Effects of Aging on Hemodynamic Kinetics in Different Intensities of Dynamic Exercise.

Healthy aging hemodynamics is known to exhibit a time-dependent loss of function. We aimed at verifying whether older men would have a slowed cardiac output and stroke volume dynamics in response to the onset ("on") and on recovery ("off") of exercise in comparison to young men. Twenty healthy active men (10 young and 10 older) were recruited. Participants performed an incremental cardiopulmonary exercise testing on a cycle ergometer, and on another day, 3 constant workload tests in different intensities. Compared to younger, older men exhibited a slower cardiac output and stroke volume dynamics in both on and off transients for all exercise intensities (all P < 0.05). During higher intensities, both younger and older men had slower hemodynamic kinetics compared to lower intensities (all P < 0.05). There was strong negative relationship between the time constant of cardiac output on-kinetics during high-intensity with maximal exercise performance in both groups (r = -0.88, P < 0.01). We interpret these findings to mean that healthy older men have slowed hemodynamic kinetics compared to younger, but this difference becomes less evident in higher intensities of exercise.

Effect of Systemic and Auricular Acupuncture with a 2/100 Hz Frequency and Nogier Frequency in Fibromyalgia: a Randomized Clinical Trial, Pilot Study.

Background: Fibromyalgia is a syndrome of chronic, generalized muscular pain, accompanied by sleep disturbances, fatigue and cardic autonomic dysfunction that will affect the quality of life. There is currently no gold standard treatment. There are limitations of studies with electroacupuncture in auricular acupuncture. Objectives: We evaluate the effects of systemic electroacupuncture (EA) with frequencies of 2/100 Hz associated of auricular acupuncture with a Nogier frequency (2.28, 4.56 and 9.12 Hz) for pain intensity, heart rate variability (HRV), and quality of life in fibromyalgia. Methods: Randomized clinical trial, a pilot study. Eighteen volunteers were randomized into a control group (CG, n = 9) and an experimental group (EG, n = 9). Six systemic EA sessions systemic and auricular were applied in the EG for 20 min, twice a week, for six weeks consecutive. The Numerical Pain Assessment Scale (NPRS), 2010 diagnostic criteria of the American College of Rheumatology (FDC 2010), Fibromyalgia Impact Questionnaire (FIQ) and analysis of HRV were the instruments used. The independent t-test compared to the groups was applied. Results: There was no statistically significant difference for the primary outcome for NPRS (p > 0.05). In the secondary outcome there was a significant difference in the total score and in some FIQ domains (p = 0.008) and some variables such as pain (p = 0.02) and anxiety (p = 0.006). There was no significant difference for the FDC 2010 and HRV variables (p > 0.05). Conclusion: 2/100 Hz systemic EA associated with the Nogier frequency positively influenced some quality of life variables; however, pain intensity, diagnostic criteria, and HRV variables did not change.

Non-invasive ventilatory support accelerates the oxygen uptake and heart rate kinetics and improves muscle oxygenation dynamics in COPD-HF patients.

BACKGROUND: The aim of this study was to explore the effects of non-invasive positive pressure ventilation (NIPPV) associated with high-intensity exercise on heart rate (HR) and oxygen uptake (V̇O2) recovery kinetics in in patients with coexistence of chronic obstructive pulmonary disease (COPD) and heart failure (HF). METHODS: This is a randomized, double blinded, sham-controlled study involving 14 HF-COPD patients, who underwent a lung function test and Doppler echocardiography. On two different days, patients performed incremental cardiopulmonary exercise testing (CPET) and two constant-work rate tests (80% of CPET peak) receiving Sham or NIPPV (bilevel mode - Astral 150) in a random order until the limit of tolerance (Tlim). During exercise, oxyhemoglobin and deoxyhemoglobin were assessed using near-infrared spectroscopy (Oxymon, Artinis Medical Systems, Einsteinweg, Netherland). RESULTS: The kinetic variables of both V̇O2 and HR during the high-intensity constant workload protocol were significantly faster in the NIPPV protocol compared to Sham ventilation (P < 0.05). Also, there was a marked improvement in oxygenation and lower deoxygenation of both peripheral and respiratory musculature in TLim during NIPPV when contrasted with Sham ventilation. CONCLUSIONS: NIPPV applied during high-intensity dynamic exercise can effectively improve exercise tolerance, accelerate HR and V̇O2 kinetics, improve respiratory and peripheral muscle oxygenation in COPD-HF patients. These beneficial results from the effects of NIPPV may provide evidence and a basis for high-intensity physical training for these patients in cardiopulmonary rehabilitation programs.

