
Bengt KayserUniversity of Lausanne | UNIL · Institute of Sports Science
Bengt Kayser
MD, PhD, PhD
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360
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Publications
Publications (360)
Introduction. Impaired sleep is a global health concern. However, the environmental factors contributing to sleep impairment in urban settings are still not well understood.
Methodology. This study involved 179 participants from a Swiss municipality (Yverdon-les-Bains), where sleep quality and diurnal sleepiness were measured using validated questi...
Background
The SOPHYA-cohort-study investigated whether the objectively characterized and perceived residential neighborhood of Swiss youth predict accelerometer-measured physical activity and activity in specific domains (participation in a sports club and cycling) five years later.
Methods
At baseline in 2014, 1230 children and adolescents aged...
BACKGROUND: Maintaining physical activity throughout life is crucial for overall health and wellbeing. Yet the age-related decline in average physical activity, a natural phenomenon also observed in animals, poses a challenge. This study aimed to investigate whether participation in organised sports supported by the Swiss Youth+Sports (Y+S) program...
Objective
To assess the effectiveness of an exercise intervention, in addition to standard care, in preventing or delaying insulin prescription in women with gestational diabetes mellitus (GDM).
Design
Randomised controlled trial.
Setting
University hospital.
Population
Pregnant women at 25–35 weeks of gestation diagnosed with GDM.
Methods
Wome...
Purpose
Although the current social, environmental, and health-related challenges call for a reflection of the place of mobility in tomorrow’s world, modern societies continue to be shaped by decades of motorization. Most European countries, including Switzerland, have not yet overcome this dependence. Exploring these issues requires finding ways t...
During sea‐level exercise, blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) in humans without a patent foramen ovale (PFO) is negatively correlated with pulmonary pressure. Yet, it is unknown whether the superior exercise capacity of Tibetans well adapted to living at high altitude is the result of lower pulmonary pressure during...
Introduction
Quality of life (QoL) is an important health indicator among children and adolescents. Evidence on the effect of physical activity (PA)-related behaviors on QoL among youth remains inconsistent. Conventional accelerometer-derived PA metrics and guidelines with a focus on whole weeks may not adequately characterize QoL relevant PA behav...
Objective
The contribution of the mitochondrial electron transfer system to insulin secretion involves more than just energy provision. We identified a small RNA fragment (mt-tRF-LeuTAA) derived from the cleavage of a mitochondrially-encoded tRNA that is conserved between mice and humans. The role of mitochondrially-encoded tRNA-derived fragments r...
Mitochondrial respiration extends beyond ATP generation, with the organelle participating in many cellular and physiological processes. Parallel changes in components of the mitochondrial electron transfer system with respiration render it an appropriate hub for coordinating cellular adaption to changes in oxygen levels. How changes in respiration...
Athletes increasingly engage in repeated sprint training consisting in repeated short all‐out efforts interspersed by short recoveries. When performed in hypoxia (RSH), it may lead to greater training effects than in normoxia (RSN); however, the underlying molecular mechanisms remain unclear. This study aimed at elucidating the effects of RSH on sk...
Objectives: This study aims to quantify the cross-sectional and prospective associations between quality of life (QoL) and moderate-to-vigorous physical activity (MVPA). Methods: This study was based on the Swiss children's Objectively measured PHYsical Activity cohort. The primary endpoint is the overall QoL score and its six dimensions. The main...
Background
Decreased ryanodine receptor type 1 (RyR1) protein levels are a well‐described feature of recessive RYR1 ‐related myopathies. The aim of the present study was twofold: (1) to determine whether RyR1 content is also decreased in other myopathies and (2) to investigate the mechanisms by which decreased RyR1 protein triggers muscular disorde...
Objective: To evaluate the efficacy of an exercise intervention, in addition to usual care, to prevent or delay insulin prescription in women with gestational diabetes mellitus (GDM).
Design: Randomised controlled trial
Setting: University hospital
Population: Women at 25-35 weeks pregnancy upon diagnosis of GDM.
Methods: In the intervention arm, w...
Rational: To discuss the use of hormonal contraception (HC) in elite women's competitive sports from an anti-doping perspective because 1) it changes the natural female hormonal milieu; 2) is used to manipulate the menstrual cycle with performance enhancement intent; 3) even though lowering endogenous testosterone levels, some HCs contain testoster...
Introduction:
Acute altitude exposure lowers arterial oxygen content (CaO2) and cardiac output ( c) at peak exercise, whilst O2 extraction from blood to working muscles remains similar. Acclimatization normalizes CaO2 but not peak c nor peak oxygen consumption ( O2p). To what extent acclimatization impacts muscle O2 extraction remains unresolved....
