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

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.

Potential Mechanisms Behind the Blood Pressure-Lowering Effect of Dynamic Resistance Training.

PURPOSE OF REVIEW: To elucidate the hemodynamic, autonomic, vascular, hormonal, and local mechanisms involved in the blood pressure (BP)-lowering effect of dynamic resistance training (DRT) in prehypertensive and hypertensive populations. RECENT FINDINGS: The systematic search identified 16 studies involving 17 experimental groups that assessed the DRT effects on BP mechanisms in prehypertensive and/or hypertensive populations. These studies mainly enrolled women and middle-aged/older individuals. Vascular effects of DRT were consistently reported, with vascular conductance, flow-mediated dilation, and vasodilatory capacity increases found in all studies. On the other hand, evidence regarding the effects of DRT on systemic hemodynamics, autonomic regulation, hormones, and vasoactive substances are still scarce and controversial, not allowing for any conclusion. The current literature synthesis shows that DRT may promote vascular adaptations, improving vascular conductance and endothelial function, which may have a role in the BP-lowering effect of this type of training in prehypertensive and hypertensive individuals. More studies are needed to explore the role of other mechanisms in the BP-lowering effect of DRT.

Comparison of morning versus evening aerobic-exercise training on heart rate recovery in treated hypertensive men: a randomized controlled trial.

Heart rate recovery (HRR) is a marker of cardiac autonomic regulation and an independent predictor of mortality. Aerobic-exercise training conducted in the evening (evening training) produces greater improvement in resting cardiac autonomic control in hypertensives than morning training, suggesting it may also result in a faster autonomic restoration postexercise. This study compared the effects of morning training and evening training on HRR in treated hypertensive men. Forty-nine treated hypertensive men were randomly allocated into three groups: morning training, evening training and control. Training was conducted three times/week for 10 weeks. Training groups cycled (45 min, moderate intensity) while control group stretched (30 min). In the initial and final assessments of the study, HRR60s and HRR300s were evaluated during the active recovery (30 W) from cardiopulmonary exercise tests (CPET) conducted in the morning and evening. Between-within ANOVAs were applied (P ≤ 0.05). Only evening training increased HRR60s and HRR300 differently from control after morning CPET (+4 ± 5 and +7 ± 8 bpm, respectively, P < 0.05) and only evening training increased HRR300s differently from morning training and control after evening CPET (+8 ± 6 bpm, P < 0.05). Evening training improves HRR in treated hypertensive men, suggesting that this time of day is better for eliciting cardiac autonomic improvements via aerobic training in hypertensives.

Post-dynamic Resistance Exercise Hypotension: Exploring Individual Responses and Predictors.

Background: Post-dynamic resistance exercise hypotension (PREH) has been largely demonstrated. However, little is known regarding the interindividual variation of PREH magnitude and its predictors (i.e. factors of influence). Aims: To assess the interindividual variation of PREH and its predictors related to the characteristics of the individuals and the exercise protocol. Methods: This study retrospectively analysed data from 131 subjects included in seven controlled trials about PREH (including at least one dynamic resistance exercise and one control session) conducted by two research laboratories. The interindividual variation was assessed by the standard deviation of the individual responses (SD IR), and linear regression analyses were conducted to explore the predictors. Results: PREH showed moderate interindividual variation for systolic (SBP, SD IR=4.4mmHg; 0.35 standardised units) and diastolic blood pressures (DBP, SD IR=3.6mmHg; 0.32 standardised units). For systolic PREH, multivariate regression analysis (R 2=0.069) revealed higher baseline SBP (B=-0.157, p=0.008) and higher number of sets (B=-3.910, p=0.041) as significant predictors. For diastolic PREH, multivariate regression analysis (R 2=0.174) revealed higher baseline DBP (B=-0.191, p=0.001) and higher exercise volume (i.e. number of exercises *sets per exercise *repetitions per sets >150; B=-4.212, p=0.001) as significant predictors. Conclusion: PREH has a considerable interindividual variation. Greater PREH magnitude is observed in individuals with higher baseline blood pressure and after exercise protocols that comprehend higher number of sets and exercise volume.

Poor sleep quality is associated with cardiac autonomic dysfunction in treated hypertensive men.

