A Step Test to Evaluate the Susceptibility to Severe High-Altitude Illness in Field Conditions.

Hermand, Eric, Léo Lesaint, Laura Denis, Jean-Paul Richalet, and François J. Lhuissier. A step test to evaluate the susceptibility to severe high-altitude illness in field conditions.

Cardiovascular physiology and pathophysiology at high altitude.

Oxygen is vital for cellular metabolism; therefore, the hypoxic conditions encountered at high altitude affect all physiological functions. Acute hypoxia activates the adrenergic system and induces tachycardia, whereas hypoxic pulmonary vasoconstriction increases pulmonary artery pressure. After a few days of exposure to low oxygen concentrations, the autonomic nervous system adapts and tachycardia decreases, thereby protecting the myocardium against high energy consumption.

Global Alliance for the Promotion of Physical Activity: the Hamburg Declaration.

Non-communicable diseases (NCDs), including coronary heart disease, stroke, hypertension, type 2 diabetes, dementia, depression and cancers, are on the rise worldwide and are often associated with a lack of physical activity (PA). Globally, the levels of PA among individuals are below WHO recommendations. A lack of PA can increase morbidity and mortality, worsen the quality of life and increase the economic burden on individuals and society.

Exponential Relationship Between Maximal Apnea Duration and Exercise Intensity in Non-apnea Trained Individuals.

It is well known that the duration of apnea is longer in static than in dynamic conditions, but the impact of exercise intensity on the apnea duration needs to be investigated. The aim of this study was to determine the relationship between apnea duration and exercise intensity, and the associated metabolic parameters. Ten healthy active young non-apnea trained (NAT) men participated in this study.

Evaluation of the Lake Louise Score for Acute Mountain Sickness and Its 2018 Version in a Cohort of 484 Trekkers at High Altitude.

Richalet, Jean-Paul, Chantal Julia, and François J. Lhuissier. Evaluation of the Lake Louise Score for acute mountain sickness and its 2018 version in a cohort of 484 trekkers at high altitude.

Exercising in Hypoxia and Other Stimuli: Heart Rate Variability and Ventilatory Oscillations.

Periodic breathing is a respiratory phenomenon frequently observed in patients with heart failure and in normal subjects sleeping at high altitude. However, until recently, periodic breathing has not been studied in wakefulness and during exercise. This review relates the latest findings describing this ventilatory disorder when a healthy subject is submitted to simultaneous physiological (exercise) and environmental (hypoxia, hyperoxia, hypercapnia) or pharmacological (acetazolamide) stimuli.

Accuracy and Reliability of Pulse O2 Saturation Measured by a Wrist-worn Oximeter.

This study aims to evaluate the accuracy of the Garmin Forerunner 245 heart rate (HR) and pulse O saturation (SpO) sensors compared with electrocardiogram and medical oximeter, from sea level to high altitude. Ten healthy subjects underwent five tests in normoxia and hypoxia (simulated altitudes from 3000 to 5500 m), consisting in a 5-min rest phase, followed by 5-min of mild exercise. Absolute error (±10 bpm for HR and ±3% for SpO, around criterion) and intraclass correlations (ICC) were calculated.

Validation of a Score for the Detection of Subjects with High Risk for Severe High-Altitude Illness.

Purpose: A decision tree based on a clinicophysiological score (severe high-altitude illness (SHAI) score) has been developed to detect subjects susceptible to SHAI. We aimed to validate this decision tree, to rationalize the prescription of acetazolamide (ACZ), and to specify the rule for a progressive acclimatization.

Methods: Data were obtained from 641 subjects in 15 European medical centers before and during a sojourn at high altitude.

Effectiveness of a therapeutic multiple-lifestyle intervention taking into account the periconceptional environment in the management of infertile couples: study design of a randomized controlled trial - the PEPCI study.

Background: Infertility is defined as the inability to conceive after 12 months of unprotected intercourse. It affects approximately one in six couples seeking pregnancy in France or western countries. Many lifestyle factors of the couples' pre and peri-conceptional environment (weight, diet, alcohol, tobacco, coffee, drugs, physical activity, stress, sleep…) have been identified as risk factors for infertility in both males and females.

Ventilatory Response to Hypoxia and Tolerance to High Altitude in Women: Influence of Menstrual Cycle, Oral Contraception, and Menopause.

Tolerance to high altitude in women might be influenced by hormonal status since female hormones modulate ventilation. Our objectives were (i) to explore in 1060 women, the influence of the phase of menstrual cycle, oral contraception, and menopause with or without hormonal treatment, on hypoxic ventilatory response at exercise (HVRe) and hypoxic cardiac response at exercise (HCRe) measured during a routine hypoxia exercise test, before an exposure to high altitude; (ii) to determine in 260 women exposed to high altitude, the influence of menopause and oral contraceptive and other drug use, on the prevalence of severe acute mountain sickness (sAMS). Four groups were defined: premenopausal with or without oral contraception and postmenopausal with or without hormonal treatment.

Low-frequency ventilatory oscillations in hypoxia are a major contributor to the low-frequency component of heart rate variability.

Purpose: Heart rate variability (HRV) may be influenced by several factors, such as environment (hypoxia, hyperoxia, hypercapnia) or physiological demand (exercise). In this retrospective study, we tested the hypothesis that inter-beat (RR) intervals in healthy subjects exercising under various environmental stresses exhibit oscillations at the same frequency than ventilatory oscillations.

