Guillaume Y Millet

Université Jean Monnet

Purpose: Despite interest in the possibility of females outperforming males in ultraendurance sporting events, little is known about the sex differences in fatigue during prolonged locomotor exercise. This study investigated possible sex differences in central and peripheral fatigue in the knee extensors and plantar flexors resulting from a 110-km...

Purpose: Sleep deprivation (SD) is characterized by reduced cognitive capabilities and endurance exercise performance and increased perceived exertion (RPE) during exercise. The combined effects of SD and exercise-induced changes in neuromuscular function and cognition are unknown. This study aimed to determine whether central fatigue is greater w...

To test the hypothesis that hypoxia centrally affects performance independently of afferent feedback and peripheral fatigue, we conducted two experiments under complete vascular occlusion of the exercising muscle under different systemic O(2) environmental conditions. In experiment 1, 12 subjects performed repeated submaximal isometric contractions...

While the industrialized world adopts a largely sedentary lifestyle, ultra-marathon running races have become increasingly popular in the last few years in many countries. The ability to run long distances is also considered to have played a role in human evolution. This makes the issue of ultra-long distance physiology important. In the ability to...

The use of electrical stimulation (ES) can contribute to our knowledge of how our neuromuscular system can adapt to physical stress or unloading. Although it has been recently challenged, the standard technique used to explore central modifications is the twitch interpolated method which consists in superimposing single twitches or high-frequency d...

Purpose: The effectiveness of a neuromuscular electrical stimulation (NMES) program has been shown to be proportional to the maximal evocable torque (MET), which is potentially influenced by pulse characteristics such as duration and frequency. The aim of this study was to compare MET between conventional and wide-pulse NMES at two different freque...

The purpose of the study was to assess sex‐related differences in resting mechanical properties and adaptations of skeletal muscles and tendons in response to trail running races of different distances using multi‐site shear wave elastography assessments of the lower limb, force capacity and blood analyses. Sex differences in resting mechanical pro...

Introduction: Performance fatigability is substantially greater when exercising in the severe versus heavy intensity domain. However, the relevance of the boundary between moderate and heavy intensity exercise, the gas exchange threshold (GET), to performance fatigability is unclear. This study compared alterations in neuromuscular function during...

The purpose of the study was to assess the influence of a preceding mountain ultramarathon on the impact between the foot and the ground and the resulting soft tissue vibrations (STV). Two sessions of measurements were performed on 52 trail runners, before and just after mountain trail running races of various distances (from 40 to 171 km). Triaxia...

The aim of this study was to investigate if acute impairments of the footwear midsole materials could interact with the modifications of the running patterns after a fatiguing trail running race. We hypothesized that introducing a control pair of shoes after the race, would modify running mechanics by partially correcting the alterations generated...

In recent years, there has been a significant expansion in female participation in endurance (road and trail) running. The often reported sex differences in maximal oxygen uptake (VO2max) are not the only differences between sexes during prolonged running. The aim of this narrative review was thus to discuss sex differences in running biomechanics,...

Objective: The aim of this study was to quantify fatigue and quality of life (QoL) in people self-reporting chronic venous disease (CVD) symptoms or at risk of CVD within a large cohort representative of the French population. The relationship between self-reported physical activity and both fatigue and QoL was also investigated. We hypothesized t...

Purpose: to investigate the time course and amplitude of performance fatigability during cycling at intensities around the maximal lactate steady state (MLSS) until task failure (TTF). Methods: 10 females and 11 males were evaluated in 8 visits: 1) ramp incremental test; 2-3) 30-min constant power output (PO) cycling for MLSS determination; 4-8)...

Introduction Cancer-related fatigue (CRF) is a debilitating symptom that affects around one-third of people for months or years after cancer treatment. In a recent study, we found that people with post-treatment CRF have greater performance fatigability. The aim of this secondary analysis was to examine the aetiology of performance fatigability in...

Prolonged stays in intensive care units (ICU) are responsible for long-lasting consequences, fatigue being one of the more debilitating. Yet, fatigue prevalence for patients that have experienced ICU stays remains poorly investigated. This study aimed to evaluate fatigue prevalence and the level of physical activity in ICU survivors from 6 months t...

