Acute Aerobic Exercise Does Not Alter the Pressor Response to the Cold Pressor Test

Circulating vasodilator compounds are elevated after acute aerobic exercise, which contribute to post‐exercise hypotension and orthostatic intolerance. This suggests that the pressor response during sympathoexciation is blunted following acute aerobic exercise. The cold pressor test (CPT) is a sympathoexcitatory maneuver that increases heart rate and blood pressure. However, it is not known if cardiovascular dynamics during 2 minutes of the CPT are altered following acute aerobic treadmill exercise. Purpose Test the hypothesis that cardiovascular responses to the CPT following acute aerobic treadmill exercise are blunted. Methods Twelve healthy participants (23±4 years, 6 females) completed a CPT before and 10 minutes after treadmill exercise (20 minutes at 65–70% of age predicted maximum heart rate). During the CPT, a hand was submerged up to the wrist in ice water (~0°C) for 120 seconds. Heart rate (ECG) and blood pressure (photoplethysmography) were continuously recorded. Stroke volume was determined using Modelflow. Cardiac output was calculated as the product of heart rate and stroke volume. Total peripheral resistance was determined by dividing mean arterial pressure by cardiac output. Data were analyzed in 30 second increments. Perceived pain (0 = no pain, 10 = most severe pain) was obtained after each CPT. Data during the CPT are presented as a change from baseline and analyzed using repeated measures ANOVA. Results Baseline heart rate was higher post exercise (64 ± 8 vs. 86 ± 13 bpm, P < 0.01). Baseline mean arterial pressure (85 ± 10 vs. 80 ± 8 mmHg, P = 0.05) and systolic blood pressure (122 ± 14 vs. 114 ± 12 mmHg, P < 0.01) were lower post exercise. Baseline diastolic blood pressure (63 ± 8 vs. 61 ± 6 mmHg, P = 0.25), stroke volume (99 ± 14 vs. 97 ± 16 mL, P = 0.35), cardiac output (6.2 ± 0.8 vs. 6.6 ± 0.8 L/min, P = 0.16), and total peripheral resistance (13.9 ± 2.8 vs. 12.3 ± 1.8 mmHg/L/min, P = 0.10) were not different between pre‐ and post‐exercise. During the CPT, the increase in heart rate was greater pre‐ vs. post‐exercise at 30 seconds (22 ± 16 vs. 17 ± 13 bpm, P = 0.02) and 60 seconds (18 ± 16 vs. 12 ± 9 bpm, P < 0.01). Pre‐ and post‐exercise mean arterial pressure increased throughout the CPT and peaked at 90 seconds for pre‐ (26 ± 10 bpm, P < 0.01) and post‐exercise (27 ± 9 mmHg, P < 0.01). There were no differences in the mean arterial pressure responses to the CPT between pre‐and post‐exercise (P > 0.99). Pre‐ and post‐exercise total peripheral resistance increased throughout the CPT and peaked at 120 seconds for pre‐ (5.7 ± 4.7 mmHg/L/min, P < 0.01) and post‐exercise (5.0 ± 3.3 mmHg/L/min, P < 0.01). There were no differences in the total peripheral resistance responses during the CPT between pre‐ and post‐exercise (P > 0.13 for all). Perceived pain of the CPT was not different between pre‐ and post‐exercise (5 ± 2 vs. 6 ± 2 a.u., P = 0.13). Conclusion Post‐exercise heart rate responses to the CPT were blunted while mean arterial pressure and total peripheral resistance responses were not different between pre‐ and post‐exercise. These data indicate that the pressor responses to the CPT are not influenced by acute aerobic exercise whereas the heart rate response is attenuated. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .