Carbohydrate and Glutamine Supplementation Attenuates the Increase in Rating of Perceived Exertion during Intense Exercise in Hypoxia Similar to 4200 m.

The rating of perceived exertion (RPE) indicates the feeling of fatigue. However, hypoxia worsens the condition and can worsen RPE. We evaluated whether carbohydrate and glutamine supplementation alters RPE and physiological markers in running at 70% peak oxygen uptake until exhaustion in a simulated altitude of 4500 m. Nine volunteers underwent three running tests at 70% peak oxygen uptake until exhaustion: (1) hypoxia and placebo, (2) hypoxia and 8% maltodextrin, and (3) hypoxia after six days of glutamine supplementation (20 g/day) and 8% maltodextrin. The exercise and supplementation were randomized and double-blinded. Lactate, heart rate, haemoglobin O2 saturation (SpO2%), and RPE (6-20 scale) were analyzed at the 15th and 30th min. The level of significance was set at p ≤ 0.05. SpO2% decreased at the 15th and 30th minutes compared to resting in placebo, carbohydrate, and glutamine supplementation. RPE increased at the 30th minute compared to the 15th minute in placebo and carbohydrate supplementation; however, there was no difference in the glutamine supplementation condition. Heart rate and lactate increased after the 15th and 30th minutes compared to resting, similar to the three conditions studied. We conclude that previous supplementation with glutamine and carbohydrate during intense exercise in hypoxia similar to 4500 m can attenuate the increase in RPE by the increase in glycemia and can be a useful strategy for people who exercise in these conditions.

Effects of carbohydrate and glutamine supplementation on cytokine production by monocytes after exercise in hypoxia: A crossover, randomized, double-blind pilot study.

OBJECTIVES: The aim of this study was to evaluate the combined effects of carbohydrate (CHO) and glutamine (Gln) supplementation on cytokine production by monocytes after exercise until exhaustion performed in hypoxia. METHODS: Fifteen physically active men underwent three exercises until exhaustion with an intensity of 70% maximal oxygen intake at a simulated height of 4500 m under the following supplementation: placebo, CHO (maltodextrin 8%/200 mL for 20 min), and CHO + Gln (Gln 20 g/d for 6 d and maltodextrin 8%/200 mL for 20 min) during exercise and for 2 h of recovery. Analysis of variance for repeated measures followed by the Tukey's post hoc test was realized and P < 0.05 was considered statistically significant. RESULTS: Oxygen saturation of arterial blood (SaO2%) decreased in the three trials compared with baseline. Two hours post-exercise, the SaO2% was high in CHO + Gln condition compared with placebo. Two hours after exercise, interleukin (IL)-1ß decreased compared with post-exercise in placebo and was lower compared with baseline in the CHO + Gln condition. Tumor necrosis factor-α decreased 2 h after exercise compared with baseline and pre-exercise in the CHO + Gln condition. No changes were observed in myeloperoxidase or IL-6 production. Two hours after exercise, Gln decreased compared with baseline and post-exercise in placebo and decreased 2 h after exercise in relation to post-exercise in the CHO condition. Gln increased post-exercise compared with pre-exercise in the CHO + Gln condition. Although erythropoietin did not change in this condition, it was high post-exercise and 2 h after exercise in the placebo condition compared with baseline and 2 h after exercise compared with baseline and pre-exercise in the CHO condition. CONCLUSIONS: Gln supplementation for 6 d before exercise, associated with CHO supplementation during exercise, was able to revert Gln reduction after exercise and after 2 h of recovery and may have contributed to reducing tumor necrosis factor-α production, suggesting a possible anti-inflammatory effect of supplementation.

Performance and altitude: Ways that nutrition can help.

