Passive Heating Attenuates Post-Exercise Cardiac Autonomic Recovery in Healthy Young Males

Post-exercise heart rate (HR) recovery (HRR) presents a biphasic pattern, which is mediated by parasympathetic reactivation and sympathetic withdrawal. Several mechanisms regulate these post-exercise autonomic responses and thermoregulation has been proposed to play an important role. The aim of this study was to test the effects of heat stress on HRR and HR variability (HRV) after aerobic exercise in healthy subjects. Twelve healthy males (25 ± 1 years, 23.8 ± 0.5 kg/m2) performed 14 min of moderate-intensity cycling exercise (40–60% HRreserve) followed by 5 min of loadless active recovery in two conditions: heat stress (HS) and normothermia (NT). In HS, subjects dressed in a whole-body water-perfused tube-lined suit to increase internal temperature (Tc) by ~1°C. In NT, subjects did not wear the suit. HR, core and skin temperatures (Tc and Tsk), mean arterial pressure (MAP) skin blood flow (SKBF), and cutaneous vascular conductance (CVC) were measured throughout and analyzed during post-exercise recovery. HRR was assessed through calculations of HR decay after 60 and 300 s of recovery (HRR60s and HRR300s), and the short- and long-term time constants of HRR (T30 and HRRt). Post-exercise HRV was examined via calculations of RMSSD (root mean square of successive RR intervals) and RMS (root mean square residual of RR intervals). The HS protocol promoted significant thermal stress and hemodynamic adjustments during the recovery (HS-NT differences: Tc = +0.7 ± 0.3°C; Tsk = +3.2 ± 1.5°C; MAP = −12 ± 14 mmHg; SKBF = +90 ± 80 a.u; CVC = +1.5 ± 1.3 a.u./mmHg). HRR and post-exercise HRV were significantly delayed in HS (e.g., HRR60s = 27 ± 9 vs. 44 ± 12 bpm, P < 0.01; HRR300s = 39 ± 12 vs. 59 ± 16 bpm, P < 0.01). The effects of heat stress (e.g., the HS-NT differences) on HRR were associated with its effects on thermal and hemodynamic responses. In conclusion, heat stress delays HRR, and this effect seems to be mediated by an attenuated parasympathetic reactivation and sympathetic withdrawal after exercise. In addition, the impact of heat stress on HRR is related to the magnitude of the heat stress-induced thermal stress and hemodynamic changes

Reliability of heart rate variability in futsal players

The main aim the present study was evaluated the reliability of the heart rate variability (HRV) indices in futsal players. Additionally the study verifi ed the reliability of different approaches for 5 min interval selection of recording. Eighteen under-20 futsal players underwent 15 min of pre-training RR interval recordings in two different day. Time and frequency domain and Poincaré Plot indices were tested. The indices were calculated using: 1) fi nal 5 min of recording; 2) 5 min of lower variance of recording, by a mathematical algorithm; 3) 5 min segment of lower variance, by an experienced operator. The HRV indices presented a wide range reliability [e.g. RRmean (ICC=0.96, SEM=3.4ms, CV=2.6%), lnRMSSD (ICC=0.88, SEM=5.9ms, CV=4.3%), lnHF (ICC=0.89, SEM=7.5ms, CV=5.9%), LFnu (ICC=0.84, SEM=13ms, CV=9.4%), LF (ICC=0.47, SEM=65.2ms,CV=38.5%) and LF/HF (ICC=0.63, SEM=83.7ms, CV=54.5%)]. The fi nal 5 min of recording was the most reliable. The results suggest that most of HRV indices presented acceptable reliability, however the RRmean, lnRMSSD, lnHF and LFnu were the most reliable

Efeito da ingestão hídrica sobre a recuperação cardiovascular pós-exercício

Physical exercise elicits an increase in heart rate (HR), blood pressure (BP) and, consequently, in the rate-pressure product (RPP). Recovery of HR immediately after exercise indicates cardiovascular health. Blood pressure also decreases after exercise, occasionally reaching values lower than pre-exercise levels (postexercise hypotension). Studies have shown a positive effect of water intake on HR recovery after exercise. However, little is known about the effect of water intake on postexercise BP and RPP responses. The objective of this study was to evaluate the effects of water intake on postexercise cardiac work assessed by HR, BP and RPP. Fourteen healthy volunteers (22 ± 1.4 years) participated in the study. The experimental session consisted of HR, systolic (SBP) and diastolic BP (DBP) recording at rest, followed by submaximal exercise on a cycle ergometer. Next, the subjects consumed water and the cardiovascular variables were recorded during recovery. In addition, a control session without postexercise water intake was performed. The RPP was calculated from the product of HR and SBP. Water intake prevented a postexercise hypotensive effect on DBP, but accelerated postexercise HR and RPP reduction during recovery when compared to the control session. It was concluded that water intake is an effective strategy to reduce postexercise cardiac work.O exercício físico promove a elevação da frequência cardíaca (FC), pressão arterial (PA) e, por consequência, do duplo produto (DP). Imediatamente após o término do exercício, há a recuperação da FC; resposta que indica boa saúde cardiovascular. A PA também apresenta queda pós-exercício, atingindo, eventualmente, valores abaixo do repouso (hipotensão pós-exercício; HPE). Estudos têm demonstrado efeito positivo da ingestão hídrica (IH) sobre a recuperação da FC pós-exercício. Pouco se sabe a respeito do efeito dessa estratégia sobre o comportamento da PA e do DP nesse período. O objetivo do estudo foi investigar o efeito da IH sobre o trabalho cardiovascular pós-exercício, por meio da avaliação da FC, PA e DP. Quatorze voluntários saudáveis (22 ± 1,4 anos) participaram desse estudo. A sessão experimental constou do registro da FC e PA sistólica (PAS) e diastólica (PAD) de repouso, seguido de exercício físico submáximo em cicloergômetro. Posteriormente, realizou-se a IH e registro das variáveis cardiovasculares na recuperação. Adicionalmente, realizou-se uma sessão controle, excluindo-se a IH pós-exercício. O DP foi calculado a partir do produto da FC pela PAS. A IH impediu a ocorrência de HPE na PAD, porém acelerou a redução da FC e do DP, no período da recuperação pós-exercício, quando comparada à sessão controle. Pode-se concluir que a IH é uma estratégia eficiente na redução do trabalho cardiovascular pós-exercício

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. Summary: 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

Reproducibility of hemodynamic, cardiac autonomic modulation and blood flow assessments in patients with intermittent claudication

Objective: To identify, in patients with peripheral artery disease and intermittent claudication (IC), the reproducibility of heart rate (HR), blood pressure (BP), rate pressure product (RPP), 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, AUC). Reproducibility was determined by intraclass coefficient correlation (ICC), typical error, coefficient of variation (CV) and limits of agreement. Results: The ICC for HR and BP were > 0.8 with CV 0.9 while CV were 0.9 while CV were < 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 hemodynamic (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

Association of health vulnerability with adverse outcomes in older people with COVID-19: a prospective cohort study

OBJECTIVES: Health vulnerability is associated with a higher risk of mortality and functional decline in older people in the community. However, few studies have evaluated the role of the Vulnerable Elders Survey (VES-13) in predicting clinical outcomes of hospitalized patients. In the present study, we tested the ability of the VES-13 to predict mortality and the need for invasive mechanical ventilation in older people hospitalized with coronavirus disease 2019 (COVID-19). METHODS: This prospective cohort included 91 participants aged X60 years who were confirmed to have COVID-19. VES-13 was applied, and the demographic, clinical, and laboratory variables were collected within 72h of hospitalization. A Poisson generalized linear regression model with robust variance was used to estimate the relative risk of death and invasive mechanical ventilation. RESULTS: Of the total number of patients, 19 (21%) died and 15 (16%) required invasive mechanical ventilation. Regarding health vulnerability, 54 (59.4%) participants were classified as non-vulnerable, 30 (33%) as vulnerable, and 7 (7.6%) as extremely vulnerable. Patients classified as extremely vulnerable and male sex were strongly and independently associated with a higher relative risk of in-hospital mortality (po0.05) and need for invasive mechanical ventilation (po0.05). CONCLUSION: Elderly patients classified as extremely vulnerable had more unfavorable outcomes after hospitalization for COVID-19. These data highlight the importance of identifying health vulnerabilities in this population

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

Water ingestion accelerates the post-exercise heart rate recovery

Post-exercise heart rate recovery is an easy-to-apply index which reflects the post-exercise vagal reactivation. Water intake produces significant changes on the cardiovascular system, promoting an increase in heart vagal modulation. The aim of this study was to investigate the influence of water intake on the heart rate recovery. Ten healthy subjects of both genders were enrolled in this study. The experimental session consisted of performing cyclergometer exercise, water intake and heart rate recovery recording. There was also a control session. From the heart rate values of exercise and recovery the deltas of 60 and 120 seconds of recovery were calculated and compared between the "water intake" and "control session" conditions. Greater delta values of 120 seconds to recover on "water intake" condition in relation to the control session were observed. The water intake accelerates the post-exercise heart rate recovery.A frequência cardíaca de recuperação pós-exercício é um índice de fácil aplicação que reflete a reativação vagal pós-exercício. A ingestão hídrica produz alterações importantes sobre o sistema cardiovascular, promovendo o aumento da modulação vagal cardíaca. O objetivo do presente estudo foi verificar a influência da ingestão hídrica sobre a frequência cardíaca de recuperação. Participaram do experimento dez indivíduos saudáveis. A sessão experimental constou de realização de exercício físico em cicloergômetro, ingestão hídrica e registro da frequência cardíaca de recuperação. Realizou-se também uma sessão de controle. A partir dos valores de frequência cardíaca do exercício e da recuperação, foram calculados os deltas de 60 e 120 segundos de recuperação e comparados entre as condições "ingestão hídrica" e "sessão controle". Observaram-se maiores valores do delta de 120 segundos de recuperação, na condição "ingestão hídrica", em relação à sessão controle. A ingestão hídrica interfere positivamente na recuperação da frequência cardíaca pós-exercício, com forte implicação clínica e desportiva

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