Reference equations of oxygen uptake for the step test in the obese population

The aim of this study was to establish reference equations for the six-minute step test (6MST) based on demographic, anthropometric, body composition, and performance variables able to predict oxygen uptake (V̇O2) in obese individuals. Seventy-three obese adults (42±14 years old, body mass index >30 kg/m2) from both sexes were included. They underwent anamnesis, body composition evaluation, and the 6MST with expired gases registered simultaneously. Three equations were developed for the obese population (n=73; 59% female). The first equation was composed of the up-and-down step cycles (UDS), sex, and age as predictors; the second equation was composed of the UDS, age, and lean mass (LM). Both equations collectively explained 68.1% of the V̇O2 variance in the 6MST, while the third equation, composed of the UDS, age, and body mass, accounted for 67.7% of the V̇O2 variance. UDS, sex, age, LM, and body mass were important V̇O2 predictors of 6MST in these obese individuals. This study contributes to the dissemination of a simple, inexpensive, and fast evaluation method that can provide important indicators of cardiorespiratory fitness and guide strategies for rehabilitation.

Mild-to-moderate COVID-19 impact on the cardiorespiratory fitness in young and middle-aged populations

The goal of the present study was to compare pulmonary function test (PFT) and cardiopulmonary exercise test (CPET) performance in COVID-19 survivors with a control group (CG). This was a cross-sectional study. Patients diagnosed with COVID-19, without severe signs and symptoms, were evaluated one month after the infection. Healthy volunteers matched for sex and age constituted the control group. All volunteers underwent the following assessments: i) clinical evaluation, ii) PTF; and iii) CPET on a cycle ergometer. Metabolic variables were measured by the CareFusion Oxycon Mobile device. In addition, heart rate responses, peak systolic and diastolic blood pressure, and perceived exertion were recorded. Twenty-nine patients with COVID-19 and 18 healthy control subjects were evaluated. Surviving patients of COVID-19 had a mean age of 40 years and had higher body mass index and persistent symptoms compared to the CG (P<0.05), but patients with COVID-19 had more comorbidities, number of medications, and greater impairment of lung function (P<0.05). Regarding CPET, patients surviving COVID-19 had reduced peak workload, oxygen uptake (V̇O2), carbon dioxide output (V̇CO2), circulatory power (CP), and end-tidal pressure for carbon dioxide (PETCO2) (P<0.05). Additionally, survivors had depressed chronotropic and ventilatory responses, low peak oxygen saturation, and greater muscle fatigue (P<0.05) compared to CG. Despite not showing signs and symptoms of severe disease during infection, adult survivors had losses of lung function and cardiorespiratory capacity one month after recovery from COVID-19. In addition, cardiovascular, ventilatory, and lower limb fatigue responses were the main exercise limitations.

Effects of respiratory muscle training on parasympathetic activity in diabetes mellitus

This study verified the effects of respiratory muscle training (RMT) on hemodynamics, heart rate (HR) variability, and muscle morphology in rats with streptozotocin-induced diabetes mellitus (DM). Thirty-six male Wistar rats were randomized into 4 groups and 34 completed the study: i) sham-sedentary (Sham-ST; n=9); ii) sham-RMT (Sham-RMT; n=9); iii) DM-sedentary (DM-ST; n=8); and iv) DM-RMT (DM-RMT; n=8). Hemodynamics were assessed by central cannulation, and R-R intervals were measured by electrocardiogram. In addition, the effects of RMT on the cross-sectional area of the diaphragm, anterior tibial, and soleus muscles were analyzed. The induction of DM by streptozotocin resulted in weight loss, hyperglycemia, reduced blood pressure, and attenuated left ventricular contraction and relaxation (P<0.05). We also observed a decrease in root mean square of successive differences between adjacent RR intervals (RMSSD) index and in the cross-sectional area of the muscles assessed, specifically the diaphragm, soleus, and anterior tibial muscles in diabetic rats (P<0.05). Interestingly, RMT led to an increase in RMSSD in rats with DM (P<0.05). The induction of DM produced profound deleterious changes in the diaphragmatic and peripheral muscles, as well as impairments in cardiovascular hemodynamics and autonomic control. Nevertheless, RMT may beneficially attenuate autonomic changes and improve parasympathetic modulation.

