP and decreases in cardiac preload that are not facilitated by vasodilatation and decreased total peripheral resistance (TPR).</p> / Thesis / Master of Science (MSc)

Reductions in baroreflex responsiveness have been thought to increase the prevalence of orthostatic hypotension in endurance trained athletes. To test this hypothesis, cardiovascular responses to orthostatic stress, cardiopulmonary and carotid baroreflex responsiveness, and the effect of cardiopulmonary receptor deactivation on carotid baroreflex responses were examined in 24 men categorized by maximal aerobic power (V02max) into one of three groups: high fit (HF, V0-2max=67.0±1.9 ml•kg^-1•min^-1), moderately fit (MF, V0-2max=50.9±1.4 ml•kg^-1•min^-1), and low fit (LF, V0-2max=38.9±1.5 ml•kg^-1•min^-1). Orthostatic stress was induced using lower body negative pressure (LBNP) at -5, -10, -15, -20, -35, and -50 torr. Cardiopulmonary baroreflex responsiveness was assessed as the slope of the relationship between forearm vascular resistance (FVR, strain gauge plethysmography) and central venous pressure (CVP, dependent arm technigue) during LBNP<-35 torr. Carotid baroreflex responsiveness was assessed as the change in heart rate (HR, electrocardiography) or mean arterial pressure (MAP, radial artery catheter) elicited by 600 msec pulses of neck pressure and neck suction (NP/NS) from +40 to -70 torr. Pressures were applied using a lead collar wrapped about the subjects' necks during held expiration. Stimulus response data were fit to a logistic model and the parameters describing the curve were compared using two-factor ANOVA. The reductions CVP, mean (MAP), systolic, and pulse pressures during LBNP were similar between groups (P<0.05). However, diastolic blood pressure increased during LBNP m all but the HF group. (P<0.05). The slope of the FVR/CVP relationship did not differ between groups, nor did the form of the carotid-cardiac baroreflex stimulus response curve change during LBNP. changes in HR elicited with NP/NS were not different between groups (£>0.05). The range of the MAP stimulus response curve, however, was significantly less in the HP group compared to either the MP or LF group (£<0.05). These data imply that carotid baroreflex control of HR is unaltered by endurance exercise training, but carotid baroreflex control of blood pressure is impaired significantly, predisposing athletes to faintness.