Metabolic and cardiac autonomic effects of high-intensity resistance training protocol in Wistar rats.

The aim of this study was to assess the effects of metabolic and autonomic nervous control on high-intensity resistance training (HRT) as determined by pancreatic glucose sensitivity (GS), insulin sensitivity (IS), blood lactate ([La]), and heart rate variability (HRV) in rats. Thirty male, albino Wistar rats (292 ± 20 g) were divided into 3 groups: sedentary control (SC), low-resistance training (LRT), and HRT. The animals in the HRT group were submitted to a high-resistance protocol with a progressively increasing load relative to body weight until exhaustion, whereas the LRT group performed the same exercise regimen with no load progression. The program was conducted 3 times per week for 8 weeks. The [La], parameters related to the functionality of pancreatic tissue, and HRV were measured. There was a significant increase in peak [La] only in the HRT group, but there was a reduction in [La] when corrected to the maximal load in both trained groups (LRT and HRT, p < 0.05). Both trained groups exhibited an increase in IS; however, compared with SC and LRT, HRT demonstrated a significantly higher GS posttraining (p < 0.05). With respect to HRV, the low-frequency (LF) band, in milliseconds squared, reduced in both trained groups, but the high-frequency band, in milliseconds squared and nu, increased, and the LF in nu, decreased only in the HRT group (p < 0.05). The HRT protocol produced significant and beneficial metabolic and cardiac autonomic adaptations. These results provide evidence for the positive benefits of HRT in counteracting metabolic and cardiovascular dysfunction.

Pulsed Laser Acupuncture in the Treatment of Pain and Heart Rate Variability in Fibromyalgia Patients: A Pilot Randomized Clinical Trial.

Introduction: Laser acupuncture (LA) is a medically approved treatment for chronic pain, especially fibromyalgia. It is widely known that all pain is related to autonomic modulation, which may influence heart rate variability (HRV). There are robust studies in the literature on the effect of LA with continuous frequency on musculoskeletal pain and autonomic modulation. However, little is known about the effect of pulsed frequency on fibromyalgia. Therefore, this study aimed to evaluate whether an individualized intervention protocol applying pulsed LA would provide benefits related to pain symptoms and cardiac autonomic modulation in patients with fibromyalgia. Methods: In this pilot randomized clinical controlled trial, the sample consisted of women with fibromyalgia between the ages of 40 and 80, randomized into two groups: a control group (CG; n=10) and an experimental group (EG; n=10). EG received the intervention twice per week for 3 weeks. Statistical analysis was conducted by delta (difference between post-intervention and pre-intervention) and the Shapiro-Wilk test (normality). For comparison between the groups, the Mann-Whitney test was used. Results: The results showed a significant reduction in pain intensity as reported via the pain numerical scale (PNS; P=0.00), generalized pain index (GPI; P=0.00), and symptom severity scale (SSS; P=0.00). There was no significant difference in any HRV variable (P>0.05). Conclusion: Pulsed LA, when applied in an individualized protocol, can reduce pain intensity, as reported on the PNS, GPI, and SSS. However, no therapeutic effect was observed for HRV.

Arterial stiffness in type 2 diabetes: determinants and indication of a discriminative value.

OBJECTIVES: To identify the clinical discriminative value and determinants of arterial stiffness in individuals with type 2 diabetes mellitus (T2DM). METHODS: This prospective cohort study included 51 individuals (53.57±9.35 years) diagnosed with T2DM (stage glucose≥126 mg/dL; diagnostic time: 87.4±69.8 months). All participants underwent an initial evaluation of personal habits, medications, and history; arterial stiffness assessment by carotid-femoral pulse wave velocity (cfPWV) using SphygmoCor; and blood laboratory analysis. A statistical analysis was performed using SPSS software, and values of p≤0.05 were considered significant. RESULTS: A cut-off cfPWV value of 7.9 m/s was identified for T2DM [Sensitivity (SE): 90% and Specificity (SP): 80%]. A subgroup analysis revealed higher glycated hemoglobin (Hb1Ac) (p=0.006), obesity (p=0.036), and dyslipidemia (p=0.013) than those with cfPWV ≥7.9 m/s. Multivariate analysis identified higher stage glucose (p=0.04), Hb1Ac (p=0.04), hypertension (p=0.001), and dyslipidemia (p=0.01) as determinant factors of cfPWV; positive and significant correlation between cfPWV and glucose (r=0.62; p=0.0003) and Hb1Ac (r=0.55; p=0.0031). CONCLUSIONS: In T2DM, an indicator of the discriminative value of arterial stiffness was cfPWV of 7.9 m/s. Clinical findings and comorbidities, such as hypertension, glucose, poor glycemic control, and dyslipidemia, were associated with and were determinants of arterial stiffness in T2DM. Reinforcement of monitoring risk factors, such as hypertension, dyslipidemia, and glycemic control, seems to be essential to the process of arterial stiffening. Confirmation of this discriminative value in larger populations is recommended.

Brain-heart autonomic axis across different clinical status and severity of chronic obstructive pulmonary disease.

PURPOSE: Impairment of cardiac autonomic integrity is common in chronic obstructive pulmonary disease (COPD) patients. The influence of the interaction between clinical and severity status on brain-heart autonomic axis (BHAA) is not well known. We aimed to investigate the BHAA function across different clinical status and severity of COPD. METHODS: Cross-sectional study involving 77 COPD patients allocated into four groups according to clinical status [acute exacerbation (GAE) or stable (GST)] and severity [less (-) or more (+)]: 1) GAE-, n = 13; 2) GAE+, n = 20; 3) GST-, n = 23; and 4) GST+, n = 21. Heart rate variability (HRV) at rest and heart rate recovery (HRR) after 6-min walk test were markers of BHAA. Mean R-R, STDRR, RMSSD, RRtri, HF, LF, SD1, SD2, ApEn and SampEn were the HRV indexes and, HRR was obtained as: HR at 1st min of recovery minus peak HR. RESULTS: A main effect of clinical status (p < 0.001) was found to vagal modulation in GAE-vs. GST- (RMSSD: 25.0 ± 14.8 vs. 12.6 ± 5.5 ms; SD1: 18.0 ± 10.6 vs. 8.9 ± 3.9 ms) and to GAE + vs. GST+ (RMSSD: 26.4 ± 15.2 vs. 15.4 ± 6.3 ms; SD1: 18.3 ± 11.2 vs. 10.9 ± 4.5 ms). An effect of clinical status (p = 0.032) and severity (p = 0.030) were found to HF (vagal) in GAE + compared to GAE- and GST+ (264.7 ± 239.0 vs. 134.7 ± 169.7 and 135.8 ± 139.7 ms2). Lower HRR was found in GAE-compared to GST- (8.0 ± 2.4 vs. 19.6 ± 2.4 bpm), p = 0.002. CONCLUSION: In COPD patients, clinical status (AECOPD or stable) was more dominant than the severity on BHAA function. A more pronounced parasympathetic modulation was found in AECOPD patients with a lower HRR to exercise.

Short-term supervised inpatient physiotherapy exercise protocol improves cardiac autonomic function after coronary artery bypass graft surgery--a randomised controlled trial.

OBJECTIVE: Coronary artery bypass grafting (CABG) is accompanied by severe impairment of cardiac autonomous regulation (CAR). This study aimed to determine whether a short-term physiotherapy exercise protocol post-CABG, during inpatient cardiac rehabilitation (CR), might improve CAR. DESIGN: Seventy-four patients eligible for CABG were recruited and randomised into physiotherapy exercise group (EG) or physiotherapy usual care group (UCG). EG patients underwent a short-term supervised inpatient physiotherapy exercise protocol consisting of an early mobilisation with progressive exercises plus usual care (respiratory exercises). UCG only received respiratory exercises. Forty-seven patients (24 EG and 23 UGC) completed the study. Outcome measures of CAR included linear and non-linear measures of heart rate variability (HRV) assessed before discharge. RESULTS: By hospital discharge, EG presented significantly higher parasympathetic HRV values [rMSSD, high frequency (HF), SD1)], global power (STD RR, SD2), non-linear HRV indexes [detrended fluctuation analysis (DFA)alpha1, DFAalpha2, approximate entropy (ApEn)] and mean RR compared to UCG (p<0.05). Conversely, higher values of mean HR, low frequency (LF) (sympathetic activity) and the LF/HF (global sympatho-vagal balance) were found in the UCG. CONCLUSIONS: A short-term supervised physiotherapy exercise protocol during inpatient CR improves CAR at the time of discharge. Thus, exercise-based inpatient CR might be an effective non-pharmacological tool to improve autonomic cardiac tone in patient's post-CABG.

Cardiovascular responses to low-intensity isometric handgrip exercise in coronary artery disease: effects of posture.

BACKGROUND: Coronary artery disease (CAD) lead to cardiovascular autonomic control disfunctions that can worsen exercise and/or posture adjustments. OBJECTIVES: To verify the cardiovascular responses to low-intensity isometric handgrip exercise performed in different postures in CAD patients. This study tested the hypothesis that the posture influences the cardiovascular responses during isometric handgrip exercise and that the presence of CAD leads to greater cardiovascular stress during this type of exercise. METHODS: We investigated cardiovascular responses to isometric handgrip exercise in 15 CAD patients (CADG) and 15 health matched-control (CG). The subjects performed isometric handgrip exercise at 30% of maximum voluntary contraction until exhaustion in SUPINE, SITTING and STANDING positions. Systolic arterial pressure, diastolic arterial pressure, mean blood pressure, heart rate, peripheral vascular resistance, cardiac output, stroke volume and double product were measured during rest (baseline), exercise (peak value) and recovery in the 1st minute (REC1). Delta PB (ΔPB, peak minus baseline) and PR1 (ΔPR1, peak minus REC1) were calculated. RESULTS: Higher ΔPB and ΔPR1 of systolic and mean arterial pressure and double product were observed in STANDING when compared to SITTING and/or SUPINE. CADG showed higher ΔPB of systolic and mean arterial pressure in all postures and higher ΔPR1 of strove volume in the SITTING. CONCLUSION: We concluded that the posture during isometric handgrip exercise influences the cardiovascular responses with STANDING leading to higher cardiovascular stress. CAD promoted higher arterial pressure responses however these responses were physiological and expected due to the presence of disease and type of exercise.

Circulatory and ventilatory power in diabetic patients: Secondary analysis of a randomized controlled trial.

BACKGROUND: Circulatory (CP) and ventilatory power (VP) have been used to improve the prognostic accuracy of cardiopulmonary exercise tests in cardiovascular disease, such as coronary artery disease. However, the effects of combined resistance and aerobic exercise program on VP and CP, especially in type 2 diabetes patients, have not been adequately investigated. Thus, this new parameter can be useful to prescribe exercise programs more assertive for this population. The present study aimed to assess the effect of 3 months of combined resistance and aerobic exercise training (CET) on CP and VP in patients with type 2 diabetes. METHODS: A randomized controlled trial was conducted involving 48 diabetic patients with an average age of 52.4 (±8.01) years old. The subjects were randomized into two groups: sedentary (SG, n = 15) and the CET group (n = 19). Cardiopulmonary exercise testing (symptom-limited incremental) was performed on a cycle ergometer, and the following parameters were measured: relative VO2 , VE /VCO2 slope, linear relationship between oxygen uptake and minute ventilation, and VCO2 . CET was performed with 30-min aerobic and 30-min resistance exercises three times a week for 12 weeks. RESULTS: Significant (p < .05) and clinical (d ≥ .80) differences were observed that favoured CET compared with SG for the following variables: heart rate, workload, VO2 relative peak, circulatory power peak, and VCO2 peak. Although no statistical difference was observed for ventilatory power, there was a clinical difference (p > .05 and d ≥ 0.80) that favoured CET. CONCLUSION: Three months of combined exercise training improved VP and CP indices in patients with type 2 diabetes when compared with a sedentary group.

Expiratory Flow Limitation at Different Exercise Intensities in Coronary Artery Disease.

INTRODUCTION: Expiratory flow limitation (EFL) during moderate intensity exercise is present in patients with myocardial infarction (MI), whereas in healthy subjects it occurs only at a high intensity. However, it is unclear whether this limitation already manifests in those with stable coronary artery disease (CAD) (without MI). MATERIALS AND METHODS: Forty-one men aged 40-65 years were allocated into (1) recent MI (RMI) group (n = 8), (2) late MI (LMI) group (n = 12), (3) stable CAD group (n = 9), and (4) healthy control group (CG) (n = 12). All participants underwent two cardiopulmonary exercise tests at a constant workload (moderate and high intensity), and EFL was evaluated at the end of each exercise workload. RESULTS: During moderate intensity exercise, the RMI and LMI groups presented with a significantly higher number of participants with EFL compared to the CG (p < 0.05), while no significant difference was observed among groups at high intensity exercise (p > 0.05). Moreover, EFL was only present in MI groups during moderate intensity exercise, whereas at high intensity all groups presented EFL. Regarding the degree of EFL, the RMI and LMI groups showed significantly higher values at moderate intensity exercise in relation to the CG. At high intensity exercise, significantly higher values for the degree of EFL were observed only in the LMI group. CONCLUSION: The ventilatory limitation at moderate intensity exercise may be linked to the pulmonary consequences of the MI, even subjects with preserved cardiac and pulmonary function at rest, and not to CAD per se.

Can high-intensity interval training change cardiac autonomic control? A systematic review.

BACKGROUND: High intensity interval training (HIIT) has been used as a cardiovascular exercise strategy to promote greater adherence in cardiovascular rehabilitation. However, little is known about the effect of this training modality on cardiac autonomic control. OBJECTIVE: To perform a systematic review to evaluate the effects of HIIT on cardiac autonomic responses in humans. METHODS: PEDro, SCOPUS and PubMed were searched from the inception to March 29th, 2018. Moreover, the methodological quality and statistical reporting from all eligible clinical trials were assessed by the PEDro scale. The articles were eligible if: The primary objective was related to the effects of HIIT on the cardiac autonomic nervous system. Outcomes evaluated were indirect measures of cardiac autonomic control, represented by HRV indexes. RESULTS: The search strategies resulted in 339 citations and 2 additional citations were identified through other sources. After deleting the duplicate articles and revising the full text, 6 articles were included. Overall, the results showed an improvement in parasympathetic and/or sympathetic modulation after HIIT, when evaluated by linear and non-linear indexes of HRV. CONCLUSIONS: HIIT is a promising tool to improve the cardiac autonomic control, with more recommendation in healthy individuals and patients with metabolic syndrome.

The additional impact of type 2 diabetes on baroreflex sensitivity of coronary artery disease patients might be undetectable in presence of deterioration of mechanical vascular properties.

Both deterioration of the mechanical vascular properties of barosensitive vessels and autonomic derangement lead to modification of baroreflex sensitivity (BRS) in coronary artery disease (CAD) individuals. Type 2 diabetes (T2D) reduces BRS as well even in absence of cardiac autonomic neuropathy. The aim of the study is to clarify whether, assigned the degree of mechanical vascular impairment and without cardiac autonomic neuropathy, the additional autonomic dysfunction imposed in CAD patients by T2D (CAD-T2D) decreases BRS further. We considered CAD (n = 18) and CAD-T2D (n = 19) males featuring similar increases of average carotid intima media thickness (ACIMT) and we compared them to age- and gender-matched healthy (H, n = 19) subjects. BRS was computed from spontaneous beat-to-beat variability of heart period (HP) and systolic arterial pressure (SAP) at supine resting (REST) and during active standing (STAND). BRS was estimated via methods including time domain, spectral, cross-spectral, and model-based techniques. We found that (i) at REST BRS was lower in CAD and CAD-T2D groups than in H subjects but no difference was detected between CAD and CAD-T2D individuals; (ii) STAND induced an additional decrease of BRS visible in all the groups but again BRS estimates of CAD and CAD-T2D patients were alike; (iii) even though with different statistical power, BRS markers reached similar conclusions with the notable exception of the BRS computed via model-based approach that did not detect the BRS decrease during STAND. In presence of a mechanical vascular impairment, indexes estimating BRS from spontaneous HP and SAP fluctuations might be useless to detect the additional derangement of the autonomic control in CAD-T2D without cardiac autonomic neuropathy compared to CAD, thus limiting the applications of cardiovascular variability analysis to typify CAD-T2D individuals. Graphical abstract Graphical representation of the baroreflex sensitivity (BRS) estimated from spontaneous fluctuations of heart period and systolic arterial pressure via transfer function (TF) in low frequency (LF) band (from 0.04 to 0.15 Hz). BRS was reported as a function of the group (i.e., healthy (H), coronary artery disease (CAD) and CAD with type 2 diabetes (CAD-T2D) groups) at REST (black bars) and during STAND (white bars). Values are shown as mean plus standard deviation. The symbol "*" indicates a significant difference between conditions within the same group (i.e., H, CAD, or CAD-T2D) and the symbol "§" indicates a significant difference between groups within the same experimental condition (i.e., REST or STAND). BRS cannot distinguish CAD and CAD-T2D groups both at REST and during STAND, while it is useful to distinguish experimental conditions and separate pathological groups from H subjects.

Noninvasive ventilation acutely modifies heart rate variability in chronic obstructive pulmonary disease patients.

OBJECTIVE: The purpose of present study was to evaluate the acute effects of bi-level positive airway pressure (BiPAP) on heart rate variability (HRV) of stable chronic obstructive pulmonary disease patients (COPD). METHODS: Nineteen males with COPD (69+/-8 years and with forced expiratory volume in 1s <50% of predicted) and eight healthy sedentary age-matched (69 years) males in the control group (CG) were evaluated during two conditions of controlled respiratory rate: spontaneous breathing (SB) and BiPAP (inspiratory and expiratory levels between 12-14 cmH(2)O and 4-6 cmH(2)O, respectively). Peripheral oxygen saturation (SpO(2)), end-tidal of carbon dioxide (ETCO(2)), systolic blood pressure (SBP) and R-R interval were obtained. HRV was analyzed by time (RMSSD and SDNN index) and frequency domains (high frequency - HF, low frequency - LF and HF/LF ratio). RESULTS: Significant reduction of ETCO(2) and SBP in both groups and increase of SpO(2) in COPD group was observed during BiPAP ventilation (p<0.05). During spontaneous breathing, patients with COPD presented lower values of LF, LF/HF and higher values of HF when compared to CG (p<0.05). However, HF was significantly reduced and LF increased during BiPAP ventilation (58+/-19-48+/-15 and 41+/-19-52+/-15 un, respectively) in COPD group. Significant correlations between delta BiPAP-SB (Delta) ETCO(2) and DeltaHF were found (r=0.89). CONCLUSIONS: Sympathetic and parasympathetic neural control of heart rate is altered in COPD patients and that BiPAP acutely improves ventilation, enhances sympathetic response and decreases vagal tonus. The improvement of ventilation caused by BiPAP was associated with reduced cardiac vagal activity in stable moderate-to-severe COPD patients.

Correction: Cardiovascular Variability Analysis and Baroreflex Estimation in Patients with Type 2 Diabetes in Absence of Any Manifest Neuropathy.

[This corrects the article DOI: 10.1371/journal.pone.0148903.].

High-Intensity Inspiratory Protocol Increases Heart Rate Variability in Myocardial Revascularization Patients.