Middle-aged and master endurance athletes exhibit similar physical performance and long-term muscle adaptation to aerobic exercise. Nevertheless, we hypothesized that the short-term plasticity of the skeletal muscle might be distinctly altered for master athletes when they are challenged by a single bout of prolonged moderate-intensity exercise. Si...

The repeated bout effect in eccentric-biased exercises is a well-known phenomenon, wherein a second bout of exercise results in attenuated strength loss and soreness compared to the first bout. We sought to determine if the repeated bout effect influences changes in lower-extremity biomechanics over the course of a 30-min downhill run. Eleven male...

Purpose: While the physiological determinants of road running have been widely studied, there is a lack of research in trail-running racing performance. The aim of our study was to determine the physiological predictors of trail-running performance in races of different distances in similar terrain and weather conditions. Methods: Seventy-five t...

Experiencing pain in one leg can alter exercise tolerance and neuromuscular fatigue (NMF) responses in the contralateral leg; however, the corticospinal modulations to non-local experimental pain induced by blood flow occlusion remain unknown. In three randomized visits, thirteen male participants performed 25% of isometric maximal voluntary contra...

Muscle oxygen uptake (V̇O2m) evaluated from changes in the near-infrared spectroscopy oxygen desaturation slope during a 5-s arterial blood flow occlusion has been proposed as an estimation of the actual V̇O2m. However, its correspondence with pulmonary oxygen uptake (V̇O2p) during exercise remains unknown. Purpose: to investigate the V̇O2m and V...

Introduction Running and cycling represent two of the most common forms of endurance exercise. However, a direct comparison of the neuromuscular consequences of these two modalities after prolonged exercise has never been made. The aim of this study was to compare the alterations in neuromuscular function induced by matched intensity and duration...

This note is to correct errata in the paper "Internal Tibial Forces and Moments During Graded Running" published in Journal of Biomechanical Engineering, Vol. 144, p. 011009 (2021), DOI: 10.1115/1.4051924. In the Data Analysis section, it was stated that, "The joint moments used in the optimization were the flexion-extension and abduction-adduction...

Aim If the development of the oxygen uptake slow component (V̇O2SC) and muscle fatigue are related, these variables should remain coupled in a time- and intensity-dependent manner. Methods Sixteen participants (7 females) visited the laboratory on seven separate occasions: 1) three 6-min moderate-intensity cycling exercise bouts proceeded by a ram...

Background Ground reaction forces (GRFs) are important for understanding human movement, but their measurement is generally limited to a laboratory environment. Previous studies have used neural networks to predict GRF waveforms during running from wearable device data, but these predictions are limited to the stance phase of level-ground running....

Physical activity is recommended for the management of cancer-related fatigue (CRF), yet the evidence is primarily based on interventions delivered during cancer treatment, with no eligibility criterion for fatigue. There is a need to examine the quantity and quality of the existing literature on physical activity for clinically-relevant CRF that c...

Background The Rating of Fatigue (ROF) scale can measure changes in perceived fatigue in a variety of contexts. Objective The aim of the present study was to translate and subsequently validate the ROF scale in the French language. Methods The study was composed of three phases. Phase 1 involved a comprehensive translation, back-translation, and...

Background: After anterior cruciate ligament reconstruction (ACLR), quadriceps strength must be maximized as early as possible. Objectives: We tested whether local vibration training (LVT) during the early post-ACLR period (i.e., ∼10 weeks) could improve strength recovery. Methods: This was a multicentric, open, parallel-group, randomized control...

The goal of this study was to analyze the effects of ground technicity on cardio-respiratory and biomechanical responses during uphill running. Ten experienced male trail-runners ran ∼ 10.5 min at racing pace on two trails with different (high and low) a priori technicity levels. These two runs were replicated (same slope, velocity, and distance) i...

Purpose Cancer-related fatigue (CRF) is a common and distressing symptom of cancer that may persist for years following treatment completion. However, little is known about the pathophysiology of CRF. Using a comprehensive group of gold-standard physiological and psychosocial assessments, this study aimed to identify correlates of CRF in a heteroge...

The etiology of changes in lower‐limb neuromuscular function, especially to the central nervous system, may be affected by exercise duration. Direct evidence is lacking as few studies have directly compared different race distances. This study aimed to investigate the etiology of deficits in neuromuscular function following short versus long trail‐...

