Orthostatic intolerance: a handicap of aging or physical deconditioning?

Despite several studies that have been investigated physical inactivity and age-related effects on orthostatic tolerance, impaired hemodynamics and postural balance responses to orthostatic stress are incorrectly attributed to aging or sedentarism alone. The isolated effects from aging and sedentarism should be investigated through comparative studies between senior athletes and age-matched controls, and physical activity assessments on aging follow-up studies. On the other hand, bed rest and space flight studies mimic accelerated physical inactivity or disuse, which is not the same physiological decline provoked by aging alone. Thus, the elementary question is: could orthostatic intolerance be attributed to aging or physical inactivity? The main purpose of this review is to provide an overview of possible mechanisms underlying orthostatic tolerance contrasting the paradigm of aging and/or physical inactivity. The key points of this review are the following: (1) to counterpoint all relevant literature on physiological aspects of orthostatic tolerance; (2) to explore the mechanistic aspects underneath the cerebrovascular, cardiorespiratory, and postural determinants of orthostatic tolerance; and (3) examine non-pharmacological interventions with the potential to counterbalance the physical inactivity and aging effects. To date, the orthostatic intolerance cannot be attributed exclusively with aging since physical inactivity plays an important role in postural balance, neurovascular and cardiorespiratory responses to orthostatic stress. These physiological determinates should be interpreted within an integrative approach of orthostatic tolerance, that considers the interdependence between physiological systems in a closed-loop model. Based on this multisystem approach, acute and chronic countermeasures may combat aging and sedentarism effects on orthostatic tolerance.

The intensity of oscillations of the photoplethysmographic waveform variability at frequencies 0.04-0.4 Hz is effective marker of hypertension and coronary artery disease in males.

Background: It is believed that the intensity of oscillations in the photoplethysmographic waveform variability reflects the activity of vascular regulatory mechanisms. However, the relationship of such fluctuations with the state of health is poorly understood.Purpose: The aim of our study was to assess the possibility of using spectral indices that reflect the intensity of oscillations of the photoplethysmographic waveform variability at frequencies 0.04-0.4 Hz as markers of hypertension and coronary artery disease. We did not study women to exclude the influence of menopause and sex hormones on the results.Materials and Methods: We compared synchronous 10-minute records of finger photoplethysmogram and respiration at rest in 30 healthy males (48.8 ± 4.5 years; data presented as Mean ± SD) versus 30 patients with hypertension (aged 49.0 ± 4.3 years) versus 30 patients with stable coronary artery disease (49.2 ± 4.8 years). Percentages of high-frequency and low-frequency ranges in the total power of photoplethysmographic waveform variability spectrum (HF% and LF%), and LF/HF ratio were assessed.Results: HF% are subject to by 2- to 5-fold increase in hypertensive patients (p < .001) and up to an 8-fold increase in patients with coronary artery disease (p < .001) when compared with healthy persons. On the contrary, LF% is reduced by 1.5-5 times in all patients when compared with healthy people (p < .001). We identified cut-off points for each photoplethysmographic index to distinguish patients with coronary artery disease or hypertension from healthy subjects. Multiple logistic regression models based on photoplethysmographic waveform variability indices had sufficient sensitivity and specificity for patients with hypertension or coronary artery disease.Conclusion: Frequency-domain indices of photoplethysmographic waveform variability (in particular, HF%, LF%, and LF/HF) are sufficiently sensitive and specific markers of hypertension and coronary artery disease in adult males.

Acute effect of photobiomodulation using light-emitting diodes (LEDs) on baroreflex sensitivity during and after constant loading exercise in patients with type 2 diabetes mellitus.

