Hypoxic high-intensity interval training in individuals with overweight and obesity.

Combining moderate-intensity exercise training with hypoxic exposure may induce larger improvement in cardiometabolic risk factors and health status compared with normoxic exercise training in obesity. Considering the greater cardiometabolic effects of high-intensity intermittent training (HIIT), we hypothesized that hypoxic high-volume HIIT (H-HIIT) would induce greater improvement in cardiorespiratory fitness and health status despite a lower absolute training workload than normoxic HIIT (N-HIIT) in overweight/obesity. Thirty-one subjects were randomized to an 8-week H-HIIT [10 male and 6 female; age: 51.0 ± 8.3 years; body mass index (BMI): 31.5 ± 4 kg·m-2] or N-HIIT (13 male and 2 female; age: 52.0 ± 7.5 years; BMI: 32.4 ± 4.8 kg·m-2) program (3 sessions/week; cycling at 80% or 100% of maximal workload for H-HIIT and N-HIIT, respectively; target arterial oxygen saturation for H-HIIT 80%, [Formula: see text] ∼0.12, i.e., ∼4,200 meters above sea level). Before and after training, the following evaluations were performed: incremental maximal and submaximal cycling tests, pulse-wave velocity, endothelial function, fasting glucose, insulin, lipid profile, and body composition. Maximal exercise (V̇o2peak: H-HIIT +14.2% ± 8.3% vs. N-HIIT +12.1 ± 8.8%) and submaximal (ventilatory thresholds) capacity and exercise metabolic responses (power output at the crossover point and at maximal fat oxidation rate) increased significantly in both groups, with no significant difference between groups and without other cardiometabolic changes. H-HIIT induced a greater peak ventilatory response (ANOVA group × time interaction F = 7.4, P = 0.016) compared with N-HIIT. In overweight/obesity, the combination of normobaric hypoxia and HIIT was not superior for improving cardiorespiratory fitness improvement compared with HIIT in normoxia, although HIIT in hypoxia was performed at a lower absolute training workload.

High-intensity interval training to promote cerebral oxygenation and affective valence during exercise in individuals with obesity.

Left/right prefrontal cortex (PFC) activation is linked to positive/negative affects, respectively. Besides, larger left PFC oxygenation during exercise relates to higher cardiorespiratory fitness (CRF). High-intensity interval training (HIIT) is superior to moderate-intensity continuous training (MICT) in improving CRF. The influence of training on PFC oxygenation and affects during exercise in individuals with obesity is, however, currently unknown. Twenty participants with obesity (14 males, 48 ± 8 years, body-mass index = 35 ± 6 kg·m-2) were randomised to MICT [50% peak work rate (WRpeak)] or HIIT (1-min bouts 100% WRpeak; 3 sessions/week, 8 weeks). Before/after training, participants completed an incremental ergocycle test. Near-infrared spectroscopy and the Feeling Scale assessed PFC oxygenation and affects during exercise, respectively. Improvements in CRF (e.g., WRpeak: 32 ± 14 vs 20 ± 13 W) were greater after HIIT vs MICT (p < 0.05). Only HIIT induced larger left PFC oxygenation (haemoglobin difference from 7 ± 6 to 10 ± 7 µmol) and enhanced affective valence (from 0.7 ± 2.9 to 2.2 ± 2.0; p < 0.05) at intensities ≥ second ventilatory threshold. Exercise-training induced changes in left PFC oxygenation correlated with changes in CRF [e.g., WRpeak (% predicted), r = 0.46] and post-training affective valence (r = 0.45; p < 0.05). HIIT specifically improved left PFC oxygenation and affects during exercise in individuals with obesity. Implementing HIIT in exercise programmes may therefore have relevant implications for the management of obesity, since greater affective response to exercise is thought to be associated with future commitment to physical activity.

Effects of high intensity interval training on sustained reduction in cardiometabolic risk associated with overweight/obesity. A randomized trial.