Hypertensives present cardiac autonomic dysfunction. Reduction in sleep quality increases blood pressure (BP) and favors hypertension development. Previous studies suggested a relationship between cardiovascular autonomic dysfunction and sleep quality, but it is unclear whether this association is present in hypertensives. Thus, this study evaluated the relationship between sleep quality and cardiac autonomic modulation in hypertensives. Forty-seven middle-aged hypertensive men under consistent anti-hypertensive treatment were assessed for sleep quality by the Pittsburgh Sleep Quality Index (PSQI-higher score means worse sleep quality). Additionally, their beat-by-beat BP and heart rate (HR) were recorded, and cardiac autonomic modulation was assessed by their variabilities. Mann-Whitney and t tests were used to compare different sleep quality groups: poor (PSQI > 5, n = 24) vs good (PSQI ≤ 5, n = 23), and Spearman's correlations to investigate associations between sleep quality and autonomic markers. Patients with poor sleep quality presented lower cardiac parasympathetic modulation (HR high-frequency band = 26 ± 13 vs 36 ± 15 nu, P = .03; HR total variance = 951 ± 1373 vs 1608 ± 2272 ms2 , P = .05) and cardiac baroreflex sensitivity (4.5 ± 2.3 vs 7.1 ± 3.7 ms/mm Hg, P = .01). Additionally, sleep quality score presented significant positive correlation with HR (r = +0.34, P = .02) and negative correlations with HR high-frequency band (r = -0.34, P = .03), HR total variance (r = -0.35, P = .02), and cardiac baroreflex sensitivity (r = -0.42, P = .01), showing that poor sleep quality is associated with higher HR and lower cardiac parasympathetic modulation and baroreflex sensitivity. In conclusion, in treated hypertensive men, poor sleep quality is associated with cardiac autonomic dysfunction.

Effect of Resistance Training on Arterial Stiffness in Healthy Subjects: A Systematic Review and Meta-Analysis.

PURPOSE OF REVIEW: The aim of this systematic review and meta-analysis was to investigate the effect of resistance training on arterial stiffness (AS) in healthy subjects. Two electronic databases (PubMed and Scielo) were searched for randomized controlled trials comparing the effect of dynamic and/or isometric resistance training stand-alone versus non-exercise control group on AS assessed by pulse wave velocity (PWV) in healthy subjects. Random-effects modeling was employed to compare delta changes (post-pre-intervention) in AS between the resistance training and control group. Data were reported as weighted mean difference (MD) and its 95% confidence intervals (CI). Statistical significance was set at 5%. RECENT FINDINGS: A total of 10 studies involving 310 participants (46.5% female; resistance training groups, n = 194; control groups, n = 116) were included in the meta-analysis. Comparing changes from pre- to post-resistance training groups versus control groups, no differences were observed in PWV (MD - 1.33 cm/s (95% CI - 34.58 to 31.91), p = 0.94, I2 = 91%). Resistance training stand-alone does not elicit changes (i.e., improvement or impairment) on AS in healthy subjects, but the high heterogeneity suggests influence of training protocol and/or personal characteristics that should be investigated in the future.

Reproducibility of post-exercise heart rate recovery indices: A systematic review.

Heart rate recovery (HRR) has been widely used to evaluate the integrity of the autonomic nervous system with a slower HRR being associated with greater cardiovascular risk. Different HRR indices have been proposed. Some evaluate HR changes from the end of exercise to a specific recovery moment (e.g. 60s - HRR60s; 120s - HRR120s; 300s - HRR300s) and others calculate time-constant decays of HR for different recovery intervals (e.g. first 30s - T30; the entire period - HRRt). Several studies have examined the reproducibility of these commonly-used HRR indices, but reported discordant findings. Thus, this systematic review was designed to synthesize the reproducibility of HRR. We included studies that evaluated short-term (<1 year) reproducibility of HRR after dynamic exercise by employing typical measures of reliability (intraclass correlation coefficient, ICC) and agreement (coefficient of variation, CV). The electronic database PubMed/Medline was searched for relevant studies published up to July 2018. From the initial 120 records identified, 15 studies were retained for the qualitative synthesis of 24 experimental conditions. During most experimental conditions, high ICC and desirable CV were reported for HRR60s (62.5 and 76.2%, respectively), HRR120s (55.6 and 71.4%) and HRR300s (50.0 and 100.0%). While, it were reported during the minority of conditions for HRRt (37.5 and 42.9%) and in none condition for T30 (0.0 and 0.0%). In conclusion, HRR60s, HRR120s and HRR300s exhibited good reproducibility for evaluating HRR in predominantly healthy males within research and clinical settings. In contrast, caution should be taken when employing other HRR indices (T30, HRRt) due to their poorer reproducibility.