To evaluate the photobiomodulation (PBM) effect on the cardiovascular autonomic control, analyzed by baroreflex sensitivity (sequence method), during constant load exercise and recovery in diabetic men, we evaluated 11 men with type 2 diabetes (DM2) (40-64 years). The constant workload exercise protocol (TECC) was performed on two different days, 14 days apart from each other, to guarantee PBM washout period. After PBM by light-emitting diode (LED) irradiation (150 J or 300 J or placebo), 10 min of rest (REST) was performed. After this period, the volunteer was positioned on a cycloergometer to start the test (1-min rest, 3-min free-load heating, 6-min constant workload-EXERCISE, 6-min free-load cool-down, 1-min rest) followed by a sitting period of 10 min (RECOVERY). The constant workload corresponded to 80%VO2GET (gas exchange threshold) identified by a previous cardiopulmonary exercise test (CPET). PBM was applied in continuous mode, contact technique, bilaterally, on both femoral quadriceps and gastrocnemius muscle groups. The electrocardiogram R-R intervals (BioAmp FE132) and the peripheral pulse pressure signals (Finometer PRO) were collected continuously throughout the protocol. Stable sequences of 256 points were chosen at REST, EXERCISE, and RECOVERY. The baroreflex sensitivity (BRS) was computed in time domain according to the sequence method (αseq). The comparison between therapies (150 J/300 J/placebo) and condition (REST, EXERCISE, and RECOVERY) was performed using the ANOVA two-way repeated measures test. There was no interaction between therapy and conditions during the TECC. There was only the condition effect (p < 0.001), showing that the behavior of αseq was similar regardless of the therapy. Photobiomodulation with 150 J or 300 J applied previously to a moderate-intensity TECC in DM2 was not able to promote cardiovascular autonomic control changes leading to an improvement in BRS.

Ultra-shortened time-domain HRV parameters at rest and following exercise in athletes: an alternative to frequency computation of sympathovagal balance.

PURPOSE: The primary purpose of this study was to determine the accuracy of the standard deviation of normal-to-normal intervals (SDNN) to root mean square of successive normal-to-normal interval differences (RMSSD) ratio from 1-min recordings (SDNN:RMSSD1-min) compared to criterion recordings, as well as its relationship to low-frequency-to-high-frequency ratio (LF:HF) at rest and following maximal exercise in a group of collegiate athletes. METHOD: Twenty athletes participated in the study. Heart rate variability (HRV) data were measured for 5 min before and at 5-10 and 25-30 min following a maximal exercise test. From each 5-min segment, the frequency-domain measures of HF, LF, and LF:HF ratio were analyzed. Time-domain measures of SDNN, RMSSD, and SDNN:RMSSD ratio were also analyzed from each 5-min segment, as well as from randomly selected 1-min recordings. RESULT: The 1-min values of SDNN, RMSSD, and SDNN:RMSSD provided no significant differences and nearly perfect intra-class correlations (ICCs ranged from 0.97 to 1.00, p < 0.001 for all) to the criterion measures from 5-min recordings. In addition, SDNN, RMSSD, and SDNN:RMSSD from the 1-min segments provided very large to nearly perfect correlations (r values ranged from 0.71 to 0.97, p < 0.001 for all) to LF, HF, and LF:HF, respectively, at each time point. CONCLUSION: The findings of the study suggest that ultra-shortened time-domain markers may be useful surrogates of the frequency-domain parameters for tracking changes in sympathovagal activity in athletes.

Brief periods of transcutaneous auricular vagus nerve stimulation improve autonomic balance and alter circulating monocytes and endothelial cells in patients with metabolic syndrome: a pilot study.

BACKGROUND: There is emerging evidence that the nervous system regulates immune and metabolic alterations mediating Metabolic syndrome (MetS) pathogenesis via the vagus nerve. This study evaluated the effects of transcutaneous auricular vagus nerve stimulation (TAVNS) on key cardiovascular and inflammatory components of MetS. METHODS: We conducted an open label, randomized (2:1), two-arm, parallel-group controlled trial in MetS patients. Subjects in the treatment group (n = 20) received 30 min of TAVNS with a NEMOS® device placed on the cymba conchae of the left ear, once weekly. Patients in the control group (n = 10) received no stimulation. Hemodynamic, heart rate variability (HRV), biochemical parameters, and monocytes, progenitor endothelial cells, circulating endothelial cells, and endothelial micro particles were evaluated at randomization, after the first TAVNS treatment, and again after 8 weeks of follow-up. RESULTS: An improvement in sympathovagal balance (HRV analysis) was observed after the first TAVNS session. Only patients treated with TAVNS for 8 weeks had a significant decrease in office BP and HR, a further improvement in sympathovagal balance, with a shift of circulating monocytes towards an anti-inflammatory phenotype and endothelial cells to a reparative vascular profile. CONCLUSION: These results are of interest for further study of TAVNS as treatment of MetS.

Soluble interleukin-1 receptor type 2 plasma levels in Parkinson's disease: relationship with cardiac autonomic profile before and after peripheral mechanical somatosensory stimulation.