Reliability and validity of six-minute step test in patients with heart failure

Exercise intolerance is the hallmark consequence of advanced chronic heart failure (HF). The six-minute step test (6MST) has been considered an option for the six-minute walk test because it is safe, inexpensive, and can be applied in small places. However, its reliability and concurrent validity has still not been investigated in participants with HF with reduced ejection fraction (HFrEF). Clinically stable HFrEF participants were included. Reliability and error measurement were calculated by comparing the first with the second 6MST result. Forty-eight hours after participants underwent the 6MST, they were invited to perform a cardiopulmonary exercise test (CPET) on a cycle ergometer. Concurrent validity was assessed by correlation between number of steps and peak oxygen uptake (V̇O2 peak) at CPET. Twenty-seven participants with HFrEF (60±8 years old and left ventricle ejection fraction of 41±6%) undertook a mean of 94±30 steps in the 6MST. Intra-rater reliability was excellent for 6MST (ICC=0.9), with mean error of 4.85 steps and superior and inferior limits of agreement of 30.6 and -20.9 steps, respectively. In addition, strong correlations between number of steps and CPET workload (r=0.76, P<0.01) and peak V̇O2 (r=0.71, P<0.01) were observed. From simple linear regression the following predictive equations were obtained with 6MST results: V̇O2 peak (mL/min) = 350.22 + (7.333 × number of steps), with R2=0.51, and peak workload (W) = 4.044 + (0.772 × number of steps), with R2=0.58. The 6MST was a reliable and valid tool to assess functional capacity in HFrEF participants and may moderately predict peak workload and oxygen uptake of a CPET.

Effect of continuous positive airway pressure associated to exercise on the breathing pattern and heart rate variability of patients undergoing coronary artery bypass grafting surgery: a randomized controlled trial

Continuous positive airway pressure (CPAP) has been used to improve gas exchange and diaphragmatic function, among others benefits. Moreover, it can be used to increase exercise tolerance and positively influence ventilatory function and breathing pattern (BP) during exercise. However, there is no information about the long-term effects of CPAP, as an adjunct to an inpatient cardiac rehabilitation (CR) program, on BP and heart rate variability (HRV) of patients after coronary artery bypass grafting surgery (CABG). Twenty patients were allocated to receive, after randomization, standard inpatient CR without CPAP (control group - CG) or CR with CPAP between 10 to 12 cmH2O (CPAP group - CPG) associated with the exercises. Participants were assessed preoperatively and on the discharge day, in the sitting rest position. Outcome measurements included BP variables, collected by respiratory inductive plethysmography, and HRV, collected by polar precision performance. The CPG presented lower values of percent rib cage inspiratory and expiratory contributions to tidal volume (%RCi and %RCe) at discharge time, compared to CG. No statistical differences between groups were observed for HRV variables and both groups presented lower values of these indices, compared to preoperative ones. In this context, the patients who received CPAP throughout the whole rehabilitation program were discharged with a better BP, which could indicate more synchronized breathing. CPAP did not influence cardiac autonomic modulation in the long term.

Impact of chronic obstructive pulmonary disease on linear and nonlinear dynamics of heart rate variability in patients with heart failure

The objective of this study was to investigate the impact of chronic obstructive pulmonary disease (COPD)-heart failure (HF) coexistence on linear and nonlinear dynamics of heart rate variability (HRV). Forty-one patients (14 with COPD-HF and 27 HF) were enrolled and underwent pulmonary function and echocardiography evaluation to confirm the clinical diagnosis. Heart rate (HR) and R-R intervals (iRR) were collected during active postural maneuver (APM) [supine (10 min) to orthostasis (10 min)], respiratory sinus arrhythmia maneuver (RSA-M) (4 min), and analysis of frequency domain, time domain, and nonlinear HRV. We found expected autonomic response during orthostatic changes with reduction of mean iRR, root mean square of successive differences between heart beats (RMSSD), RR tri index, and high-frequency [HF (nu)] and an increased mean HR, low-frequency [LF (nu)], and LF/HF (nu) compared with supine only in HF patients (P<0.05). Patients with COPD-HF coexistence did not respond to postural change. In addition, in the orthostatic position, higher HF nu and lower LF nu and LF/HF (nu) were observed in COPD-HF compared with HF patients. HF patients showed an opposite response during RSA-M, with increased sympathetic modulation (LF nu) and reduced parasympathetic modulation (HF nu) (P<0.05) compared with COPD-HF patients. COPD-HF directly influenced cardiac autonomic modulation during active postural change and controlled breathing, demonstrating an autonomic imbalance during sympathetic and parasympathetic maneuvers compared with isolated HF.

