Jan G Bourgois

Ghent University | UGhent · Department of Movement and Sports Sciences

Purpose : To gather information on practices and perceptions of high-performance experts regarding their athletes’ muscle fiber-type composition (MFTC) and its estimation. Methods : A questionnaire on the noninvasive versus invasive estimation of MFTC was completed by 446 experts including coaches and sport-science/sports-medicine staff. Moreover,...

Purpose Apnea duration is dependent on three factors: oxygen storage, oxygen consumption, hypoxia and hypercapnia tolerance. While current literature focuses on maximal apneas to improve apnea duration, apnea trained individuals use timed-repeated submaximal apneas, called “O2 and CO2 tables”. These tables claim to accommodate the body to cope with...

Acute breath‐holding (apnoea) induces a spleen contraction leading to a transient increase in haemoglobin concentration. Additionally, the apnoea‐induced hypoxia has been shown to lead to an increase in erythropoietin concentration up to 5 h after acute breath‐holding, suggesting long‐term haemoglobin enhancement. Given its potential to improve hae...

Purpose The aim of this study was to characterize W' recovery kinetics in response to a partial W' depletion. We hypothesized that W' recovery following partial depletion would be better described by a biexponential than by a monoexponential model. Methods Nine healthy men performed a ramp incremental exercise test, three to five constant load tri...

Purpose: The goal of this study was to investigate to what extent acute heat exposure would affect the parameters of the power-duration relationship, i.e. CP and W', using multiple constant workload tests to exhaustion, in women and men. Methods: 24 young physically active participants (12 men, 12 women) performed 3 to 5 constant load tests to d...

PurposeThe aim of this study was to compare critical power (CP) and work capacity W′, and W′ reconstitution (W′REC) following repeated maximal exercise between women and men.Methods Twelve women (\(\dot{V}\)O2PEAK: 2.53 ± 0.37 L·min−1) and 12 men (\(\dot{V}\)O2PEAK: 4.26 ± 0.30 L·min−1) performed a minimum of 3 constant workload tests, to determine...

Objectives To investigate possible persistent performance deficits after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in elite athletes. Methods A prospective cohort study in three Belgian professional male football teams was performed during the 2020 − 2021 season. Participants were submitted to strength, jump, and sprin...

Balenine possesses some of carnosine’s and anserine’s functions, yet it appears more resistant to the hydrolysing CN1 enzyme. The aim of this study was to elucidate the stability of balenine in the systemic circulation and its bioavailability in humans following acute supplementation. Two experiments were conducted in which (in vitro) carnosine, an...

Purpose: The purpose of this study was to examine the suitability of a single ramp incremental test to predict critical power (CP) and W'. We hypothesized that CP would correspond to the corrected power output (PO) at the respiratory compensation point (RCP) and W' would be calculable from the work done above RCP. Methods: 153 healthy young peop...

Purpose: To examine the differences in training load (TL) metrics when quantifying training sessions differing in intensity and duration. The relationship between the TL metrics and the acute performance decrement measured immediately after the sessions was also assessed. Methods: Eleven male recreational cyclists performed 4 training sessions i...

Carnosine (β-alanyl-L-histidine) and its methylated analogues anserine and balenine are highly concentrated endogenous dipeptides in mammalian skeletal muscle that are implicated in exercise performance. Balenine has a much better bioavailability and stability in human circulation upon acute ingestion, compared to carnosine and anserine. Therefore,...

Background: Recent studies suggest that acute-combined carnosine and anserine supplementation has the potential to improve the performance of certain cycling protocols. Yet, data on optimal dose, timing of ingestion, effective exercise range, and mode of action are lacking. Three studies were conducted to establish dosing and timing guidelines con...

PurposeThe aim of this study was to examine how respiratory (RT) and lactate thresholds (LT) are affected by acute heat exposure in the two most commonly used incremental exercise test protocols (RAMP and STEP) for functional evaluation of aerobic fitness, exercise prescription and monitoring training intensities.Methods Eleven physically active ma...

Purpose: To analyze the physical profile and training program of a world-class lightweight double sculls rowing crew toward the Tokyo 2020 Olympics. Method: A case study in which both rowers performed physical testing in November 2020 and April 2021 (anthropometrics, incremental rowing test, and power profiling). The training program (38 wk) in...

Purpose This study longitudinally examined the interchangeable use of critical power (CP), the maximal lactate steady state (MLSS) and the respiratory compensation point (RCP) (i.e., whole-body thresholds), and breakpoints in muscle deoxygenation (m[HHb]BP) and muscle activity (iEMGBP) (i.e., local thresholds). Methods Twenty-one participants were...

Objectives: The aim of this study was to investigate the association between SARS-CoV-2 infection and muscle strain injury in elite athletes. Methods: A prospective cohort study in three Belgian professional male football teams was performed during the first half of the 2020-2021 season (June 2020-January 2021). Injury data were collected using...