Barclay, Holly, Saptarshi Mukerji, Bengt Kayser, and Jui-Lin Fan. Appetite, hypoxia and acute mountain sickness: A 10-hour normobaric hypoxic chamber study. High Alt Med Biol. 24:000-000, 2023. Background: The effects of hypoxia and acute mountain sickness (AMS) on appetite and food preferences are moot, especially during the early phase of hypoxic...
Introduction
Neuromuscular electrical stimulation (NMES) is used in athletes to enhance muscle strength (Filipovic et al., 2012) or in patients to restore muscle strength (Nussbaum et al., 2017). The increased maximal voluntary contraction (MVC) torque of one limb (e.g. right leg) while transcutaneous NMES is concomitantly applied to the contralat...
Decreased ryanodine receptor type 1 (RyR1) protein is a hallmark of recessive RYR1-related myopathies (RyR1-RM), which are caused by recessive mutations in the RYR1 gene. It is not clear how the decrease in the RyR1 protein triggers muscular disorders. Furthermore, it is a hot topic whether a decrease in RyR1 protein levels can also occur during no...
Hypoxia is a condition of oxygen levels below normoxia and opposite to hyperoxia. We here define the normoxic reference state by three complementary precepts: (A) ambient normoxia at sea level in the contemporary atmosphere and corresponding dissolved O2 concentrations at air saturation of aqueous environments; (B) biological compartmental O2 level...
Background:
Objective mobility goals for elderly hospitalised medical patients remain debated. We therefore studied steps parameters of elderly patients hospitalised for an acute illness, to determine goals for future interventional trials and medical practice.
Methods:
Observational study conducted from February to November 2018 in a medical wa...
Baroreflex sensitivity (BRS) is a measure of cardiovagal baroreflex and is lower in normobaric and hypobaric hypoxia compared to normobaric normoxia. The aim of this study was to assess the effects of hypobaria on BRS in normoxia and hypoxia. Continuous blood pressure and ventilation were recorded in eighteen seated participants in normobaric normo...
External expiratory flow limitation (EFLe) can be applied in healthy subjects to mimic the effects of chronic obstructive pulmonary disease during exercise. At maximal exercise intensity, EFLe leads to exercise intolerance owing to respiratory pump dysfunction limiting venous return. We quantified blood shifts between body compartments to determine...
Contralateral facilitation, i.e., the increase in contralateral maximal voluntary strength that is observed when neuromuscular electrical stimulation (NMES) is applied to the ipsilateral homonymous muscle, has previously been reported for the knee extensors but the neurophysiological mechanisms remain to be investigated. The aim of this study was t...
Introduction: A lack of knowledge among laypersons about the hazards of high-altitude exposure contributes to morbidity and mortality from acute mountain sickness (AMS), high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE) among high-altitude travelers. There are guidelines regarding the recognition, prevention, and treatme...
Objective: To evaluate the efficacy of an exercise intervention, in addition to usual care, to prevent or delay insulin prescription in women with gestational diabetes mellitus (GDM). Design: Randomised controlled trial Setting: University hospital Population: Women at 25-35 weeks pregnancy upon diagnosis of GDM. Methods: In the intervention arm, w...
Background
Prehabilitation may improve postoperative clinical outcomes among patients undergoing major abdominal surgery. This study evaluated the potential effects of a high-intensity interval training (HIIT) program performed before major abdominal surgery on patients’ cardiorespiratory fitness and functional ability (secondary outcomes of pilot...
Organized biannually in the Swiss Alps since 1984, the “Patrouille des Glaciers” (PDG) is one of the most challenging long-distance ski mountaineering (skimo) team competitions in the world. The race begins in Zermatt (1,616 m) and ends in Verbier (1,520 m), covering a total distance of 53 km with a cumulated 4,386 m of ascent and 4,482 m of descen...
Oxygen uptake (V'O 2 ) at exercise onset is determined in part by acceleration of pulmonary blood flow (Q'p). Impairments in the Q'p response can decrease exercise tolerance. Prior research has shown that voluntary respiratory maneuvers can augment venous return, but the corollary impacts on cardiac function, Q'p and early-exercise V'O 2 remain unc...
Sustained ryanodine receptor (RyR) Ca 2+ leak is associated with pathological conditions such as heart failure or skeletal muscle weakness. We report that a single session of sprint interval training (SIT), but not of moderate intensity continuous training (MICT), triggers RyR1 protein oxidation and nitrosylation leading to calstabin1 dissociation...
Objective
To assess the feasibility of a prehabilitation program and its effects on physical performance and outcomes after major abdominal surgery.
