Exercise increases arterial stiffness independent of blood pressure in older Veterans

Abstract

Background: Exercise-induced changes in arterial function could contribute to a hypertensive response to exercise (HRE) in older individuals. We performed the present analysis to define the acute arterial stiffness response to exercise in ambulatory older adults.

Methods: Thirty-nine Veterans (>60 years old), without known cardiovascular disease, participated in this study, including 19 Veterans who were hypertensive (70.8 ± 6.8 years, 53% women) and 20 Veterans who were normotensive (72.0 ± 9.3 years, 40% women). Arterial stiffness parameters were measured locally with carotid artery ultrasound and regionally with carotid-femoral pulse wave velocity (cfPWV) before and during the 10 min after participants performed a Balke maximal exercise treadmill stress test.

Results: The arterial stiffness response to exercise was similar for control and hypertensive participants. At 6 min postexercise, cfPWV was significantly increased (Δ1.5 ± 1.9 m/s, P = 0.004) despite mean blood pressure (BP) having returned to its baseline value (Δ1 ± 8 mmHg, P = 0.79). Arterial mechanics modeling also showed BP-independent increases in arterial stiffness with exercise ( P < 0.05). Postexercise cfPWV was correlated with postexercise SBP ( r = 0.50, P = 0.004) while baseline cfPWV ( r = 0.13, P = 1.00), and postexercise total peripheral resistance ( r = -0.18, P = 1.00) were not.

Conclusion: In older Veterans, exercise increases arterial stiffness independently of BP and the arterial stiffness increase with exercise is associated with increased postexercise SBP. BP-independent increases in arterial stiffness with exercise could contribute to a HRE in older adults.

Figure 1:

Diagram of the study visit day 1 timeline. A. First, baseline measurements were performed including carotid ultrasound, brachial blood pressure (BP), and carotid-femoral pulse wave velocity. B. Second, a maximal exercise stress test was performed. C. Finally, immediately post-exercise the participant returned to examination table and measurements were repeated for 10 minutes.

Figure 2:

Graphical representation of the participant specific models used to analyze the arterial stiffness response to exercise. Baseline data are shown as black circles, exercise data are shown as gray squares, and model calculations are shown as red stars. For Model 1, stiffness was calculated with the baseline pressure-diameter (PD) curve and post-exercise blood pressure (BP). For Model 2, stiffness was calculated with the baseline BP curve and post-exercise PD curve. The participant shown in Figure 2 is not representative as they had noticeable carotid artery vasodilation, however these data were chosen to show as the pre- and post-exercise PD curves are clearly separated.

Figure 3:

Hemodynamic and arterial stiffness responses to exercise. Time refers to time after exercise. Exercise A. increased systolic blood pressure (SBP), mean arterial pressure (MAP), and diastolic BP (DBP), B. increased heart rate (HR), C. decreased total peripheral resistance (TPR), D. increased carotid-femoral PWV (cfPWV), E. increased carotid Peterson’s elastic modulus (PEM), and F. did not change carotid artery diameter. Abbreviations: CT – Control, HT – hypertensive

Figure 4:

Arterial stiffness response to exercise for all participants plotted against change in mean blood pressure (MAP). Abbreviations: cfPWV – carotid-femoral pulse wave velocity, PEM – Peterson’s elastic modulus.

Figure 5:

Correlations of A. baseline, B. peak post-exercise, and C. pre-post exercise change in carotid-femoral pulse wave velocity (cfPWV) with the peak post-exercise systolic blood pressure (SBP) Abbreviations: CT – Control, HT – hypertensive, r – Pearson correlation coefficient

Figure 6:

Measured changes in arterial stiffness (black line) for both groups and arterial mechanics modeling of changes in arterial stiffness due to blood pressure dependent effects (blue line) and blood pressure independent effects (orange line) for A. carotid-femoral pulse wave velocity (cfPWV) and B. carotid Peterson’s elastic modulus (PEM). Results show significant BP-independent increases in arterial stiffness following exercise. For clarity, error bars are only shown for the directly measured stiffness values. Changes in cfPWV were modeled based on mean BP. Results for diastolic BP were similar and are presented in the supplemental results.