Intra-arterial blood pressure response in hypertensive subjects during low- and high-intensity resistance exercise

Abstract

Objective: The aim of this study was to describe blood pressure responses during resistance exercise in hypertensive subjects and to determine whether an exercise protocol alters these responses.

Introduction: Resistance exercise has been recommended as a complement for aerobic exercise for hypertensive patients. However, blood pressure changes during this kind of exercise have been poorly investigated in hypertensives, despite multiple studies of normotensives demonstrating significant increases in blood pressure.

Methods: Ten hypertensive and ten normotensive subjects performed, in random order, two different exercise protocols, composed by three sets of the knee extension exercise conducted to exhaustion: 40% of the 1-repetition maximum (1RM) with a 45-s rest between sets, and 80% of 1RM with a 90-s rest between sets. Radial intra-arterial blood pressure was measured before and throughout each protocol.

Results: Compared with normotensives, hypertensives displayed greater increases in systolic BP during exercise at 80% (+80 +/-3 vs. +62 +/-2 mmHg, P<0.05) and at 40% of 1RM (+75 +/-3 vs. +67 +/-3 mmHg, P<0.05). In both exercise protocols, systolic blood pressure returned to baseline during the rest periods between sets in the normotensives; however, in the hypertensives, BP remained slightly elevated at 40% of 1RM. During rest periods, diastolic blood pressure returned to baseline in hypertensives and dropped below baseline in normotensives.

Conclusion: Resistance exercise increased systolic blood pressure considerably more in hypertensives than in normotensives, and this increase was greater when lower-intensity exercise was performed to the point of exhaustion.

Keywords: Autonomic nervous system; Exercise intensity; Hypertension; Resistive exercise; Strength exercise.

Figure 1

Systolic blood pressure (SBP) measured during each heart beat in a representative hypertensive subject performing a set of leg extension exercises until exhaustion at 40% of 1RM (repetition maximum).

Figure 2

Systolic blood pressure (SBP, solid lines) and diastolic blood pressure (DBP, dashed lines) measured before (Pre), during sets (S), and during rest periods (R) of knee extension exercises performed at 40% of the 1-repetition maximum (1RM, panels a and b) and 80% of 1RM (panels c and d) in hypertensive subjects (panels a and c) and normotensive subjects (panels b and d). *, P<0.05 vs. Pre.

Figure 3

Systolic blood pressure (SBP) responses, expressed as the value during a set minus the pre-exercise value (ΔSBP), during each of three sets (S1, S2, and S3) of knee extension resistance exercises performed to exhaustion at 40% and 80% of 1RM (repetition maximum) in hypertensive (HT) and normotensive (NT) subjects. †, P<0.05 vs. normotensive subjects; ‡, P<0.05 vs. 80% of 1RM.

Figure 4

Diastolic blood pressure (DBP) responses, expressed as the value during a set minus the pre-exercise value (ΔDBP), during each of three sets (S1, S2, and S3) of knee extension resistance exercises performed to exhaustion at 40% and 80% of 1RM (repetition maximum) in hypertensive (HT) subjects and normotensive (NT) subjects.