Paulo J.C. Vieira

Inspiratory muscle training improves blood flow to resting and exercising limbs in patients with chronic heart failure.

OBJECTIVES We tested the hypothesis that inspiratory muscle loading could result in exaggerated peripheral vasoconstriction in resting and exercising limbs and that inspiratory muscle training (IMT) could attenuate this effect in patients with chronic heart failure (CHF) and inspiratory muscle weakness. BACKGROUND Inspiratory muscle training improves functional capacity of patients with CHF, but the mechanisms of this effect are unknown. METHODS Eighteen patients with CHF and inspiratory muscle weakness (maximal inspiratory pressure <70% of predicted) and 10 healthy volunteers participated in the study. Inspiratory muscle loading was induced by the addition of inspiratory resistance of 60% of maximal inspiratory pressure, while blood flow to the resting calf (CBF) and exercising forearm (FBF) were measured by venous occlusion plethysmography. For the patients with CHF, blood flow measurements as well as ultrasound determination of diaphragm thickness were made before and after a 4-week program of IMT. RESULTS With inspiratory muscle loading, CHF patients demonstrated a more marked reduction in resting CBF and showed an attenuated rise in exercising FBF when compared with control subjects. After 4 weeks of IMT, CHF patients presented hypertrophy of the diaphragm and improved resting CBF and exercise FBF with inspiratory muscle loading. CONCLUSIONS In patients with CHF and inspiratory muscle weakness, inspiratory muscle loading results in marked reduction of blood flow to resting and exercising limbs. Inspiratory muscle training improves limb blood flow under inspiratory loading in these patients.

Hemodynamic Responses to Resistance Exercise With Restricted Blood Flow in Young and Older Men

Abstract Vieira, PJC, Chiappa, GR, Umpierre, D, Stein, R, and Ribeiro, JP. Hemodynamic responses to resistance exercise with restricted blood flow in young and older men. J Strength Cond Res 27(8): 2288–2294, 2013—Exercise with blood flow restriction promotes significant improvements, and it has been considered an attractive exercise strategy, especially for older individuals. However, the acute cardiovascular responses to resistance exercise with blood flow restriction (BFR) are not fully known. The purpose of this study was to evaluate the hemodynamic responses during resistance exercise with BFR in young and older individuals. We compared hemodynamic responses in 15 young (30 ± 3 years) and 12 older (66 ± 7 years) subjects during low-intensity resistance biceps curl exercise with (BFR-RE) or without (RE) BFR in a random and crossover design. Heart rate (HR), mean blood pressure (MBP), calf blood flow (CBF), and calf vascular resistance (CVR) were evaluated. Both groups presented similar values at baseline. Compared with RE, HR and MBP were higher during BFR-RE for both the groups, and these changes were maintained during the recovery period. In both the groups, BFR-RE elicited larger decreases in CBF and increased CVR. Both groups showed a significant increase in double product during BFR-RE. In conclusion, resistance exercise with BFR elicits greater hemodynamic changes in healthy young and older subjects, with responses of similar magnitudes in both groups. The safety of BFR in clinical practice demands further study in vulnerable populations.

Neuromuscular electrical stimulation improves clinical and physiological function in COPD patients

BACKGROUND Neuromuscular electrical stimulation (NMES) improves muscle performance and exercise tolerance in chronic obstructive pulmonary disease (COPD) patients. In contrast, no study has assessed the effect of NMES on dynamic hyperinflation (DH) in COPD. This study investigated the effect of short-term, high-frequency NMES on DH in patients with COPD. METHODS Twenty patients were randomly allocated to either a NMES applied bilaterally to the quadriceps muscles (n = 11: 8 weeks, 5 days/week, twice/day, 45 min/session) or a control group (n = 09). All patients received respiratory physical therapy and stretching exercises. Free fat mass, pulmonary function, time to exercise tolerance (Tlim), 6-min walk test distance (6-MWTD), tumor necrosis factor (TNF-α) and β-endorphin levels, Borg dyspnea and leg score (BDS and BLS) and quality of life by the St. Georges Respiratory Questionnaire score (SGRQ) were examined before and after the intervention. RESULTS Compared with the control group, NMES increased FEV1 and FEV1/FVC, 6-MWD and Tlim (P < 0.01) and reduced BDS and SGRQ (P < 0.01). Additionally, changes in the Tlim were positively correlated with respiratory improvements in FEV1 (rho = 0.48, P < 0.01). Also, NMES reduced TNF-α and increased β-endorphin levels, compared with the control group (P < 0.001). CONCLUSION In summary, 8 weeks of NMES promotes reduction of the perceived sensation of dyspnea during exercise in patients with COPD. This finding is accompanied by improvements in FEV1, exercise tolerance and quality of life, and DH. Interestingly, these findings may be associated with enhanced vasodilatory function and a reduction in inflammatory responses. CLINICAL TRIAL REGISTRATION NCT01695421.

