Blunted blood pressure response to exercise and isolated muscle metaboreflex activation in patients with cirrhosis.

We sought to test the hypothesis that the cardiovascular responses to isolated muscle metaboreflex activation would be blunted in patients with cirrhosis. Eleven patients with cirrhosis and 15 healthy controls were evaluated. Blood pressure (BP; oscillometric method), contralateral forearm blood flow (FBF; venous occlusion plethysmography), and heart rate (HR; electrocardiogram) were measured during baseline, isometric handgrip at 30% of maximal voluntary contraction followed by postexercise ischemia (PEI). Forearm vascular conductance (FVC) was calculated as follows: (FBF / mean BP) × 100. Changes in HR during handgrip were similar between groups but tended to be different during PEI (controls: Δ 0.5 ± 1.1 bpm vs. cirrhotic patients: Δ 3.6 ± 1.0 bpm, P = 0.057). Mean BP response to handgrip (controls: Δ 20.9 ± 2.7 mm Hg vs. cirrhotic patients: Δ 10.6 ± 1.5 mm Hg, P = 0.006) and PEI was attenuated in cirrhotic patients (controls: Δ 16.1 ± 1.9 mm Hg vs. cirrhotic patients: Δ 7.2 ± 1.4 mm Hg, P = 0.001). In contrast, FBF and FVC increased during handgrip and decreased during PEI similarly between groups. These results indicate that an abnormal muscle metaboreflex activation explained, at least partially, the blunted pressor response to exercise exhibited by cirrhotic patients. Novelty: Patients with cirrhosis present abnormal muscle metaboreflex activation. BP response was blunted but forearm vascular response was preserved. HR response was slightly elevated.

Effects of physical exercise on baroreflex sensitivity and renal sympathetic nerve activity in chronic nicotine-treated rats.

Chronic nicotine exposure may increase cardiovascular risk by impairing the cardiac autonomic function. Besides, physical exercise (PE) has shown to improve cardiovascular health. Thus, we aimed to investigate the effects of PE on baroreflex sensitivity (BRS), heart rate variability (HRV), and sympathetic nerve activity (SNA) in chronically nicotine-exposed rats. Male Wistar rats were assigned to four independent groups: Control (treated with saline solution), Control+Ex (treated with saline and submitted to treadmill training), Nicotine (treated with Nicotine), and Nicotine+Ex (treated with nicotine and submitted to treadmill training). Nicotine (1 mg·kg-1) was administered daily for 28 consecutive days. PE consisted of running exercise (60%-70% of maximal aerobic capacity) for 45 min, 5 days per week, for 4 weeks. At the end of the protocol, cardiac BRS, HRV, renal SNA (rSNA), and renal BRS were assessed. Nicotine treatment decreased absolute values of HRV indexes, increased low frequency/high frequency ratio of HRV, reduced the bradycardic and sympatho-inhibitory baroreceptor reflex responses, and reduced the rSNA. PE effectively restored time-domain HRV indexes, the bradycardic and sympatho-inhibitory reflex responses, and the rSNA in chronic nicotine-treated rats. PE was effective in preventing the deterioration of time-domain parameters of HRV, arterial baroreceptor dysfunction, and the rSNA after nicotine treatment.

Healthy lifestyle moderates the relationship between cardiovascular disease with blood pressure, body composition, carotid intima-media thickness, and glycated hemoglobin among adults.

We investigate whether the adherence to healthy lifestyle recommendations (regular physical activity, healthy diet, reduced alcohol consumption, nonsmoking) moderates the relationship between cardiovascular disease (CVD) and its risk factors (obesity, diabetes, dyslipidemia, and hypertension) with clinical variables among adults. This cross-sectional population-based study comprised 862 adults (39.3 ± 11.4 years, 46.4% men) from Florianópolis, Brazil. Clinical variables were systolic (SBP) and diastolic blood pressure, waist circumference, body mass index (BMI), percentage of body fat, muscular strength, carotid intima-media thickness (IMT), high sensitive C-reactive protein, and lipid and glucose metabolism markers. Multiple linear regression adjusted for confounding factors was used. Reduced IMT and HbA1c were observed in males with CVD or its risk factors who adopted healthy lifestyle recommendations (p < 0.001), and lower SBP levels were observed in females without CVD or its risk factors (p = 0.034). Females with CVD or its risk factors who followed healthy lifestyle recommendations showed higher BMI (p = 0.035). Adherence to number of healthy lifestyle recommendations moderated cardiovascular health in adults with CVD and without CVD. Novelty The adherence to healthy lifestyle recommendations moderated the relationship between IMT and HbA1c with CVD or its risk factors among males. The lower values of SBP among females without CVD or its risk factors were moderated by the adherence to healthy lifestyle recommendations.