Effects of high- and moderate-intensity exercise on central hemodynamic and oxygen uptake recovery kinetics in CHF-COPD overlap

The oxygen uptake (V˙O2) kinetics during onset of and recovery from exercise have been shown to provide valuable parameters regarding functional capacity of both chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF) patients. To investigate the influence of comorbidity of COPD in patients with CHF with reduced ejection fraction on recovery from submaximal exercise, 9 CHF-COPD male patients and 10 age-, gender-, and left ventricle ejection fraction (LVEF)-matched CHF patients underwent constant-load exercise tests (CLET) at moderate and high loads. The V˙O2, heart rate (HR), and cardiac output (CO) recovery kinetics were determined for the monoexponential relationship between these variables and time. Within-group analysis showed that the recovery time constant of HR (P<0.05, d=1.19 for CHF and 0.85 for CHF-COPD) and CO (P<0.05, d=1.68 for CHF and 0.69 for CHF-COPD) and the mean response time (MRT) of CO (P<0.05, d=1.84 for CHF and 0.73 for CHF-COPD) were slower when moderate and high loads were compared. CHF-COPD patients showed smaller amplitude of CO recovery kinetics (P<0.05) for both moderate (d=2.15) and high (d=1.07) CLET. Although the recovery time constant and MRT means were greater in CHF-COPD, CHF and CHF-COPD groups were not differently affected by load (P>0.05 in group vs load analysis). The ventilatory efficiency was related to MRT of V˙O2 during high CLET (r=0.71). Our results suggested that the combination of CHF and COPD may further impair the recovery kinetics compared to CHF alone.

Validation of the two-minute step test in obese with comorbibities and morbidly obese patients

Cardiopulmonary fitness assessment is a valuable resource to obtain quantitative indicators of an individual's physical performance. The cardiopulmonary exercise test (CPX), considered the gold standard test for this evaluation, is costly and difficult to be accessed by the general population. In order to make this evaluation more accessible, and to better reflect the performance of daily life activities, alternative tests were proposed. Morbidly obese patients present limitations that impair physical performance assessment and could benefit from a test of shorter duration, provided it is validated. This observational study aimed to validate the two-minute step test (2MST) as a tool to evaluate functional capacity (FC) in obese with comorbidities and morbidly obese patients, compared the 2MST with CPX as a measure of physical performance, and developed a predictive equation to estimate peak oxygen uptake (VO2) in the 2MST. The CPX and the 2MST were performed and metabolic and ventilatory parameters were recorded in 31 obese individuals (BMI>35 kg/m2). Pearson correlation and multiple linear regression analyses were performed to evaluate the peak VO2 best predictors. Bland-Altman analysis was performed to assess the agreement between the two methods. Peak VO2 measured by CPX and 2MST showed a strong correlation (r=0.70, P<0.001) and there was a moderate correlation between peak VO2 of the 2MST and the number of up-and-down step cycles (UDS) (r=0.55; P=0.01). The reference equation obtained was: VO2 (mL·kg-1·min-1) = 13.341 + 0.138 × total UDS - (0.183 × BMI), with an estimated standard error of 1.3 mL·kg-1·min-1. The 2MST is a viable, practical, and easily accessible test for FC. UDS and BMI can predict peak VO2 satisfactorily.

Ultra-short-term heart rate variability during resistance exercise in the elderly

Despite the appeal of ultra-short-term heart rate variability (HRV) methods of analysis applied in the clinical and research settings, the number of studies that have investigated HRV by analyzing R-R interval (RRi) recordings shorter than 5 min is still limited. Moreover, ultra-short-term HRV analysis has not been extensively validated during exercise and, currently, no indications exist for its applicability during resistance exercise. The aim of the present study was to compare ultra-short-term HRV analysis with standard short-term HRV analysis during low-intensity, dynamic, lower limb resistance exercise in healthy elderly subjects. Heart rate (HR) and RRi signals were collected from 9 healthy elderly men during discontinuous incremental resistance exercise consisting of 4-min intervals at low intensities (10, 20, 30, and 35% of 1-repetition maximum). The original RRi signals were segmented into 1-, 2-, and 3-min sections. HRV was analyzed in the time domain (root mean square of the of differences between adjacent RRi, divided by the number of RRi, minus one [RMSSD]), RRi mean value and standard deviation [SDNN] (percentage of differences between adjacent NN intervals that are greater than 50 ms [pNN50]), and by non-linear analysis (short-term RRi standard deviation [SD1] and long-term RRi standard deviation [SD2]). No significant difference was found at any exercise intensity between the results of ultra-short-term HRV analysis and the results of standard short-term HRV analysis. Furthermore, we observed excellent (0.70 to 0.89) to near-perfect (0.90 to 1.00) concordance between linear and non-linear parameters calculated over 1- and 2-min signal sections and parameters calculated over 3-min signal sections. Ultra-short-term HRV analysis appears to be a reliable surrogate of standard short-term HRV analysis during resistance exercise in healthy elderly subjects.

