Cannabidiol in sport: Ergogenic or else?

In the sports domain, cannabis is prohibited by the World Anti-Doping Agency (WADA) across all sports in competition since 2004. The few studies on physical exercise and cannabis focused on the main compound i.e. Δ9-tetrahydrocannabinol. Cannabidiol (CBD) is another well-known phytocannabinoid present in dried or heated preparations of cannabis. Unlike Δ9-tetrahydrocannabinol, CBD is non-intoxicating but exhibits pharmacological properties that are interesting for medical use. The worldwide regulatory status of CBD is complex and this compound is still a controlled substance in many countries. Interestingly, however, the World Anti-Doping Agency removed CBD from the list of prohibited substances - in or out of competition - since 2018. This recent decision by the WADA leaves the door open for CBD use by athletes. In the present opinion article we wish to expose the different CBD properties discovered in preclinical studies that could be further tested in the sport domain to ascertain its utility. Preclinical studies suggest that CBD could be useful to athletes due to its anti-inflammatory, analgesic, anxiolytic, neuroprotective properties and its influence on the sleep-wake cycle. Unfortunately, almost no clinical data are available on CBD in the context of exercise, which makes its use in this context still premature.

France's 2018 Report Card on Physical Activity for Children and Youth: Results and International Comparisons.

BACKGROUND: Insufficient levels of physical activity and increasing sedentary time among children and youth are being observed internationally. The purpose of this paper is to summarize findings from France's 2018 Report Card on physical activity for children and youth, and to make comparisons with its 2016 predecessor and with the Report Cards of other countries engaged in the Global Matrix 3.0. METHODS: The France's 2018 Report Card was developed following the standardized methodology established for the Global Matrix 3.0 by grading 10 common physical activity indicators using best available data. Grades were informed by national surveys, peer-reviewed literature, government and nongovernment reports, and online information. RESULTS: The expert panel awarded the following grades: overall physical activity, D; organized sport participation and physical activity, C-; active play, INC; active transportation, C-; sedentary behaviors, D-; physical fitness, B-; family and peers, INC; school, B; community and the built environment, INC; and government, C. CONCLUSIONS: Very concerning levels of physical activity and sedentary behaviors among French children and youth were observed, highlighting the urgent need for well-designed national actions addressing the presented physical inactivity crisis. The top 3 strategies that should be implemented in priority to improve the lifestyle of French children and youth are provided.

Muscle Oxygen Supply and Use in Type 1 Diabetes, From Ambient Air to the Mitochondrial Respiratory Chain: Is There a Limiting Step?

OBJECTIVE: Long before clinical complications of type 1 diabetes (T1D) develop, oxygen supply and use can be altered during activities of daily life. We examined in patients with uncomplicated T1D all steps of the oxygen pathway, from the lungs to the mitochondria, using an integrative ex vivo (muscle biopsies) and in vivo (during exercise) approach. RESEARCH DESIGN AND METHODS: We compared 16 adults with T1D with 16 strictly matched healthy control subjects. We assessed lung diffusion capacity for carbon monoxide and nitric oxide, exercise-induced changes in arterial O2 content (SaO2, PaO2, hemoglobin), muscle blood volume, and O2 extraction (via near-infrared spectroscopy). We analyzed blood samples for metabolic and hormonal vasoactive moieties and factors that are able to shift the O2-hemoglobin dissociation curve. Mitochondrial oxidative capacities were assessed in permeabilized vastus lateralis muscle fibers. RESULTS: Lung diffusion capacity and arterial O2 transport were normal in patients with T1D. However, those patients displayed blunted exercise-induced increases in muscle blood volume, despite higher serum insulin, and in O2 extraction, despite higher erythrocyte 2,3-diphosphoglycerate. Although complex I- and complex II-supported mitochondrial respirations were unaltered, complex IV capacity (relative to complex I capacity) was impaired in patients with T1D, and this was even more apparent in those with long-standing diabetes and high HbA1c. [Formula: see text]O2max was lower in patients with T1D than in the control subjects. CONCLUSIONS: Early defects in microvascular delivery of blood to skeletal muscle and in complex IV capacity in the mitochondrial respiratory chain may negatively impact aerobic fitness. These findings are clinically relevant considering the main role of skeletal muscle oxidation in whole-body glucose disposal.