Introduction: Systemic inflammation promotes neurodegeneration in Parkinson's disease (PD). Interleukin-1 receptor type 2 (sIL-1R2) plasma levels increase during inflammation. Data on sIL-1R2 in PD patients and its relationship with PD cardiac autonomic profile are limited, given the possible anti-inflammatory effect of vagal activation. Previously, automated mechanical peripheral somatosensory stimulation (AMPSS) enhanced cardiac vagal modulation. Objectives were to 1) evaluate sIL-1R2 plasma concentrations in PD patients and healthy controls and 2) investigate the correlations between sIL-1R2 and cardiac autonomic indices obtained by spectrum analysis of heart rate variability before and after AMPSS. Methods: sIL-1R2 plasma levels were assessed in 48 PD patients and 50 healthy controls. Electrocardiogram and beat-by-beat arterial pressure were recorded at baseline and after 5 AMPSS sessions in 16 PD patients. Results: PD patients had higher sIL-1R2 levels than controls. In the PD subgroup, an inverse correlation between sIL-1R2 and HFnu was found. There was a negative correlation between changes induced by AMPSS on HFnu and sIL-1R2. Discussion: Higher sIL-1R2 levels in PD patients reflect the inflammatory dysregulation associated with the disease. In PD patients, higher sIL-1R2 was associated with reduced cardiovagal tone. Increased cardiovagal modulation following AMPSS was associated with lower sIL-1R2 levels in Parkinson's disease patients, suggesting inflammatory state improvement.

Dysautonomia in Parkinson's Disease: Impact of Glucocerebrosidase Gene Mutations on Cardiovascular Autonomic Control.

Evidence from clinical practice suggests that PD patients with the Glucocerebrosidase gene mutations (GBA-PD) are characterized by more severe dysautonomic symptoms than patients with idiopathic PD (iPD). Therefore, an accurate assessment of cardiovascular autonomic control (CAC) is necessary to clarify the role of GBA mutations in the pathophysiology of PD. We evaluated the CAC at rest and during orthostatic challenge of 15 iPD, 15 GBA-PD and 15 healthy controls (CTR). ECG and respiration were recorded in supine position and during active standing. The analysis of Heart Rate Variability (HRV) was performed on ECG recordings using two different approaches, linear spectral analysis and non-linear symbolic analysis. GBA-PD patients presented more frequently an akinetic-rigid phenotype and cognitive dysfunction than iPD patients. Both iPD and GBA-PD group were characterized by a lower spectral HRV than CTR group. At rest, the GBA-PD group was characterized by a lower parasympathetic modulation and a shift of the sympathovagal balance toward a sympathetic predominance compared to the CTR group. Moreover, the GBA-PD patients presented a lower HR increment and a lower or absent reduction of the vagal modulation in response to the active standing than iPD patients. Lastly, the cardiovascular autonomic dysfunction in PD patients was associated with longer disease duration, and with the occurrence of REM sleep behavior disorder and constipation. Our findings suggest a more severe impairment of the CAC in PD patients with GBA mutations. These results and further studies on the role of GBA mutations could allow a stratification based on cardiovascular risk in PD patients and the implementation of specific prevention programs.

Cardiovascular autonomic modulation differences between moderate-intensity continuous and high-intensity interval aerobic training in women with PCOS: A randomized trial.

Background: Moderate-intensity continuous training (MICT) is strongly recommended for polycystic ovarian syndrome (PCOS) treatment. However, recent studies have suggested that high-intensity interval training (HIIT) would promote great benefits for cardiac autonomic control. Therefore, we investigated whether the benefits of HIIT related to cardiovascular autonomic control were greater than those of MICT in women with PCOS. Methods: Women with PCOS were randomly allocated through a blind draw into three groups: control, MICT, and HIIT. The control group did not undergo exercise, whereas those in the MICT and HIIT groups underwent 16 weeks of aerobic physical training. All groups were evaluated before and after the 16 weeks of intervention in the following aspects: quantification of serum lipids, testosterone, fasting insulin and blood glucose; physical fitness through cardiopulmonary testing; analysis of heart rate variability (HRV) by linear (time domain and frequency domain) and non-linear (symbolic analysis) methods, analysis of blood pressure variability (BPV) and spontaneous baroreflex sensitivity (BRS). Results: The final analysis, each group comprised 25 individuals. All groups had similar baseline parameters. After 16 weeks, intragroup comparison showed that the MICT and HIIT groups had a reduction in baseline heart rate (P < 0.001; P < 0.001, respectively) and testosterone levels P < 0.037; P < 0.012, respectively) associated with an increase in VO2peak (MICT, P < 0.001; HIIT, P < 0.001). The MICT (P < 0.36) and HIIT (P < 0.17) groups also showed an increase in cardiac vagal modulation, however only observed in the non-linear analysis. The intergroup comparison showed no differences between the MICT and HIIT groups in any of the hormonal, metabolic and autonomic parameters evaluated, including testosterone, peak oxygen uptake (VO2peak), HRV, BPV and BRS. Conclusion: HIIT and MICT showed similar results for the different parameters evaluated. This suggests that both training protocols can be recommended for the treatment of PCOS. Brazilian Clinical Trials Registry (RBR-78qtwy).