Cardiorespiratory and metabolic determinants during moderate and high resistance exercise intensities until exhaustion using dynamic leg press: comparison with critical load

The objective of this study was to assess cardiovascular, respiratory, and metabolic responses during a commonly used dynamic leg press resistance exercise until exhaustion (TEx) at different intensities and compare with critical load (CL). This was a prospective, cross-sectional, controlled, and crossover study. Twelve healthy young men (23±2.5 years old) participated. The subjects carried out three bouts of resistance exercise in different percentages of 1 repetition maximum (60, 75, and 90% 1RM) until TEx. CL was obtained by means of hyperbolic model and linearization of the load-duration function. During all bout intensities, oxygen uptake (VO2), carbon dioxide production (VCO2), ventilation (VE), and respiratory exchange ratio (RER) were obtained. Variations (peak-rest=Δ) were corrected by TEx. In addition, systolic and diastolic blood pressure (SBP and DBP), blood lactate concentration [La-] and Borg scores were obtained at the peak and corrected to TEx. CL induced greater TEx as well as number of repetitions when compared to all intensities (P<0.001). During CL, Borg/TEx, ΔSBP/TEx, ΔDBP/TEx, and [La-] were significantly lower compared with 90% load (P<0.0001). In addition, VO2, VCO2, VE, and RER were higher during CL when compared to 90 or 75%. TEx was significantly correlated with VO2 on CL (r=0.73, P<0.05). These findings support the theory that CL constitutes the intensity that can be maintained for a very long time, provoking greater metabolic and ventilatory demand and lower cardiovascular and fatigue symptoms during resistance exercise.

Relationship between aerobic capacity and pelvic floor muscles function: a cross-sectional study

The objective of this study was to evaluate the relationship between aerobic capacity and pelvic floor muscles (PFM) function in adult women. Women aged 18 or over and without urinary dysfunction or other chronic diseases were eligible to participate. They completed the habitual physical activity (HPA) questionnaire, underwent a PFM functional evaluation by palpation and perineometry, and performed a submaximal (between 75 and 85% of maximum heart rate) cardiopulmonary exercise (CPX) test to determine the ventilatory anaerobic threshold (VAT). Forty-one women were included (35±16 years, 75% physically active, 17% very active, and 8% sedentary and 17% presented grade 1 PFM contraction, 31.8% grade 2, 26.8% grade 3, and 24.4% grade 4, according to the modified Oxford Scale). The average PFM contraction pressure obtained by perineometer was 53±26 cmH2O and the average oxygen consumption at VAT (VO2VAT) obtained from CPX was 14±2 mL·kg-1·min-1. Significant correlations were found between PFM contraction pressure and VO2VAT (r=0.55; P<0.001); between PFM contraction pressure and HPA score (r=0.38; P=0.02); between age and VO2VAT (r=-0.25; P=0.049); and between VO2VAT and HPA score (r=0.36; P=0.02). An age-adjusted multiple linear regression equation (R2=0.32) was derived to estimate VO2VAT from the contraction value obtained by perineometer, so that the PFM contraction pressure was able to predict VO2VAT. The equation was validated using data from another group of 20 healthy women (33±12 years; PFM contraction: 49±23 cmH2O) and no significant difference was found between actual VO2VAT and predicted VO2VAT (13.1±1.9 vs 13.8±2.0 mL·kg-1·min-1). In conclusion, PFM function is associated with aerobic capacity in healthy women and PFM contraction pressure may be used to estimate VO2VAT in this population.

Does the incremental shuttle walk test require maximal effort in young obese women?

Obesity is a chronic disease with a multifaceted treatment approach that includes nutritional counseling, structured exercise training, and increased daily physical activity. Increased body mass elicits higher cardiovascular, ventilatory and metabolic demands to varying degrees during exercise. With functional capacity assessment, this variability can be evaluated so individualized guidance for exercise training and daily physical activity can be provided. The aim of the present study was to compare cardiovascular, ventilatory and metabolic responses obtained during a symptom-limited cardiopulmonary exercise test (CPX) on a treadmill to responses obtained by the incremental shuttle walk test (ISWT) in obese women and to propose a peak oxygen consumption (VO2) prediction equation through variables obtained during the ISWT. Forty obese women (BMI ≥30 kg/m2) performed one treadmill CPX and two ISWTs. Heart rate (HR), arterial blood pressure (ABP) and perceived exertion by the Borg scale were measured at rest, during each stage of the exercise protocol, and throughout the recovery period. The predicted maximal heart rate (HRmax) was calculated (210 – age in years) (16) and compared to the HR response during the CPX. Peak VO2 obtained during CPX correlated significantly (P<0.05) with ISWT peak VO2 (r=0.79) as well as ISWT distance (r=0.65). The predictive model for CPX peak VO2, using age and ISWT distance explained 67% of the variability. The current study indicates the ISWT may be used to predict aerobic capacity in obese women when CPX is not a viable option.