Beetroot Juice Does Not Enhance Supramaximal Intermittent Exercise Performance in Elite Endurance Athletes.

Objective: Nitrate (NO3-)-rich beetroot juice (BR) is recognized as an ergogenic supplement that improves exercise tolerance during submaximal to maximal intensity exercise in recreational and competitive athletes. A recent study has investigated the effectiveness of BR on exercise performance during supramaximal intensity intermittent exercise (SIE) in Olympic-level track cyclists, but studies conducted in elite endurance athletes are scarce. The present study aimed to determine whether BR supplementation enhances the tolerance to SIE in elite endurance athletes.Methods: Eleven elite endurance athletes (age: 21.7 ± 3.7 years, maximal oxygen uptake [Formula: see text] 71.1 ± 5.2 mL·kg-1·min-1) performed an SIE test until exhaustion following either a 3-day BR supplementation (340 mg/d) or a placebo (PL) supplementation (<2.5 mg/d) in a randomized, single blind, placebo-controlled, and crossover study. The exercise test consisted of 15-second cycling exercise bouts at 170% of the maximal aerobic power interspersed with 30-second passive recovery periods. Gas exchange was measured during SIE tests as local muscle O2 delivery and extraction were assessed by near infrared spectroscopy.Results: The number of repetitions completed was not significantly different between BR (13.9 ± 4.0 reps) and PL conditions (14.2 ± 4.5 reps). BR supplementation did not affect oxygen uptake ([Formula: see text]) during SIE tests (BR: 3378.5 ± 681.8 mL·min-1, PL: 3466.1 ± 505.3 mL·min-1). No significant change in the areas under curves was found for local muscle total hemoglobin (BR: 6816.9 ± 1463.1 arbitrary units (a.u.), PL: 6771.5 ± 3004.5 a.u.) and deoxygenated hemoglobin (BR: 6619.7 ± 875.8 a.u., PL: 6332.7 ± 1336.8 a.u.) during time-matched work + recovery periods from SIE tests following BR supplementation.Conclusions: BR supplementation does not enhance the tolerance to SIE in elite endurance athletes and affects neither [Formula: see text] nor local muscle O2 delivery and extraction.

Active Versus Passive Recovery in High-Intensity Intermittent Exercises in Children: An Exploratory Study.

This study aimed to compare the effect of active recovery (AR) versus passive recovery (PR) on time to exhaustion and time spent at high percentages of peak oxygen uptake ( peakV˙O2 ) during short, high-intensity intermittent exercises in children. Twelve children (9.5 [0.7] y) underwent a graded test and 2 short, high-intensity intermittent exercises (15 s at 120% of maximal aerobic speed) interspersed with either 15 seconds of AR (50% of maximal aerobic speed) or 15-second PR until exhaustion. A very large effect (effect size = 2.42; 95% confidence interval, 1.32 to 3.52) was observed for time to exhaustion in favor of longer time to exhaustion with PR compared with AR. Trivial or small effect sizes were found for peakV˙O2 , peakHR, and peak ventilation between PR and AR, while a moderate effect in favor of higher average V˙O2 values (effect size = -0.87; 95% confidence interval, -1.76 to -0.01) was found using AR. The difference between PR and AR for the time spent above 80% (t80%) and 90% (t90%) of peakV˙O2 was trivial. Despite the shorter running duration in AR, similar t80% and t90% were spent with AR and PR. Time spent at a high percentage of peakV˙O2 may be attained by running 3-fold shorter using AR compared with using PR.

High-intensity interval training in overweight and obese children and adolescents: systematic review and meta-analysis.