Background: Considering the potential greater cardiocirculatory effects of high intensity interval training (HIIT), we hypothesized that a 2-month supervised high volume short interval HIIT would induce greater improvements in CRF and cardiometabolic risk and increase long-term maintenance to physical activity compared to isocaloric moderate intensity continuous training (MICT) in overweight/obesity. Methods: Sixty (19 females) subjects with overweight/obesity were randomized to three training programs (3 times/week for 2 months): MICT (45 min, 50% peak power output-PPO), HIIT (22 × 1-min cycling at 100% PPO/1-min passive recovery) and HIIT-RM (RM: recovery modulation, i.e. subjects adjusted passive recovery duration between 30s and 2 min). After the intervention, participants no longer benefited from supervised physical activity and were instructed to maintain the same exercise modalities on their own. We assessed anthropometrics, body composition, CRF, fat oxidation, lipid profile, glycemic balance, low-grade inflammation, vascular function, spontaneous physical activity and motivation for eating at three time points: baseline (T0), 4 days after the end of the 2-month supervised training program (T2) and 4 months after the end of the training program (T6). Results: HIIT/HIIT-RM induced greater improvement in VO2peak (between +14% and +17%), power output at ventilatory thresholds and at maximal fat oxidation rate (+25%) and waist circumference (-1.53 cm) compared to MICT and tended to decrease insulin resistance. During the four-month follow-up period during which exercise in autonomy was prescribed, HIIT induced a greater preservation of CRF, decreases in total and abdominal fat masses and total cholesterol/HDL. Conclusion: We have shown greater short-term benefits induced by a high volume short interval (1 min) HIIT on cardiorespiratory fitness and cardiometabolic risk over an isocaloric moderate intensity continuous exercise in persons with overweight/obesity. We also showed greater long-term effects (i.e. after 4 months) of this exercise modality on the maintenance of CRF, decreases in total and abdominal fat masses and total cholesterol/HDL.

Cardiovascular and metabolic responses to passive hypoxic conditioning in overweight and mildly obese individuals.

Although severe intermittent hypoxia (IH) is well known to induce deleterious cardiometabolic consequences, moderate IH may induce positive effects in obese individuals. The present study aimed to evaluate the effect of two hypoxic conditioning programs on cardiovascular and metabolic health status of overweight or obese individuals. In this randomized single-blind controlled study, 35 subjects (54 ± 9.3 yr, 31.7 ± 3.5 kg/m2) were randomized into three 8-wk interventions (three 1-h sessions per week): sustained hypoxia (SH), arterial oxygen saturation ([Formula: see text]) = 75%; IH, 5 min [Formula: see text] = 75% - 3 min normoxia; normoxia. Ventilation, heart rate, blood pressure, and tissue oxygenation were measured during the first and last hypoxic conditioning sessions. Vascular function, blood glucose and insulin, lipid profile, nitric oxide metabolites, and oxidative stress were evaluated before and after the interventions. Both SH and IH increased ventilation in hypoxia (+1.8 ± 2.1 and +2.3 ± 3.6 L/min, respectively; P < 0.05) and reduced normoxic diastolic blood pressure (-12 ± 15 and -13 ± 10 mmHg, respectively; P < 0.05), whereas changes in normoxic systolic blood pressure were not significant (+3 ± 9 and -6 ± 13 mmHg, respectively; P > 0.05). IH only reduced heart rate variability (e.g., root-mean-square difference of successive normal R-R intervals in normoxia -21 ± 35%; P < 0.05). Both SH and IH induced no significant change in body mass index, vascular function, blood glucose, insulin and lipid profile, nitric oxide metabolites, or oxidative stress, except for an increase in superoxide dismutase activity following SH. This study indicates that passive hypoxic conditioning in obese individuals induces some positive cardiovascular and respiratory improvements despite no change in anthropometric data and even a reduction in heart rate variability during IH exposure.

A short bout of high-intensity intermittent exercise before moderate-intensity prolonged exercise as a mean to potentiate fat oxidation ?

