Effect of acute dietary nitrate consumption on submaximal oxygen consumption and oxidative stress in hypoxia

Reduced partial pressure of oxygen impairs exercise performance at altitude. Acute nitrate supplementation, at sea level may reduce oxygen cost during submaximal exercise in hypoxia. Therefore, we investigated the metabolic response during exercise at altitude following acute nitrate consumption. Ten well-trained (61.01±7.37 ml/kg/min) males (age 28±7 yr) completed 3 experimental trials (T1, T2, T3). T1 included baseline demographics, a maximal aerobic capacity test (VO2max) and five submaximal intensity cycling determination bouts at an elevation of 1600m. A 4-day dietary washout, minimizing consumption of nitrate rich foods, preceded T2 and T3. In a randomized, double-blind, placebo-controlled, crossover fashion, subjects consumed a placebo (PL) or nitrate rich (NR) beverage 2.5 hours prior to T2 and T3. Exercise at 3500m (T2 and T3) consisted of a 5-min warm-up (25% VO2max) and four 5-min cycling bouts (40, 50, 60, 70% of VO2max) each separated a 4-min rest period. Cycling RPM and watts for each submaximal bout were determined during T1. Pre-exercise plasma nitrite was elevated following NR consumption compared to PL (p\u3c0.05). Oxygen consumption, respiratory exchange ratio, oxygen saturation, heart rate and rating of perceived exertion were not different at any submaximal intensity between NR and PL treatments. Blood lactate, however, was reduced following NR consumption compared to PL at 40 and 60% of VO2max (p\u3c.0.05). Following exercise, compared to rest, catalase and 8-isoprostane increased at 3500m in both the placebo and nitrate rich groups (p\u3c0.05). There was no difference between groups (placebo vs nitrate rich) for either of these markers of oxidative stress. Our findings suggest that acute nitrate supplementation prior to exercise at 3500m does not reduce oxygen cost or oxidative stress, but may reduce lactate production at lower intensity workloads

Comparison of Whole-Body Cooling Techniques for Athletes and Military Personnel

International Journal of Exercise Science 10(2): 294-300, 2017. The purpose of this study was to evaluate cooling rates of The Polar Life Pod®, a military protocol and cold water immersion. A randomized, repeated measures design was used to compare three treatment options. Participants exercised in an environmental chamber, where they followed a military march protocol on a treadmill, followed by the application of one of three treatments: Cold water immersion tub (5 – 10 °C), Polar Life Pod® (5 – 10 °C), Ice sheets at onset (5 – 10 °C). Mean cooling rate for CWI was 0.072 ºC/min, 0.046ºC/min for ice sheets, and 0.040ºC/min for The Polar Life Pod®. There was a significant difference between conditions (F2,26=13.564, p=0.001, ES=0.511, 1-β=0.969). There was a significant difference in cooling rate among The Polar Life Pod® and CWI (p = 0.006), and no significant difference among The Polar Life Pod® and Ice Sheets (p = 0.103). There was a significant difference of time to cool among the three conditions F2,26 = 13.564, p = 0.001 , ES = 0.401, 1-β = 0.950. Our results support multiple organizations that deem CWI as the only acceptable treatment, when compared to the cooling rates of The Polar Life Pod® and ice sheets

Nitrate-containing beetroot enhances myocyte metabolism and mitochondrial content

Beetroot (甜菜 tián cài) juice consumption is of current interest for improving aerobic performance by acting as a vasodilator and possibly through alterations in skeletal muscle metabolism and physiology. This work explored the effects of a commercially available beetroot supplement on metabolism, gene expression, and mitochondrial content in cultured myocytes. C2C12 myocytes were treated with various concentrations of the beetroot supplement for various durations. Glycolytic metabolism and oxidative metabolism were quantified via measurement of extracellular acidification and oxygen consumption, respectively. Metabolic gene expression was measured using quantitative reverse transcription–polymerase chain reaction, and mitochondrial content was assessed with flow cytometry and confocal microscopy. Cells treated with beetroot exhibited significantly increased oxidative metabolism, concurrently with elevated metabolic gene expression including peroxisome proliferator-activated receptor gamma coactivator-1 alpha, nuclear respiratory factor 1, mitochondrial transcription factor A, and glucose transporter 4, leading to increased mitochondrial biogenesis. Our data show that treatment with a beetroot supplement increases basal oxidative metabolism. Our observations are also among the first to demonstrate that beetroot extract is an inducer of metabolic gene expression and mitochondrial biogenesis. These observations support the need for further investigation into the therapeutic and pharmacological effects of nitrate-containing supplements for health and athletic benefits