INTRODUCTION: While High Intensity Interval Training is praised in many populations for its beneficial effects on body composition and cardiometabolic health, its use among obese youth remain uncertain. This study aimed at determining whether HIIT is effective to improve aerobic fitness and reduce cardiometabolic risk factors in overweight and obese youth. EVIDENCE ACQUISITION: A systematic search was conducted and articles reporting studies that investigated the effects of HIIT in 6 to 18-year-old youth were eligible. Meta-analyses were performed when appropriate. EVIDENCE SYNTHESIS: Fifteen studies were included for the systematic review and meta-analyses. HIIT significantly improves maximal oxygen uptake (1.117 [95% CI: 0.528 to 1.706], P<0.001), and reduces body mass (-0.295 [95% CI: -0.525 to -0.066], P<0.05), body fat (-0.786 [95% CI: -1.452 to -0.120], P<0.05), systolic and diastolic blood pressure (-1.026 [95% CI: -1.370 to -0.683], P<0.001; -0.966 [95% CI: -1.628 to -0.304], P<0.01 respectively), and the HOMA-IR (-1.589 [95% CI: -2.528 to -0.650], P<0.01). However, there is significant heterogeneity, and low to high inconsistency for most cardiometabolic risk factors and aerobic fitness. CONCLUSIONS: Although few studies have reported cardiometabolic risks, HIIT may also be as effective as traditional endurance continuous training to decrease blood pressure and insulin resistance. HIIT is effective to improve aerobic fitness, body composition, and cardiometabolic risk factors in obese youth, but data are insufficient to determine whether it is more effective than traditional continuous submaximal intensity exercise training.

Plasma asymmetric dimethylarginine concentrations are not related to differences in maximal oxygen uptake in endurance trained and untrained men.

NEW FINDINGS: What is the central question of this study? Is there an association of plasma concentration of asymmetric dimethylarginine, which is related to exercise capacity in patients with cardiovascular diseases, with oxygen delivery and subsequently exercise capacity in healthy subjects in the absence of the potentially confounding influence of inflammation and oxidative stress? What is the main finding and its importance? Plasma asymmetric dimethylarginine concentrations are not related to exercise capacity in healthy subjects, while O2 delivery in the working skeletal muscle during the maximal graded-exercise test is not associated with any of the l-arginine analogues. ADMA alone does not play a crucial role in local muscle perfusion and in maintaining exercise capacity. ABSTRACT: Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide (NO) synthesis that could limit oxygen (O2 ) delivery in the working skeletal muscles by altering endothelium-dependent vasodilatation. Exercise capacity is associated with plasma ADMA concentrations in patients with cardiovascular diseases, but this issue has still not been investigated in healthy subjects. We aimed to determine whether plasma ADMA concentrations were negatively associated with exercise capacity in young healthy male subjects. Ten men with maximal oxygen uptake ( V ̇ O 2 max ) > 65 mL kg-1  min-1 were included in the high exercise capacity group (HI-FIT), and 10 men with V ̇ O 2 max  < 45 mL kg-1  min-1 were included in the low exercise capacity group (LO-FIT). Plasma ADMA and other l-arginine analogue concentrations were measured before and after a maximal graded-exercise test by liquid chromatography-tandem mass spectrometry. Microvascular O2 delivery during exercise was estimated through the pattern from the sigmoid model of muscle deoxygenation in the vastus lateralis measured by near infrared spectroscopy. V ̇ O 2 max was 60% higher in the HI-FIT group (median: 70.2 mL kg-1  min-1 ; IQR: 68.0-71.9 mL kg-1  min-1 ) than in the LO-FIT group (median: 43.8 mL kg-1  min-1 ; IQR: 34.8-45.3 mL kg-1  min-1 ). Plasma ADMA concentrations did not differ between the LO-FIT and HI-FIT groups before (0.50 ± 0.06 vs. 0.54 ± 0.07 µmol L-1 , respectively) and after the maximal incremental exercise test (0.49 ± 0.08 vs. 0.55 ± 0.03 µmol L-1 , respectively). There was no significant association of plasma ADMA concentrations with the pattern of local muscle deoxygenation and exercise capacity. Exercise capacity and microvascular O2 delivery are not related to plasma ADMA concentrations in young healthy male subjects. Our findings show that ADMA does not play a crucial role in local muscle perfusion and in maintaining exercise capacity without pathological conditions.

