Relationship Between The Blood Pressure Responses To Acute And Chronic Aerobic Exercise Among Adults With Hypertension

Abstract

Aerobic exercise acutely reduces blood pressure (BP) 5-7 mmHg among adults with hypertension, termed postexercise hypotension (PEH). PEH has been shown to be highly correlated to the BP response to exercise training in the laboratory. However, this relationship has yet to be explored under ambulatory conditions and compared to a control sham session (CONTROL) which is necessary to account for the circadian variation in ambulatory BP (ABP). PURPOSE: To examine the relationship between PEH (ABPACUTE) and the systolic BP (ASBP) and diastolic ambulatory BP (ADBP) responses to aerobic exercise training (ABPCHRONIC). METHODS: Adults with hypertension (n=24) completed a graded-exercise stress test (GEST) and CONTROL before and after 12wk moderate intensity aerobic exercise training. Ambulatory BP was assessed immediately after each experiment until the next morning and averaged at hourly intervals over 19hr. ABPACUTE was the difference between pre-training GEST minus CONTROL ABP. ABPCHRONIC was post- minus pre-training CONTROL ABP. ANCOVA tested differences in ABP over time with resting BP as a covariate. Multiple variable regression examined relationships among ABPACUTE and ABPCHRONIC. RESULTS: Subjects were middle-aged (52.3±10.8y), physically inactive adults with hypertension (136.3±10.7 / 85.2±8.9mmHg). Following the GEST, ABPACUTE (ASBP/ADBP) were lower -5.9±5.7mmHg /-2.9±4.1mmHg than CONTROL (ps<0.006). Following 12wk of aerobic exercise training, post-training ABP CONTROL (137.9±11.0 / 81.7±6.5mmHg) was not different than pre-training ABP CONTROL (137.5±6.6 / 80.5±5.7; ps>0.404). Multivariable regression analysis revealed that resting SBP, body mass index (BMI), and ASBPACUTE explained ~40% of the variance in ASBPCHRONIC, with ASBPACUTE explaining ~17% of the variance in ASBPCHRONIC (p=0.03). Similarly, resting DBP, BMI, and ADBPACUTE explained ~40% of the variance in ADBPCHRONIC, while DBPACUTE explained ~11% of the variance to DBPCHRONIC (p=0.06). CONCLUSION: ABPACUTE explained ~11-17% of the variability in exercise training-induced changes in ABPCHRONIC. The magnitude of the correlations we observed between ABPACUTE and ABPCHRONIC under ambulatory conditions appear to be less than those reported previously in the laboratory and merit further investigation.