Effects of dynamic, isometric and combined resistance training on blood pressure and its mechanisms in hypertensive men

Abstract

Although dynamic resistance training (DRT) and isometric handgrip training (IHT) may decrease blood pressure (BP) in hypertensives, the effects of these types of training have not been directly compared, and a possible additive effect of combining IHT to DRT (combined resistance training-CRT), has not been investigated. Thus, this study compared the effects of DRT, IHT and CRT on BP, systemic hemodynamics, vascular function, and cardiovascular autonomic modulation. Sixty-two middle-aged men with treated hypertension were randomly allocated among four groups: DRT (8 exercises, 50% of 1RM, 3 sets until moderate fatigue), IHT (30% of MVC, 4 sets of 2 min), CRT (DRT + IHT) and control (CON - stretching). In all groups, the interventions were administered 3 times/week for 10 weeks. Pre- and post-interventions, BP, systemic hemodynamics, vascular function and cardiovascular autonomic modulation were assessed. ANOVAs and ANCOVAs adjusted for pre-intervention values were employed for analysis. Systolic BP decreased similarly with DRT and CRT (125 ± 11 vs. 119 ± 12 and 128 ± 12 vs. 119 ± 12 mmHg, respectively; P < 0.05), while peak blood flow during reactive hyperaemia (a marker of microvascular function) increased similarly in these groups (774 ± 377 vs. 1067 ± 461 and 654 ± 321 vs. 954 ± 464 mL/min, respectively, P < 0.05). DRT and CRT did not change systemic hemodynamics, flow-mediated dilation, and cardiovascular autonomic modulation. In addition, none of the variables were changed by IHT. In conclusion, DRT, but not IHT, improved BP and microvascular function in treated hypertensive men. CRT did not have any additional effect in comparison with DRT alone.

Keywords: Autonomic modulation; Hemodynamics; Hypertension; Strength training; Vascular function.

Fig. 1

Flow diagram of the current trial. N number of participants, BMI body mass index, COVID-19 coronavirus disease 2019, HIV human immunodeficiency virus, BP blood pressure, EXP experimental session, MI myocardial infarction, DRT dynamic resistance training, IHT isometric handgrip training, CRT combined resistance training, CON control

Fig. 2

Between-groups comparisons of changes (post-intervention – pre-intervention) adjusted for pre-intervention values for the following variables: systolic blood pressure (SBP – A), diastolic blood pressure (DBP – B), systemic vascular resistance (SVR – C), cardiac output (CO – D), stroke volume (SV – E) and heart rate (HR – F). DRT dynamic resistance training, IHT isometric handgrip training, CRT combined resistance training, CON control. Analysis: One-way ANCOVA adjusted for pre-intervention values. Bold values mean significant result

Fig. 3

Between-groups comparisons of changes (post-intervention – pre-intervention) adjusted for pre-intervention values for the following variables: ratio between low- and high-frequency bands of R-R interval variability (LF/HF_R-R –A), low-frequency band of systolic blood pressure variability (LF_SBP – B), baroreflex sensitivity (BRS – C), baseline vascular conductance (VC – D), baseline blood flow (BF – E), peak blood flow (F), peak shear rate (G) and flow-mediated dilation (FMD - H). DRT dynamic resistance training, IHT isometric handgrip training, CRT combined resistance training, CON control, nl natural logarithm. Analysis: One-way ANCOVA adjusted for pre-intervention values. Bold values mean significant result