Moderate-intensity continuous exercise (MICE) improves fat oxidation. High-intensity intermittent exercise (HIIE) is thought to have a greater potential for fat oxidation but it might be too demanding in the long term for patients. We hypothesized that an initial bout of HIIE could maximize fat oxidation during MICE and the following passive recovery. Eighteen healthy participants performed two acute isocaloric exercise sessions at random. MICE consisted of 45-min cycling at 50% of maximal aerobic power (Pmax). COMB began with five 1-min bouts of HIIE at Pmax (interspaced with 1-min recovery periods) followed by 35-min MICE. Gas exchange allowed substrate oxidation rate assessment.Expressed as a % of energy expenditure, fat oxidation (%) increased during in the passive recovery following COMB (Recovery: 36.0 ± 19.4 vs 23.0 ± 20.3%; ES: 0.66; p < 0.0001). An initial bout of HIIE preceding a prolonged moderate-intensity exercise may potentiate fat oxidation during the following recovery. This might be relevant for health management of overweight/obese persons.

Maximal exercise capacity in patients with obstructive sleep apnoea syndrome: a systematic review and meta-analysis.

Maximal aerobic capacity is a strong health predictor and peak oxygen consumption (V'O2peak) is considered a reflection of total body health. No systematic reviews or meta-analyses to date have synthesised the existing data regarding V'O2peak in patients with obstructive sleep apnoea (OSA).A systematic review of English and French articles using PubMed/MEDLINE and Embase included studies assessing V'O2peak in OSA patients either in mL·kg-1·min-1 compared with controls or in % predicted. Two independent reviewers analysed the studies, extracted the data and assessed the quality of evidence.Mean V'O2peak expressed in mL·kg-1·min-1 was significantly lower in patients with OSA than in controls (mean difference -2.7 mL·kg-1·min-1; p<0.001; n=850). This reduction in V'O2peak was found to be larger in non-obese patients (body mass index <30 kg·m-2). Mean V'O2peak % pred was 89.9% in OSA patients (n=643).OSA patients have reduced maximal aerobic capacity, which can be associated with increased cardiovascular risks and reduced survival in certain patient subgroups. Maximal exercise testing can be useful to characterise functional limitation and to evaluate health status in OSA patients.

High-intensity training reduces intermittent hypoxia-induced ER stress and myocardial infarct size.

Chronic intermittent hypoxia (IH) is described as the major detrimental factor leading to cardiovascular morbimortality in obstructive sleep apnea (OSA) patients. OSA patients exhibit increased infarct size after a myocardial event, and previous animal studies have shown that chronic IH could be the main mechanism. Endoplasmic reticulum (ER) stress plays a major role in the pathophysiology of cardiovascular disease. High-intensity training (HIT) exerts beneficial effects on the cardiovascular system. Thus, we hypothesized that HIT could prevent IH-induced ER stress and the increase in infarct size. Male Wistar rats were exposed to 21 days of IH (21-5% fraction of inspired O2, 60-s cycle, 8 h/day) or normoxia. After 1 wk of IH alone, rats were submitted daily to both IH and HIT (2 × 24 min, 15-30m/min). Rat hearts were either rapidly frozen to evaluate ER stress by Western blot analysis or submitted to an ischemia-reperfusion protocol ex vivo (30 min of global ischemia/120 min of reperfusion). IH induced cardiac proapoptotic ER stress, characterized by increased expression of glucose-regulated protein kinase 78, phosphorylated protein kinase-like ER kinase, activating transcription factor 4, and C/EBP homologous protein. IH-induced myocardial apoptosis was confirmed by increased expression of cleaved caspase-3. These IH-associated proapoptotic alterations were associated with a significant increase in infarct size (35.4 ± 3.2% vs. 22.7 ± 1.7% of ventricles in IH + sedenary and normoxia + sedentary groups, respectively, P < 0.05). HIT prevented both the IH-induced proapoptotic ER stress and increased myocardial infarct size (28.8 ± 3.9% and 21.0 ± 5.1% in IH + HIT and normoxia + HIT groups, respectively, P = 0.28). In conclusion, these findings suggest that HIT could represent a preventive strategy to limit IH-induced myocardial ischemia-reperfusion damages in OSA patients.