Oxidative stress and metabolic parameters are differently affected by fructose when rats were kept sedentary or underwent swimming exercise.

The current study evaluated whether fructose supplementation affects oxidative stress and metabolic parameters in the liver and gastrocnemius muscle of rats subjected to swimming exercise. Male adult Wistar rats received a fructose solution (10%) or water during 1 h before exercise and during the rest interval by the intragastric route. The swimming protocol consisted of 6 days: each day, rats underwent 3 sessions of 17 min each, with a load of 5% of body mass, and rest intervals of 3 min. Fructose supplementation changed metabolic and oxidative parameters in the liver and gastrocnemius muscle of sedentary rats. Swimming exercise counteracted the increase of triglyceride levels in plasma and liver induced by fructose supplementation. It also reduced thiobarbituric acid reactive species levels in the liver, and catalase and superoxide dismutase activities in the gastrocnemius muscle of supplemented rats. However, fructose supplementation worsened metabolic (hepatic triglyceride levels) and oxidative parameters (thiobarbituric acid reactive species levels) in the liver and gastrocnemius of exercised rats. This study demonstrates that oxidative stress and metabolic parameters were differently affected by fructose supplementation when rats were kept sedentary or underwent swimming exercise. The present results indicate the need of a new insight of the role of fructose supplementation during physical exercise.

Pre-exercise ß-hydroxy-ß-methylbutyrate free-acid supplementation improves work capacity recovery: a randomized, double-blinded, placebo-controlled study.

The purpose of this study was to investigate the effects of a single-dose of ß-hydroxy-ß-methylbutyrate free acid (HMB-FA) supplementation on muscle recovery after a high-intensity exercise bout. Twenty-three trained young males were randomly assigned to receive either a single-dose supplementation of 3 g of HMB-FA (n = 12; age, 22.8 ± 3.0 years) or placebo (PLA; n = 11; age, 22.9 ± 3.1 years). A muscle damage protocol was applied 60 min after supplementation, and consisted of 7 sets of 20 drop jumps from a 60-cm box with 2-min rest intervals between sets. Muscle swelling, countermovement jump (CMJ), maximal voluntary isometric torque (MVIT), and work capacity (WC) were measured before, immediately after, and 24, 48, and 72 h after the exercise protocol. Muscle swelling, CMJ, and MVIT changed similarly in both groups after the exercise protocol (p < 0.001), but returned to pre-exercise levels after 24 h in both groups. WC decreased similarly in both groups after the exercise protocol (p < 0.01). For HMB-FA, WC returned to pre-exercise level 24 h after exercise protocol. However, for PLA, WC did not return to pre-exercise level even 72 h after the exercise protocol. In summary, a single-dose of HMB-FA supplementation improved WC recovery after a high-intensity exercise bout. However, HMB-FA did not affect the time-course of muscle swelling, MVIT, and CMJ recovery.

Exercise tolerance during muscle contractions below and above the critical torque in different muscle groups.

The objective of this study was to test the hypotheses that end-test torque (ET) (expressed as % maximal voluntary contraction; MVC) is higher for plantar flexors (PF) than knee extensors (KE) muscles, whereas impulse above ET (IET) is higher for KE than PF. Thus, we expected that exercise tolerance would be longer for KE than PF only during the exercise performed above ET. After the determination of MVC, 40 men performed two 5-min all-out tests to determine ET and IET. Eleven participants performed a further 4 intermittent isometric tests, to exhaustion, at ET + 5% and ET - 5%, and 1 test for KE at the exercise intensity (%MVC) corresponding to ET + 5% of PF. The IET (7243.2 ± 1942.9 vs. 3357.4 ± 1132.3 N·m·s) and ET (84.4 ± 24.8 vs. 73.9 ± 19.5 N·m) were significantly lower in PF compared with KE. The exercise tolerance was significantly longer for PF (300.7 ± 156.7 s) than KE (156.7 ± 104.3 s) at similar %MVC (∼60%), and significantly shorter for PF (300.7 ± 156.7 s) than KE (697.0 ± 243.7 s) at ET + 5% condition. However, no significant difference was observed for ET - 5% condition (KE = 1030.2 ± 495.4 s vs. PF = 1028.3 ± 514.4 s). Thus, the limit of tolerance during submaximal isometric contractions is influenced by absolute MVC only during exercise performed above ET, which seems to be explained by differences on both ET (expressed as %MVC) and IET values.

Respiratory muscle training decreases diaphragm DNA damage in rats with heart failure.

