Gaël Guilhem

• PhD
• Lab Head at French Institute of Sport (INSEP)

This study investigated the effects of active and/or passive warm-up tasks on the hamstring muscles stiffness through elastography and passive torque measurements. On separate occasions, fourteen males randomly completed four warm-up protocols comprising Control, Cycling, Foam-rolling or Cycling plus Foam-rolling (Mixed). The stiffness of the hamst...

Purpose: Muscle fascicles-tendon interactions are the main determinant in production of high joint velocity. Currently, no study has investigated the muscle fascicles behaviour of knee extensor muscles until the highest reachable velocity (e.g., unloaded knee extension). We aimed to track the changes in vastus lateralis fascicles length during kne...

Purpose: Muscle strengthening is commonly based on the use of isoinertial loading, whereas variable resistances such as pneumatic loading may be implemented to optimize training stimulus. The purpose of the present study was to determine the effect of the ratio between pneumatic and isoinertial resistance on the force-velocity relationship during...

Aim: Defining the origins of muscle injury has important rehabilitation and exercise applications. However, current knowledge of muscle damage mechanics in human remains unclear in vivo. This study aimed to determine the relationships between muscle-tendon unit mechanics during maximal eccentric contractions and the extent of subsequent functional...

Changes in muscle stiffness after exercise-induced muscle damage have been classically inferred from passive torque-angle curves. Elastographic techniques can be used to estimate the shear modulus of a localized muscular area. This study aimed to quantify the changes in shear elastic modulus in different regions of the elbow flexors after eccentric...

Purpose: The application of horizontal resistance is key in sprint training to modulate velocity and promote adaptations. However, the interaction between velocity and resistance on muscle excitation remains insufficiently studied. This study assessed the electromyographic (EMG) activity of thigh and gluteal muscles in response to varying velocity...

Objective: In Athletics (Track and Field), athletes can be affected by injuries, especially in their quest for top performance. Therefore, we aim to provide an overview of the current knowledge about the problem of injuries in Athletics. Main findings: It is necessary to maintain a clear definition of “injury” when stakeholders in Athletics discuss...

Purpose: Muscle mechanics is paramount in our understanding of motor performance. However, little is known regarding the sensitivity of fascicle dynamics and connective tissues stiffness to exercise duration and ambient temperature during running, both increasing muscle temperature. This study aimed to determine gastrocnemius medialis (GM) fascicle...

The present study aimed to: (1) investigate sleep architecture in response to an overload training and taper periods among endurance runners; and (2) assess the sleep benefits of a high‐heat‐capacity mattress topper. Twenty‐one trained male endurance runners performed a 2‐week usual training regimen (baseline) followed by 2‐week overload and taper...

Muscle volume is a useful quantitative biomarker in sports, but also for the follow-up of degenerative musculo-skelletal diseases. In addition to volume, other shape biomarkers can be extracted by segmenting the muscles of interest from medical images. Manual segmentation is still today the gold standard for such measurements despite being very tim...

Objective: To describe the epidemiology of injury complaints related to the athletics activity in elite athletics (track and field) athletes practicing disciplines with sprints (i.e., sprints, hurdles, combined events, long jump, and triple jump). Methods: We conducted a cross-sectional study on elite sprinting athletes licensed with the French Fed...

Purpose: Investigate acute locomotor, internal (heart rate (HR) and ratings of perceived exertion (RPE)) and neuromuscular responses to using wearable resistance loading for soccer-specific training. Methods: Twenty-six footballers from a French 5th division team completed a 9-week parallel-group training intervention (intervention group: n = 14...

Purpose This study aimed to investigate the effect of whole-body cryotherapy (WBC), cold-water immersion (CWI) and passive recovery (PAS) on tennis recovery. Methods Thirteen competitive male tennis players completed three consecutive match-like tennis protocols, followed by recovery (WBC, CWI, PAS) in a crossover design. Five tennis drills and se...