Low Cardiorespiratory Fitness is Partially Linked to Ventilatory Factors in Obese Adolescents.

AIM: To examine the role of ventilatory constraint on cardiorespiratory fitness in obese adolescents. METHODS: Thirty obese adolescents performed a maximal incremental cycling exercise and were divided into 2 groups based on maximal oxygen uptake (VO2peak): those presenting low (L; n = 15; VO2peak: 72.9 ± 8.6% predicted) or normal (N; n = 15; VO2peak: 113.6 ± 19.2% predicted) cardiorespiratory fitness. Both were compared with a group of healthy controls (C; n = 20; VO2peak: 103.1 ± 11.2% predicted). Ventilatory responses were explored using the flow volume loop method. RESULTS: Cardiorespiratory fitness (VO2peak, in % predicted) was lower in L compared with C and N and was moderately associated with the percent predicted forced vital capacity (FVC) (r = .52; p < .05) in L. At peak exercise, end inspiratory point was lower in L compared with N and C (77.4 ± 8.1, 86.4 ± 7.7, and 89.9 ± 7.6% FVC in L, N, and C, respectively; p < .05), suggesting an increased risk of ventilatory constraint in L, although at peak exercise this difference could be attributed to the lower maximal ventilation in L. CONCLUSION: Forced vital capacity and ventilatory strategy to incremental exercise slightly differed between N and L. These results suggest a modest participation of ventilatory factors to exercise intolerance.

Body composition assessment of people with overweight/obesity with a simplified magnetic resonance imaging method.

To develop a simplified magnetic resonance imaging method (MRI) to assess total adipose tissue (AT) and adipose tissue free mass (ATFM) from three single MRI slices in people with overweight/obesity in order to implement body composition follow-up in a clinical research setting. Body composition of 310 participants (70 women and 240 men, age: 50.8 ± 10.6 years, BMI: 31.3 ± 5.6 kg.m-2) was assessed with 3 single slices (T6-T7, L4-L5 and at mid-thigh) MRI. Multiple regression analysis was used to develop equations predicting AT and ATFM from these three single slices. Then we implemented a longitudinal phase consisting in a 2-month exercise training program during which we tested the sensitivity of these equations in a subgroup of participants with overweight/obesity (n = 79) by comparing the exercise-induced variations between predicted and measured AT and ATFM. The following equations: total AT = - 12.74105 + (0.02919 × age) + (4.27634 × sex (M = 0, F = 1)) + (0.22008 × weight) + (26.92234 × AT T6-T7) + (23.70142 × AT L4-L5) + (37.94739 × AT mid-thigh) and total ATFM = - 33.10721 + (- 0.02363 × age) + (- 3.58052 × sex (M = 0, F = 1)) + (30.02252 × height) + (0.08549 × weight) + (11.36859 × ATFM T6-T7) + (27.82244 × ATFM L4-L5) + (58.62648 × ATFM mid-thigh) showed an excellent prediction (adjusted R2 = 97.2% and R2 = 92.5%; CCC = 0.986 and 0.962, respectively). There was no significant difference between predicted and measured methods regarding the AT variations (- 0.07 ± 2.02 kg, p = 0.70) and the ATFM variations (0.16 ± 2.41 kg, p = 0.49) induced by 2-months of exercise training. This simplified method allows a fully accurate assessment of the body composition of people with obesity in less than 20 min (10 min for images acquisition and analysis, respectively), useful for a follow-up.

Effects of a physical activity and endometriosis-based education program delivered by videoconference on endometriosis symptoms: the CRESCENDO program (inCRease physical Exercise and Sport to Combat ENDOmetriosis) protocol study.