Respiratory muscle training (RMT) promotes beneficial effects on respiratory mechanics, heart and lung morphological changes, and hemodynamic variables in rats with heart failure (HF). However, the relation between RMT effects and diaphragm oxidative stress remains unclear. Therefore, the aim of this study was to evaluate the RMT effects on diaphragm DNA damage in HF rats. Wistar rats were allocated into 4 groups: sedentary sham (Sed-Sham, n = 8), trained sham (RMT-Sham, n = 8), sedentary HF (Sed-HF, n = 8), and trained HF (RMT-HF, n = 8). The animals underwent a RMT protocol (30 min/day, 5 days/week for 6 weeks), whereas sedentary animals did not exercise. Groups were compared by a two-way ANOVA and Tukey's post hoc tests. In rats with HF, RMT promoted reduction in pulmonary congestion (p < 0.0001) and left ventricular end diastolic pressure (p < 0.0001). Moreover, RMT produced a decrease in the diaphragm DNA damage in HF rats. This was demonstrated through the reduction in the percentage of tail DNA (p < 0.0001), tail moment (p < 0.01), and Olive tail moment (p < 0.001). These findings showed that a 6-week RMT protocol in rats with HF promoted an improvement in hemodynamic function and reduces diaphragm DNA damage.

Role of vitamin A oral supplementation on oxidative stress and inflammatory response in the liver of trained rats.

The use of dietary supplements to enhance the benefit of exercise training is a common practice. The liver is the organ where all substances are metabolized, and certain supplements have been associated with liver injury. Vitamin A (VA), a liposoluble vitamin stored in the liver, is commonly used as an antioxidant supplement. Here, we evaluated the effect of chronic VA supplementation on oxidative damage and stress parameters in trained rats. Animals were divided into the following groups: sedentary (SE), sedentary/VA (SE+VA), exercise training (ET), and exercise training/VA (ET+VA). During 8 weeks, animals were subjected to swimming (0%, 2%, 4%, 6% body weight) for 5 days/week and a VA daily intake of 450 retinol equivalents/day. Parameters were evaluated by enzymatic activity analysis, ELISA, and Western blotting. VA caused liver lipid peroxidation and protein damage in exercised rats and inhibited the increase in HSP70 expression acquired with exercise alone. The ET group showed higher levels of antioxidant enzyme activity, and VA inhibited this adaptation. Expression of the pro-inflammatory cytokines, interleukin (IL)-1ß, and tumor necrosis factor-α was reduced in the ET+VA group, while the anti-inflammatory cytokine, IL-10, was increased. Western blotting showed that both exercised groups had lower levels of the receptor for advanced glycation end products, suggesting that VA did not affect this receptor. Our study demonstrated that, although VA caused oxidative damage, a controlled administration might exert anti-inflammatory effects. Further studies with higher VA doses and longer ET interventions would elucidate more the effects of the supplementation and exercise on liver parameters.

Association between inspiratory muscle weakness and slowed oxygen uptake kinetics in patients with chronic obstructive pulmonary disease.

Patients with chronic obstructive pulmonary disease (COPD) may have poor inspiratory muscle function, which reduces minute and alveolar ventilation, leading to increased hypoxemia and slow pulmonary oxygen uptake kinetics. However, little is known about the effect of inspiratory muscle weakness (IMW) on oxygen uptake kinetics in patients with COPD. Thus, we tested the hypothesis that COPD patients with IMW have slowed oxygen uptake kinetics. An observational study was conducted that included COPD patients with moderate to severe airflow limitation and a history of intolerance to exercise. Participants were divided into 2 groups: (IMW+; n = 22) (IMW-; n = 23) of muscle weakness. The maximal inspiratory, expiratory, and sustained inspiratory strength as well as the maximal endurance of the inspiratory muscles were lower in IMW+ patients (36 ± 9.5 cm H2O; 52 ± 14 cm H2O; 20 ± 6.5 cm H2O; 94 ± 84 s, respectively) than in IMW- patients (88 ± 12 cm H2O; 97 ± 28 cm H2O; 82.5 ± 54 cm H2O; 559 ± 92 s, respectively; p < 0.05). Moreover, the 6-min walk test and peak oxygen uptake were reduced in the IMW+ patients. During the constant work test, oxygen uptake kinetics were slowed in the IMW+ compared with IMW- patients (88 ± 29 vs 61 ± 18 s, p < 0.05). Our findings demonstrate that inspiratory muscle weakness in COPD is associated with slowed oxygen uptake kinetics, and thus, reduced functional capacity.

Effect of acute nitrate ingestion on V̇O2 response at different exercise intensity domains.