Morning versus Evening Aerobic Training Effects on Blood Pressure in Treated Hypertension.

INTRODUCTION: The acute blood pressure (BP) decrease is greater after evening than morning exercise, suggesting that evening training (ET) may have a greater hypotensive effect. OBJECTIVE: This study aimed to compare the hypotensive effect of aerobic training performed in the morning versus evening in treated hypertensives. METHODS: Fifty treated hypertensive men were randomly allocated to three groups: morning training (MT), ET, and control (C). Training groups cycled for 45 min at moderate intensity (progressing from the heart rate of the anaerobic threshold to 10% below the heart rate of the respiratory compensation point), while C stretched for 30 min. Interventions were conducted 3 times per week for 10 wk. Clinic and ambulatory BP and hemodynamic and autonomic mechanisms were evaluated before and after the interventions. Clinic assessments were performed in the morning (7:00-9:00 AM) and evening (6:00-8:00 PM). Between-within ANOVA was used (P ≤ 0.05). RESULTS: Only ET decreased clinic systolic BP differently from C and MT (morning assessment -5 ± 6 mm Hg and evening assessment -8 ± 7 mm Hg, P < 0.05). Only ET reduced 24 h and asleep diastolic BP differently from C and MT (-3 ± 5 and -3 ± 4 mm Hg, respectively, P < 0.05). Systemic vascular resistance decreased from C only in ET (P = 0.03). Vasomotor sympathetic modulation decreased (P = 0.001) and baroreflex sensitivity (P < 0.02) increased from C in both training groups with greater changes in ET than MT. CONCLUSIONS: In treated hypertensive men, aerobic training performed in the evening decreased clinic and ambulatory BP due to reductions in systemic vascular resistance and vasomotor sympathetic modulation. Aerobic training conducted at both times of day increases baroreflex sensitivity, but with greater after ET.

Reproducibility of Hemodynamic, Cardiac Autonomic Modulation, and Blood Flow Assessments in Patients with Intermittent Claudication.

BACKGROUND: The aim of this study is to identify, in patients with peripheral artery disease and intermittent claudication (IC), the reproducibility of heart rate (HR), blood pressure (BP), rate pressure product, heart rate variability (HRV), and forearm and calf blood flow (BF) and vasodilatory assessments. METHODS: Twenty-nine patients with IC underwent test and retest sessions, 8-12 days apart. During each session, HR, BP, HRV, BF, and vasodilatory responses were measured by electrocardiogram, auscultation, spectral analysis of HRV (low frequency, LFR-R; high frequency, HFR-R), and strain gauge plethysmography (baseline BF, post-occlusion BF, post-occlusion area under the curve). Reproducibility was determined by intra-class correlation coefficient (ICC), typical error, coefficient of variation (CV), and limits of agreement. RESULTS: The ICC for HR and BP was >0.8 with CV <9%. For most HRV measures, ICC was >0.9 while CV was <7%, except for LF/HF (ICC = 0.737, CV = 93.8%). The ICC for forearm and calf baseline BF assessments was >0.9 while CV was <19%; variable ICC and CV for vasodilatory responses were exhibited for calf (0.653-0.770, 35.2-37.7%) and forearm (0.169-0.265, 46.2-55.5%). CONCLUSIONS: In male patients with IC, systemic hemodynamics (HR and BP), cardiac autonomic modulation (LFR-R and HFR-R), and forearm and calf baseline BF assessments exhibited excellent reproducibility, whereas the level of reproducibility for vasodilatory responses were moderate to poor. Assessment reproducibility has highlighted appropriate clinical tools for the regular monitoring of disease/intervention progression in patients with IC.

Postexercise hypotension as a clinical tool: a "single brick" in the wall.

After an exercise session, a reduction of blood pressure (BP) is expected, a phenomenon called postexercise hypotension (PEH). PEH as a predictor of chronic training responses for BP has been broadly explored. It suggests that when PEH occurs after each exercise sessions, its benefits may summate over time, contributing to the chronic adaptation. Thus, PEH is an important clinical tool, acting as a "single brick" in the wall, and building the chronic effect of decreasing BP. However, there is large variation in the literature regarding methodology and results, creating barriers for understanding comparisons among PEH studies. Thus, the differences among subjects' and exercise protocols' characteristics observed in the studies investigating PEH must be considered when readers interpret the results. Furthermore, understanding of these factors of influence might be useful for avoiding misinterpretations in future comparisons and how the subjacent mechanisms contribute to the BP reduction after exercise.