OBJECTIVE: To evaluate heart rate variability during an inspiratory muscle endurance protocol at three different load levels [30%, 60% and 80% of maximal inspiratory pressure], in patients who had previously undergone coronary artery bypass grafting. METHODS: Nineteen late postoperative myocardial revascularization patients participating in a cardiovascular rehabilitation program were studied. Maximal inspiratory pressure maneuvers were performed. An inspiratory muscle endurance protocol at 30%, 60% and 80% of maximal inspiratory pressure was applied for four minutes each, in random order. Heart rate and RR intervals were recorded and heart rate variability was analyzed by time (RMSSD-the mean of the standard deviations for all R-R intervals, and RMSM-root-mean square differences of successive R-R intervals) and frequency domains indices (high and low frequency) in normalized units. ANOVA for repeated measurements was used to compare heart rate variability indices and Student t-test was used to compare the maximal inspiratory pressure and maximal expiratory pressure values. RESULTS: Heart rate increased during performance of maximal respiratory pressures maneuvers, and the maximal inspiratory pressure and maximal expiratory pressure mean values were significantly lower than predicted values (P <0.05). RMSSD increased significantly at 80% in relation to rest and 30% of maximal inspiratory pressure and RMSM decreased at 30% and 60% of maximal inspiratory pressure in relation to rest (P <0.05). Additionally, there was significant and progressive decrease in low frequency and increase in high frequency at 30%, 60% and 80% of maximal inspiratory pressure in relation to the resting condition. CONCLUSION: These results suggest that respiratory muscle training at high intensities can promote greater parasympathetic activity and it may confer important benefits during a rehabilitation program in post-coronary artery bypass grafting.

Arterial stiffness in type 2 diabetes: determinants and indication of a discriminative value

OBJECTIVES: To identify the clinical discriminative value and determinants of arterial stiffness in individuals with type 2 diabetes mellitus (T2DM). METHODS: This prospective cohort study included 51 individuals (53.57±9.35 years) diagnosed with T2DM (stage glucose≥126 mg/dL; diagnostic time: 87.4±69.8 months). All participants underwent an initial evaluation of personal habits, medications, and history; arterial stiffness assessment by carotid-femoral pulse wave velocity (cfPWV) using SphygmoCor; and blood laboratory analysis. A statistical analysis was performed using SPSS software, and values of p≤0.05 were considered significant. RESULTS: A cut-off cfPWV value of 7.9 m/s was identified for T2DM [Sensitivity (SE): 90% and Specificity (SP): 80%]. A subgroup analysis revealed higher glycated hemoglobin (Hb1Ac) (p=0.006), obesity (p=0.036), and dyslipidemia (p=0.013) than those with cfPWV ≥7.9 m/s. Multivariate analysis identified higher stage glucose (p=0.04), Hb1Ac (p=0.04), hypertension (p=0.001), and dyslipidemia (p=0.01) as determinant factors of cfPWV; positive and significant correlation between cfPWV and glucose (r=0.62; p=0.0003) and Hb1Ac (r=0.55; p=0.0031). CONCLUSIONS: In T2DM, an indicator of the discriminative value of arterial stiffness was cfPWV of 7.9 m/s. Clinical findings and comorbidities, such as hypertension, glucose, poor glycemic control, and dyslipidemia, were associated with and were determinants of arterial stiffness in T2DM. Reinforcement of monitoring risk factors, such as hypertension, dyslipidemia, and glycemic control, seems to be essential to the process of arterial stiffening. Confirmation of this discriminative value in larger populations is recommended.

Cardiovascular Variability Analysis and Baroreflex Estimation in Patients with Type 2 Diabetes in Absence of Any Manifest Neuropathy.