Longitudinal Follow-Up of Physical Activity During School Recess: Impact of Playground Markings.

To promote physical activity (PA) among children, few studies have reported long-term effects of playground marking during school recess. The aim of this study was to investigate the impact of a playground design on children's recess PA across 12 months and to evaluate the influence of covariates on the intervention effects with accelerometry data. Two hundred and eighty-three children (aged 6-11 years) were selected from 3 elementary schools. Two experimental schools received a recess-based intervention; the third one served as a control group. The design of playgrounds was based on a multicolored zonal design. Children's PA was measured with a uniaxial accelerometer twice a day (morning and afternoon recess) during a 4-day school week. Times spent below and above different PA levels, varying from sedentary (SED, <1.5 METs), light PA (LPA, <4 METs), and from moderate to very high (MVPA, ≥ 4 METs) were calculated before and after 6 and 12 months intervention. A three level (time, pupil, school) multilevel analysis was used to control the intervention effect across time on SED, LPA, and MVPA. The playground intervention was effective after 6 months for LPA (+2.5%, CI 0.65/4.29, P < 0.01) and after 12 months for MVPA (+3.1%, CI 0.62/5.54, P < 0.01). Moreover, negative non-significant intervention effects were found for SED and LPA. Baseline PA and sex were significant covariates to the contrary of body mass index and age. Playground markings intervention can modify positively long-term school recess total PA.

Acute effects of repeated cycling sprints in hypoxia induced by voluntary hypoventilation.

PURPOSE: This study aimed to investigate the acute responses to repeated-sprint exercise (RSE) in hypoxia induced by voluntary hypoventilation at low lung volume (VHL). METHODS: Nine well-trained subjects performed two sets of eight 6-s sprints on a cycle ergometer followed by 24 s of inactive recovery. RSE was randomly carried out either with normal breathing (RSN) or with VHL (RSH-VHL). Peak (PPO) and mean power output (MPO) of each sprint were measured. Arterial oxygen saturation, heart rate (HR), gas exchange and muscle concentrations of oxy-([O2Hb]) and deoxyhaemoglobin/myoglobin ([HHb]) were continuously recorded throughout exercise. Blood lactate concentration ([La]) was measured at the end of the first (S1) and second set (S2). RESULTS: There was no difference in PPO and MPO between conditions in all sprints. Arterial oxygen saturation (87.7 ± 3.6 vs 96.9 ± 1.8% at the last sprint) and HR were lower in RSH-VHL than in RSN during most part of exercise. The changes in [O2Hb] and [HHb] were greater in RSH-VHL at S2. Oxygen uptake was significantly higher in RSH-VHL than in RSN during the recovery periods following sprints at S2 (3.02 ± 0.4 vs 2.67 ± 0.5 L min-1 on average) whereas [La] was lower in RSH-VHL at the end of exercise (10.3 ± 2.9 vs 13.8 ± 3.5 mmol.L-1; p < 0.01). CONCLUSIONS: This study shows that performing RSE with VHL led to larger arterial and muscle deoxygenation than with normal breathing while maintaining similar power output. This kind of exercise may be worth using for performing repeated sprint training in hypoxia.

Cardiorespiratory Responses to Continuous and Intermittent Exercises in Children.