Important differences between hypertensive middle-aged women and men in cardiovascular autonomic control-a critical appraisal.

BACKGROUND: Normotensive premenopausal women show a vagal predominance of cardiac autonomic modulation, whereas age-matched men show a predominance of sympathetic modulation. However, some women develop systemic arterial hypertension (SAH) even with preserved ovarian function. Our hypothesis is that these women may have cardiovascular autonomic parameters similar to those of hypertensive men, even when subjected to pharmacological treatment. We aimed to investigate cardiovascular autonomic control and baroreflex sensitivity (BRS) in hypertensive premenopausal women and age-matched men. METHODS: One hundred volunteers between 18 and 45 years of age were assigned to two groups (50 participants each): a hypertensive group including patients with a history of SAH for at least 6 months (25 men and 25 women), who were under treatment with monotherapy (losartan, 25-50 mg/kg); and a normotensive group (25 men and 25 women). Anthropometric, hemodynamic, metabolic, and autonomic cardiovascular assessments were performed focusing on BRS, autonomic modulation of heart rate variability (HRV), and blood pressure variability (BPV). RESULTS: On HRV analysis, women showed higher values of high-frequency (HF) oscillations in absolute and normalized units, lower values ​of low-frequency (LF) in normalized units, and lower LF/HF ratio, as compared with men. When the normotensive and hypertensive groups were compared, hypertensive groups showed lower values ​of total variance and of LF and HF bands in absolute units. On BRS, hypertensive groups showed lower values than the normotensive group. CONCLUSION: Regardless of blood pressure control through pharmacological treatment, hypertensive patients continued to have reduced HRV compared to normotensive, and hypertensive men had more autonomic impairment than hypertensive premenopausal women.

Effects of transcutaneous auricular vagus nerve stimulation on cardiovascular autonomic control in health and disease.

Autonomic nervous system (ANS) dysfunction is a well-known feature of cardiovascular diseases (CVDs). Studies on heart rate variability (HRV), a non-invasive method useful in investigating the status of cardiovascular autonomic control, have shown that a predominance of sympathetic modulation not only contributes to the progression of CVDs but has a pivotal role in their onset. Current therapies focus more on inhibition of sympathetic activity, but the presence of drug-resistant conditions and the invasiveness of some surgical procedures are an obstacle to complete therapeutic success. On the other hand, targeting the parasympathetic branch of the autonomic nervous system through invasive vagus nerve stimulation (VNS) has shown interesting results as alternative therapeutic approach for CVDs. However, the invasiveness and cost of the surgical procedure limit the clinical applicability of VNS and hinder the research on the physiological pathway involved. Transcutaneous stimulation of the auricular branch of the vagus nerve (tVNS) seems to represent an important non-invasive alternative with effects comparable to those of VNS with surgical implant. Thus, in the present narrative review, we illustrate the main studies on tVNS performed in healthy subjects and in three key examples of CVDs, namely heart failure, hypertension and atrial fibrillation, highlighting the neuromodulatory effects of this technique.

Blood pressure variability, heart functionality, and left ventricular tissue alterations in a protocol of severe hemorrhagic shock and resuscitation.