Blunted vascular responses but preserved endothelial vasodilation after submaximal exercise in chronic heart failure

Background Patients with chronic heart failure (CHF) have abnormal vascular responses to acute exercise; however, regular aerobic training improves endothelial function in these patients. We hypothesized that, because of their attenuated vascular responses, CHF patients would present abnormal endothelium-dependent vasodilatation after a single exercise session. Methods Thirteen CHF patients and 13 healthy controls participated in two experiments, on different days, using a crossover design: (i) control (25-min seated at rest), and (ii) a submaximal exercise session (25-min cycling). Measurements of heart rate, blood pressure (BP), venous occlusion plethysmography forearm blood flow (FBF), and reactive hyperemia were made before and after (immediately, 10, 30, 60 min, and 24 h) each experimental condition. Results CHF patients had no changes in the mean BP throughout the protocols, whereas mean BP was reduced up to 60 min after exercise in controls. In CHF patients, FBF was increased and forearm vascular resistance was reduced up to 10 min after exercise, whereas these changes were sustained up to 30 min after exercise in controls. Reactive hyperemia was significantly increased up to 30 min after exercise in both groups. Conclusion Patients with CHF have increased postexercise FBF and decreased forearm vascular resistance; however, these responses last longer in healthy individuals. Despite the attenuated postexercise vascular responses, patients with CHF respond to a single-cycle exercise session with improved forearm endothelium-dependent vasodilation. Eur J Cardiovasc Prev Rehabil 16:53-59

Effects of aerobic exercise intensity on ambulatory blood pressure and vascular responses in resistant hypertension: a crossover trial.

Background: Resistant hypertension often exposes patients to poor blood pressure (BP) control, resulting in clinical vulnerability, possible need for device-based procedures (denervation) and increased therapy costs. Regular exercise markedly benefits patients with hypertension, including resistant patients. However, little is known about short-term exercise effects in resistant hypertension. Objective: To evaluate acute hemodynamic effects of exercise in resistant hypertension. Method: After maximal exercise testing, 20 patients (54.0 ± 5.7 years, 30.2 ± 4.9 kg/m2) with resistant hypertension participated in three crossover interventions, in random order, and on separate days: control (45′ of rest), and light intensity and moderate intensity (45′ of aerobic exercise at 50 and 75% of maximum heart rate, respectively). Ambulatory BP, forearm blood flow (with subsequent calculation of vascular resistance), and reactive hyperemia were measured before and after interventions trough venous occlusion plethysmography. Results: Compared with control, both exercise intensities reduced ambulatory systolic pressure over 5 h (light: −7.7 ± 2.4 mmHg and moderate: −9.4 ± 2.8 mmHg, P < 0.01), whereas only light intensity reduced diastolic pressure (−5.7 ± 2.2 mmHg, P < 0.01). Light intensity also lowered systolic and diastolic pressures over 10-h daytime (−3.8 ± 1.3 and −4.0 ± 1.3 mmHg, respectively, P < 0.02), night-time (−6.0 ± 2.4 and −6.1 ± 1.6 mmHg, respectively, P < 0.05), and diastolic pressure over 19 h (−4.8 ± 1.2 mmHg, P < 0.01). Forearm blood flow changed (decreased) compared with baseline only at 50 min after light intensity (P < 0.05). After the control and light intensity sessions, vascular resistance increased at the end of 1 h, and after moderate intensity, it decreased only at the moment (∼2 min) immediately after intervention (P < 0.05). Conclusion: A single session of light or moderate aerobic exercise acutely reduces ambulatory BP in resistant hypertension, although benefits persist longer following light intensity.

Inspiratory resistance decreases limb blood flow in COPD patients with heart failure

To the Editor: Chronic heart failure (CHF) with reduced left ventricular ejection fraction is a common and disabling comorbidity of chronic obstructive pulmonary disease (COPD) [1]. Understanding the mechanisms underlying exercise intolerance is paramount to providing a rationale to effectively rehabilitate the fast-growing population of patients with COPD plus CHF. The inspiratory muscles, in particular, are characteristically overloaded in COPD plus CHF, with greater elastic and resistive work of breathing. Moreover, these muscles might be functionally weakened as ventilation increases during exercise in patients with COPD [2]. It has been postulated that fatiguing contractions would stimulate diaphragmatic thinly myelinated group III and unmyelinated group IV fibres, thereby increasing limb sympathetic outflow and vascular resistance. The so-called respiratory muscle metaboreflex would then redirect blood flow from locomotor to respiratory muscles to avoid, or at least postpone, the impending failure of the “vital pump” [3, 4]. In this context, we previously found marked blood flow reduction to nonactive and active limbs during inspiratory resistive loading in CHF [5]. Work from our laboratory also showed improved peripheral muscle oxygen delivery after respiratory muscle unloading (under stable cardiac output and arterial oxygen content) in CHF-free COPD [6] and COPD-free CHF [7]. It is therefore conceivable that the coexistence of CHF would potentiate the respiratory muscle metaboreflex in patients with a primary diagnosis of COPD. After giving informed consent, 22 optimally treated patients with moderate-to-severe (Global Initiative for Chronic Obstructive Lung Disease stage II–III) COPD (10 with coexistent CHF, i.e. left ventricular ejection fraction <45% by echocardiography) and 10 age- and sex-matched controls underwent a ramp-incremental exercise test for …