The aim of the study was to characterize aerobic responses to high intensity intermittent (HIIE) and continuous (CE) exercises in prepubertal children. 26 children aged 8 to 11-year-old took part in a preliminary session to determine peakVO2 and Maximal Aerobic Velocity (MAV). In 5 subsequent experimental visits, the participants completed 2 CE and 3 HIIE sessions in a randomized order. HIIE consisted of short intermittent 10-s and 20-s running bouts at 100 to 130% MAV, interspersed with recovery periods of equal duration (S-HIIE1 and S-HIIE2 respectively) and 5-s of sprinting and jumping at maximal intensity with 15-s recovery periods (S-HIIE3). CE consisted of 2 10-min running periods at 80% and 85% MAV with a 5-min recovery period. CE protocols elicited higher average VO2 and exercise time spent above 95% of peakVO2 compared to the HIIE protocols. S-HIIE 1 and S-HIIE 2 elicited similar average VO2 response, higher than S-HIIE 3. Our study shows that CE activated the aerobic system to a greater extent than S-HIIE in prepubertal children, as reflected by the time above 95% of peakVO2 during exercise. However, isotime S-HIIE protocols comprising 10-s or 20-s exercise bouts at an intensity above MAV result in similar times above 95% of peakVO2 during exercise.

Exercise training and high-fat diet elicit endocannabinoid system modifications in the rat hypothalamus and hippocampus

The purpose of the present study was to examine the effect of chronic exercise on the hypothalamus and hippocampus levels of the endocannabinoids (eCBs) anandamide (AEA) and 2-arachidonoylglycerol (2-AG) and of two AEA congeners and on the expression of genes coding for CB1, CB2 receptors (Cnr1 and Cnr2, respectively), and the enzymes responsible for eCB biosynthesis and degradation, in rats fed with a standard or high-fat diet. Male Wistar rats (n = 28) were placed on a 12-week high-fat (HFD) or standard diet period, followed by 12 weeks of exercise training for half of each group. Tissue levels of eCBs and related lipids were measured by liquid chromatography mass spectrometry, and expression of genes coding for CB1 and CB2 receptors and eCB metabolic enzymes was measured by quantitative real-time polymerase chain reaction (qPCR). HFD induced a significant increase in 2-AG (p < 0.01) in hypothalamus. High-fat diet paired with exercise training had no effect on AEA, 2-AG, and AEA congener levels in the hypothalamus and hippocampus. Cnr1 expression levels were significantly increased in the hippocampus in response to HFD, exercise, and the combination of both (p < 0.05). Our results indicate that eCB signaling in the CNS is sensitive to diet and/or exercise

Results From the First French Report Card on Physical Activity for Children and Adolescents.

BACKGROUND: Many countries publish periodic Report Cards on physical activity for children and youth. This paper presents the results from the first French Report Card providing a systematic synthesis and assessment of the national engagements to facilitate childhood physical activity. METHODS: A search for nationally representative data on 8 indicators of physical activity was conducted and the data were assessed by an expert panel according to international procedures. Whether children across France are achieving specific benchmarks was rated using an established grading framework [A, B, C, D, F, or INC (incomplete)]. Data were interpreted, grades assigned and detailed in the 2016 Report Card that was produced and disseminated. RESULTS: The expert panel awarded the following grades: Overall Physical Activity: INC; Organized Sport Participation: D; Active Transportation: D; Sedentary Behaviors: D; Family and Peers: INC; School: B; Community and the Built Environment: INC; Government Strategies and Investment: INC. CONCLUSIONS: The grades reveal that efforts must be done to improve youth's physical activity and that several gaps in the literature still need to be addressed. Collectively the results highlight that children's physical activity levels are low and that further national supports and investments are needed to promote childhood healthy active living in France.

Effects of chronic exercise on the endocannabinoid system in Wistar rats with high-fat diet-induced obesity

The endocannabinoid system is dysregulated during obesity in tissues involved in the control of food intake and energy metabolism. We examined the effect of chronic exercise on the tissue levels of endocannabinoids (eCBs) and on the expression of genes coding for cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2) (Cnr1 and Cnr2, respectively) in the subcutaneous (SAT) and visceral adipose tissues and in the soleus and extensor digitorim longus (EDL) muscles, in rats fed with standard or high-fat diet. Twenty-eight male Wistar rats were placed on high-fat diet or standard diet (HFD and Ctl groups, respectively) during 12 weeks whereafter half of each group was submitted to an exercise training period of 12 weeks (HFD + training and Ctl + training). Tissue levels of eCBs were measured by LC-MS while expressions of genes coding for CB1 and CB2 receptors were investigated by qPCR. High-fat diet induced an increase in anandamide (AEA) levels in soleus and EDL (p < 0.02). In soleus of the HFD group, these changes were accompanied by elevated Cnr1 messenger RNA (mRNA) levels (p < 0.05). In EDL, exercise training allowed to reduce significantly this diet-induced AEA increase (p < 0.005). 2-Arachidonoylglycerol (2-AG) levels were decreased and increased by high-fat diet in SAT and EDL, respectively (p < 0.04), but not affected by exercise training. Unlike the HFD + training group, 2-AG levels in soleus were also decreased in the HFD group compared to Ctl (p < 0.04). The levels of eCBs and Cnr1 expression are altered in a tissue-specific manner following a high-fat diet, and chronic exercise reverses some of these alterations (AU)

