Pierre Samozino

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• PhD
• Professor (Associate) at Université Savoie Mont Blanc

Alpine skiing performance hinges on the dynamic interaction between the skier and the ski-snow interface. Ground reaction forces are fundamental in controlling these interactions, yet surprisingly little research exists characterising 3-D turn kinetics. This study aimed to profile the evolution of ground reaction forces and torques signatures appli...

Purpose This study aimed to analyse the sex differences in the rate of torque development (RTD) and torque–velocity parameters with and without normalisation for maximal voluntary torque (MVT). Methods Right-leg knee extensors were tested in 64 healthy and active participants (31 F and 33 M). MVT and RTD were obtained under isometric conditions. I...

Understanding how to precisely program resisted sprinting to enhance sprint phase-based adaptations is an important yet underexplored topic. This pilot study examined the impact of high-load sled-resisted sprint training when varying distance and repetitions for the same overall volume on acceleration capabilities and performance. Twenty under-19 n...

We investigate the contribution of isometric rate of torque development (RTD) and maximal voluntary torque (MVT) to the dynamic force production capacities of knee extensors obtained from the torque–velocity (TV) relationship, that is, the theoretical maximal velocity (V0), torque (T0), and maximal power (Pmax). Single‐leg knee extensors were teste...

This study aimed to introduce and validate a novel method for assessing dynamic fatigue components through a single-sprint test, addressing the limitations of traditional multi-sprint evaluations. We tested this method on twenty-one participants by computing torque-cadence relationships from two iso-friction sprints at varying friction levels (3% a...

In many sports, practitioners must reach their maximal jump height ( h max ) under time constraints. This requires a reduction of the countermovement depth and so of the push-off distance ( h PO ). The purpose of this study was to investigate how h PO influences force–velocity ( F – v ) profiles ( , , , and S Fv ) and performance. Eleven participan...

Purpose Alpine skiing races are physically demanding events characterized by numerous repeated near-maximal activations of the lower limb muscles. Although this type of task is known to induce neuromuscular fatigue, electromyographic activity (EMG) adaptations after repeated maximal-intensity skiing have not been previously investigated. Methods S...

Le modèle Force-Vitesse-Endurance (FoVE) est un nouveau cadre théorique couplé à une modélisation innovante pour évaluer les muscles striés squelettiques. Il se base sur les relations fondamentales « force-vitesse » et « force-temps » qui décrivent les capacités de production de force du muscle en fonction respectivement de la vitesse de contractio...

In giant slalom, the ability to apply a high amount of force in the radial direction is essential for performance. A race is characterized by repeated turns performed at high velocity, potentially inducing fatigue. Therefore, this study aimed to assess the effect of fatigue on performance, trajectory characteristics, and force production capacities...

This study presents a novel method for evaluating the submaximal velocity-force (V(F)) relationship in mountain ultramarathon races using crowdsourced data from Strava.com. The dataset includes positional data from 408 participants of the 171-km UTMB® 2023 race (9,850-m D+). The race was divided into 100-m segments. The mean net propulsive force an...

Peak tibial accelerations are used to monitor impact severity during distance running and as input for bio-feedback. Here, peak tibial accelerations were compared between rearfoot and forefoot strikes. Two different studies were undertaken by independent research centres. Tibial acceleration and optical motion capture were collected in 14 rearfoot...

Background Anterior cruciate ligament reconstruction (ACLR) continues to be associated with a variable rate of return to sports and a concerning rate of further anterior cruciate ligament injury. Persistent functional deficits may explain these results and support the need to keep exploring lower limb functional indexes, especially during vertical...

Purpose Based on the critical power (Pc or critical force; Fc) concept, a recent mathematical model formalised the proportional link between the decrease in maximal capacities during fatiguing exercises and the amount of impulse accumulated above Fc. This study aimed to provide experimental support to this mathematical model of muscle fatigability...

The purpose of this study was to evaluate the changes in core stability, core strength, ergometer rowing technique and power output after a a specific core training program. 13 young rowers followed an 8-week training program consisting of 20min additional training realized 4 to 5 times a week composed of low load core stability, high load dynamic...

Background : The force–velocity relationship suggests that maximal power ( P max ) can only be produced in optimal torque ( T opt ) and cadence ( C opt ). However, the cadence at which mean maximal power (MMP) is produced has never been studied. This study aimed to determine the individual MMP–cadence relationship from in situ data. Method : We ana...

Muscle fatigue is the decay in the ability of muscles to generate force, and results from neural and metabolic perturbations. This article presents an integrative mathematical model that describes the decrease in maximal force capacity (i.e. fatigue) over exercises performed at intensities above the critical force Fc (i.e. severe domain). The model...