BACKGROUND: Endometriosis is a chronic disease characterized by growth of endometrial tissue outside the uterine cavity which could affect 200 million women (The term "woman" is used for convenience. Individuals gendered as man or as nonbinary can also suffer from this disease) worldwide. One of the most common symptoms of endometriosis is pelvic chronic pain associated with fatigue. This pain can cause psychological distress and interpersonal difficulties. As for several chronic diseases, adapted physical activity could help to manage the physical and psychological symptoms. The present study will investigate the effects of a videoconference-based adapted physical activity combined with endometriosis-based education program on quality of life, pain, fatigue, and other psychological symptoms and on physical activity. METHODS: This multicentric randomized-controlled trial will propose to 200 patients with endometriosis to be part of a trial which includes a 6-month program with 45 min to more than 120 min a week of adapted physical activity and/or 12 sessions of endometriosis-based education program. Effects of the program will be compared to a control group in which patients will be placed on a waiting list. All participants will be followed up 3 and 6 months after the intervention. None of the participants will be blind to the allocated trial arm. The primary outcome measure will be quality of life. Secondary outcomes will include endometriosis-related perceived pain, fatigue, physical activity, and also self-image, stereotypes, motivational variables, perceived support, kinesiophobia, basic psychological need related to physical activity, and physical activity barriers. General linear models and multilevel models will be performed. Predictor, moderator, and mediator variables will be investigated. DISCUSSION: This study is one of the first trials to test the effects of a combined adapted physical activity and education program for improving endometriosis symptoms and physical activity. The results will help to improve care for patients with endometriosis. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05831735 . Date of registration: April 25, 2023.

Prediction of maximal lactate steady state in runners with an incremental test on the field.

During a maximal incremental ergocycle test, the power output associated with Respiratory Exchange Ratio equal to 1.00 (RER = 1.00) predicts maximal lactate steady state (MLSS). We hypothesised that these results are transferable for runners on the field. Fourteen runners performed a maximal progressive test, to assess the speed associated with RER = 1.00, and several 30 minutes constant velocity tests to determine the speed at MLSS. We observed that the speeds at RER = 1.00, at the second ventilatory threshold (VT2) and at MLSS did not differ (15.7 ± 1.1 km · h⁻¹, 16.2 ± 1.4 km · h⁻¹, 15.5 ± 1.1 km · h⁻¹ respectively). The speed associated with RER = 1.00 was better correlated with that at MLSS (r = 0.79; p = 0.0008) than that at VT2 (r = 0.73; p = 0.002). Neither the concentration of blood lactate nor the heart rate differed between the speed at RER = 1.00 and that at MLSS from the 10th and the 30th minute of the constant velocity test. Bland and Altman analysis showed a fair agreement between the speed at MLSS and that at RER (0.2 ± 1.4 km · h⁻¹). This study demonstrated that the speed associated with RER = 1.00 determined during maximal progressive track running allows a fair estimation of the speed associated with MLSS, markedly decreasing the burden of numerous invasive tests required to assess it.

Hypoxic Exercise Training to Improve Exercise Capacity in Obese Individuals.

INTRODUCTION: Combining exercise training with hypoxic exposure has been recently proposed as a new therapeutic strategy to improve health status of obese individuals. Whether hypoxic exercise training (HET) provides greater benefits regarding body composition and cardiometabolic parameters than normoxic exercise training (NET) remains, however, unclear. We hypothesized that HET would induce greater improvement in exercise capacity and health status than NET in overweight and obese individuals. METHODS: Twenty-three subjects were randomized into 8-wk HET (11 men and 1 woman; age, 52 ± 12 yr; body mass index, 31.2 ± 2.4 kg·m) or NET (eight men and three women; age, 56 ± 11 yr; body mass index, 31.8 ± 3.2 kg·m) programs (three sessions per week; constant-load cycling at 75% of maximal heart rate; target arterial oxygen saturation for HET 80%, FiO2 ~0.13, i.e., ~3700 m a.s.l.). Before and after the training programs, the following evaluations were performed: incremental maximal and submaximal cycling tests, measurements of pulse-wave velocity, endothelial function, fasting glucose, insulin and lipid profile, blood NO metabolites and oxidative stress, and determination of body composition by magnetic resonance imaging. RESULTS: Peak oxygen consumption and maximal power output increased significantly after HET only (peak oxygen consumption HET + 10% ± 11% vs NET + 1% ± 10% and maximal power output HET + 11% ± 7% vs NET + 3% ± 10%, P < 0.05). Submaximal exercise responses improved similarly after HET and NET. Except diastolic blood pressure which decreased significantly after both HET and NET, no change in vascular function, metabolic status and body composition was observed after training. Hypoxic exercise training only increased nitrite and reduced superoxide dismutase concentrations. CONCLUSIONS: Combining exercise training and hypoxic exposure may provide some additional benefits to standard NET for obese individual health status.