Autonomic control of blood pressure (BP) and heart rate (HR) is crucial during bleeding and hemorrhagic shock (HS) to compensate for hypotension and hypoxia. Previous works have observed that at the point of hemodynamic decompensation a marked suppression of BP and HR variability occurs, leading to irreversible shock. We hypothesized that recovery of the autonomic control may be decisive for effective resuscitation, along with restoration of mean BP. We computed cardiovascular indexes of baroreflex sensitivity and BP and HR variability by analyzing hemodynamic recordings collected from five pigs during a protocol of severe hemorrhage and resuscitation; three pigs were sham-treated controls. Moreover, we assessed the effects of severe hemorrhage on heart functionality by integrating the hemodynamic findings with measures of plasma high-sensitivity cardiac troponin T and metabolite concentrations in left ventricular (LV) tissue. Resuscitation was performed with fluids and norepinephrine and then by reinfusion of shed blood. After first resuscitation, mean BP reached the target value, but cardiovascular indexes were not fully restored, hinting at a partial recovery of the autonomic mechanisms. Moreover, cardiac troponins were still elevated, suggesting a persistent myocardial sufferance. After blood reinfusion all the indexes returned to baseline. In the harvested heart, LV metabolic profile confirmed the acute stress condition sensed by the cardiomyocytes. Variability indexes and baroreflex trends can be valuable tools to evaluate the severity of HS, and they may represent a more useful end point for resuscitation in combination with standard measures such as mean values and biological measures. NEW & NOTEWORTHY Autonomic control of blood pressure was highly impaired during hemorrhagic shock, and it was not completely recovered after resuscitation despite global restoration of mean pressures. Moreover, a persistent myocardial sufferance emerged from measured cardiac troponin T and metabolite concentrations of left ventricular tissue. We highlight the importance of combining global mean values and biological markers with measures of variability and autonomic control for a better characterization of the effectiveness of the resuscitation strategy.

Comparative study of short-term cardiovascular autonomic control in cardiac surgery patients who underwent coronary artery bypass grafting or correction of valvular heart disease.

Introduction: Our aim was to perform a comparative study of short-term cardiovascular autonomic control in cardiac surgery patients who underwent coronary artery bypass grafting (CABG) or surgical correction of valvular heart disease (SCVHD ). Methods: The synchronous 15 minutes records of heart rate variability (HRV) and finger's photoplethysmographic waveform variability (PPGV) were performed in 42 cardiac surgery patients (12 women) aged 61.8 ± 8.6 years (mean ± standard deviation), who underwent CABG, and 36 patients (16 women) aged 54.2 ± 14.9 years, who underwent SCVHD , before surgery and in 5-7 days after surgery. Conventional time and frequency domain measures of HRV and index S of synchronization between the slow oscillations in PPGV and HRV were analyzed. We also calculated personal dynamics of these indices after surgery. Results: We found no differences (Р > 0.05) in all studied autonomic indices (preoperative and post-surgery) between studied patients' groups, except for the preoperative heart rate, which was higher in patients who underwent SCVHD (P = 0.013). We have shown a pronounced preoperative and post-surgery variability (magnitude of inter-quartile ranges) of all autonomic indices in studied patients. In the cluster analysis based on cardiovascular autonomic indices (preoperative and post-surgery), we divided all patients into two clusters (38 and 40 subjects) which did not differ in all clinical characteristics (except for the preoperative hematocrit, P = 0.038), index S, and all post-surgery HRV indices. First cluster (38 patients) had higher preoperative values of the HR, TP, HF, and HF%, and lower preoperative values of the LF% and LF/HF. Conclusion: The variability of cardiovascular autonomic indices in on-pump cardiac surgery patients (two characteristic clusters were identified based on preoperative indices) was not associated with their clinical characteristics and features of surgical procedure (including cardioplegia).

Role of aerobic physical training on cardiac autonomic and morphophysiological dysfunction in hypertensive rats subjected to ovarian hormone deprivation