Methods
In this prospective pilot study, patients underwent prehabilitation involving three training sessions per week for 3 weeks preoperatively. The feasibility of delivering the intervention was as...
BACKGROUND: The COVID-19 pandemic and the resulting containment measures had and still have a profound impact on everyday life. Both the fear of infection and the imposed restrictions can have biopsychosocial consequences. The aim of the present study was to analyze whether there is a difference in the health-related quality of life (HRQoL) of prim...
We investigated how nonpain-based exercise therapy intensity (light-to-moderate or vigorous) affects improvements in walking performance and cardiorespiratory fitness of patients with symptomatic lower-extremity peripheral artery disease (PAD). We searched the Embase, MEDLINE, Cochrane, Web of Science, and Google Scholar databases up to April 2021...
Background:
The influence of regular breath-hold training on hematological variables is not fully understood. We monitored hematological variables in breath-hold divers' (BHDs) and active controls over a year expecting both breath-hold training and seasonal effects.
Methods:
In 11 recreational BHDs (36 ± 9 yrs, 177 ± 8 cm, 72 ± 9 kg) and 12 acti...
The Wim Hof breathing method (WHBM) combines periods of hyperventilation (HV) followed by voluntary breath-holds (BH) at low lung volume. It has been increasingly adopted by coaches and their athletes to improve performance, but there was no published research on its effects. We determined the feasibility of implementing a single WHBM session befor...
The creation of WADA contributed to harmonization of anti‐doping and changed doping behavior and prevalence in the past 22 years. However, the system has developed important deficiencies and limitations that are causing harm to sports, athletes and society. These issues are related to the lack of evidence for most substances on the Prohibited List...
Objectives: We tested the hypotheses that respiratory muscle endurance training (RMET) improves endurance cycling performance differently in women and men and more so in hypoxia than in normoxia.
Design: A prospective pre–post cross-over study with two testing conditions.
Methods: Healthy and active women (seven, 24 ± 4 years, mean ± standard devia...
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...
Objective
Prehabilitation programs claim to improve exercise capacity and postoperative outcomes. The study aim was to assess the feasibility of a prehabilitation program and its effects on fitness and clinical outcomes after major abdominal surgery.
Methods
In this prospective pilot study, patients were assigned to high-intensity physical exercis...
The effectiveness of neuromuscular electrical stimulation (NMES) for rehabilitation is proportional to the evoked torque. The progressive increase in torque (extra torque) that may develop in response to low intensity wide-pulse high-frequency (WPHF) NMES holds great promise for rehabilitation as it overcomes the main limitation of NMES, namely dis...
The hematological module of the Athlete Biological Passport (ABP) is used in elite sport for antidoping purposes. Its aim is to better target athletes for testing and to indirectly detect blood doping. The ABP allows to monitor hematological variations in athletes using selected primary blood biomarkers [hemoglobin concentration (Hb) and reticulocy...
The Tibetans’ better aerobic exercise capacity at altitude remains ill-understood. We tested the hypothesis that Tibetans display better muscle and brain tissue oxygenation during exercise in hypoxia. Using near-infrared spectrometry (NIRS) to provide indices of tissue oxygenation, we measured oxy- and deoxy-hemoglobin ([O2Hb] and [HHb], respective...
Despite a wealth of sport nutrition guidelines for adult athletes, there are currently no nutrition guidelines for youth winter sports athletes. Whilst it may be pragmatic to apply nutrition guidelines for adult athletes to youth winter sports athletes, it is inappropriate. Due to a paucity of research on youth athletes, it is impossible to provide...
Because of the enduring rise in the prevalence of obesity worldwide, there is continued interest in hypoxia as a mechanism underlying the pathophysiology of obesity and its comorbidities and as a potential therapeutic adjunct for the management of the disease. Lifelong exposure to altitude is accompanied by a lower risk for obesity, whereas altitud...
New findings:
What is the central question of this study? The initial increase in oxygen uptake (
V
̇
O
2
) at exercise onset results from pulmonary perfusion changes secondary to an increased venous return. Breathing mechanics contribute to venous return through abdominal and intrathoracic pressures variation. Can voluntary breathing techniqu...
Background:
Lack of physical activity (PA) is the fourth risk factor for all-cause mortality. Regular PA reduces noncommunicable disease (NCD) and mortality risk. The built environment (BE) is a determinant of spontaneous daily PA. Professionals who plan and build the BE therefore affect public health. We tested the hypothesis of a lack of formal...