Purpose: Muscle architecture is associated with motor performance and muscle injury. While muscle architecture and knee-flexor eccentric strength change with growth, the influence of anthropometric measures on these properties is rarely considered. This study aimed to investigate the relationship between hamstring muscle architecture and knee-flex...

Purpose: Heat acclimation (HA) is recommended before competing in hot and humid conditions. HA has also been recently suggested to increase muscle strength, but its effects on human’s muscle and tendon mechanical properties are not yet fully understood. This study investigated the effect of active HA on gastrocnemius medialis (GM) muscle-tendon pro...

To directly compare five commonly used on-field systems (motorized linear encoder, laser, radar, global positioning system, and timing gates) during sprint acceleration to (i) measure velocity–time data, (ii) compute the main associated force–velocity variables, and (iii) assess their respective inter-trial reliability. Eighteen participants perfor...

Knee extension and hip flexion range of motion (ROM) and functional performance of the hamstrings are of great importance in many sports. The aim of this study was to investigate if static stretching (SS) or vibration foam rolling (VFR) induce greater changes in ROM, functional performance, and stiffness of the hamstring muscles. Twenty-five male v...

While heat exposure has been shown to increase the rate of force development (RFD), the underlying processes remain unknown. This study investigated the effect of heat on gastrocnemius medialis (GM) muscle-tendon properties and interactions. Sixteen participants performed electrically-evoked and voluntary contractions combined with ultrafast ultras...

The impact of sleep on performance is fundamental for ultra-endurance athletes, but studies on this issue are rare. The current investigation examined the sleep and performance of a cyclist engaged in a simulated 10,000 km tour. The sleep behavior of the athlete (age, 57; height, 1.85 m; mass, 81 kg) before, during (i.e., 23 nights), and after the...

• To individualise injury risk reduction measures could help to better match athlete's individual characteristics and should thus improve their effectiveness. • To individualise injury risk reduction measures could help to improve athlete adherence into such measures and consequently their effectiveness. • This maximised individualised approach is...

This study aimed to determine the relationship between the torque-generating capacity in sprint cycling and the strength capacity of the six lower-limb muscle groups in male and female world-class sprint cyclists. Eleven female and fifteen male top-elite cyclists performed 5-s sprints at maximal power in seated and standing positions. They also per...

This study aimed to quantify in- and between-match characteristics and mechanical workload variations elicited by a congested schedule in high-level female ice hockey. Six players were monitored during four international pre-season exhibition matches against the same opponent. Two different methods (Player Load and Accel’Rate) were used to assess s...

In regular times, implementing exercise-based injury prevention programs into the training routine of high-level and professional athletes represents a key and challenging aspect to decrease injury risk. Barriers to implementing such prevention programs have previously been identified such as lack of resources, logistic issues or motivation. The CO...

A single proprioceptive neuromuscular facilitation (PNF) stretching exercise can increase the range of motion (ROM) of a joint but can lead to a decrease in performance immediately after the stretching exercise. Post-stretching activation (PSA) exercises are known as a possible way to counteract such a drop in performance following a single stretch...

Perez, J, Guilhem, G, and Brocherie, F. Ice hockey forward skating force-velocity profiling using single unloaded vs. multiple loaded methods. J Strength Cond Res XX(X): 000-000, 2021-This study aimed to compare skating force-velocity relationships determined throughout sprints performed against various loaded conditions or inferred from movement k...

This study aimed to compare the force-velocity mechanical variables derived from high-speed video- and radar-based method during forward skating sprint in ice hockey. Thirteen elite female ice hockey players performed two 40-m forward skating sprints to determine, in the horizontal plane, maximal velocity reached (Vmax), relative maximal theoretica...

While the Player Load is a widely-used parameter for physical demand quantification using wearable accelerometers, its calculation is subjected to potential errors related to rotational changes of the reference frame. The aims of this study were (i) to assess the concurrent validity of accelerometry-based Player Load against force plates; (ii) to v...

