Consistency of hemodynamic and autonomic mechanisms underlying post-exercise hypotension

Post-exercise hypotension (PEH) is a clinically relevant phenomenon, but its mechanisms vary between different studies and between the participants within each study. Additionally, it is possible that PEH mechanisms are not consistent in each individual (i.e. within-individual variation), which has not been investigated yet. Thus, the aim of the current study was to assess the within-individual consistency of PEH hemodynamic and autonomic mechanisms. For that, 30 subjects performed 4 sessions divided in 2 blocks (test and retest). In each block, an exercise (cycling, 45 min, 50%VO2peak) and a control (seated rest, 45 min) session was randomly conducted. Blood pressure (BP) and its mechanisms were evaluated pre- and post-interventions. In each block, individual responses were calculated as post-exercise minus post-control, and a response was considered present when its magnitude reached the typical error of the measurement. Consistencies were evaluated by comparing test and retest responses through kappa coefficient (k). PEH consistency was calculated using role sample, while mechanisms consistency was evaluated in those with consistent PEH. Twenty-one (70%) participants showed consistent PEH, 5 (17%) presented PEH in only test or retest and 4 (13%) had absent PEH response, characterising a good consistency (k = 0.510). Regarding mechanisms’ responses, good consistency was found for heart rate (k = 0.456), sympathovagal balance (k = 0.438), and baroreflex sensitivity (k = 0.458); while systemic vascular resistance (k = 0.152), cardiac output (k = −0.400), stroke volume (k = −0.055), and sympathetic vasomotor modulation (k = −0.096) presented marginal consistencies. Thus, PEH is a highly consistent physiological phenomenon, although its mechanisms present variable consistencies

Post-exercise hypotension and its hemodynamic determinants depend on the calculation approach

Post-exercise hypotension (PEH) has been assessed by three calculation approaches: I = (post-exercise − pre-exercise), II = (post-exercise − post-control), and III = [(post-exercise − pre-exercise) − (post-control − pre-control)]. This study checked whether these calculation approaches influence PEH and its determinants. For that, 30 subjects underwent two exercise (cycling, 45 min, 50% VO2 peak) and two control (seated rest, 45 min) sessions. Systolic (SBP) and diastolic (DBP) blood pressures, cardiac output (CO), systemic vascular resistance (SVR), heart rate (HR), and stroke volume (SV) were measured pre- and post-interventions in each session. The mean value for each moment in each type of session was calculated, and responses to exercise were analyzed with each approach (I, II, and III) to evaluate the occurrence of PEH and its determinants. Systolic PEH was significant when calculated by all approaches (I = −5 ± 1, II = −11 ± 2, and III = −11 ± 2 mmHg, p < 0.05), while diastolic PEH was only significant when calculated by approaches II and III (−6 ± 1 and −6 ± 1 mmHg, respectively, p < 0.05). CO decreased significantly after the exercise when calculated by approach I, but remained unchanged with approaches II and III, while SVR increased significantly with approach I, but decreased significantly with approaches II and III. HR was unchanged after the exercise with approach I, but increased significantly with approaches II and III, while SV decreased significantly with all approaches. Thus, PEH and its hemodynamic determinants are influenced by the calculation approach, which should be considered when designing, analyzing, and comparing PEH studies

Recommendations in Post-exercise Hypotension: Concerns, Best Practices and Interpretation

Post-exercise hypotension (PEH) is a clinically relevant phenomenon that has been widely investigated. However, the characteristics of study designs, such as familiarization to blood pressure measurements, duration of PEH assessments or strategies to analyze PEH present discrepancies across studies. Thus identifying key points to standardize across PEH studies is necessary to help researchers to build stronger study designs, to facilitate comparisons across studies, and to avoid misinterpretations of results. The goal of this narrative review of methods used in PEH studies was therefore to gather and find possible influencers in the characteristics of study design and strategies to analyze blood pressure. Data found in this review suggest that PEH studies should have at least two familiarization screening visits, and should assess blood pressure for at least 20 min, but preferably for 120 min, during recovery from exercise. Another important aspect is the strategy to analyze PEH, which may lead to different interpretations. This information should guide a priori study design decisions

Reproducibility of heart rate recovery in patients with intermittent claudication