Purpose: The purpose of this commentary is to outline some of the pitfalls when using the fitness-fatigue model to unravel the interaction between training load and performance. By doing so, we encourage sport scientists and coaches to interpret the parameters from the model with some extra caution. Conclusions: Caution is needed when interpreti...

Purpose: Acute apnea is known to induce decreases in oxyhemoglobin desaturation (SpO2) and increases in erythropoietin concentration ([EPO]). This study examined the potential of an apnea training program to induce erythropoiesis and increase hematological parameters and exercise performance. Methods: Twenty-two male subjects were randomly divid...

Background Hamstring strain injuries (HSI) are prevalent in team sports and occur frequently in the later phase of matches. In the search for interindividual factors that determine muscle fatigue and possibly injury risk, muscle fibre typology is a likely candidate. Objective The aim of the study was to determine whether muscle fibre typology is a...

Introduction: Quickly recognising distress and drowning is an essential skill for lifeguards. In a recent in situ study, we showed that experienced lifeguards do not look at different locations, but the duration of their fixations is longer and more variable than that of inexperienced lifeguards (Vansteenkiste et al., 2020). The current study inves...

Background COVID-19 substantially impacts cardiorespiratory functioning, potentially affecting physical performance of elite athletes. Objective To investigate the association between COVID-19 and physical performance in elite male football players. Design A prospective cohort study during the first half of the 2020–2021 season. Setting Belgian...

Background Because of the high injury rate currently seen in soccer players and the exceptional pandemic circumstances, the question arises to what extent this reported increase in injury incidence is associated with COVID-19. Objectives The aim of this study was to investigate the association between COVID-19 and muscle strain injury occurrence i...

Introduction: Acute apnea evokes bradycardia and peripheral vasoconstriction in order to conserve oxygen, which is more pronounced with face immersion. This response is contrary to the tachycardia and increased blood flow to muscle tissue related to the higher oxygen consumption during exercise. The aim of this study was to investigate cardiovascul...

Purpose: This study aimed to determine the influencing factors of potential differences in sleep architecture between elite (EG) and nonelite (NEG) female artistic gymnasts. Methods: Twelve EG (15.1 [1.5] y old) and 10 NEG (15.3 [1.8] y old) underwent a nocturnal polysomnography after a regular training day (5.8 [0.8] h vs 2.6 [0.7] h), and, on...

PurposeThe aims of this study were (1) to investigate if the respiratory compensation point (RCP) as derived from ramp incremental (RI) exercise could accurately predict the power output (PO) at the maximal lactate steady state (MLSS), and (2) to compare its accuracy with the second lactate threshold (LT2) obtained from step incremental (SI) exerci...

This study focused on the steady-state phase of exercise to evaluate the relative contribution of metabolic instability (meas-ured with NIRS and haematochemical markers) and muscle activation (measured with EMG) to the oxygen consumption (V O 2) slow component (V O 2sc) in different intensity domains. We hypothesized that (i) after the transient ph...

Background Regular physical activity is the prime modality for the prevention of numerous non-communicable diseases and has also been advocated for resilience against COVID-19 and other infectious diseases. However, there is currently no systematic and quantitative evidence synthesis of the association between physical activity and the strength of...

Purpose: The aims of this study were [1] to model the temporal profile of W' recovery following exhaustion, [2] to estimate the contribution of changing V˙O2 kinetics to this recovery, and [3] to examine associations with aerobic fitness and muscle fiber type (MFT) distribution. Methods: 21 men (age=25±2 yr, V˙O2peak=54.4±5.3 mL·min-1·kg-1) perf...

This study aimed to identify the strongest predictive variables of winning and losing in the highest Belgian soccer division. A predictive machine learning model based on a broad range of variables (n = 100) was constructed, using a dataset consisting of 576 games. To avoid multicollinearity and reduce dimensionality, Variance Inflation Factor (thr...

Purpose: To determine if there is a link between the demands of competitive game activity and performance profiles of elite female field hockey players. Methods: Global positioning systems (GPS) were used to quantify running performance of elite female field hockey players (N = 20) during 26 competitive games. Performance profiles were assessed...

Introduction. The purpose was to investigate the effect the recovery intensity domain on W' reconstitution. We used the W'BAL model as a framework and tested its predictive capabilities (W'PRED) across the different intensity domains. Methods. Twelve young men (51.7 ± 5.9 mL•kg−1•min−1) completed a ramp incremental test, three to five constant pow...

In the past 30 years, mathematical modelling of the VO 2 response during metabolic transitions (i.e. VO 2 kinetics) by a sequence of first-order exponential functions has offered a non-invasive means to probe the physiological mechanisms of O 2 delivery and utilization [7, 10]. An alternative second-order exponential fitting has been recently propo...