Cardiac autonomic modulation during progressive upper limb exercise by patients with coronary artery disease

The purpose of this study was to investigate the behavior of heart rate (HR) and HR variability (HRV) during different loads of resistance exercise (incline bench press) in patients with coronary artery disease (CAD) and healthy sedentary controls. Ten healthy men (65 ± 1.2 years, control group, CG) and 10 men with clinically stable CAD (66 ± 2.4 years, CADG) were recruited. A discontinuous progressive protocol was applied with an initial load of 10 percent of the maximum load achieved in the 1RM (1 repetition maximum) with increases of 10 percent until 30 percent 1RM was reached, which was followed by subsequent increases of 5 percent 1RM until exhaustion. HRV was analyzed by linear and non-linear methods. There was a significant reduction in rMSSD (CG: 20 ± 2 to 11 ± 3 ms; CADG: 19 ± 3 to 9 ± 1 ms) and SD1 indexes (CG: 14 ± 2 to 8 ± 1 ms; CADG: 14 ± 2 to 7 ± 1 ms). An increase in HR (CG: 69 ± 5 to 90 ± 5 bpm; CADG: 62 ± 4 to 75 ± 4 bpm) and in systolic blood pressure (CG: 124 ± 3 to 138 ± 3 mmHg; CADG: 122 ± 6 to 126 ± 9 bpm) were observed (P < 0.05) when comparing pre-effort rest and 40 percent 1RM in both groups. Furthermore, an increase in RMSM index was also observed (CG: 28 ± 3 to 45 ± 9 ms; CADG: 22 ± 2 to 79 ± 33 ms), with higher values in CADG. We conclude that loads up to 30 percent 1RM during incline bench press result in depressed vagal modulation in both groups, although only stable CAD patients presented sympathetic overactivity at 20 percent 1RM upper limb exercise.

Effects of different levels of positive airway pressure on breathing pattern and heart rate variability after coronary artery bypass grafting surgery

The application of continuous positive airway pressure (CPAP) produces important hemodynamic alterations, which can influence breathing pattern (BP) and heart rate variability (HRV). The aim of this study was to evaluate the effects of different levels of CPAP on postoperative BP and HRV after coronary artery bypass grafting (CABG) surgery and the impact of CABG surgery on these variables. Eighteen patients undergoing CABG were evaluated postoperatively during spontaneous breathing (SB) and application of four levels of CPAP applied in random order: sham (3 cmH2O), 5 cmH2O, 8 cmH2O, and 12 cmH2O. HRV was analyzed in time and frequency domains and by nonlinear methods and BP was analyzed in different variables (breathing frequency, inspiratory tidal volume, inspiratory and expiratory time, total breath time, fractional inspiratory time, percent rib cage inspiratory contribution to tidal volume, phase relation during inspiration, phase relation during expiration). There was significant postoperative impairment in HRV and BP after CABG surgery compared to the preoperative period and improvement of DFAα1, DFAα2 and SD2 indexes, and ventilatory variables during postoperative CPAP application, with a greater effect when 8 and 12 cmH2O were applied. A positive correlation (P < 0.05 and r = 0.64; Spearman) was found between DFAα1 and inspiratory time to the delta of 12 cmH2O and SB of HRV and respiratory values. Acute application of CPAP was able to alter cardiac autonomic nervous system control and BP of patients undergoing CABG surgery and 8 and 12 cmH2O of CPAP provided the best performance of pulmonary and cardiac autonomic functions.