Here we investigated the effects of physical training on cardiovascular autonomic control and cardiac morphofunctional parameters in spontaneously hypertensive rats (SHRs) subjected to ovarian hormone deprivation. Forty-eight 10-week-old SHRs were divided into two groups: ovariectomized (OVX, n=24) and sham (SHAM, n=24). Half of each group (n=12) was trained by swimming for 12 weeks (OVX-T and SHAM-T). Cardiac morphology and functionality were assessed using echocardiography, and autonomic parameters were assessed using double pharmacological autonomic block, baroreflex sensitivity (BRS), and analyses of heart rate variability (HRV) and blood pressure variability (BPV). Ovariectomy did not influence the cardiac autonomic tonus balance unlike physical training, which favored greater participation of the vagal autonomic tonus. Ovariectomy and aerobic physical training did not modify HRV and BRS, unlike BPV, for which both methods reduced low-frequency oscillations, suggesting a reduction in sympathetic vascular modulation. Untrained ovariectomized animals showed a reduced relative wall thickness (RWT) and increased diastolic and systolic volumes and left ventricular diameters, resulting in increased stroke volume. Trained ovariectomized animals presented reduced posterior wall thickness and RWT as well as increased final diastolic diameter, left ventricular mass, and stroke volume. Ovarian hormone deprivation in SHRs promoted morphofunctional adaptations but did not alter the evaluation of cardiac autonomic parameters. In turn, aerobic physical training contributed to a more favorable cardiac autonomic balance to the vagal autonomic component and promoted morphological adaptations but had little effect on cardiac functionality.

Chronic cholinergic stimulation promotes changes in cardiovascular autonomic control in spontaneously hypertensive rats.

Hypertension is often accompanied by autonomic dysfunction, which is detrimental to cardiac regulation. On the other hand, cholinergic stimulation through inhibition of acetylcholinesterase appears to have beneficial effects on cardiac autonomic control. Thus, our objective was to investigate the effects of chronic cholinergic stimulation on hemodynamic and cardiovascular autonomic control parameters in spontaneously hypertensive rats (SHR). For this, 26-week-old SHR (N = 32) and Wistar Kyoto rats (WK; N = 32) were divided into two groups: one treated with vehicle (H2O; N = 16) and the other treated with pyridostigmine bromide (PYR; N = 16) in drinking water (25 mg/kg/day) for 2 weeks. All groups were subjected to recording of arterial pressure (AP) and heart rate (HR), quantification of ejection fraction (EF), evaluation of cardiac tonic autonomic balance by means of double autonomic blockade with methylatropine and propranolol, analysis of systolic AP (SAP) and HR variability (HRV), and evaluation of baroreflex sensitivity (BRS). AP, HR, and EF were reduced in the SHR-PYR group compared with the SHR-H2O group. Evaluation of autonomic parameters revealed an increase in vagal tone participation in cardiac tonic autonomic balance and reduced SAP variability; however, no changes were observed in HRV or BRS. These results suggest that chronic cholinergic stimulation with pyridostigmine bromide promotes reduction in the hemodynamic parameters AP, HR, and EF. Additionally, tonic autonomic balance was improved and a reduction in LF oscillations of SAP variability was observed that could not be attributed to BRS, as the latter did not change. Further studies should be conducted to identify the mechanisms involved in the observed responses.

Are there relationship between internal and external load of aerobic training with heart rate variability in women? / Há relação da carga interna e externa do treinamento aeróbio com variabilidade da frequência cardíaca em mulheres?

ABSTRACT The purpose was to investigate the relationship between internal training load (ITL), external training load (ETL) and heart rate variability (HRV) in women. 16 women (48.2 ± 6.4 yrs) performed HRV recordings (i.e. lnRMSSD - cardiovagal modulation) and Incremental Shuttle Walk Test (ISWT) before and after 12 aerobic training sessions. HRV threshold (HRVT) were used to prescribe aerobic ETL. The session rating of perceived exertion (s-RPE) was analyzed and served as the measure of ITL. The score found for ITL in the 12 sessions was 2878 ± 380 arbitrary units and ETL were 36822 ± 5852 m. A significant difference was observed in the lnRMSSD (3.14 ± 0.30 vs. 3.43 ± 0.38 ms−1; P = 0.001). There were observed large correlation between lnRMSSD at baseline vs ISWT (r = 0.73, P = 0.001), HRVT (r = 0.67, P = 0.004) and ITL (r = 0.62, P = 0.011). Very large correlation between individual smallest worthwhile change lnRMSSD after training and ITL (r = 0.81, P = 0.0001) was observed. There is a strong association between the HRV and aerobic performance (HRVT and ISWTdistance) and strong relationship between HRV and the potential to accumulate ITL, but not aerobic ETL in women.

