The effects of the antihypertensive agent Losartan (Lo), on acute exercise performance was assessed in six sedentary, hypertensive women. The purpose, benefits and potential risks of the study were explained to each subject and their informed consent received. In a double blinded crossover design subjects were randomized to 7 days of (Lo) 50 mg, once every morning or placebo (Pl). Subjects reported to the laboratory for an exercise trial on the 7th treatment day. They received the final treatment dose 2.5 hours before the exercise trial. Blood samples for analysis of plasma renin activity (PRA) and Angiotensin II (Ang II) were obtained 15 min before the exercise trial began. In each trial, the subject rested for 15 min in a seated position on the stationary cycle. Hemodynamic and respiratory measurements were obtained. They began exercise at a workload equivalent to 45% VO2 pk for 15 min, immediately followed by a progression of 30 Watt*2 min-1 until volitional fatigue. Measurements included: blood pressure, heart rate, respiratory gas exchange, cardiac output (Q) and rate of perceived exertion (RPE). Total peripheral resistance index (TPRI), stroke volume index (SVI) and rate pressure product (RPP) were calculated. Compared to the pre-administration conditions, 1 week of Losartan treatment significantly reduced (p< .05) resting MAP, SBP and DBP in these subjects. Losartan treatment did not modify submaximal exercise HR, Q, VO2 or RPE. The RPP also was not different between the Lo and Pl trials at rest (p >.05), but was reduced at peak exercise with Lo treatment (p<.05). Losartan significantly reduced calculated TPRI at rest (p< .05) in comparison with Pl (12%) but not during steady-state exercise. Circulating plasma levels of Ang II and PRA were significantly higher with Lo (p<.05). In conclusion, Losartan, a new antihypertensive medication, reduced BP without altering exercise performance in hypertensive women. Losartan is an appropriate first line antihypertensive agent to use in treatment of hypertensive individuals who wish to participate in a regular exercise program. / Ph. D.

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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)