For lifeguards, recognizing a swimmer in trouble is a key factor in the rescue process. Although reports show that lifeguards outperform non-lifeguards in their surveillance task, it is unclear to what extent this difference is reflected in gaze behaviour. In the current study, gaze behaviour of nine novice and seven experienced beach lifeguards wa...

During heavy and severe constant-load exercise, VO2 displays a slow component (VO2sc) typically interpreted as a loss of efficiency of locomotion. In the ongoing debate on the underpinnings of the VO2sc, recent studies suggested that VO2sc could be attributed to a prolonged shift in energetic sources rather than loss of efficiency. We tested the hy...

Purpose: Acute breath-holding deprives the human body from oxygen. In an effort to protect the brain, the diving response is initiated, coupling several physiological responses. The aim of this study was to describe the physiological responses to apnea at the cardiac, peripheral and cerebral level. Methods: 31 physically active subjects (17 male...

The aim of this study was to determine the frequency of upper respiratory tract symptoms (URS) in elite female gymnasts during a training season. In addition, we aimed to observe the extent to which salivary immunoglobulin A (sIgA) is associated with URS in these athletes, including potential effects of the season and timing of sample collection. O...

Objectives This study aimed at proposing a new heart rate (HR) method to track aerobic metabolism in soccer by: i) validating a recently developed HR index (HRindex) in professional soccer players ii) comparing HRindex vs the most common HR indexes and iii) testing the agreement between measured and estimated VO2 values using HRindex. Design cross...

Introduction: This study aimed to model the dissociation in the V˙O2/power output (PO) relationship between ramp incremental (RI) and constant work rate (CWR) exercise and to develop a novel strategy that resolves this gap and enables an accurate translation of the RI V˙O2 into a constant power output. Methods: Nine young men completed two RI te...

Purpose: Numerous methods exist to quantify training load (TL). However, the relationship with performance is not fully understood. Therefore the purpose of this study was to investigate the influence of the existing TL quantification methods on performance modeling and the outcome parameters of the fitness-fatigue model. Methods: During a perio...

Purpose: Intense exercise evokes a spleen contraction releasing red blood cells into blood circulation. The same mechanism is found following acute apnea, increasing [Hb] by 2 to 5%. The aim of this study was twofold: [1] to identify the optimal apnea modalities to acutely increase [Hb] and [2] use these modalities to examine whether pre-race apne...

The purpose of the present study was to assess the effects of aerobic interval training on muscle and brain oxygenation to incremental ramp exercise. Eleven physically active subjects performed a 6-week interval training period, proceeded and followed by an incremental ramp exercise to exhaustion (25 W min–1). Throughout the tests pulmonary gas exc...

Training-intensity distribution (TID), or the intensity of training and its distribution over time, has been considered an important determinant of the outcome of a training program in elite endurance athletes. The polarized and pyramidal TID, both characterized by a high amount of low-intensity training (below the first lactate or ventilatory thre...

Vermeire, KM, Vandewiele, G, Caen, K, Lievens, M, Bourgois, JG, and Boone, J. Training progression in recreational cyclists: no linear dose-response relationship with training load. J Strength Cond Res XX(X): 000-000, 2019-The purpose of the study was to assess the relationship between training load (TL) and performance improvement in a homogeneous...

Lievens, M, Bourgois, JG, and Boone, J. Periodization of plyometrics: Is there an optimal overload principle? J Strength Cond Res XX(X): 000-000, 2019-This study investigated the acute and chronic effects of 3 plyometric training (PT) programs with equal training loads (intensity × volume × frequency) on speed, agility, and jumping performance. For...

Splenic contraction is an important response to acute apnea causing the release of red blood cells into blood circulation. Current literature shows higher spleen volumes and greater spleen contractions in trained apnea divers compared to untrained individuals, but the influence of training is presently unknown. Thirteen subjects daily performed fiv...

Purpose: This study aimed to investigate the effects of different work and recovery characteristics on the W' reconstitution and to test the predictive capabilities of the W'BAL model. Methods: Eleven male participants (22±3 yr, 55±4 mL.min.kg) completed three to five constant work rate tests to determine CP and W'. Subsequently, subjects perfor...

Purpose: This study aimed to predict the session Rate of Perceived Exertion (sRPE) in soccer and determine the main predictive indicators of the sRPE. Methods: A total of 70 External Load Indicators (ELIs), Internal Load Indicators (ILIs), Individual Characteristics (ICs) and Supplementary Variables (SVs) were used to build a predictive model. Re...