Interferential electrical stimulation improves peripheral vasodilatation in healthy individuals

BACKGROUND Interferential electrical stimulation (IES), which may be linked to greater penetration of deep tissue, may restore blood flow by sympathetic nervous modulation; however, studies have found no association between the frequency and duration of the application and blood flow. We hypothesized that 30 min of IES applied to the ganglion stellate region might improve blood flow redistribution. OBJECTIVES The purpose of this study was to determine the effect of IES on metaboreflex activation in healthy individuals. METHOD Interferential electrical stimulation or a placebo stimulus (same protocol without electrical output) was applied to the stellate ganglion region in eleven healthy subjects (age 25±1.3 years) prior to exercise. Mean blood pressure (MBP), heart rate (HR), calf blood flow (CBF) and calf vascular resistance (CVR) were measured throughout exercise protocols (submaximal static handgrip exercise) and with recovery periods with or without postexercise circulatory occlusion (PECO+ and PECO -, respectively). Muscle metaboreflex control of calf vascular resistance was estimated by subtracting the area under the curve when circulation was occluded from the area under the curve from the AUC without circulatory occlusion. RESULTS At peak exercise, increases in mean blood pressure were attenuated by IES (p<0.05), and the effect persisted under both the PECO+ and PECO- treatments. IES promoted higher CBF and lower CVR during exercise and recovery. Likewise, IES induced a reduction in the estimated muscle metaboreflex control (placebo, 21±5 units vs. IES, 6±3, p<0.01). CONCLUSION Acute application of IES prior to exercise attenuates the increase in blood pressure and vasoconstriction during exercise and metaboreflex activation in healthy subjects.

Exercise capacity in adolescent and adult patients with post infectious bronchiolitis obliterans.

Post‐infectious bronchiolitis obliterans (PBO) is a chronic lung disease characterized by the persistence of continuous obstructive respiratory symptoms following an acute and severe respiratory infection in children under 3 years old. The purpose of the present study was to investigate if adolescents and adults with diagnosis of PBO have reduced aerobic capacity and identify factors related with exercise performance.

Effects of limonoids from Cipadessa fruticosa on fall armyworm.

Six mexicanolide limonoids isolated from the dichloromethane extract of the fruits of Cipadessa fruticosa Blume (Meliaceae) were evaluated against Spodoptera frugiperda (J. E. Smith). Gedunin was used as a positive control. When incorporated into an artificial diet of neonates at 50.0 mg kg-1, febrifugin A showed 73.3% mortality. All the compounds showed moderate insecticidal activity, except for ruageanin A, when compared with the control. Febrifugin also showed growth inhibition and antifeedant activities (at 100.0 mg kg-1). The correlation between the insecticidal activity of the isolated compounds and their chemical structure was discussed.

Factors associated with inspiratory muscle weakness in patients with HIV-1

BACKGROUND the impact of human immunodeficiency virus type 1 (HIV-1) on lung function is well known and associated with a reduction in pulmonary ventilation. Moreover, the use of highly active antiretroviral therapy has been associated with mitochondrial dysfunction and decreased muscle strength. However, there is scarce information about the factors associated with inspiratory muscle weakness in these patients. OBJECTIVE the purpose of the present study was to investigate the factors associated with inspiratory muscle weakness in patients with HIV-1. METHODS two-hundred fifty seven patients with HIV-1 were screened and categorized into two groups: (1) IMW+ (n=142) and (2) IMW- (n=115). Lung function (FEV1, FVC and FEV1/FVC), maximum inspiratory pressure, distance on the six-minute walk test and CD4 cell count were assessed. RESULTS the mean duration of HIV infection was similar in the two groups. The following variables were significantly different between groups: mean duration of highly active antiretroviral therapy (81±12 in IMW+ versus 38±13 months in IMW-; p=0.01), and CD4 cell count (327±88 in IMW+ versus 637±97cells/mm(3) in IMW-; p=0.02). IMW+ presented reduced lung function (FEV1, FVC, FEV1/FVC). CONCLUSION patients with IMW+ had lower distance on the six-minute walk test in comparison to the IMW- group. The duration of highly active antiretroviral therapy, distance traveled on the 6MWT and CD4 count were determinants of IMW in patients with HIV.