Background: Warm-up is commonly performed by track-and-field athletes before performing maximal sprinting activities. Whilst some warm-up strategies may enhance athletes' physical and mental readiness, less is known about the current athletes' behaviors and warm-up practices in track and field. Therefore, this study aimed to identify the warm-up p...

The purpose of this investigation was (1) to test the effect of movement restriction of the free leg during unilateral vertical jump on performance and power output comparing 2 different jump techniques: flexed (Classic technique) and straight (FC Luzern technique) free leg, and (2) to test the correlation between performance and power output obtai...

Abstract Background: Alpine skiing involves the conversion of potential energy into kinetic energy, with the “velocity barrier” (VB) at each moment corresponding to the maximal velocity at which the athlete can ski while staying within the boundaries of the gates and maintaining control. Nevertheless, this concept has never been proven by evidence....

Purpose: This study aimed to determine relationships between parameters of force-production capacity in sprinting and opposition skill efficiency in rugby union games according to position. Methods: The sprint force-velocity profile of 33 professional rugby union players divided into 2 subgroups (forwards and backs) was measured on a 30-m sprint...

Purpose To compare linear and curvilinear models describing the force–velocity relationship obtained in lower-limb acyclic extensions, considering experimental data on an unprecedented range of velocity conditions. Methods Nine athletes performed lower-limb extensions on a leg-press ergometer, designed to provide a very broad range of force and ve...

Muscle fatigability corresponds to the decrease in the ability of muscles to generate force. The Critical Power (Pc) concept [1] predicts the point at which fatigue develops in such a way that the required constant intensity will no longer be sustainable (W’ reserve is emptied). During all-out tests, the power plateau is reached at the end of the t...

When poor reliability of “output” variables is reported, it can be difficult to discern whether blame lies with the measurement (ie, the inputs) or the overarching concept. This commentary addresses this issue, using the force-velocity-power (FvP) profile in jumping to illustrate the interplay between concept, method, and measurement reliability. W...

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...

Le Scouarnec, J, Samozino, P, Andrieu, B, Thubin, T, Morin, JB, and Favier, FB. Effects of repeated sprint training with progressive elastic resistance on sprint performance and anterior-posterior force production in elite young soccer players. J Strength Cond Res 36(6): 1675-1681, 2022-This study aimed to determine whether repeated sprint training...

Purpose: The aims of this study were to (1) assess the concurrent validity of global positioning systems (GPSs) against a radar device to measure sprinting force-velocity (F-v) profiles and (2) evaluate the interunit reliability of 10-Hz GPS devices (Vector S7, Catapult Innovations). Methods: Sixteen male elite U18 rugby union players (178.3 [7....

Funding Acknowledgements Type of funding sources: Other. Main funding source(s): Doctoral contract 2018-2022 Background Several studies have shown the importance of the relationship between the power-force-velocity profile (PFVP) and sport performance in elite athletes through optimised exercise training.[1] Optimising the training programme is co...

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...

Movement velocity has been viewed as one of the bilateral deficit (BLD) determinants. This research tested the velocity effect on BLD during a half-squat exercise. The role of muscle excitation in BLD was also assessed. BLD amplitude was assessed in 12 male soccer players while performing a half-squat exercise with incremental load. During the exer...

An a-posteriori multicentre reliability study was conducted to compare the between-session reliability of the force-velocity relationship parameters (force-intercept [F0], velocity-intercept [v0], and maximum power [Pmax]) between different regression models during the bench press (BP) and bench press throw (BPT) exercises. Data from four and three...

Over the years, the foot tapping test protocol has been proposed by scientists to identify the capabilities of the lower limb neuromuscular system in the medical context; however, to our knowledge, no studies have established its usefulness and relationship to athletic performance. The aim of the present study was to test the reliability, criterion...

This study investigated time-courses of physiological and psychological parameters of rowers during the first 1,500 m of a simulated race on a rowing ergometer using different pacing strategies. This provided a picture of the physiological and psychological state of the rowers at the start of the last 500 m of their race. Investigated strategies co...

Background: The aim of this study was to test the effects of cycling shoe outsole stiffness on both performance and comfort parameters during sub- and supra-maximal cycling tests. Methods: Two groups of recreational women tested three cycling shoe conditions with differing outsole stiffness. One group of 8 women performed four cycling tests of 3 m...

The aim was to determine the respective influences of sprinting maximal power output (PHmax) and mechanical Force‐velocity (F‐v) profile (i.e. ratio between horizontal force production capacities at low and high velocities) on sprint acceleration performance. A macroscopic biomechanical model using an inverse dynamics approach applied to the athlet...