Purpose The purpose of the study was to investigate the effects of using a vibration foam roll (VFR) or a non-vibration foam roll (NVFR) on maximum voluntary isometric contraction peak torque (MVIC), range of motion (ROM), passive resistive torque (PRT), and shear modulus. Methods Twenty-one male volunteers visited the laboratory on two separate d...

To investigate the reliability of the ballistic hip thrust (BHT) test performed on force plates as a diagnostic tool to monitor posterior chain neuromuscular status and compare its usefulness with the counter movement jump (CMJ). Twenty-two male football players from an elite Under-19 French Ligue 1 football club (16.4 ± 0.6 years) performed two as...

This study characterised the thigh muscle-tendon unit length variations (MTUv) in elite alpine skiing. MTUv were modelled for seven muscles from knee and hip angles in 17 national team skiers during 1602 cycles (546 Slalom (SL), 908 Giant-Slalom (GS), 136 Super-Giant (SG) and 12 Downhill (DH) cycles). The biarticular rectus femoris showed a dynamic...

Objective To analyse the rates of lower limb muscle injuries in athletics disciplines requiring different running velocities during international athletics championships. Design Prospective total population study. Methods During 13 international athletics championships (2009 - 2019) national medical teams and local organizing committee physicians...

Revue de l'Association des Entraîneurs Français d'Athlétisme - n°239 - 3e trimestre 2020

The International Olympic Committee (IOC) has supported athletes’ health protection1 by funding research centres dedicated to prevention and treatment of sports-related injuries and illnesses.2 After establishing four centres in 2009,2 the IOC research centres network expanded to 9 institutions in 20143 and the 2019 round recognised 11 centres.4 He...

The present study aimed to determine the effect of hyperthermia on both electrochemical and mechanical components of the electromechanical delay (EMD), using very-high-frame-rate ultrasound. Electrically evoked peak twitch force, EMD, electrochemical (Dm, i.e., delay between stimulation and muscle fascicle motion) and mechanical (Tm, i.e., delay be...

INTRODUCTION: Muscle performance is positively related to muscle size (1) and tendon stiffness (2). Joint flexibility in the hip correlates with muscle stiffness (3). However, so far it is not yet well understood if and how muscle stiffness is related to muscle performance parameters such as flexibility, isometric and dynamic strength, especially i...

Introduction: Modern tennis players face congested schedules that force the adoption of various recovery strategies. Thus, recovery must be fine-tuned with an accurate quantification of its impacts, especially with regards to training-induced fatigue. The present study aimed to examine the training type clusters and recovery practices adopted by el...

Interactions between human movement and surfaces have previously been studied to understand the influence of surface properties on the mechanics and energetics of jumping. However, little is known about the muscle-tendon unit (MTU) mechanics associated with muscle activity and leg adjustments induced by different surfaces during this movement. This...

Elite athletes face congested schedules with increased competition frequency and restricted time for training periods. Therefore, time is lacking to design long-term sport-specific block periodization. This study aimed to investigate the effects of adding a 14-day off-ice high-intensity training (HIT) shock microcycle to the usual training content...

https://blogs.bmj.com/bjsm/2020/08/09/healthy-return-to-performance-in-elite-athletes-and-para-athletes-after-the-covid-19-lockdown/

This study investigated how joint angle influences fascicle shortening dynamics of gastrocnemius medialis (GM) during explosive contractions, and the resulting impact on rate of torque development (RTD). Sixteen participants performed six sets of five maximal explosive voluntary isometric plantar flexions at -20°, -10°, 0° (neutral position), 10°,...

This study aimed to investigate the correlations between players’ mechanical capacities determined during off- and on-ice tests. Whole body force-velocity relationships were assessed in elite female ice hockey players (n = 17) during jumping [squat jump (SJ) height], running (5 m and 30 m) and skating (5 m and 40 m) sprint tasks. Mechanical capacit...

