Gregoire P Millet

Gregoire P Millet
University of Lausanne | UNIL ·  Institut des sciences du sport

Professor
Investigating the benefits, risks and limitations of hypoxia conditioning for everyone (from patients to athletes).

About

635
Publications
452,725
Reads
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14,539
Citations
Introduction
Translational approach (molecular to systemic responses - animals & humans - mechanistic to clinical) on effects of hypoxia on muscular, vascular and cerebral functions in athletes & patients obese, PAD, hypertensive, elderly. Effect of hypobaria. ... Optimization of interval-training. VO2 kinetics, Assessment of fatigue (NM, HRV, PPG). Ultra-endurance. Ex pro triathlete (French champion; 4th Europe Ch) and elite coach (many World Ch & Olympic games) Proud of my loving family
Additional affiliations
August 2012 - January 2015
University of Lausanne
Position
  • Managing Director
August 2010 - present
University of Lausanne
Position
  • Professor
July 2010 - November 2016
University of Lausanne
Position
  • Professor

Publications

Publications (635)
Article
Significance: Oxygen is indispensable for aerobic life but its utilization exposes cells and tissues to oxidative stress; thus, tight regulation of cellular, tissue and systemic oxygen concentrations is crucial. Here, we review the current understanding of how the human organism (mal-)adapts to low (hypoxia) and high (hyperoxia) oxygen levels and...
Article
Hypoxia is caused by insufficient oxygen availability for the organism leading to reduced oxygen delivery to tissues and cells. It has been regarded as a severe threat to human health and it is indeed implicated in pathophysiological mechanisms involved in the development and progression of many diseases. Nevertheless, the potential of controlled h...
Article
Adequate oxygen supply is essential for the human brain to meet its high energy demands. Therefore, elaborate molecular and systemic mechanism are in place to enable adaptation to low oxygen availability. Anxiety and depressive disorders are characterized by alterations in brain oxygen metabolism and of its components, such as mitochondria or hypox...
Article
Objective: Heart rate variability (HRV) is commonly used to diagnose overreaching and monitor athletes’ responses to training. Baroreflex sensitivity (BRS) is modified by changes in training load and might be another means to detect overreaching. The goal of this study was to assess BRS and HRV changes in two groups of athletes responding either ne...
Article
Full-text available
Purpose: To investigate differences in athletes' knowledge, beliefs, and training practices during COVID-19 lockdowns with reference to sport classification and sex. This work extends an initial descriptive evaluation focusing on athlete classification. Methods: Athletes (12,526; 66% male; 142 countries) completed an online survey (May-July 2020...
Article
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The aim of this research was to investigate the role of trait emotional intelligence (EI) in recovery stress states in a mountain ultra-marathon (MUM) race. Recovery stress states of 13 finishers were assessed before, during, and immediately after the end of an extreme MUM, whereas emotional intelligence was assessed 2 days before the MUM race. Tem...
Article
Traditional guidelines state that substantial muscle development requires training at least 70% of the one-repetition maximum (1RM) load. However, recent evidence has proven that low load training (20-40 % 1RM) combined with moderate blood flow restriction (BFR) can also lead to improvements in muscle mass and strength. While BFR has primarily been...
Article
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Regular exercise confers multifaceted and well-established health benefits. Yet, transient and asymptomatic increases in markers of cardio-renal injury are commonly observed in ultra-endurance athletes during and after competition. This has raised concerns that chronic recurring insults could cause long-term cardiac and/or renal damage. Indeed, ext...
Article
Full-text available
Purpose: To investigate differences in athletes' knowledge, beliefs, and training practices during COVID-19 lockdowns with reference to sport classification and sex. This work extends an initial descriptive evaluation focusing on athlete classification. Methods: Athletes (12,526; 66% male; 142 countries) completed an online survey (May-July 2020) a...
Article
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Introduction: The determination of the optimal occlusion level is a key parameter in blood flow restriction (BFR). This study aimed to compare the effects of elastic (BStrong) vs. nylon (Hokanson) BFR cuffs on blood flow in the lower and upper limbs. Methods: Eleven healthy participants undertook several BFR sessions with 2 different cuffs of simil...
Article
Purpose: The aim of the present study was to assess left ventricular (LV) morphological and regional functional adaptations in backs and forwards elite rugby union (RU) players. Methods: Thirty-nine elite male RU players and twenty sedentary controls have been examined using resting echocardiography. RU players were divided into two groups, forw...
Article
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Preterm birth (before 37 weeks gestation) accounts for ~10% of births worldwide and remains one of the leading causes of death in children under 5 years of age. Preterm born adults have been consistently shown to be at an increased risk for chronic disorders including cardiovascular, endocrine/metabolic, respiratory, renal, neurologic, and psychiat...