High altitudes are a challenge for human physiology and for sports enthusiasts. Several reasons lead to deterioration in performance at high altitudes. Hypoxia owing to high altitude causes a breakdown of homeostasis with imbalance in several physiological systems, including the immune system. The reduction in mucosal immunity and inflammation and the predominance of the humoral immune response causes a condition of immunosuppression and an increased likelihood of infection. In addition, it is known that worsening of the immune response is associated with reduced performance. On the other hand, immunonutrition plays an important role in modulating the effects of physical exercise on the immune system. However, to our knowledge, few studies have evaluated the effect of nutrition on the immune system after exercise in hypoxia. Although the association between exercise and hypoxia has been shown to be more severe for the body owing to the sum of stressful agents, supplementation with carbohydrates and glutamine seems to play a relevant role in mitigating immunosuppressive effects. These findings, although limited by the fact that they are the result of very few studies, shed light on a relevant theme for sports physiology and nutrition and suggest that both supplements may be useful for athletes, visitors, and workers in high-altitude regions. The aim of this review was to discuss the effects of high-altitude hypoxia on the human body from the point of view of exercise immunology because it is known that transient immunosuppression after strenuous exercise and competition should be followed by reduction in training overload and worse performance.

Effect of moderate exercise under hypoxia on Th1/Th2 cytokine balance.

INTRODUCTION AND OBJECTIVE: Moderate exercise performed in normoxia can be immunostimulatory, while strenuous exercise can be immunosuppressive. However, less is known about the effects of exercise under hypoxia on cytokines. The aim of this study was to evaluate the effects of an acute exercise session performed under hypoxia similar to an altitude of 4200 m on cytokine balance. Our hypothesis was that exercise, even of moderate intensity, associated with hypoxia may induce different changes in relation to the normoxic condition. METHODS: Eight healthy male volunteers were exercised on a treadmill for 1 hour at an intensity of 50% VO2peak under normoxic or hypoxic condition (4200 m). Blood samples were collected at rest and immediately 1 hour after the exercise, respectively to determine cytokines, hormones and metabolites. The two-way ANOVA and the Bonferroni post hoc test were used and the significance adopted was P < .05. RESULTS: While IL-2, the IL-2/IL-4 ratio and glutamine decreased under hypoxia, IL-6 and IL-1ra increased. There were increases in the IL-2/IL-4 ratio, IL-6, IL-1ra and IL-10/TNF-α in normoxia. There were no differences in cortisol or glucose. CONCLUSION: Moderate exercise under hypoxia condition changes the Th1/Th2 balance including IL-2, IL-4 and TNF-α cytokines, suggesting a Th2 response after 1 hour rest.

Physiological and cytokine response to acute exercise under hypoxic conditions: a pilot study.

BACKGROUND: Studies have demonstrated that exercise in hypoxia situations induces a cytotoxicity effects. However, the cytokines participation in this condition is remaining unknown. Thus, the aim the present study was to evaluate physiological parameters and inflammatory profiles in response to acute exercise after five hours of hypoxic conditions. METHODS: Fourteen healthy men were distributed randomly into two groups: normoxic exercise (N.=7) and hypoxic exercise (N.=7). All volunteers were blinded to the protocol. Initially, all subjects were submitted to chamber normobaric in a room fitted for altitude simulations of up to 4500 m, equivalent to a barometric pressure of 433 mmHg. All analyses began at 7:00 a.m. and was maintained for 5 hours; the fraction of inspired oxygen (FiO2) was 13.5%. The groups began a 60-minute session of physical exercise starting at 11:00 a.m., at 50% of peak VO2 (50% VO2peak). Blood was collected for cytokine analysis in the morning upon waking, before the 60-minute exercise session and immediately thereafter. RESULTS: The heart rate during 60 minutes' exercise training was significantly increased in both exercise groups (P<0.05), and the oxygen saturation was reduced under hypoxic conditions during exercise (P<0.05). After exercise, significant increases were found for IL-1ra and IL-10 under hypoxic conditions (P<0.05) and for IL-6 for both groups (P<0.05). TNF-α was not altered under either environmental condition. CONCLUSIONS: Our data demonstrate that acute exercise performance in hypoxic conditions can promotes early inflammatory response, leads for immunosuppression state.

Acute physical exercise under hypoxia improves sleep, mood and reaction time.