Hamstring strain injuries (HSI) involve tissue disruption and pain, which can trigger long-term adaptations of muscle coordination. However, little is known about the effect of previous HSI on muscle coordination, and in particular, after the completion of rehabilitation and in the absence of symptoms. This study aimed to determine if elite athlete...

Purpose Muscle–tendon units are forcefully stretched during rapid deceleration events such as landing. Consequently, tendons act as shock absorbers by buffering the negative work produced by muscle fascicles likely to prevent muscle damage. Landing surface properties can also modulate the amount of energy dissipated by the body, potentially effecti...

The effect of training on hamstring flexibility has been widely assessed through the measurement of the maximal range of motion or passive torque. However, these global measures do not provide direct information on the passive muscle mechanical properties of individual muscle. This characterization is crucial to better understand the effect of inte...

New findings: What is the central question of this study? Do neural and/or mechanical factors determine the extent of muscle damage induced by eccentric contractions? What is the main finding and its importance? The extent of muscle damage induced by eccentric contractions is related to both mechanical strain and corticospinal excitability measure...

The aims of this study were to ensure that the skating velocity describes a mono-exponential function in order to determine the reliability of radar-derived profiling results from skating sprint accelerations applying sprint running force-velocity assessment approach. Eleven young highly-trained female ice hockey players performed two 40-m skating...

Aim To compare the effect of low- vs. high-volume of eccentric-biased hamstring training programs on knee-flexor strength and fascicle length changes in elite soccer players. Methods Nineteen elite youth soccer players took part in this study and were randomly assigned into two subgroups. For 6 weeks in-season, groups performed either a low (1 set...

Animal tendons have been shown to act as shock absorbers to protect muscle fascicles from exercise‐induced damage during landing tasks. Meanwhile, the contribution of tendinous tissues to damping activities such as landing has been less explored in humans. The aim of this study was to analyze in vivo fascicle‐tendon interactions during drop landing...

The application of a series of extremely high accelerative motor-driven quick releases while muscles contract isometrically (i.e. slack test) has been proposed to assess unloaded velocity in human muscle. This study aimed to measure gastrocnemius medialis fascicle (VF) and tendinous tissues shortening velocity during motor-driven quick releases per...

We investigated the effects of the initial length of the muscle-tendon unit (MTU) and muscle pre-activation on muscle-tendon interactions during plantarflexion performed at maximal velocity. Ultrasound images of gastrocnemius medialis were obtained on 11 participants in three conditions: 1) active plantarflexion performed at maximal velocity from t...

Incontournable de la pratique sportive, l’échauffement est aujourd’hui bien intégré dans les routines de préparation avant l’entraînement et la compétition. Du cerveau jusqu’au muscle, cet article propose de décrire les effets majeurs des différentes techniques d’échauffement et d’apprécier dans quelle mesure elles favorisent l’atteinte d’une perfo...

PurposeThis study aimed to determine whether an increase in muscle shear modulus measured 30 min after eccentric exercise (30 min) reflects the magnitude of force deficit measured 48-h post-exercise (48 H). MethodsA total of 53 healthy participants were distributed in five groups. Four groups performed either repeated eccentric elbow flexions or kn...

The present case study allowed an examination of the link between sleep and injury occurrence in an elite male soccer player competing in French League 1 and Union of European Football Associations matches. During 4 months, a mixed method approach was used, combining actigraphic sleep assessment with qualitative interviews on a daily basis. Three i...

Si la performance sportive est un processus éminemment complexe et multi-factoriel, le mouvement nécessaire à la réalisation de cette performance est le résultat de la contraction du muscle et/ou de l’énergie transmise par les tissus élastiques (en particulier les tendons) aux leviers osseux [1]. Le muscle représente ainsi le véritable « moteur » d...