Acute Dietary Nitrate Supplementation Does Not Attenuate Oxidative Stress or the Hemodynamic Response During Submaximal Exercise in Hypobaric Hypoxia

Purpose: To investigate changes in oxidative stress, arterial oxygen saturation (SaO2), blood pressure (BP), and heart rate (HR) while exercising in hypobaric hypoxia following acute dietary nitrate supplementation. Methods: Nine well-trained (60.8±7.8 ml/kg/min) males (29±7 years) visited the lab on 3 occasions, each separated by 1 week. Visit 1 included a maximal aerobic cycling test (VO2max) and 5 five-minute increasing intensity exercise bouts in a normobaric environment (1600m). A single dose of either a nitrate-depleted placebo (PL) or nitrate-rich (NR; 12.8 mmol nitrate) beverage was consumed 2.5 hours prior to exercise during visit 2 and 3 (3500m) in a double-blind, placebo-controlled, crossover study consisting of a 5-minute cycling warm-up and four bouts, each of 5-minute durations, separated by 4-minute periods of passive rest. Exercise wattages were determined during visit 1 and corresponded to 25, 40, 50, 60, 70% of normobaric VO2max. Catalase and 8 isoprostane were measured pre-exercise and post-exercise (immediately and 1-hour post-exercise, respectively). Results: Dietary nitrate increased plasma nitrite (1.53±0.83 uM) compared to PL (0.88±0.56 uM) (pThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

The absorptive effects of orobuccal non-liposomal nano-sized glutathione on blood glutathione parameters in healthy individuals: A pilot study.

BackgroundGlutathione is an endogenous antioxidant found in oxidized (GSSG) and reduced (GSH) forms. Glutathione depletion is indicative of oxidative stress and occurs in various pathological conditions and following extreme exercise activity. Raising blood glutathione concentration has potential to attenuate and prevent chronic disease and also to improve recovery from exercise. There are a number of challenges to achieving this through traditional dietary supplements, and thus there is a need to develop optimized delivery methods to improve blood glutathione status. This study evaluated the effect of a novel glutathione formulation on blood glutathione parameters in healthy individuals.Methods15 (8 male) healthy individuals (25±5y old, 78.0±14.6kg) participated in a single-blinded randomized placebo-controlled crossover study, with a minimum one-week washout period between treatments. Participants were overnight fasted and administered 1mL of a non-liposomal nano-size glutathione solution (NLNG) containing 200mg of glutathione or 1mL of placebo lacking glutathione. The solution was held in the mouth for 90 seconds before the remainder was swallowed. Blood was collected at baseline, 5, 10, 30, 60 and 120 minutes post-treatment. Protein-bound plasma and erythrocyte lysate concentrations of GSH and GSSG were measured at all time points using previously validated procedures. Linear mixed effects models were used to compare differences between baseline and post-treatment glutathione concentrations between NLNG and placebo for each parameter.ResultsThere was a significant main effect for treatment type, such that increases in GSH concentration in erythrocyte lysate were greater following NLNG than placebo (p = 0.001). Similar significant main effects for treatment were also found for total (protein bound + erythrocyte lysate) GSH (p = 0.015) and GSSG (p = 0.037) concentration, as well as total blood glutathione pool (GSH+GSSG, p = 0.006).DiscussionNLNG increased multiple blood glutathione parameters compared to placebo. Future research should examine whether NLNG can attenuate oxidative stress

Medical marijuana, recreational cannabis, and cardiovascular health: a scientific statement from the American Heart Association.

Cannabis, or marijuana, has potential therapeutic and medicinal properties related to multiple compounds, particularly Δ-9-tetrahydrocannabinol and cannabidiol. Over the past 25 years, attitudes toward cannabis have evolved rapidly, with expanding legalization of medical and recreational use at the state level in the United States and recreational use nationally in Canada and Uruguay. As a result, the consumption of cannabis products is increasing considerably, particularly among youth. Our understanding of the safety and efficacy of cannabis has been limited by decades of worldwide illegality and continues to be limited in the United States by the ongoing classification of cannabis as a Schedule 1 controlled substance. These shifts in cannabis use require clinicians to understand conflicting laws, health implications, and therapeutic possibilities. Cannabis may have therapeutic benefits, but few are cardiovascular in nature. Conversely, many of the concerning health implications of cannabis include cardiovascular diseases, although they may be mediated by mechanisms of delivery. This statement critically reviews the use of medicinal and recreational cannabis from a clinical but also a policy and public health perspective by evaluating its safety and efficacy profile, particularly in relationship to cardiovascular health