Effects of acute salbutamol inhalation on quadriceps force and fatigability.

INTRODUCTION: Oral beta2-agonist administration improves muscle function in persons without asthma. We performed a double-blind, randomized, controlled crossover study to assess whether acute inhaled salbutamol administration improves muscle strength and fatigability in healthy moderately trained subjects. METHODS: Quadriceps muscle strength was measured during maximal voluntary contraction (MVC) and femoral nerve magnetic stimulation (potentiated single twitch, TwQpeak) before and after (i) a maximal incremental cycling test (n = 10) and (ii) 50 maximal isometric one-leg extensions (n = 9). Each exercise test was performed on three occasions, after salbutamol (200 and 800 microg) or placebo inhalation. RESULTS: Before exercise, treatments had no significant effect on MVC [(placebo) 597 +/- 146 N vs (200 microg) 629 +/- 151 N vs (800 microg) 610 +/- 148 N] and TwQpeak [(placebo) 215 +/- 83 N vs (200 microg) 227 +/- 69 N vs (800 microg) 250 +/- 84 N]. Maximal power during cycling and maximal force during leg extensions did not differ between treatments. Treatments had no effect on MVC and TwQpeak reductions at 30 min [MVC: (placebo) -8 +/- 9% vs (200 microg) -9 +/- 7% vs (800 microg) -8 +/- 5%; TwQpeak: (placebo) -29 +/- 13% vs (200 microg) -23 +/- 15% vs (800 microg) -20 +/- 8%] and 60 min [MVC: (placebo) -12 +/- 17% vs (200 microg) -6 +/- 9% vs (800 microg) -8 +/- 8%; TwQpeak: (placebo) -20 +/- 21% vs (200 microg) -19 +/- 23% vs (800 microg) -8 +/- 7%] after cycling. Similarly, reductions in MVC and TwQpeak were not significantly different between treatments at 30 [MVC: (placebo) -11 +/- 9% vs (200 microg) -12 +/- 7% vs (800 microg) -8+/- 16%; TwQpeak: (placebo) -37 +/- 12% vs (200 microg) -33 +/- 20% vs (800 microg) -32 +/- 16%] and 60 min [MVC: (placebo) -10 +/- 11% vs (200microg) -11 +/- 6% vs (800 microg) -8 +/- 20%; TwQpeak: (placebo) -30 +/- 11% vs (200 microg) -28 +/- 24% vs (800 microg) -27 +/- 15%] after leg extensions. Treatments did not modify maximal voluntary activation at any time of the protocol. CONCLUSION: Acute therapeutic or supratherapeutic doses of inhaled salbutamol have no effect on quadriceps strength, fatigue, and recovery in men without asthma.

Obstructive Sleep Apnea Syndrome, Objectively Measured Physical Activity and Exercise Training Interventions: A Systematic Review and Meta-Analysis.

A systematic review of English and French articles using Pubmed/Medline and Embase included studies assessing objective physical activity levels of obstructive sleep apnea (OSA) patients and exploring the effects of exercise training on OSA severity, body mass index (BMI), sleepiness, and cardiorespiratory fitness [peak oxygen consumption (VO2peak)]. Two independent reviewers analyzed the studies, extracted the data, and assessed the quality of evidence. For objective physical activity levels, eight studies were included. The mean number of steps per day across studies was 5,388 (95% CI: 3,831-6,945; p < 0.001), which was by far lower than the recommended threshold of 10,000 steps per day. For exercise training, six randomized trials were included. There was a significant decrease in apnea-hypopnea-index following exercise training (mean decrease of 8.9 events/h; 95% CI: -13.4 to -4.3; p < 0.01), which was accompanied by a reduction in subjective sleepiness, an increase in VO2peak and no change in BMI. OSA patients present low levels of physical activity and exercise training is associated with improved outcomes. Future interventions (including exercise training) focusing on increasing physical activity levels may have important clinical impacts on both OSA severity and the burden of associated co-morbidities. Objective measurement of physical activity in routine OSA management and well-designed clinical trials are recommended. Registration # CRD42017057319 (Prospero).