Spectral and symbolic analysis of the effect of gender and postural change on cardiac autonomic modulation in healthy elderly subjects

The objective of this study was to use linear and non-linear methods to investigate cardiac autonomic modulation in healthy elderly men and women in response to a postural change from the supine to the standing position. Fourteen men (66.1 ± 3.5 years) and 10 women (65.3 ± 3.3 years) were evaluated. Beat-to-beat heart rate was recorded in the supine and standing positions. Heart rate variability was studied by spectral analysis, including both low (LFnu-cardiac sympathetic modulation (CSM) indicator) and high (HFnu-cardiac vagal modulation (CVM) indicator) frequencies in normalized units as well as the low frequency/high frequency (LF/HF) ratio. Symbolic analysis was performed using the following indexes: 0V percent (CSM indicator), 1V percent (CSM and CVM indicators), 2LV percent (predominantly CVM indicator) and 2ULV percent (CVM indicator). Shannon entropy was also calculated. Men presented higher LFnu and LF/HF ratio and lower HFnu and 1V percent symbolic index (57.56, 4.14, 40.53, 45.96, respectively) than women (24.60, 0.45, 72.47, 52.69, respectively) in the supine position. Shannon entropy was higher among men (3.53) than among women (3.33) in the standing position, and also increased according to postural change in men (3.25; 3.53). During postural change, the LFnu (24.60; 49.85) and LF/HF ratio (0.45; 1.72) increased, with a concomitant decrease in HFnu (72.47; 47.56) and 2LV percent (14.10; 6.95) in women. Women presented increased CSM in response to postural change and had higher CVM and lower CSM than men in the supine position. In conclusion, women in the age range studied presented a more appropriate response to a postural change than men, suggesting that cardiac autonomic modulation may be better preserved in women than in men.

Atividade autonômica em uma adolescente com ventrículo único submetida à intervenção fisioterapêutica: relato de caso / Autonomic activity in an adolescent with a single ventricle who underwent physical therapy intervention: case report

OBJETIVO: Avaliar a atividade autonômica de uma adolescente com ventrículo único (VU), sem correção cirúrgica, participante de um programa de fisioterapia. MATERIAIS E MÉTODOS: Paciente do sexo feminino, 14 anos, com diagnóstico de VU tipo esquerdo, sem correção cirúrgica. A atividade autonômica foi avaliada pela variabilidade da freqüência cardíaca (VFC) nas posições supina e sentada, e pela manobra para acentuar a arritmia sinusal respiratória (M-ASR) no início do primeiro (A1), segundo (A2) e terceiro anos (A3) de tratamento fisioterapêutico cardiovascular (TFC) ambulatorial. Os intervalos RR e a freqüência cardíaca batimento a batimento foram calculados e armazenados para posterior análise. A VFC foi avaliada pelos índices RMSSD e RMSM e no domínio da freqüência pelas bandas de alta e baixa freqüência em unidades normalizadas (AFun e BFun, respectivamente) e pela razão BF/AF. O TFC constou de exercícios respiratórios associados a exercícios ativos e resistidos gerais, durante dois anos. RESULTADOS: De A1 para A3, o RMSM reduziu (14,5 por cento), a banda de BFun (42,2 por cento) e a razão BF/AF aumentou (117,0 por cento), e a banda AFun diminuiu (35,2 por cento). Em todas as situações, a banda BFun foi maior e a AFun foi menor na posição sentada. Além disso, a resposta parassimpática à M-ASR aumentou da situação A1 para A3 em 7,4 e 47,3 por cento, respectivamente. CONCLUSÕES: Concluímos que, na paciente estudada, a redução da VFC parece estar associada com o avanço da doença, porém, não houve prejuízos frente à mudança postural. Adicionalmente, o TFC proposto incrementou a resposta parassimpática durante a M-ASR.

OBJECTIVE: To evaluate the autonomic activity of an adolescent with a single ventricle without surgical correction who participated in a physical therapy program. METHODS: This was a 14-year-old female patient with a left-type single ventricle who had not undergone any surgical intervention. The autonomic activity was evaluated according to the heart rate variability in the supine and seated positions and by means of the respiratory sinus arrhythmia accentuation maneuver (RSA-M) in the beginning of the first, second and third years of outpatient cardiovascular physical therapy treatment. The RR intervals and beat-to-beat heart rate were calculated and stored for subsequent analysis. The heart rate variability was evaluated by means of the RMSSD and RMSM indexes and in the frequency domain with high and low frequency bands in normalized units (HFnu and LFnu, respectively) and using the LF/HF ratio. The cardiovascular physical therapy consisted of respiratory exercises associated with active and general resistance exercises, for two years. RESULTS: From the first to the third year, the RMSM decreased (14.5 percent), LFnu band increased (42.2 percent), LF/HF ratio increased (117.0 percent) and HFnu decreased (35.2 percent). In all of the situations, the LFnu band was higher and HFnu was lower in the seated position. Additionally, the parasympathetic response to RSA-M increased from the first to the third years in 7.4 percent and 47.3 percent, respectively. CONCLUSIONS: We concluded that, for the patient studied, the reduction in heart rate variability seemed to be associated with the advance of the disease. Nevertheless, there was no damages related to postural change. In addition, the cardiovascular physical therapy proposed increased the parasympathetic response during RSA-M.