While nitrate supplementation influences oxygen uptake (V̇O2) response to exercise, this effect may be intensity dependent. The purpose of this study was to investigate the effect of acute nitrate supplementation on V̇O2 response during different exercise intensity domains in humans. Eleven men ingested 10 mg·kg-1 body mass (8.76 ± 1.35 mmol) of sodium nitrate or sodium chloride (placebo) 2.5 h before cycling at moderate (90% of gas exchange threshold; GET), heavy (GET + 40% of the difference between GET and peak oxygen uptake (V̇O2peak), Δ 40) or severe (GET + 80% of the difference between GET and V̇O2peak, Δ 80) exercise intensities. Volunteers performed exercise for 10 min (moderate), 15 min (heavy) or until exhaustion (severe). Acute nitrate supplementation had no effect on any V̇O2 response parameters during moderate and severe exercise intensities. However, the V̇O2 slow amplitude (nitrate: 0.93 ± 0.36 L·min-1 vs. placebo: 1.13 ± 0.59 L·min-1, p = 0.04) and V̇O2 slow gain (nitrate: 5.81 ± 2.37 mL·min-1·W-1 vs. placebo: 7.09 ± 3.67 mL·min-1·W-1, p = 0.04) were significantly lower in nitrate than in placebo during the heavy exercise intensity. There was no effect of nitrate on plasma lactate during any exercise intensity (p > 0.05). Time to exhaustion during the severe exercise intensity was also not affected by nitrate (p > 0.05). In conclusion, acute nitrate supplementation reduced the slow component of V̇O2 only when performing heavy-intensity exercise, which might indicate an intensity-dependent effect of nitrate on V̇O2 response.

Translation and cross-cultural adaptation of the PARmed-X for Pregnancy into Brazilian Portuguese.

We describe the translation and cross-cultural adaptation of the PARmed-X for Pregnancy for use in Brazilian Portuguese. The original instrument was developed in English for health screening prior to and guidelines for prenatal exercise. We followed the ten steps according to the Translation and Cultural Adaptation International Society for Pharmacoeconomics and Outcomes Research guidelines. Our template can be used by other health professionals for translation and verification of the original tool into their native language.

Carbohydrate supplementation attenuates decrement in performance in overtrained rats.

Carbohydrate ingestion at the end of a single exercise is recognized as delaying fatigue and accelerating recovery, but whether chronic ingestion can prevent overtraining during periods of intense training has not yet been elucidated. This study aimed to determine whether carbohydrate supplementation minimizes overtraining in Wistar rats. The animals underwent 11 weeks of training (running) on a treadmill, and the last 3 weeks were designed to induce overtraining. One group was supplemented with carbohydrates (EX-CHO) (n = 13), 1 group had no supplementation (EX) (n = 10), and a third group remained inactive (C) (n = 9). Performance tests were given before training (Pr1) and at the 8th (Pr2) and 11th (Pr3) training week. Food intake, body weight, testosterone, cortisol, malondialdehyde, creatine kinase, and activities of the PI3-K, Akt-1, mTOR, and GSK-3 enzymes were measured. In the EX group, there was a significant 32.6% performance decrease at Pr3 when compared with Pr2. In addition, at protocol completion, the EX-CHO group had a greater gastrocnemius weight than did the C group (p = 0.02), which the EX group did not. Training caused anorexia, decreased testosterone (p = 0.001), and increased malondialdehyde (p = 0.009) in both exercise groups compared with the C group, with no influence of carbohydrate supplementation on these variables (p > 0.05). Compared with in the C group, the activity of Akt-1 was higher in the EX-CHO group but not in the EX group (p = 0.013). Carbohydrate supplementation promoted an attenuation in the performance decrement and maintained gastrocnemius muscle mass in animals that had undergone overtraining protocols, which was accompanied by increased activity of the Akt-1 molecular indicator.

Postexercise rehydration: potassium-rich drinks versus water and a sports drink.