Although cold application (i.e., cryotherapy) may be useful to treat sports injuries and to prevent muscle damage, it is unclear whether it has adverse effects on muscle mechanical properties. This study aimed to determine the effect of air-pulsed cryotherapy on muscle stiffness estimated using ultrasound shear wave elastography. Myoelectrical acti...

Compared to isokinetic and isometric tests, isoinertial movements have been poorly used to assess single-joint performance. Two calculation procedures were developed to estimate mechanical performance during single-joint isoinertial movements performed on a customised isokinetic dynamometer. The results were also compared to appreciate the effects...

Introduction: This study compared voluntary activation during isometric, concentric, and eccentric maximal knee extensions at different joint angles. Methods: Fifteen participants performed isometric, concentric, and eccentric protocols (9 contractions each). For each protocol, the central activation ratio (CAR) was randomly measured at 50°, 75°...

Dinghy sailors lean their upper body over the windward side of the boat ('hiking') to keep the boat's balance and maximise its speed. Sustaining the hiking position is essential for competitive performance and this study examined sport-specific differences of muscles relevant for hiking in elite sailors. Knee extensor muscle strength as well as tru...

Purpose: This study compared the effects of isoload (IL) and isokinetic (IK) knee extensor eccentric exercises on changes in muscle damage and neuromuscular parameters to test the hypothesis that the changes would be different after IL and IK exercises. Methods: Twenty-two young men were paired based on their strength and placed to IL (N = 11) o...

Nous avons tous en tête l’image d’un athlète portant la main derrière la cuisse, stoppé dans sa course par une douleur vive. Cet événement est souvent le résultat d’une lésion des fibres musculaires des ischiojambiers, muscles qui participent à la flexion du genou et à l’extension de la hanche. Comment préserver les sportifs de cette blessure et qu...

This study tested the relationship between the magnitude of muscle damage and both central and peripheral modulations during and after eccentric contractions of plantar flexors. Eleven participants performed 10 sets of 30 maximal eccentric contractions of the plantar flexors at 45°·s⁻¹. Maximal voluntary torque, evoked torque (peripheral component)...

Introduction: This study aimed to quantify the effect of exercise-induced muscle damage on both the electrochemical and mechanical components of electromechanical delay using very high frame rate ultrasound. Methods: Fifteen participants underwent electrically-evoked contractions of the medial gastrocnemius muscle with an ultrasound transducer o...

This study aimed to compare the force (F)-velocity (v)-power (P)-time (t) relationships of female and male world-class sprinters. A total of 100 distance-time curves (50 women and 50 men) were computed from international 100-m finals, to determine the acceleration and deceleration phases of each race: (a) mechanical variables describing the velocit...

This study aimed to compare the response of salivary hormones of track and field athletes induced by preparation and pre-competitive training periods in an attempt to comment on the physiological effects consistent with the responses of each of the proteins measured. Salivary testosterone, cortisol, alpha-amylase, immunoglobulin A (IgA), chromogran...

This study aimed to compare the force (F) - velocity (v) - power (P) - time (t) relationships of female and male world-class sprinters. A total of one hundred distance-time curves (50 women and 50 men), were computed from international 100-m finals, to determine the acceleration and deceleration phases of each race: 1) mechanical variables describi...

Inter-individual variability of performance in fast movements is commonly explained by a difference in maximal muscle-shortening velocity, due to differences in the proportion of fast-twitch fibers. To provide a better understanding of the capacity to generate fast motion, this study aimed i) to measure, for the first time in vivo, the maximal fasc...

Performance during human movements is highly related to force and velocity muscle capacities. Those capacities are highly developed in elite athletes practicing power-oriented sports. However, it is still unclear whether the balance between their force and velocity-generating capacities constitutes an optimal profile. In this study, we aimed to det...

The aim of this session is to present elastography techniques and the use of the supersonic shear imaging technique for muscle studies with application to sports. 35 min will be dedicated to demo in real time to illustrate the presentations and questions from the audience. This session is sponsored by the Supersonic Imaging company.