Aims. Apnea training has recently been proposed as a simple and cheap method to stimulate erythropoietin (EPO) production and increase hemoglobin (Hb) concentration and hematocrit (Hct). This study aimed to investigate both acute and chronic effects of apnea on spleen volume and hematological values through an 8-week apnea training program. Method...

Basketball players display different performance characteristics when in different playing positions. Traditional statistical techniques such as Multivariate Analyses of Variance (MANOVA's) are insufficient when predicting specific positions. Alternatively linear statistical models, such as discriminant analysis, have been used. Recently non-linear...

Unexplained abnormal fatigue is characterized by chronic fatigue persisting for at least six months and not sufficiently explained by any recognized medical condition. In this pilot study, twelve individuals with abnormal fatigue remaining unexplained after thorough screening were investigated using a near-infrared (NIR) spectroscopy handgrip test....

Purpose The interchangeable use of whole-body exercise thresholds and breakpoints (BPs) in the local oxygenation response, as measured via near-infrared spectroscopy (NIRS), has recently been questioned in scientific literature. Therefore, the present study aimed to longitudinally investigate the interrelationship of four commonly used exercise t...

Training load (TL) and recovery should be in optimal balance to obtain maximal performance gains. We aimed to study sleep as a recovery technique and its relationship with TL and performance in elite athletes. Twenty-six elite female artistic gymnasts were divided into an under 13 (n = 6), an under 14 (n = 6), a junior (n = 7; 14–15y) and a senior...

Background: Apply a more novel approach to systematically examine (1) associations of clustered cardio-metabolic risk and cardio-metabolic risk factors, and (2) theoretical substitution of sedentary time with either sleep, light physical activity (LPA) or moderate-and-vigorous physical activity (MVPA) and substituting LPA with MVPA. Methods: Phy...

A tribute to Dr J. Rogge’ aims to systematically review muscle activity and muscle fatigue during sustained submaximal quasi‐isometric knee extension exercise (hiking) related to Olympic dinghy sailing as a tribute to Dr Rogge's merits in the world of sports. Dr Jacques Rogge is not only the former President of the International Olympic Committee,...

Een adequate hydratatie wordt herkend als een sleutelaspect in het behoud van het prestatieniveau. Het doel van deze studie was drieledig: 1) een overzicht bieden van de pretraining hydratatiestatus (PHS) van teamsport atleten, 2) het in kaart brengen van de vochtbalans en het elektrolytenverlies tijdens wedstrijdspecifieke trainingen bij verschill...

BACKGROUND: High-level team sport athletes are exposed to high training loads (TL) [1]. Soccer can be considered as an intermittent high intensity activity where an optimal level of aerobic (VO2max > 60 ml/min/kg) and anaerobic fitness is required [2]. This study aims to examine internal TL, using session Rating of Perceived Exertion (sRPE) as propo...

In the past two decades oxygenation responses to incremental ramp exercise, measured non-invasively by means of near-infrared spectroscopy at different locations in the body, have advanced the insights on the underpinning mechanisms of the whole-body pulmonary oxygen uptake ([Formula: see text]) response. In healthy subjects the complex oxygenation...

Background We aimed to study the independent associations of 10-year change in sedentary behaviour (SB), moderate-to-vigorous physical activity (MVPA) and objectively measured cardiorespiratory fitness (CRF), with concurrent change in clustered cardiometabolic risk and its individual components (waist circumference, fasting glucose, high-density li...

BACKGROUND: We aimed to study the independent associations of 10-year change in sedentary behaviour (SB), moderate-to-vigorous physical activity (MVPA) and objectively measured cardiorespiratory fitness (CRF), with concurrent change in clustered cardiometabolic risk and its individual components (waist circumference, fasting glucose, high-density l...

We aimed to study the independent associations of sedentary time (ST), moderate-to-vigorous physical activity (MVPA), and objectively measured cardiorespiratory fitness (CRF) with clustered cardio-metabolic risk and its individual components (waist circumference, fasting glucose, HDL-cholesterol, triglycerides and blood pressure). We also investiga...

Unstandardized regression coefficients of sedentary behavior, moderate-to-vigorous physical activity and cardiorespiratory fitness for cardio-metabolic markers. (DOCX)

Pearson correlation coefficients for the association between physical activity, sedentary time, physical fitness and cardio-metabolic markers. (DOCX)

Approximately 3.2 million people die of non-communicable diseases (NCD) each year due to insufficient physical activity. Physical activity guidelines are possibly perceived as too demanding and might thus pose a barrier. We addressed the question if a more stable physical activity pattern is associated with higher levels of health-related fitness t...

Objectives: Since fatigue seems related to poorer physical fitness rather than to gender, we analyzed the physiological responses in female medicine and physical education students during a 30 minutes sustained cardiopulmonary resuscitation (CPR) sequence. Methods: Handgrip strength and maximal aerobic power (V02 max) determined strength and end...