Purpose: Fatigue has previously been investigated in trail running by comparing maximal isometric force before and after the race. Isometric contractions may not entirely reflect fatigue-induced changes, so that dynamic evaluation is warranted. The aim of the present study was to compare the magnitude of the decrement of maximal isometric force vs...

The stress experienced by the tibia has contributions from the forces and moments acting on the tibia. We sought to quantify the influence of running grade on internal tibial forces and moments. Seventeen participants ran at 3.33 m/s on an instrumented treadmill at 0°, ±5°, and ±10° while motion data were captured. Ankle joint contact force was est...

Neuromuscular electrical stimulation (NMES) applied to skeletal muscles is an effective rehabilitation and exercise training modality. However, the relatively low muscle force and rapid muscle fatigue induced by NMES limits the stimulus provided to the neuromuscular system, and subsequent adaptations. We hypothesise that adaptations to NMES will be...

Introduction: Females have been shown to experience less neuromuscular fatigue than males in knee extensors (KE) and less peripheral fatigue in plantar flexors (PF) following ultra-trail running, but it is unknown if these differences exist for shorter trail running races and whether this may impact running economy. The purpose of this study was t...

Purpose: This study utilized downhill running as a model to investigate the repeated bout effect (RBE) on neuromuscular performance, running biomechanics, and metabolic cost of running. Methods: Ten healthy recreational male runners performed two 30-min bouts of downhill running (DR1 and DR2) at -20% slope and 2.8 m/s 3 weeks apart. Neuromuscula...

Low-frequency and high-frequency wide-pulse neuromuscular electrical stimulation (NMES) can generate extra-torque (ET) via afferent pathways. Superimposing tendon vibration (TV) to NMES can increase the activation of these afferent pathways and favour ET generation. Knowledge of the characteristics of ET is essential to implement these stimulation...

Purpose The effect of trail running competitions on cost of running (Cr) remains unclear and no study has directly examined the effect of distances in similar conditions on Cr. Accordingly, the aims of this study were to (i) assess the effect of trail running races of 40–170 km on Cr and (ii) to assess whether the incline at which Cr is measured in...

Introduction Older adults with cancer suffer from the combined effects of ageing, cancer disease and treatment side effects. The main treatment for patients with haematological malignancies is chemotherapy, associated with significant toxicities. Chemotherapy can alter patients’ physical function and quality of life which are often already diminish...

Objective The purpose of the pilot MOVE-C study was to examine the effects of a 12-week high-intensity interval training (HIIT) plus lifestyle education program on quality of life (QoL), behavioural and psychosocial outcomes among inactive adults with coeliac disease. Design This study used a 3 (time: baseline, immediately post and three months po...

Ultra-endurance has been defined as any exercise bout that exceeds 6 h. A number of exceptional, record-breaking performances by female athletes in ultra-endurance sport has roused speculation that they might be predisposed to success in such events. Indeed, while the male-to-female performance gap in traditional endurance sport (e.g., marathon) re...

Neuromuscular fatigue (NMF) and exercise performance are affected by exercise intensity and sex differences. However, whether slight changes in power output (PO) below and above the maximal lactate steady-state (MLSS) impact NMF and subsequent performance (time to exhaustion, TTE) is unknown. Purpose: This study compared NMF and TTE in females an...

Introduction. Lower extremity chronic venous disease (CVD) is a common cause of lower extremity pain and discomfort in the adult population of Western countries. The typical self-reported symptoms of CVD are aching, cramping, fatigue, heaviness, restlessness, and swelling. Physical activity is often evoked as a non-pharmacological and non-surgical...

Purpose To provide a comprehensive review of studies that have investigated fatigue in intensive care unit (ICU) survivors and questions the potential link between intensive care unit-acquired weakness (ICUAW), fatigability and fatigue. We also question whether the central nervous system (CNS) may be the link between these entities. Material and m...

Around one third of intensive care unit (ICU) patients will develop severe neuromuscular alterations, known as intensive care unit-acquired weakness (ICUAW), during their stay. The diagnosis of ICUAW is difficult and often delayed as a result of sedation or delirium. Indeed, the clinical evaluation of both Medical Research Council score and maximal...

Cervicomedullary stimulation provides a means of assessing motoneuron excitability. Previous studies demonstrated that during low-intensity sustained contractions, small cervicomedullary evoked potentials (CMEPs) conditioned using transcranial magnetic stimulation (TMS-CMEPs) are reduced, whilst large TMS-CMEPs are less affected. Since small TMS-CM...