This study aimed to quantify the validity and reliability of load–velocity (LV) relationship of hill sprinting using a range of different hill gradients and to describe the effect of hill gradient on sprint performance. Twenty-four collegiate-level athletes performed a series of maximal sprints on either flat terrain or hills of gradients 5.2, 8.8...

Background A test battery is recommended after anterior cruciate ligament reconstruction (ACLR) to help decision-making of return to sport (RTS). Running is important in RTS continuum, but it is currently not included in the usual test batteries. Could running pattern asymmetry, which can be observed after ACLR, be considered as a risk factor of AC...

The goal of this study was to analyse 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) in...

PurposeTheoretical 100-m performance times (t100-m) of a top athlete at Mexico-City (2250 m a.s.l.), Alto-Irpavi (Bolivia) (3340 m a.s.l.) and in a science-fiction scenario “in vacuo” were estimated assuming that at the onset of the run: (i) the velocity (v) increases exponentially with time; hence (ii) the forward acceleration (af) decreases linea...

Background The ability to dynamically reintegrate proprioceptive signals after they have been perturbated is impaired in certain pathologies. Evaluation of proprioceptive reintegration is useful for clinical practice but currently requires expensive laboratory tools. We developed a simple method, accessible to clinicians. Research question: Is two-...

The orientation of the ground reaction force (GRF) vector is a key determinant of human sprint acceleration performance and has been described using ratio of forces (RF) which quantifies the ratio of the antero-posterior component to the resultant GRF. Different methods have previously been used to calculate step-averaged RF, and this study therefo...

Clear decreases in horizontal force production capacity during sprint acceleration have been reported after hamstring injuries (HI) in football players. We hypothesized that lower FH0 is associated with a higher HI occurrence in football players. We aimed to analyze the association between sprint running horizontal force production capacities at lo...

Assessing football players' sprint mechanical outputs is key to the performance management process (e.g. talent identification, training, monitoring, return-to-sport). This is possible using linear sprint testing to derive force-velocity-power outputs (in laboratory or field settings), but testing requires specific efforts and the movement assessed...

Purpose: compare linear and curvilinear models to describe the force-velocity relationship, especially on the velocity end, in lower limb acyclic extensions. Methods: nine athletes performed horizontal lower limb extensions on a leg press ergometer allowing to set from very high to very low (i.e. horizontal assisted extensions) resistive and inerti...

Comprehensive information regarding neuromuscular function, as assessed through force-velocity-power (FVP) profiling, is of importance for training optimization in athletes. However, neuromuscular function is highly task-specific, potentially governed by dissimilarity of the overall orientation of forceapplication. The hip thrust (HT) exercise is t...

In jumping, countermovement increases net propulsive force and improves performance. We aimed to test whether this countermovement effect is velocity specific and examine the degree to which this varies between athletes, sports or performance levels. Force-velocity profiles were compiled in high-level skiers (N= 23) and sprinters (N= 30), with thei...

Résumé Le handball est particulièrement traumatisant au niveau des membres inférieurs. Le Star Excursion Balance Test modifié est un test fonctionnel qui évalue le contrôle postural dynamique du membre inférieur et permet de repérer les joueurs à risque de blessures au niveau des membres inférieurs. Cependant, les performances obtenues dépendent du...

To train hamstring muscle specifically to sprint, strengthening programs should target exercises associated with horizontal force production and high levels of hamstring activity. Therefore, the objectives of this study were to analyze the correlation between force production capacities during sprinting and hamstring strengthening exercises, and to...

Specific force capacities might be a limiting factor for alpine skiing performance, yet there is little consensus on the capabilities in question, and whether they differ between disciplines. We aimed to test discipline (speed and technical) and performance (event-specific world standing) effects on lower-limb force-production qualities. National-l...

Alpine ski racers require diverse physical capabilities. While enhanced force production is considered key to high-level skiing, its relevance is convoluted. The aims of this study were to i) clarify the association between performance path length and velocity, ii) test the importance of radial force, and iii) explore the contribution of force magn...

In alpine ski racing, different line choices can drastically affect turn or sectional performance. The straight-line transition between two turns is the main phase where skiers can gain speed in a race, open their trajectory, or reduce their path length. Between two turns, a skier can foster speed increase by spending more time in a straight line,...

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...

Assessing football players’ sprint mechanical outputs is key to the performance management process (e.g. talent identification, training, monitoring, return-to-sport). This is possible using linear sprint testing to derive force-velocity-power outputs (in laboratory or field settings), but (i) testing requires specific efforts and (ii) the movement...