Estudo da modulação autonômica da freqüência cardíaca em repouso de pacientes idosos com doença pulmonar obstrutiva crônica / Study on autonomic heart rate modulation at rest among elderly patients with chronic obstructive pulmonary disease

OBJETIVO: Avaliar a variabilidade da freqüência cardíaca (VFC) de pacientes idosos com doença pulmonar obstrutiva crônica (DPOC) e de idosos saudáveis frente à mudança postural. MÉTODOS: Foram estudados 9 indivíduos com DPOC (70 anos) e 8 saudáveis (68 anos). A freqüência cardíaca e os intervalos R-R (iR-R) do eletrocardiograma foram registrados durante 360 s nas posturas supina e sentada. A VFC foi analisada no domínio do tempo (DT) (índice RMSSD - raiz quadrada da média dos quadrados das diferenças entre os iR-R sucessivos e SDNN - desvio-padrão da média dos iR-R normais em ms) e no domínio da freqüência (DF), pelas bandas de baixa (BF) e alta freqüência (AF) em unidades absolutas (ua) e normalizadas (un), e da razão BF/AF. Para análise intergrupo e intragrupo foram utilizados os testes de Mann-Whitney e Wilcoxon, respectivamente, com nível de significância de p< 0,05 (valores em mediana). RESULTADOS: No DT, o grupo controle (GC) apresentou valores significativamente maiores do RMSSD (14,6 versus 8,3ms) e SDNN (23,0 versus 13,5ms) na postura sentada, quando comparado ao grupo DPOC (GD). No DF, o GC apresentou valores significativamente maiores dos componentes de AF, na posição supina (39,0 versus 7,8 ua) e dos componentes de BF (146,7 versus 24,4 ua) e AF (67,6 versus 22,7 ua), na posição sentada, bem como do espectro total de potência (552,5 versus 182,9ms²). CONCLUSÃO: Pacientes portadores de DPOC apresentaram redução da VFC com diminuição da atividade simpática e vagal e não apresentaram ajustes autonômicos frente à mudança postural, assim como os idosos saudáveis.

OBJECTIVE: To evaluate heart rate variability (HRV) among elderly patients with chronic obstructive pulmonary disease (COPD) and healthy elderly individuals, during postural change. METHOD: Nine individuals with COPD (70 years old) and eight healthy individuals (68 years old) were studied. Heart rate and electrocardiographic R-R intervals (iR-R) were recorded for 360 seconds in the supine and seated positions. HRV was analyzed in the time domain (TD) (RMSSD index, i.e. the root mean square of the squares of the differences between successive iR-R records, and the SDNN index, i.e. the mean standard deviation of normal iR-R in ms) and in the frequency domain (FD), from the low-frequency (LF) and high-frequency (HF) bands in absolute units (au) and normalized units (nu), and the LF/HF ratio. The Mann-Whitney and Wilcoxon Tests respectively were utilized for inter--group and intra-group analysis, with a significant level of p< 0.05 (median values). RESULTS: In TD, the control group (CG) presented significantly higher values for the RMSSD index (14.6 versus 8.3 ms) and the SDNN index (23 versus 13.5 ms) in the seated position, in comparison with the COPD group (DG). In FD, the CG presented significantly higher values for HF components, in the supine position (39 versus 7.8 au), and for LF components (146.7 versus 24.4 au) and HF (67.6 versus 22.7 au), in the seated position, as well as for the total power spectrum (552.5 versus 182.9 ms²). CONCLUSION: Patients with COPD presented reduced HRV with decreased sympathetic and vagal activity. Additionally, neither the COPD patients nor the healthy elderly participants presented autonomic alterations with postural change.