Background: Postexercise heart rate recovery (HRR) is a non-invasive tool for cardiac autonomic function assessment. Reproducibility of HRR has been established in healthy subjects; however, no study has evaluated this reproducibility in clinical populations who may present autonomic dysfunction. Patients with peripheral artery disease and intermittent claudication (IC) often present altered cardiac autonomic function and HRR could be an interesting tool for evaluating autonomic responses to interventions in this population. Therefore, the reproducibility of HRR should be determined in this specific population. Objective: To determine the reproducibility of HRR indices in patients with IC. Methods: Nineteen men with IC underwent two repeated maximal treadmill tests. Raw HR and relative HRR (difference to exercise peak) indices measured at 30, 60, 120, 180, 240 and 300s of recovery were evaluated. The presence of systematic bias was assessed by comparing test and retest mean values via paired t-test. Reliability was assessed by intraclass correlation coefficient (ICC), and agreement by typical error (TE), coefficient of variation (CV) and minimal detectable difference (MDD). Results: There were no significant differences between the test and retest values of all raw HR and relative HRR indices (P ≥ 0·05), except for HR120s (P = 0·032). All indices exhibited excellent reliability (ICC ≥ 0·78). Raw HR and relative HRR indices showed TEs ≤ 6·4 bpm and MDDs ≤ 17·8 bpm. In addition, all indices showed CVs ≤ 13·2%, except HRR30s (CV = 45·6%). Conclusions: The current results demonstrated that most HRR indices were highly reproducible with no systematic error, excellent reliability and good agreement in patients with IC following maximal graded exercise

Can blood pressure decrease after maximal exercise test predict the blood pressure lowering effect of aerobic training in treated hypertensive men?

The acute decrease in blood pressure (BP) observed after a session of exercise (called post-exercise hypotension) has been proposed as a tool to predict the chronic reduction in BP induced by aerobic training. Therefore, this study investigated whether post-exercise hypotension observed after a maximal exercise test is associated to the BP-lowering effect of aerobic training in treated hypertensives. Thirty hypertensive men (50 ± 8 years) who were under consistent anti-hypertensive treatment underwent a maximal exercise test (15 watts/min until exhaustion), and post-exercise hypotension was determined by the difference between BP measured before and at 30 min after the test. Subsequently, the patients underwent 10 weeks of aerobic training (3 times/week, 45 min/session at moderate intensity), and the BP-lowering effect of training was assessed by the difference in BP measured before and after the training period. Pearson correlations were employed to evaluate the associations. Post-maximal exercise test hypotension was observed for systolic and mean BPs (−8 ± 6 and −2 ± 4 mmHg, all P 0.05). Post-exercise hypotension assessed 30 min after a maximal exercise test cannot be used to predict the BP-lowering effect of aerobic training in treated hypertensive men

Effects of dynamic, isometric, and combined resistance training on ambulatory blood pressure in treated men with hypertension: a randomized controlled trial

Ambulatory blood pressure (ABP) monitoring is a widespread recommendation for the diagnosis and management of hypertension. Dynamic resistance training (DRT) and isometric handgrip training (IHT) have been recommended for hypertension treatment, but their effects on ABP have been poorly studied. Additionally, combined dynamic and isometric handgrip resistance training (CRT) could produce an additive effect that has yet to be tested. Thus, this randomized controlled trial was designed to evaluate the effects of DRT, IHT and CRT on mean ABP and ABP variability. Fifty-nine treated men with hypertension were randomly allocated to 1 of four groups: DRT (8 dynamic resistance exercises, 50% of 1RM, 3 sets until moderate fatigue), IHT (4 sets of 2 min of isometric handgrip at 30% of MVC), CRT (DRT + IHT) and control (CON – 30 min of stretching). Interventions occurred 3 times/week for 10 weeks, and ABP was assessed before and after the interventions. ANOVAs and ANCOVAs adjusted for pre-intervention values were employed for analysis. Mean 24-hour, awake and asleep BPs did not change in either group throughout the study (all, P> 0.05). Nocturnal BP fall as well as the standard deviation, coefficient of variation and the average real variability of ABP also did not change significantly in either group (all, P 0.05). In treated men with hypertension, 10 weeks of DRT, IHT or CRT does not decrease ABP levels nor change ABP variability