Methods: Spectra from RR intervals and ventilation ([Formula: see text]E) were collected from 37 healthy young male subjects who participated in 5 previous studies focused on ventilatory oscillations (or periodic breathing) during exercise in hypoxia, hyperoxia and hypercapnia.

Daily life physical activity in patients with chronic stage IV sarcoidosis: A multicenter cohort study.

Background And Objectives: Little is known about the consequences of chronic sarcoidosis on daily life physical activity (DL). The aim of this prospective study was to measure DL in patients with chronic sarcoidosis and to determine its relationship to clinical and functional parameters.

Methods: Fifty-three patients with chronic sarcoidosis and 28 healthy control subjects were enrolled in this multicenter prospective study.

Effect of dead space on breathing stability at exercise in hypoxia.

Recent studies have shown that normal subjects exhibit periodic breathing when submitted to concomitant environmental (hypoxia) and physiological (exercise) stresses. A mathematical model including mass balance equations confirmed the short period of ventilatory oscillations and pointed out an important role of dead space in the genesis of these phenomena. Ten healthy subjects performed mild exercise on a cycloergometer in different conditions: rest/exercise, normoxia/hypoxia and no added dead space/added dead space (aDS).

Systemic blood pressure at exercise in hypoxia in hypertensive and normotensive patients.

Objectives: The current study aimed to determine whether acute hypoxia exposure in laboratory conditions associated with exercise induces an increase in systemic blood pressure (BP) in normotensive and hypertensive patients, and whether hypertensive patients are more prone to develop severe acute mountain sickness (sAMS). Finally, to determine if BP changes at exercise in acute hypoxia in hypertensive patients are predictive factors for sAMS.

Methods: From 2012 to 2015, 852 normotensive and 106 hypertensive patients went through an acute hypoxia exercise test before a sojourn at high altitude.

Ventilatory oscillations at exercise in hypoxia: A mathematical model.

We evaluated the mechanisms responsible for the instability of ventilation control system under simultaneous metabolic (exercise) and environmental (hypoxia) stresses, promoting the genesis of periodic breathing. A model following the main concepts of ventilatory control has been tested, including cardiovascular and respiratory parameters, characteristics of peripheral and central chemoreceptors, at mild exercise in hypoxia (FIO=0.145).

Ventilatory oscillations at exercise: effects of hyperoxia, hypercapnia, and acetazolamide.

Periodic breathing has been found in patients with heart failure and sleep apneas, and in healthy subjects in hypoxia, during sleep and wakefulness, at rest and, recently, at exercise. To unravel the cardiorespiratory parameters liable to modulate the amplitude and period of ventilatory oscillations, 26 healthy subjects were tested under physiological (exercise) and environmental (hypoxia, hyperoxia, hyperoxic hypercapnia) stresses, and under acetazolamide (ACZ) treatment. A fast Fourier transform spectral analysis of breath-by-breath ventilation (V˙E) evidenced an increase in V˙E peak power under hypercapnia (vs.

Aging, Tolerance to High Altitude, and Cardiorespiratory Response to Hypoxia.

Richalet, Jean-Paul, and François J. Lhuissier. Aging, tolerance to high altitude, and cardiorespiratory response to hypoxia.

Electrocardiographic changes during exercise in acute hypoxia and susceptibility to severe high-altitude illnesses.

Background: The goals of this study were to compare ECG at moderate exercise in normoxia and hypoxia at the same heart rate, to provide evidence of independent predictors of hypoxia-induced ECG changes, and to evaluate ECG risk factors of severe high-altitude illness.

Methods And Results: A total of 456 subjects performed a 20-minute hypoxia exercise test with continuous recording of ECG and physiological measurements before a sojourn above 4000 m. Hypoxia did not induce any conduction disorder, arrhythmias, or change in QRS axis.

Periodic breathing in healthy humans at exercise in hypoxia.

Periodic breathing is frequent in heart failure or ventilatory disorders during sleep, and common during sleep at high altitude, but has been rarely studied in wakefulness and during exercise. A retrospective analysis of ventilation from hypoxia exercise tests was realized in 82 healthy subjects separated into two groups with either high or low ventilatory response to hypoxia at exercise (HVRe). A fast Fourier transform spectral analysis of the breath-by-breath ventilation (V̇e) signal, O2 saturation, and end-tidal PCO2 evidenced a periodic pattern with a period of 11.

Ageing and cardiorespiratory response to hypoxia.

The risk of severe altitude-induced diseases is related to ventilatory and cardiac responses to hypoxia and is dependent on sex, age and exercise training status. However, it remains unclear how ageing modifies these physiological adaptations to hypoxia. We assessed the physiological responses to hypoxia with ageing through a cross-sectional 20 year study including 4675 subjects (2789 men, 1886 women; 14-85 years old) and a longitudinal study including 30 subjects explored at a mean 10.

Ventilatory and cardiac responses to hypoxia at submaximal exercise are independent of altitude and exercise intensity.

The hypoxic exercise test combining a 4,800-m simulated altitude and a cycloergometer exercise at 30% of normoxic maximal aerobic power (MAP) is used to evaluate the individual chemosensitivity to hypoxia in submaximal exercise conditions. This test allows the calculation of three main parameters: the decrease in arterial oxygen saturation induced by hypoxia at exercise (ΔSa(e)) and the ventilatory (HVR(e)) and cardiac (HCR(e)) responses to hypoxia at exercise. The aim of this study was to determine the influence of altitude and exercise intensity on the values of ΔSa(e), HVR(e), and HCR(e).