Fluid retention, thirst quenching, tolerance, and palatability of different drinks were assessed. On 4 different days, 12 healthy, physically active volunteers (24.4 ± 3.2 years old, 74.75 ± 11.36 kg body mass (mean ± S.D)), were dehydrated to 2.10% ± 0.24% body mass by exercising in an environmental chamber (32.0 ± 0.4 °C dry bulb, 53.8 ± 5.2% relative humidity). Each day they drank 1 of 4 beverages in random order: fresh coconut water (FCW), bottled water (W), sports drink (SD), or potassium-rich drink (NEW); volume was 120% of weight loss. Urine was collected and perceptions self-reported for 3 h. Urine output was higher (p < 0.05) for W (894 ± 178 mL) than SD (605 ± 297 mL) and NEW (599 ± 254 mL). FCW (686 ± 250 mL) was not different from any other drink (p > 0.05). Fluid retention was higher for SD than W (68.2% ± 13.0% vs. 51.3% ± 12.6%, p = 0.013), but not for FCW and NEW (62.5% ± 15.4% and 65.9% ± 15.4%, p > 0.05). All beverages were palatable and well tolerated; none maintained a positive net fluid balance after 3 h, but deficit was greater in W versus SD (p = 0.001). FCW scored higher for sweetness (p = 0.03). Thirst increased immediately after exercise but returned to baseline after drinking a small volume (p < 0.0005). In conclusion, additional potassium in FCW and NEW did not result in additional rehydration benefits over those already found in a conventional sports drink with sodium.

Heart rate at 4 s after the onset of exercise in endurance-trained men.

It has been suggested that the increase in heart rate (HR) at the onset of exercise is caused by vagal withdrawal. In fact, endurance runners show a lower HR in maximum aerobic tests. However, it is still unknown whether endurance runners have a lower HR at 4 s after the onset of exercise (4th-sec-HR). We sought to measure the HR at the onset of the 4 s exercise test (4-sET), clarifying its relationship to heart rate variability (HRV), spectral indices, and cardiac vagal index (CVI) in endurance runners (ER) and healthy untrained controls (CON). HR at 4th-sec-HR, CVI, and percent HR increase during exercise were analyzed in the 4-sET. High frequency spectrum (HF-nu), low frequency spectrum (LF-nu), and low frequency/high frequency band ratio (LF/HF) were analyzed from the HRV. ER showed a significantly higher HF, and both a lower LF and LF/HF ratio compared with the CON. ER presented a significantly lower 4th-sec-HR, although neither CVI nor HR increases during exercise were statistically different from the CON. In conclusion, ER presented a lower 4th-sec-HR secondary to increased vagal influence over the sinus node. CVI seems to be too weak to use for discriminating individuals with respect to the magnitude of HR vagal control.

Exercise training as treatment in cancer cachexia.

Cachexia is a wasting syndrome that may accompany a plethora of diseases, including cancer, chronic obstructive pulmonary disease, aids, and rheumatoid arthritis. It is associated with central and systemic increases of pro-inflammatory factors, and with decreased quality of life, response to pharmacological treatment, and survival. At the moment, there is no single therapy able to reverse cachexia many symptoms, which include disruption of intermediary metabolism, endocrine dysfunction, compromised hypothalamic appetite control, and impaired immune function, among other. Growing evidence, nevertheless, shows that chronic exercise, employed as a tool to counteract systemic inflammation, may represent a low-cost, safe alternative for the prevention/attenuation of cancer cachexia. Despite the well-documented capacity of chronic exercise to counteract sustained disease-related inflammation, few studies address the effect of exercise training in cancer cachexia. The aim of the present review was hence to discuss the results of cachexia treatment with endurance training. As opposed to resistance exercise, endurance exercise may be performed devoid of equipment, is well tolerated by patients, and an anti-inflammatory effect may be observed even at low-intensity. The decrease in inflammatory status induced by endurance protocols is paralleled by recovery of various metabolic pathways. The mechanisms underlying the response to the treatment are considered.

Sex differences in brain cholinergic activity in MSG-obese rats submitted to exercise.

Obesity is an epidemic disease most commonly caused by a combination of increased energy intake and lack of physical activity. The cholinergic system has been shown to be involved in the regulation of food intake and energy expenditure. Moreover, physical exercise promotes a reduction of fat pads and body mass by increasing energy expenditure, but also influences the cholinergic system. The aim of this study is to evaluate the interaction between physical exercise (swimming) and central cholinergic activity in rats treated with monosodium glutamate (MSG, a model for obesity) during infancy. Our results show that MSG treatment is able to induce obesity in male and female rats. Specifically, MSG-treated rats presented a reduced body mass and nasoanal length, and increased perigonadal and retroperitoneal fat pads in relation to the body mass. Physical exercise was able to reduce body mass in both male and female rats, but did not change the fat pads in MSG-treated rats. Increased food intake was only seen in MSG-treated females submitted to exercise. Cholinergic activity was increased in the cortex of MSG-treated females and physical exercise was able to reduce this activity. Thalamic cholinergic activity was higher in sedentary MSG-treated females and exercised MSG-treated males. Hypothalamic cholinergic activity was higher in male and female MSG-treated rats, and was not reduced by exercise in the 2 sexes. Taken together, these results show that MSG treatment and physical exercise have different effects in the cholinergic activity of males and females.