Article
The determinants of success in Olympic Games competition are specific to the athletic demands of the sporting event. A global evaluation to quantify the athletic demands across the spectrum of the Olympic Games sport events has not previously been conducted. Thus far, the interpretation and the comparison of sport physiological characteristics with...
Article
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The pre-term birth survival rate has increased considerably in recent decades, and research investigating the long-term effects of premature birth is growing. Moreover, altitude sojourns are increasing in popularity and are often accompanied by various levels of physical activity. Individuals born pre-term appear to exhibit altered acute ventilator...
Article
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Easy-to-use and accurate heart rate variability (HRV) assessments are essential in athletes’ follow-up, but artifacts may lead to erroneous analysis. Artifact detection and correction are the purpose of extensive literature and implemented in dedicated analysis programs. However, the effects of number and/or magnitude of artifacts on various time-...
Article
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Whereas the negative effects of aging and smoking on pulmonary function are undisputed, the potential favorable effects of physical activity on the aging process of the otherwise healthy lung remain controversial. This question is of particular clinical relevance when reduced pulmonary function compromises aerobic exercise capacity (maximal oxygen...
Article
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Purpose Repeated sprint ability is an integral component of team sports. This study aimed to evaluate fatigability development and its aetiology during and immediately after a cycle repeated sprint exercise performed until a given fatigability threshold. Methods On an innovative cycle ergometer, 16 healthy males completed an RSE (10-s sprint/28-s...
Article
This study aimed to investigate the impact of an extreme mountain ultramarathon (MUM) on spontaneous electrical brain activity in a group of 16 finishers. By using 4-minute high-density electroencephalographic (EEG) recordings with eyes closed before and after a 330-km race (mean duration: 125±17 hours; sleep duration: 7.7±2.9 hours), spectral powe...
Article
Mitochondrial health is based on a delicate balance of specific mitochondrial functions (e.g. metabolism, signaling, dynamics) that are impaired in neurodegenerative diseases. Rescuing mitochondrial function by selectively targeting mitochondrial stressors, such as reactive oxygen species, inflammation or proteotoxic insults (“bottom-up” approaches...
Article
Purpose: To describe the effects of travel distance and bio-meteorological conditions on the 2020 multi-hosting UEFA European Championship's match outcomes and progress in competition. Methods: Teams' basecamps, distance from match venues, match outcomes (defeat, draw and win), bio-meteorological data (ambient air temperature, relative humidity...
Article
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Objectives: Explore training-related knowledge, beliefs and practices of athletes and the influence of COVID-19-related lockdowns. Methods: Athletes [n = 12,526 classified: world-class (13%), international (21%), national (36%), state (24%), and recreational (6%)] completed an online survey (50 d; 17th May to 5th July 2020) exploring their trainin...
Article
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Objectives The effects of ultra-distance on cardiac remodeling and fibrosis are unclear. Moreover, there are no data reporting the kinetics of cardiac alterations throughout the event and during recovery. Our aim was to investigate the kinetics of biological markers including new cardiac fibrosis biomarkers suppression of tumorigenicity 2 (ST2) and...
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Introduction Training intensity and nutrition may influence adaptations to training performed in hypoxia and consequently performance outcomes at altitude. This study investigates if performance at simulated altitude is improved to a larger extent when high-intensity interval training is performed in normobaric hypoxia and if this is potentiated wh...
Article
This study aimed to assess the effects of an off-season period of repeated-sprint training in hypoxia induced by voluntary hypoventilation at low lung volume (RSH-VHL) on off-ice re-peated-sprint ability (RSA) in ice hockey players. Thirty-five high-level youth ice hockey players completed 10 sessions of running repeated sprints over a 5-week peri...
Article
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Neuropeptide Y 1–36 (NPY1–36) is a vasoconstrictor peptide co-secreted with norepinephrine (NE) by nerve endings during sympathetic activation. NPY1–36 potentiates NE action post-synaptically through the stimulation of the Y1 receptor, whereas its metabolite NPY3–36 resulting from DPP4 action activates Y2 presynaptic receptors, inhibiting NE and ac...
Article
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Purpose Main purposes of pre-acclimatization by hypoxia conditioning (HC) are the prevention of high-altitude illnesses and maintenance of aerobic exercise performance. However, robust evidence for those effects or evidence-based guidelines for exposure strategies, including recommendations to ensure safety, are largely lacking. Therefore, we summa...