The aim of this study was to assess the history of exertional heat illness (EHI), heat preparation, cooling strategies, heat related symptoms, and hydration during an ultra-endurance running event in a warm and humid environment. This survey-based study was open to all people who participated in one of the three ultra-endurance races of the Grand R...

Cancer-related fatigue can continue long after curative cancer treatment. The aim of this study was to investigate sleep and rest–activity cycles in fatigued and non-fatigued cancer survivors. We hypothesized that sleep and rest–activity cycles would be more disturbed in people experiencing clinically-relevant fatigue, and that objective measures o...

BACKGROUND: Endurance running events are known to cause inflammation and result in increased cytokine production. However, the effects of ultramarathons on cytokine profiles are not well characterized. OBJECTIVE: The aim of this study was to describe and compare the effects of a trail (40 km) race and an ultra-trail (171 km) race on leukocyte conc...

New findings: What is the central question of this study? Are spinal and/or supraspinal perturbations implicated in central fatigue induced in the plantar flexor muscles following prolonged trail running races? What is the main finding and its importance? The study confirmed the presence of central fatigue following various trail running distances...

Understanding the immune responses elicited by SARS-CoV-2 infection is critical in terms of protection against reinfection and, thus, for public health policy and vaccine development for COVID-19. In this study, using either live SARS-CoV-2 particles or retroviruses pseudotyped with the SARS-CoV-2 S viral surface protein (Spike), we studied the neu...

We examined whether transcranial magnetic stimulation (TMS) delivered to the motor cortex allows assessment of muscle relaxation rates in unfatigued and fatigued knee extensors (KE). We assessed the ability of this technique to measure time course of fatigue-induced changes in muscle relaxation rate and compared relaxation rate from resting twitche...

PurposeTreatment of head and neck cancer (HNC) results in severe weight loss, mainly due to the loss of lean body mass. Consequently, decreases in muscular strength and health-related quality of life (HRQL) occur. This study investigated the feasibility of a 12-week novel strength training (NST) and conventional strength training (CST) intervention...

Fatigue‐related mechanisms induced by low‐intensity prolonged contraction in lower‐limb muscles are currently unknown. This study investigated central fatigue kinetics in the knee extensors during a low‐intensity sustained isometric contraction. Eleven subjects sustained a 10% maximal voluntary contraction (MVC) until task failure (TF) with neuromu...

Résumé Introduction L’objectif principal de notre étude a été de comparer les caractéristiques des finishers par rapport aux abandonneurs dans une population de coureurs d’Ultra-Trail proche des barrières horaires. Méthodes Il s’agissait d’une étude observationnelle, descriptive et comparative portant sur deux courses d’Ultra-Trail françaises mon...

Physical activity (PA) is recommended for the management of cancer-related fatigue (CRF), yet the evidence is primarily based on interventions delivered during cancer treatment, with no eligibility criterion for fatigue. The objective of this systematic review was to summarize and evaluate the effect of PA on CRF after cancer treatment (i.e. post-c...

The quadriceps-intermittent-fatigue (QIF) test assesses knee extensors strength, endurance and performance fatigability in isometric condition. We aimed to assess reliability and agreement for this test in dynamic conditions and with the use of transcranial magnetic stimulation. On two separate sessions, 20 young adults (25±4 yr, 10 women) performe...

Blood rheology is a key determinant of tissue perfusion at rest and during exercise. The present study investigated the effects of race distance on hematological, blood rheological and red blood cell (RBC) senescence parameters. Eleven runners participated in a 40 km race (MCC, elevation gain: 2,300 m) and 12 others in the Ultra-Trail du Mont Blanc...

PurposeLower limbs’ neuromuscular force capabilities can only be determined during single sprints if the test provides a good fit of the data in the torque-velocity (T–V) and power-velocity (P–V) relationships. This study compared the goodness of fit of single sprints performed against traditional (7.5% of the body mass) vs. optimal load (calculate...

INTRODUCTION: NMES-induced isometric contractions may arise from the direct activation of motor axons [i.e. efferent pathway; conventional (CONV) NMES] and/or from the recruitment of motoneurons in the spinal cord through the depolarization of sensory axons (i.e. afferent pathway) [1]. This “extra” contraction, the so-called “extra force (EF)” is f...