New findings:
What is the central question of this study? The pathophysiology of acute mountain sickness (AMS), involving the respiratory, renal and cerebrovascular systems, remains poorly understood. How do the early adaptations in these systems during a simulated altitude of 5000 m relate to AMS risk? What is the main finding and its importance?...
The hematological module of the Athlete Biological Passport (ABP) is used in elite sport for antidoping purposes. Its aim is to better target athletes for testing and to indirectly detect blood doping. The ABP allows to monitor hematological variations in athletes using selected primary blood biomarkers (hemoglobin concentration ([Hb] and reticuloc...
Rationale:
Preoperative poor physical fitness and respiratory muscle weakness are associated with postoperative pulmonary complications that result in prolonged hospital length of stay and increased mortality.
Objectives:
Examine the effect of preoperative exercise training on the risk of postoperative pulmonary complications across different su...
Sprint interval training (SIT) has emerged as a time-efficient training regimen for young individuals. Here, we studied whether SIT is effective also in elderly individuals and whether the training response was affected by treatment with the antioxidants vitamin C and E. Recreationally active elderly (mean age 65) men received either vitamin C (1 g...
Prolonged measurement of total body volume variations (deltaVb) with whole-body, flow-based plethysmography (WBP) results in a drift of the signal due to changes in temperature and humidity inside the plethysmograph and to numerical integration of the flow to obtain deltaVb. This drift has been previously corrected with the application of a wavelet...
One of the claims sometimes advanced in favour of anti-doping is that allowing doping would lead to a uniform increase in performance in comparison to no doping. The idea is that if all athletes would use doping, this would just shift the playing field to a higher level without a change in ranking, but at a higher health cost. In this paper, we cri...
Purpose
The present study aimed to determine whether whole-body fat oxidation and muscle deoxygenation kinetics parameters during exercise were related in individuals with different aerobic fitness levels.
Methods
Eleven cyclists [peak oxygen uptake (V.O2peak): 64.9 ± 3.9 mL⋅kg–1⋅min–1] and 11 active individuals (V.O2peak: 49.1 ± 7.4 mL⋅kg...
Purpose: The present study aimed to determine whether whole-body fat oxidation and muscle deoxygenation kinetics parameters during exercise were related in individuals with different aerobic fitness levels. Methods: Eleven cyclists [peak oxygen uptake (VO 2peak): 64.9 ± 3.9 mL·kg −1 ·min −1 ] and 11 active individuals (VO 2peak : 49.1 ± 7.4 mL·kg −...
The placebo effect is a biological response to psychosocial environmental cues surrounding the use of inert or active substances or methods. Placebo effects can be exploited for performance enhancement purposes and their use is not forbidden in sport. WADA's Code stipulates that at least two out of three criteria must be met to put something on the...
Introduction
Baroreflex sensitivity (BRS) is essential to ensure rapid adjustment to variations in blood pressure (BP). Spontaneous baroreflex function can be assessed using continuous recordings of blood pressure. The goal of this study was to compare four methods for BRS quantification [the sequence, Bernardi’s (BER), frequency and transfer funct...
Purpose
Mechanisms underlying the efficacy of sprint interval training (SIT) remain to be understood. We previously reported that an acute bout of SIT disrupts the integrity of the sarcoplasmic reticulum (SR) Ca²⁺ release channel, the ryanodine receptor 1 (RyR1), in recreationally active human subjects. We here hypothesize that in addition to impro...
Background:
The outcome of surgery in deconditioned patients can be improved through prehabilitation. This study examined the effect of prehabilitation in patients diagnosed with lung cancer.
Methods:
Candidates for lung cancer resection were assigned to high-intensity interval training (n = 74) or usual care (n = 77). Cardiopulmonary exercise t...
Background:
The associations among cortisol levels, body water status, and acute mountain sickness (AMS) remain unclear. We investigated associations between AMS prevalence and severity with resting saliva cortisol levels at low altitude (LA) and high altitude (HA) and with fluid balance during a HA stay.
Methods:
Twenty-two physically fit and hea...
Background:
Mechanisms underlying acute mountain sickness (AMS) remain unclear. Corticosteroids are effective for prevention and treatment suggesting a role for deficient endogenous cortisol. The cortisol awakening response (CAR), the increase in cortisol secretion over the first 30-45 minutes after morning awakening, better reflects the hypothalam...
Short chapter on the future of sport
Purpose
No studies have evaluated the potential benefits of wide-pulse high-frequency (WPHF) neuromuscular electrical stimulation (NMES) despite it being an interesting alternative to conventional NMES. Hence, this study evaluated neuromuscular adaptations induced by 3 weeks of WPHF NMES.
Methods
Ten young healthy individuals (training group) comp...