Simultaneous determination of tryptophan and 8 metabolites in human plasma by liquid chromatography/tandem mass spectrometry.

Tryptophan (Trp) is an essential amino-acid and the precursor of many biologically active substances such as kynurenine (KYN) and serotonin (5HT). Its metabolism is involved in different physiopathological states, such as cardiovascular diseases, cancer, immunomodulation or depression. Hence, the quantification of Trp catabolites, from both KYN and 5HT pathways, might be usefulfor the discovery of novel diagnostic and follow-up biomarkers. We have developed a simple method for quantification of Trp and 8 of its metabolites,involved in both KYN and 5HT pathways, using liquid chromatography coupled to tandem mass spectrometry. We also validated the methodin human plasma samples, according to NF EN ISO 15189 criteria. Our method shows acceptable intra- and inter-day coefficients of variation (CV) (<12% and <16% respectively). The linearity entirelycovers the human plasma range. Stabilities of whole blood and of residues weredetermined, as well as the use of 2 different types of collectiontube, enabling us to adapt our process. Matrix effects and reference values showed good agreement compared to the literature. We propose here a method allowing the simultaneous quantification of a panel of Trp catabolites, never used before to our knowledge. This method, witha quickchromatographic runtime (15min) and simple sample preparation, has beenvalidated according to NF EN ISO 15189 criteria. The method enables the detailed analysis of these metabolic pathways, which are thought to be involved in a number of pathological conditions.

High intensity aerobic exercise training improves chronic intermittent hypoxia-induced insulin resistance without basal autophagy modulation.

Chronic intermittent hypoxia (IH) associated with obstructive sleep apnea (OSA) is a major risk factor for cardiovascular and metabolic diseases (insulin resistance: IR). Autophagy is involved in the pathophysiology of IR and high intensity training (HIT) has recently emerged as a potential therapy. We aimed to confirm IH-induced IR in a tissue-dependent way and to explore the preventive effect of HIT on IR-induced by IH. Thirty Swiss 129 male mice were randomly assigned to Normoxia (N), Intermittent Hypoxia (IH: 21-5% FiO2, 30 s cycle, 8 h/day) or IH associated with high intensity training (IH HIT). After 8 days of HIT (2*24 min, 50 to 90% of Maximal Aerobic Speed or MAS on a treadmill) mice underwent 14 days IH or N. We found that IH induced IR, characterized by a greater glycemia, an impaired insulin sensitivity and lower AKT phosphorylation in adipose tissue and liver. Nevertheless, MAS and AKT phosphorylation were greater in muscle after IH. IH associated with HIT induced better systemic insulin sensitivity and AKT phosphorylation in liver. Autophagy markers were not altered in both conditions. These findings suggest that HIT could represent a preventive strategy to limit IH-induced IR without change of basal autophagy.

Physiological Responses to Two Hypoxic Conditioning Strategies in Healthy Subjects.