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Effects of chronic exercise on the endocannabinoid system in Wistar rats with high-fat diet-induced obesity.

The endocannabinoid system is dysregulated during obesity in tissues involved in the control of food intake and energy metabolism. We examined the effect of chronic exercise on the tissue levels of endocannabinoids (eCBs) and on the expression of genes coding for cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2) (Cnr1 and Cnr2, respectively) in the subcutaneous (SAT) and visceral adipose tissues and in the soleus and extensor digitorim longus (EDL) muscles, in rats fed with standard or high-fat diet. Twenty-eight male Wistar rats were placed on high-fat diet or standard diet (HFD and Ctl groups, respectively) during 12 weeks whereafter half of each group was submitted to an exercise training period of 12 weeks (HFD + training and Ctl + training). Tissue levels of eCBs were measured by LC-MS while expressions of genes coding for CB1 and CB2 receptors were investigated by qPCR. High-fat diet induced an increase in anandamide (AEA) levels in soleus and EDL (p < 0.02). In soleus of the HFD group, these changes were accompanied by elevated Cnr1 messenger RNA (mRNA) levels (p < 0.05). In EDL, exercise training allowed to reduce significantly this diet-induced AEA increase (p < 0.005). 2-Arachidonoylglycerol (2-AG) levels were decreased and increased by high-fat diet in SAT and EDL, respectively (p < 0.04), but not affected by exercise training. Unlike the HFD + training group, 2-AG levels in soleus were also decreased in the HFD group compared to Ctl (p < 0.04). The levels of eCBs and Cnr1 expression are altered in a tissue-specific manner following a high-fat diet, and chronic exercise reverses some of these alterations.

Effect of dietary nitrate supplementation on metabolic rate during rest and exercise in human: A systematic review and a meta-analysis.

BACKGROUND: Recent randomized controlled trials have suggested that dietary nitrate (NO3(-)), found in beetroot and other vegetables, and inorganic NO3(-) salts decrease metabolic rate under resting and exercise conditions. OBJECTIVE: Our aim was therefore to determine from a systematic review and meta-analysis whether dietary NO3(-) supplementation significantly reduces metabolic rate, expressed as oxygen uptake (VO2), under resting and exercise conditions in healthy humans and those with cardiorespiratory diseases. DESIGN: A systematic article search was performed on electronic databases (PubMed, Scopus and Web of Science) from February to March 2015. The inclusion criteria included 1) randomized controlled trials; 2) studies reporting the effect of NO3(-) on VO2 under resting and/or exercise conditions; 3) comparison between dietary NO3(-) supplementation and placebo. Random-effects models were used to calculate the pooled effect size. RESULTS: Twenty nine randomized placebo-controlled trials were included in the systematic review, and 26 of which were included in the meta-analysis. Dietary NO3(-) supplementation significantly decreases VO2 during submaximal intensity exercise [-0.26 (95% IC: -0.38, -0.15), p < 0.01], but not in the sub-analysis of subjects with chronic diseases [-0.09 (95% IC: -0.50, 0.32), p = 0.67]. When data were separately analyzed by submaximal intensity domains, NO3(-) supplementation reduces VO2 during moderate [-0.29 (95% IC: -0.48,-0.10), p < 0.01] and heavy [-0.33 (95% IC: -0.54,-0.12), p < 0.01] intensity exercise. When the studies with the largest effects were excluded from the meta-analysis, there is a trend for a VO2 decrease under resting condition in dietary NO3(-) supplementation [-0.28 (95% IC: -0.62, 0.05), p = 0.10]. CONCLUSION: Dietary NO3(-) supplementation decreases VO2 during exercise performed in the moderate and heavy intensity domains in healthy subjects. The present meta-analysis did not show any significant effect of dietary NO3(-) supplementation on metabolic rate in subjects with chronic diseases, despite enhanced exercise tolerance.