RESUMO O objetivo foi investigar a relação da carga interna de treinamento (CIT), carga externa de treinamento (CET) e variabilidade da frequência cardíaca (VFC) em mulheres. 16 mulheres (48,2 ± 6,4 anos) realizaram medidas de VFC em repouso (variável lnRMSSD - modulação cardiovagal) e o teste incremental de caminhada (TIC) antes e depois de 12 semanas de treinamento aeróbio. O limiar da VFC (LVFC) foi utilizado para prescrição da CET. A percepção subjetiva de esforço (PSE) foi utilizada para cálculo da CIT. O valor de CIT encontrado nas 12 sessões foi de 2878 ± 380 unidades arbitrárias e para CET de 36822 ± 5852 m. Foi observada diferença significativa para lnRMSSD (3,14 ± 0,30 vs. 3,43 ± 0,38 ms−1; P = 0.001). Verificou-se uma correlação grande entre lnRMSSD basal e TIC (r = 0.73, P = 0.001), LVFC (r = 0.67, P = 0.004) e CIT (r = 0.62, P = 0.011). Foi encontrada uma correlação muito grande entre a mínima diferença detectável individual do lnRMSSD após treinamento e CIT. Conclui-se que há uma forte relação entre VFC e performance aeróbia (LVFC e TICdistância), VFC e acúmulo de CIT, porém, sem relação com a CET acumulada nas 12 semanas nas mulheres estudadas.

Effects of mechanical stimulation of the feet on gait and cardiovascular autonomic control in Parkinson's disease.

Motor impairment in Parkinson's disease (PD) is partly due to defective central processing of lower limb afferents. Concomitant alterations in cardiovascular autonomic control leading to orthostatic hypotension may worsen motor ability. We evaluated whether mechanical activation of feet sensory afferents could improve gait and modify the response of cardiovascular autonomic control to stressors in 16 patients (age 66 ± 2 yr) with idiopathic PD (Hoehn & Yhar scale 2-3) on their usual therapy. Eight subjects (group A) were randomized to undergo skin pressure (0.58 ± 0.04 kg/mm(2)) stimulation at the hallux tip and first metatarsal joint (effective stimulation; ES) of both feet. Eight remaining patients (group B) underwent sham stimulation (SS) followed by ES. Three-dimensional movement analysis provided quantitative indexes of movement disability before (baseline) and 24 h after ES and SS. Spectral analysis of heart rate and blood pressure variability provided markers of cardiac sympatho-vagal (LF/HF) and vascular sympathetic (LFSAP) modulations. Markers were measured at rest and during 75° head-up tilt, before and 24 h after ES and SS. After ES, step length and gait velocity increased, upright rotation velocity was enhanced, and step number was decreased. After ES, LFSAP declined. The increase in LF/HF and LFSAP induced by tilt was greater than before feet stimulation. No changes in gait and autonomic parameters were observed after SS. Twenty-four hours after ES, patients with PD showed improved gait and increased cardiac and vascular sympathetic modulation during upright position compared with baseline. Conversely, SS was ineffective on both movement and autonomic parameters, indicating a site specificity effect of the stimulation.

Autonomic Cardiovascular Damage during Post-menopause: the Role of Physical Training.

Menopause is part of the aging process and is characterized by the natural cessation of menstruation; during this time, the production of ovarian hormones, especially estrogen, is sharply reduced. This reduction can cause symptoms and disorders that affect most women and can interfere with their quality of life. Women are also more susceptible to cardiovascular diseases during this period, considering that these ovarian hormones would be associated with a protective effect on the cardiovascular system, by acting at various levels, contributing to the body homeostasis. Among several effects on the cardiovascular system, the ovarian hormones seem to play an important role in the autonomic control of heart rate and blood pressure. A reduction in ovarian hormones causes an autonomic imbalance and increases the risk of cardiovascular diseases. In fact, this increased risk is justified by the key role the autonomic nervous system plays in all cardiac regulatory mechanisms, exerting a tonic and reflexive influence on the main variables of the cardiovascular system. The autonomic system controls various cardiovascular parameters, such as the modulation of heart rate and blood pressure, myocardial contractility and venous capacitance, directly participating in the regulation of cardiac output. Over the years, the standard treatment for menopause symptoms and disorders has been hormone replacement therapy (HRT). However, many studies have indicated the risks of HRT, which justify the need for new non-pharmacological therapies. To this end, physical training, mainly aerobic, has been applied with excellent results on the cardiovascular autonomic nervous system, as it reduces the risk of cardiac diseases and improves the survival rate with direct beneficial effects on the quality of life of these women during the aging process.