Article
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Pre-term birth is associated with numerous cardio-respiratory sequelae in children. Whether these impairments impact the responses to exercise in normoxia or hypoxia remains to be established. Fourteen prematurely-born (PREM) (Mean ± SD; gestational age 29 ± 2 weeks; age 9.5 ± 0.3 years), and 15 full-term children (CONT) (gestational age 39 ± 1 wee...
Article
Traveling to high altitude destinations is associated with risks like high altitude sicknesses and impaired sleep and performance. Although antioxidant supplementation may be beneficial, conflicting study results impede clear clinical guidelines. Herein we highlight the potential of the antioxidant compound melatonin that is surprisingly poorly inv...
Article
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Hypoxia is an essential topic in medical or biological sciences. The main aims of the present study were to examine the most important medical articles (i.e., the top 100 most cited) on hypoxia. We examine how the Nobel-prize awarded hypoxia inducible factor (HIF)-pathway discovery in the early 1990s has changed the thematic composition of this bod...
Preprint
Objective: Continuous monitoring of biosignals via wearable sensors has quickly expanded in the medical and wellness fields. At rest, automatic detection of vital parameters is generally accurate. However, in conditions such as high-intensity exercise, sudden physiological changes occur to the signals, compromising the robustness of standard algori...
Article
We aimed to gauge the interstitial lung water accumulation following moderate-intensity exercise under normobaric and hypobaric hypoxic conditions in a group of preterm born but otherwise healthy young adults. Sixteen pre-term-born individuals (age = 21±2yrs.; gestational age = 29±3wk.; birth weight = 1160±273 g) underwent two 8 -h hypoxic/altitud...
Article
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Purpose: This study aimed to investigate the differences between normobaric (NH) and hypobaric hypoxia (HH) on supine heart rate variability (HRV) during a 24-h exposure. We hypothesized a greater decrease in parasympathetic-related parameters in HH than in NH. Methods: A pooling of original data from forty-one healthy lowland trained men was analy...
Article
Background: This study investigated the resting ventilatory response to hypercapnia in prematurely born adults. Materials and Methods: Seventeen preterm and fourteen full-term adults were exposed to normoxic hypercapnia (two 5-minute periods at 3% and 6% carbon dioxide [CO2] interspersed by 5-minute in normoxia). Pulmonary ventilation (VE) and end-...
Conference Paper
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Background The formation of cardiac fibroid deposits due to intense exercise may be involved in cardiac arrhythmias. Galectin-3 (Gal-3) and suppression of tumorogenicity2 (ST2) are considered as markers for fibrosis development and cardiac remodeling. Objective The aim of our study was to examine the evolution of both in trailers who ran the Tor d...
Article
To the Editor We read with great interest the Original Investigation recently published in this journal by Dr Ried-Larsen and colleagues.¹ The authors reported decreased mortality from all causes and from cardiovascular diseases associated with cycling in adults with diabetes. The large sample size and the robust analyses are strengths of the study...
Article
Purpose: The authors compared the effects of active preconditioning with local and systemic hypoxia during submaximal cycling. Methods: On separate visits, 14 active participants completed 4 trials. Each visit was composed of 1 preconditioning phase followed, after 40 minutes of rest, by 3 × 6-minute cycling bouts (intensity = 85% of critical po...
Article
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Introduction - The body of scientific literature on sports and exercise continues to expand. The summer and winter Olympic games will be held over a 7-month period in 2021–2022. Objectives - We took this rare opportunity to quantify and analyse the main bibliometric parameters (i.e., the number of articles and citations) across all Olympic sports t...
Article
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Huntington’s disease (HD) is a rare hereditary neurodegenerative disorder characterized by multiple metabolic dysfunctions including defects in mitochondrial homeostasis and functions. Although we have recently reported age-related changes in the respiratory capacities in different brain areas in HD mice, the precise mechanisms of how mitochondria...
Article
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Background. Weak muscle strength has been associated with a wide range of adverse health outcomes. Yet, whether individuals with weaker muscle strength are more at risk for hospitalization due to severe COVID-19 is still unclear. The objective of this study was to investigate the independent association between muscle strength and COVID-19 hospital...
Article
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PurposeTo test the hypothesis that interval-training (IHT) would be impaired by hypoxia to a larger extent than repeated-sprint training (RSH) and that dietary nitrate (NO3−) would mitigate the detrimental effect of hypoxia to a larger extent during IHT than RSH.Methods Thirty endurance-trained male participants performed IHT (6 × 1 min at 90%∆ wit...
Article
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Background: Living at moderate altitude may be associated with health benefits, including reduced mortality from male colorectal and female breast cancer. We aimed to determine altitude-dependent incidence and mortality rates of those cancers and put them in the context of altitude-associated lifestyle differences. Methods: Incidence cases and d...