Exercise training and high-fat diet elicit endocannabinoid system modifications in the rat hypothalamus and hippocampus.

The purpose of the present study was to examine the effect of chronic exercise on the hypothalamus and hippocampus levels of the endocannabinoids (eCBs) anandamide (AEA) and 2-arachidonoylglycerol (2-AG) and of two AEA congeners and on the expression of genes coding for CB1, CB2 receptors (Cnr1 and Cnr2, respectively), and the enzymes responsible for eCB biosynthesis and degradation, in rats fed with a standard or high-fat diet. Male Wistar rats (n = 28) were placed on a 12-week high-fat (HFD) or standard diet period, followed by 12 weeks of exercise training for half of each group. Tissue levels of eCBs and related lipids were measured by liquid chromatography mass spectrometry, and expression of genes coding for CB1 and CB2 receptors and eCB metabolic enzymes was measured by quantitative real-time polymerase chain reaction (qPCR). HFD induced a significant increase in 2-AG (p < 0.01) in hypothalamus. High-fat diet paired with exercise training had no effect on AEA, 2-AG, and AEA congener levels in the hypothalamus and hippocampus. Cnr1 expression levels were significantly increased in the hippocampus in response to HFD, exercise, and the combination of both (p < 0.05). Our results indicate that eCB signaling in the CNS is sensitive to diet and/or exercise.

Effect of dietary nitrate supplementation on tolerance to supramaximal intensity intermittent exercise.

Dietary nitrate (NO3(-)) supplementation has been shown to increase exercise tolerance and improve oxidative efficiency during aerobic exercise in healthy subjects. We tested the hypothesis that a 3-day supplementation in beetroot juice (BJ) rich in NO3(-) would improve the tolerance to supramaximal intensity intermittent exercise consisting of 15-s exercise periods at 170% of the maximal aerobic power interspersed with 30-s passive recovery periods. The number of repetitions completed before reaching volitional exhaustion was significantly higher in the BJ than in the placebo condition (26.1 ± 10.7 versus 21.8 ± 8.0 respectively, P < 0.05). In contrast to previous findings during exercise performed at intensity below the peak oxygen uptake (VO2peak), oxygen uptake (VO2) was unaffected (BJ: 2735 ± 345 mL kg(-1) min(-1) vs. placebo: 2787 ± 346 mL kg(-1) min(-1), NS). However, the Area Under the Curve for microvascular total hemoglobin (AUC-THb) in the vastus lateralis muscle assessed by near infrared spectroscopy during 3 time-matched repetitions was significantly increased with NO3(-) supplementation (BJ: 9662 ± 1228 a.u. vs. placebo:8178 ± 1589 a.u.; P < 0.05). Thus, increased NO3(-) (BJ: 421.5 ± 107.4 µM vs placebo:39.4 ± 18.0 µM) and NO2(-) (BJ: 441 ± 184 nM vs placebo: 212 ± 119 nM) plasma levels (P < 0.001 for both) are associated with improved muscle microvascular Red Blood Cell (RBC) concentration and O2 delivery during intense exercise, despite no effect on resting femoral artery blood flow, and vascular conductance. Maximal voluntary force during an isometric leg extensor exercise, and blood lactate levels were also unaffected by NO3(-) supplementation. To conclude, dietary NO3(-) supplementation enhances tolerance to exercise at supramaximal intensity, with increased microvascular total RBC concentration in the working muscle, in the absence of effect on contractile function and resting hemodynamic parameters.