This study aimed to assess the effect of two sessions of acute physical exercise at 50% VO2peak performed under hypoxia (equivalent to an altitude of 4500 m for 28 h) on sleep, mood and reaction time. Forty healthy men were randomized into 4 groups: Normoxia (NG) (n = 10); Hypoxia (HG) (n = 10); Exercise under Normoxia (ENG) (n = 10); and Exercise under Hypoxia (EHG) (n = 10). All mood and reaction time assessments were performed 40 min after awakening. Sleep was reassessed on the first day at 14 h after the initiation of hypoxia; mood and reaction time were measured 28 h later. Two sessions of acute physical exercise at 50% VO2peak were performed for 60 min on the first and second days after 3 and 27 h, respectively, after starting to hypoxia. Improved sleep efficiency, stage N3 and REM sleep and reduced wake after sleep onset were observed under hypoxia after acute physical exercise. Tension, anger, depressed mood, vigor and reaction time scores improved after exercise under hypoxia. We conclude that hypoxia impairs sleep, reaction time and mood. Acute physical exercise at 50% VO2peak under hypoxia improves sleep efficiency, reversing the aspects that had been adversely affected under hypoxia, possibly contributing to improved mood and reaction time.

Carbohydrate and glutamine supplementation modulates the Th1/Th2 balance after exercise performed at a simulated altitude of 4500 m.

OBJECTIVE: The aim of this study was to evaluate the effect of carbohydrate or glutamine supplementation, or a combination of the two, on the immune system and inflammatory parameters after exercise in simulated hypoxic conditions at 4500 m. METHODS: Nine men underwent three sessions of exercise at 70% VO2peak until exhaustion as follows: 1) hypoxia with a placebo; 2) hypoxia with 8% maltodextrin (200 mL/20 min) during exercise and for 2 h after; and 3) hypoxia after 6 d of glutamine supplementation (20 g/d) and supplementation with 8% maltodextrin (200 mL/20 min) during exercise and for 2 h after. All procedures were randomized and double blind. Blood was collected at rest, immediately before exercise, after the completion of exercise, and 2 h after recovery. Glutamine, cortisol, cytokines, glucose, heat shock protein-70, and erythropoietin were measured in serum, and the cytokine production from lymphocytes was measured. RESULTS: Erythropoietin and interleukin (IL)-6 increased after exercise in the hypoxia group compared with baseline. IL-6 was higher in the hypoxia group than pre-exercise after exercise and after 2 h recovery. Cortisol did not change, whereas glucose was elevated post-exercise in the three groups compared with baseline and pre-exercise. Glutamine increased in the hypoxia + carbohydrate + glutamine group after exercise compared with baseline. Heat shock protein-70 increased post-exercise compared with baseline and pre-exercise and after recovery compared with pre-exercise, in the hypoxia + carbohydrate group. No difference was observed in IL-2 and IL-6 production from lymphocytes. IL-4 was reduced in the supplemented groups. CONCLUSION: Carbohydrate or glutamine supplementation shifts the T helper (Th)1/Th2 balance toward Th1 responses after exercise at a simulated altitude of 4500 m. The nutritional strategies increased in IL-6, suggesting an important anti-inflammatory effect.

Yerba mate extract (Ilex paraguariensis) attenuates both central and peripheral inflammatory effects of diet-induced obesity in rats.

To clarify the effects of natural dietary components on the metabolic consequences of obesity, we examined the effects of yerba mate extract Ilex paraguariensis on both central and peripheral inflammatory effects of diet-induced obesity and correlated the hypothalamic tumor necrosis factor (TNF)-α level with adipose depot weight. Wistar rats were divided into four groups: a control group (CTL) fed with chow diet, a second group fed with chow diet plus yerba mate extract (CTL+E), a third group fed with a high-fat diet rich in saturated fatty acids (HFD) and a fourth group fed with HFD plus yerba mate extract (HFD+E). Enzyme-linked immunosorbent assay, Western blotting, colorimetric method and treatment by gavage were utilized as materials and methods. The HFD groups showed a significant increase in food intake (kcal), body weight, adipose tissue and leptin level in comparison to CTL and CTL+E. HFD leads to increase of both central and peripheral inflammatory effects, and deregulation of insulin pathway. In addition, yerba mate extract intake blunted the proinflammatory effects of diet-induced obesity in rats by reducing the phosphorylation of hypothalamic IKK and NFκBp65 expression and increasing the phosphorylation of IκBα, the expression of adiponectin receptor-1 and consequently the amount of IRS-2. Moreover, the increase in interleukin (IL)-6 levels in the liver and muscle and of the IL-10/TNF-α ratio in groups that received yerba mate extract showed the anti-inflammatory effects of this natural substance. Taken together, our data suggest that the use of yerba mate extract may be useful for reducing low-grade obesity-associated inflammation.