Objective: Hypoxic exposure can be used as a therapeutic tool by inducing various cardiovascular, neuromuscular, and metabolic adaptations. Hypoxic conditioning strategies have been evaluated in patients with chronic diseases using either sustained (SH) or intermittent (IH) hypoxic sessions. Whether hypoxic conditioning via SH or IH may induce different physiological responses remains to be elucidated. Methods: Fourteen healthy active subjects (7 females, age 25 ± 8 years, body mass index 21.5 ± 2.5 kg·m-2) performed two interventions in a single blind, randomized cross-over design, starting with either 3 x SH (48 h apart), or 3 x IH (48 h apart), separated by a 2 week washout period. SH sessions consisted of breathing a gas mixture with reduced inspiratory oxygen fraction (FiO2), continuously adjusted to reach arterial oxygen saturations (SpO2) of 70-80% for 1 h. IH sessions consisted of 5 min with reduced FiO2 (SpO2 = 70-80%), followed by 3-min normoxia, repeated seven times. During the first (S1) and third (S3) sessions of each hypoxic intervention, cardiorespiratory parameters, and muscle and pre-frontal cortex oxygenation (near infrared spectroscopy) were assessed continuously. Results: Minute ventilation increased significantly during IH sessions (+2 ± 2 L·min-1) while heart rate increased during both SH (+11 ± 4 bpm) and IH (+13 ± 5 bpm) sessions. Arterial blood pressure increased during all hypoxic sessions, although baseline normoxic systolic blood pressure was reduced from S1 to S3 in IH only (-8 ± 11 mmHg). Muscle oxygenation decreased significantly during S3 but not S1, for both hypoxic interventions (S3: SH -6 ± 5%, IH -3 ± 4%); pre-frontal oxygenation decreased in S1 and S3, and to a greater extent in SH vs. IH (-13 ± 3% vs. -6 ± 6%). Heart rate variability indices indicated a significantly larger increase in sympathetic activity in SH vs. IH (lower SDNN, PNN50, and RMSSD values in SH). From S1 to S3, further reduction in heart rate variability was observed in SH (SDNN, PNN50, and RMSSD reduction) while heart rate variability increased in IH (SDNN and RMSSD increase). Conclusions: These results showed significant differences in heart rate variability, blood pressure, and tissue oxygenation changes during short-term SH vs. IH conditioning interventions. Heart rate variability may provide useful information about the early adaptations induced by such intervention.

Bronchial hyperresponsiveness, airway inflammation, and airflow limitation in endurance athletes.

BACKGROUND: Whereas a high prevalence of bronchial abnormalities has been reported in endurance athletes, its underlying mechanisms and consequences during exercise are still unclear. STUDY OBJECTIVES: The purpose of this study was to assess the following: (1) bronchial responsiveness to methacholine and to exercise; (2) airway inflammation; and (3) airflow limitation during intense exercise in endurance athletes with respiratory symptoms. DESIGN: Cross-sectional observational study. SETTING: Lung function and exercise laboratory at a university hospital. PATIENTS AND MEASUREMENTS: Thirty-nine endurance athletes and 13 sedentary control subjects were explored for the following: (1) self-reported respiratory symptoms; (2) bronchial hyperresponsiveness (BHR) to methacholine and exercise; (3) airflow limitation during intense exercise; and (4) bronchial inflammation using induced sputum and nitric oxide (NO) exhalation. RESULTS: Fifteen athletes (38%) showed BHR to methacholine and/or exercise in association with bronchial eosinophilia (mean [+/- SD] eosinophil count, 4.1 +/- 8.5% vs 0.3 +/- 0.9% vs 0%, respectively), higher NO concentrations (19 +/- 10 vs 14 +/- 4 vs 13 +/- 4 parts per billion, respectively), a higher prevalence of atopy, and more exercise-induced symptoms compared with non-hyperresponsive athletes and control subjects (p < 0.05). Furthermore, airflow limitation during intense exercise was observed in eight athletes, among whom five had BHR. Athletes with airflow limitation reported more symptoms and had FEV1, FEV1/FVC ratio, and forced expiratory flow at midexpiratory phase values of 14%, 9%, and 29%, respectively, lower compared with those of nonlimited athletes (p < 0.05). CONCLUSION: BHR in endurance athletes was associated with the criteria of eosinophilic airway inflammation and atopy, whereas airflow limitation during exercise was primarily a consequence of decreased resting spirometric values. Both BHR and bronchial obstruction at rest with subsequent expiratory flow limitation during exercise may promote respiratory symptoms during exercise in athletes.