Regional cerebral hemodynamic response to incremental exercise is blunted in poorly controlled patients with uncomplicated type 1 diabetes.

OBJECTIVE: Cerebral vasoreactivity to pharmacologically induced hypercapnia is impaired in poorly controlled patients with type 1 diabetes but otherwise free from microangiopathy. However, whether this response is also compromised during exercise, a daily-life physiological condition challenging regional cerebral hemodynamics, is unknown. We aimed to investigate prefrontal cortex hemodynamics during incremental maximal exercise in patients with uncomplicated type 1 diabetes, taking into account long-term glycemic control as well as exercise- and diabetes-influenced vasoactive stimuli. RESEARCH DESIGN AND METHODS: Two groups of patients (type 1 diabetes with adequate glycemic control [T1D-A], n = 8, HbA1c 6.8 ± 0.7% [51 ± 7.7 mmol/mol]; type 1 diabetes with inadequate glycemic control [T1D-I], n = 10, HbA1c 9.0 ± 0.7% [75 ± 7.7 mmol/mol]) were compared with 18 healthy control subjects (CON-A and CON-I) matched for physical activity and body composition. Throughout exercise, near-infrared spectroscopy allowed investigation of changes in oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb), and total hemoglobin (THb) in the prefrontal cortex. Venous and arterialized capillary blood was sampled during exercise to assess for factors that may alter prefrontal cortex hemodynamics and oxygenation. RESULTS: No differences were observed between T1D-A and CON-A, but VO2max was impaired (P < 0.05) and cerebral blood volume (THb) increase blunted (P < 0.05) in T1D-I compared with CON-I. Nonetheless, O2Hb appeared unaltered in T1D-I probably partly due to blunting of simultaneous neuronal oxygen extraction (i.e., a lower HHb increase; P < 0.05). There were no intergroup differences in arterial oxygen content, Paco2, pH, [K(+)], and free insulin levels. CONCLUSIONS: Maximal exercise highlights subtle disorders of both hemodynamics and neuronal oxygenation in the prefrontal cortex of poorly controlled patients with type 1 diabetes. These findings may warn clinicians of brain endothelial dysfunction occurring even before overt microangiopathy during exercise.

Bedtime and sleep timing but not sleep duration are associated with eating habits in primary school children.

OBJECTIVE: In the context of childhood obesity progression, sleep patterns have been associated with unhealthy eating habits and energy intake. The association between several eating habits and sleep patterns in children has been recently studied. The aim of this study was to explore the association between sleep patterns, eating habits, and physical fitness in primary school children. METHODS: A total of 236 children of 6 to 10 years old were recruited. Anthropometric characteristics and body composition were measured, and cardiorespiratory (20-m shuttle run test) and musculoskeletal (squat jump and cycling peak power) fitness tests were performed. Parents were asked to fill out an eating habits questionnaire, and children were classified into 4 categories as a function of the number of eating risk factors they presented. Parents completed a questionnaire about their child's bedtime and waking hours during weekdays and weekends. RESULTS: Weight (p < .01), waist circumference, and fat mass (p < .05) were significantly higher in late sleepers (27.6 ± 6.3 kg; 60.1 ± 7.6 cm; 19.52 ± 7.44) compared with normal sleepers (25.4 ± 3.7 kg; 58.2 ± 4.9 cm; 17.44% ± 6.23%). None of the physical fitness parameters were associated with sleep duration, bedtime, wake-up time, nor were they significantly different between late and normal sleepers. Bedtime was significantly earlier in children consuming breakfast everyday (08:30 vs. 09:00 PM, p < .01); later in children snacking (09:15 vs. 09:30 PM, p < .05) or watching TV at lunch (10:00 vs 09:30 PM, p < .05). There is an association between the proportion of normal and late sleepers and the accumulation of healthy eating habits (p < .001). CONCLUSION: Bedtime and sleep timings (normal or late sleepers) are associated with eating habits in primary school children. It seems necessary to consider the number of unhealthy eating habits adopted by children when studying these associations.