Article
Living at moderate altitude (up to about 2,000 m) was shown to be associated with distinct health benefits, including lower mortality from cardiovascular diseases and certain cancers. However, it remains unclear, whether those benefits are mainly due to environmental conditions (e.g., hypoxia, temperature, solar ultra-violet radiation) or differenc...
Article
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Recent advances in wearable technologies integrating multi-modal sensors have enabled the in-field monitoring of several physiological metrics. In sport applications, wearable devices have been widely used to improve performance while minimizing the risk of injuries and illness. The objective of this project is to estimate breathing rate (BR) from...
Article
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Physical activity has been proposed as a protective factor for COVID-19 hospitalization. However, the mechanisms underlying this association are unclear. We examined the association between physical activity and COVID-19 hospitalization and whether this relationship was explained by other risk factors (chronic conditions, weak muscle strength). We...
Article
The absolute reliance of the mammalian brain on oxygen to generate ATP renders it acutely vulnerable to hypoxia, whether at high altitude or in clinical settings of anemia or pulmonary disease. Hypoxia is pivotal to the pathogeneses of myriad neurological disorders, including Alzheimer’s, Parkinson’s and other age-related neurodegenerative diseases...
Article
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Mitochondria are central regulators of cellular metabolism, most known for their role in energy production. They can be “enhanced” by physical activity (including exercise), which increases their integrity, efficiency and dynamic adaptation to stressors, in short “mitochondrial fitness”. Mitochondrial fitness is closely associated with cardiorespir...
Article
Alpha-synuclein aggregation and mitochondrial dysfunction are main pathological hallmarks of Parkinson's disease (PD) and several other neurodegenerative diseases, collectively known as synucleinopathies. However, increasing evidence suggests that they may not be sufficient to cause PD. Here we propose the role of hypoxia as a missing link that con...
Article
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The purpose of this study was to investigate the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on the skeletal muscle in Apolipoprotein E knockout (ApoE KO) and wild-type (WT) C57BL/6J mice. ApoE KO mice fed with a high-fat diet were randomly allocated into: Control group without exercise (ApoE...
Article
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Regular exercise is associated with pronounced health benefits. The molecular processes involved in physiological adaptations to exercise are best understood in skeletal muscle. Enhanced mitochondrial functions in muscle are central to exercise-induced adaptations. However, regular exercise also benefits the brain and is a major protective factor a...
Article
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Globally, about 400 million people reside at terrestrial altitudes above 1500 m, and more than 100 million lowlanders visit mountainous areas above 2500 m annually. The interactions between the low barometric pressure and partial pressure of O 2 , climate, individual genetic, lifestyle and socioeconomic factors, as well as adaptation and acclima-ti...
Article
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The aim of this study was first to determine if level, uphill and downhill running energy cost (ECR) values were correlated at different slopes and for different running speeds; and second to determine the influence of lower limb strength on ECR. Twenty-nine healthy subjects completed a randomized series of 4-min running bouts on an instrumented tr...
Article
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Objectives: The effects of altitude residence on ageing, longevity and mortality are poorly understood. While adaptations to chronic exposure to altitude may exert beneficial effects on cardiovascular risk factors and some types of cancer, an elevated risk to die from chronic respiratory diseases has been reported. Moreover, high-altitude residenc...
Article
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Aim The optimal exercise intensity to improve endothelial function remains unclear, as well as whether the addition of hypoxia could potentiate this function. Therefore, the aim of this study was to compare the effects of different exercise intensities in normoxia and hypoxia on vascular reactivity and nitric oxide (NO) bioavailability in mice. Me...
Article
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Like in other neurodegenerative diseases, protein aggregation, mitochondrial dysfunction, oxidative stress and neuroinflammation are hallmarks of Parkinson’s disease (PD). Differentiating characteristics of PD include the central role of α-synuclein in the aggregation pathology, a distinct vulnerability of the striato-nigral system with the related...
Article
Marathon running involves complex mechanisms that cannot be measured with objective metrics or laboratory equipment. The emergence of wearable sensors introduced new opportunities , allowing the continuous recording of relevant parameters. The present study aimed to assess the evolution of stride-by-stride spatio-temporal parameters, stiffness, and...
Article
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Introduction Sleep deprivation has deleterious effects on cardiovascular health. Using wearable health trackers, non-invasive physiological signals, such as heart rate variability (HRV), photoplethysmography (PPG), and baroreflex sensitivity (BRS) can be analyzed for detection of the effects of partial sleep deprivation on cardiovascular responses....