Eficácia da intervenção fisioterapêutica associada ou não à respiração por pressão positiva intermitente (RPPI) após cirurgia cardíaca com circulação extracorpórea / Efficacy of physiotherapy intervention associated to intermitent posiitive pressure breathing after cardiac surgery with cardiopulmonary bypass

Este artigo objetivou avaliar as alterações na função pulmonar (FP) e força muscular respiratória (FMR)e eficácia de dois protocolos distintos em pacientes submetidos à cirurgia cardíaca (CC) com circulação extracorpórea (CEC). Método: 21 pacientes foram divididos em: GPPI (n=8), realizaram exercícios respiratórios com RPPI, associados à intervenção fisioterapêutica (IF); e GIF (n=13) realizaram somente IF. A FP foi avaliada pela espirometria no pré e 5º pós-operatório (PO) e a FMR pelas pressões respiratórias máximas (PImax e PEmax) no pré, 1º e 5º PO. O teste de Wilcoxon, Friedman e Man-Whitney foram utilizados para comparãções intra e intergrupos, respectivamente. Resultados: não foram observadas diferenças significativas nos parâmetros antropométricos, aspectos clínicos e cirúrgicos entre os grupos. Foram encontrados valores significativamente menores no 5º PO em comparação à situação pré-operatória no GIF para a capacidade vital (CV), capacidade vital forçada (CVF), volume expiratório forçado no 1º segundo (VEF1), pico de fluxo (PF) e fluxo expiratório forçado (PEF). No entanto, para GPPI apenas o VEF1 permaneceu significativamente reduzido após a intervenção (p<0,05). Para a PImax e PEmax observou-se redução do pré-operatório para o 1º PO em ambos os grupos. Porém, apenas a PEmax atingiu valores próximos aos dos pré-operatório até o 5ºPO em ambos os grupos, enquanto a PImax permaneceu significativamente reduzida no GIF. Na análise intergrupos não foram observadas diferenças significativas para nenhuma das variáveis analisadas. Conclusões: concluímos que pacientes submetidos à CC com CEC sofrem prejuízos na FP e FMR, e que nenhum dostratamentos aplicados (IF ou IF+RPPI) mostrou significante superioridade com relação ao outro.

L-carnitine as an ergogenic aid for patients with chronic obstructive pulmonary disease submitted to whole-body and respiratory muscle training programs

The effects of adding L-carnitine to a whole-body and respiratory training program were determined in moderate-to-severe chronic obstructive pulmonary disease (COPD) patients. Sixteen COPD patients (66 ± 7 years) were randomly assigned to L-carnitine (CG) or placebo group (PG) that received either L-carnitine or saline solution (2 g/day, orally) for 6 weeks (forced expiratory volume on first second was 38 ± 16 and 36 ± 12 percent, respectively). Both groups participated in three weekly 30-min treadmill and threshold inspiratory muscle training sessions, with 3 sets of 10 loaded inspirations (40 percent) at maximal inspiratory pressure. Nutritional status, exercise tolerance on a treadmill and six-minute walking test, blood lactate, heart rate, blood pressure, and respiratory muscle strength were determined as baseline and on day 42. Maximal capacity in the incremental exercise test was significantly improved in both groups (P < 0.05). Blood lactate, blood pressure, oxygen saturation, and heart rate at identical exercise levels were lower in CG after training (P < 0.05). Inspiratory muscle strength and walking test tolerance were significantly improved in both groups, but the gains of CG were significantly higher than those of PG (40 ± 14 vs 14 ± 5 cmH2O, and 87 ± 30 vs 34 ± 29 m, respectively; P < 0.05). Blood lactate concentration was significantly lower in CG than in PG (1.6 ± 0.7 vs 2.3 ± 0.7 mM, P < 0.05). The present data suggest that carnitine can improve exercise tolerance and inspiratory muscle strength in COPD patients, as well as reduce lactate production.

Efeitos agudos da aplicacao do BiPAP sobre a tolerancia ao exercicio fisico em pacientes com doenca pulmonar obstrutiva cronica (DPOC) / Acute effects of BiPAP application on physical exercise tolerance among chronic obstructive pulmonary disease patients

Pacientes com Doenca Pulmonar Obstrutiva Cronica (DPOC) apresentam prejuizos sobre a capacidade de exercicio fisico. A ventilacao nao-invasiva (VNI) tem sido associada ao exercicio fisico com o objetivo de melhorar a tolerancia aos esforcos nesses pacientes. Objetivos: avaliar os efeitos agudos da aplicacao da pressao positiva nas vias aereas por dois niveis pressoricos(BiPAP) sobre a tolerancia ao exercicio fisico, a dispneia e a saturacao periferica de oxigenio (SpO2) em pacientes com DPOC. Material e metodos: foram estudados 27 pacientes com DPOC (68+-8,3 anos) com volume expiratorio forcado no 1 segundo (VEEF1) < 50 por cento do previsto e sintomas de dispneia aos esforcos. os pacientes foram submetyidos, de modo randomizado, a dois testes de caminhada de 6 minutos em esteira (TC6E); um com a aplicacao do BiPAP, com niveis pressoricos inspirados de 14+-1 cmH2O, e o outro sem o BiPAP