INTRODUCTION: Indexes derived from spontaneous heart period (HP) and systolic arterial pressure (SAP) fluctuations can detect autonomic dysfunction in individuals with type 2 diabetes mellitus (DM) associated to cardiovascular autonomic neuropathy (CAN) or other neuropathies. It is unknown whether HP and SAP variability indexes are sensitive enough to detect the autonomic dysfunction in DM patients without CAN and other neuropathies. METHODS: We evaluated 68 males aged between 40 and 65 years. The group was composed by DM type 2 DM with no manifest neuropathy (n = 34) and healthy (H) subjects (n = 34). The protocol consisted of 15 minutes of recording of HP and SAP variabilities at rest in supine position (REST) and after active standing (STAND). The HP power in the high frequency band (HF, from 0.15 to 0.5 Hz), the SAP power in the low frequency band (LF, from 0.04 to 0.15 Hz) and BRS estimated via spectral approach and sequence method were computed. RESULTS: The HF power of HP was lower in DM patients than in H subjects, while the two groups exhibited comparable HF power of HP during STAND. The LF power of SAP was similar in DM and H groups at REST and increased during STAND in both groups. BRSs estimated in the HF band and via baroreflex sequence method were lower in DM than in H and they decreased further during STAND in both populations. CONCLUSION: Results suggest that vagal control of heart rate and cardiac baroreflex control was impaired in type 2 DM, while sympathetic control directed to vessels, sympathetic and baroreflex response to STAND were preserved. Cardiovascular variability indexes are sensitive enough to typify the early, peculiar signs of autonomic dysfunction in type-2 DM patients well before CAN becomes manifest.

Circulatory and Ventilatory Power: Characterization in Patients with Coronary Artery Disease.

BACKGROUND: Circulatory power (CP) and ventilatory power (VP) are indices that have been used for the clinical evaluation of patients with heart failure; however, no study has evaluated these indices in patients with coronary artery disease (CAD) without heart failure. OBJECTIVE: To characterize both indices in patients with CAD compared with healthy controls. METHODS: Eighty-seven men [CAD group = 42 subjects and healthy control group (CG) = 45 subjects] aged 40-65 years were included. Cardiopulmonary exercise testing was performed on a treadmill and the following parameters were measured: 1) peak oxygen consumption (VO2), 2) peak heart rate (HR), 3) peak blood pressure (BP), 4) peak rate-pressure product (peak systolic HR x peak BP), 5) peak oxygen pulse (peak VO2/peak HR), 6) oxygen uptake efficiency (OUES), 7) carbon dioxide production efficiency (minute ventilation/carbon dioxide production slope), 8) CP (peak VO2 x peak systolic BP) and 9) VP (peak systolic BP/carbon dioxide production efficiency). RESULTS: The CAD group had significantly lower values for peak VO2 (p < 0.001), peak HR (p < 0.001), peak systolic BP (p < 0.001), peak rate-pressure product (p < 0.001), peak oxygen pulse (p = 0.008), OUES (p < 0.001), CP (p < 0.001), and VP (p < 0.001) and significantly higher values for peak diastolic BP (p = 0.004) and carbon dioxide production efficiency (p < 0.001) compared with CG. Stepwise regression analysis showed that CP was influenced by group (R2 = 0.44, p < 0.001) and VP was influenced by both group and number of vessels with stenosis after treatment (interaction effects: R2 = 0.46, p < 0.001). CONCLUSION: The indices CP and VP were lower in men with CAD than healthy controls.

Identification of anaerobic threshold by analysis of heart rate variability during discontinuous dynamic and resistance exercise protocols in healthy older men.

The purposes of this study were to determine anaerobic threshold (AT) during discontinuous dynamic and resistive exercise protocols by analysing of heart rate variability (HRV) and blood lactate (BL) in healthy elderly subjects and compare the cardiovascular, metabolic and autonomic variables obtained from these two forms of exercise. Fourteen elderly (70 ± 4 years) apparently healthy males underwent the following tests: (i) incremental ramp test on cycle ergometer, (ii) one repetition maximum (1RM) leg press at 45°, (iii) a discontinuous exercise test on a cycle ergometer (DET-C) protocol and (iv) a resistance exercise leg press (DET-L) protocol. Heart rate, blood pressure and BL were obtained during each increment of exercise intensity. No significant differences (P>0·05) were found between methods of AT determination (BL and HRV) nor the relative intensity corresponding to AT (30% of maximum intensity) between the types of exercise (DET-C and DET-L). Furthermore, no significant differences (P>0·05) were found between the DET-C and DET-L in relation to HRV, however, the DET-L provided higher values of systolic blood pressure and BL (P<0·05) from the intensity corresponding to AT. We conclude that HRV was effective in determination of AT, and the parasympathetic modulation responses obtained during dynamic and resistive exercise protocols were similar when compared at the same relative intensity. However, DET-L resulted in higher values of blood pressure and BL at workloads beyond AT.