Assessing football players' sprint mechanical outputs is key to the performance management process (e.g. talent identification, training, monitoring, return-to-sport). This is possible using linear sprint testing to derive force-velocity-power outputs (in laboratory or field settings), but (i) testing requires specific efforts and (ii) the movement...

Context Strength-endurance mainly depends on the power output, which is often expressed relative to the individual’s maximal power capability (Pmax). However, an individual can develop the same power, but in different combinations of force and velocity (force-velocity condition). Also, at matched power output, changing the force-velocity condition...

The purpose of this study was (i) to assess the differences in relative glide time and both ski edging angle and plantar pressure mediolateral distribution in skiers of different levels and (ii) to further investigate the relationships between the aforementioned variables. Twelve male cross-country skiers (6 national and 6 regional level) skied at...

This study aimed to: 1) understand how the calculation of step-averaged ratio of forces (RF; horizontal component as a percentage of total ground reaction force (GRF) magnitude) affects the RF-horizontal velocity (vH) profile; 2) establish the importance of RF to early acceleration (i.e. up to the end of step 4) performance; 3) assess how well the...

Purpose: The goal of this study was to compare the force production capacities between boulderers, lead climbers and speed climbers during a pull-up test using a force-velocity-power profile. Methods: 24 high elite climbers (11 boulderers, 8 lead climbers, 5 speed climbers) realized two pull-ups at different percentages of their body mass (0%, 30%...

We tested the hypothesis that the degree of adaptation to highly focused sprint training at opposite ends of the sprint Force-Velocity (FV) spectrum would be associated with initial sprint FV profile in rugby athletes. Training-induced changes in sprint FV profiles were computed before and after an eight-week in-season resisted or assisted sprint t...

The purpose of this study was to evaluate improvements in functional performance through the use of the Limb Symmetry Index of Single and Triple Hop tests between 12 and 52 weeks after anterior cruciate ligament reconstruction, and to compare these values with usual time-based and performance-based criteria used during the return to sport continuum...

This study aimed to compare the magnitude of the force-velocity (F-V) relationship parameters (maximum force [F0], maximum velocity [V0], F-V slope, and maximum power [Pmax])between the squat jumps (SJ) performed from different knee angles. The F-V relationships of 12 men were assessed in 3 sessions during the SJ performed from a knee angle of 80º...

Studies have suggested that older individuals are more fatigable than young adults when power loss, measured during single-joint contractions, is considered the fatigue index; however, age-related differences in fatigue considering power measurements during multi-joint movements (e.g., cycling) have not been fully elucidated yet. This study examine...

This study aimed to describe the seasonal changes in the sprint force-velocity (Fv) profile of professional soccer players. The sprint Fv profile of 21 male soccer players competing in the first division of the Spanish soccer league was evaluated 6 times: preseason 1 (September 2015), in-season 1 (November 2015), in-season 2 (January 2016), in-seas...

Background The force-velocity-power (FVP) profile is used to describe dynamic force production capacities, which is of great interest in training high performance athletes. However, FVP may serve a new additional tool for cardiac rehabilitation (CR) of coronary artery disease (CAD) patients. The aim of this study was to compare the FVP profile betw...

Sport scientists and strength and conditioning coaches are showing growing interest in the magnitude, orientation, and application of ground reaction force during acceleration actions in sport, as it can identify the key mechanical determinants of performance. Horizontal force-velocity pro-filing or sprint profiling helps practitioners understand t...

After anterior cruciate ligament reconstruction (ACLR), a test battery is often performed to allow the 2nd step of Return to Sport (RTS-2) continuum: the return to play. Lower limb force production capacities assessment during sprinting could be interesting because it is safe for the graft, provides complementary information in addition to usual fu...

Introduction: Musculoskeletal monitoring is sometimes used in the framework of injury prevention and to identify subjects at risk of injuries. The objective was to determine a « variation profile » musculoskeletal parameters that are potentially involved in the occurrence of injuries in young alpine skiers. Method: Five elite alpine skiers (17.6 ±...

Use this spreadsheet to compute the sprint mechanical outputs from 4 to 6 split times or velocity-time data. Watch the video tutorial here: https://www.youtube.com/watch?v=T-VrkU_Ev6w&t=152s https://jbmorin.net/2017/12/13/a-spreadsheet-for-sprint-acceleration-force-velocity-power-profiling/

Lower limbs muscle force capabilities can be determined during all-out sprints, but the method is accurate only if the testing protocol provides a good fit of the data in the torque-velocity (T-V) and power-velocity (P-V) relationship curves. This study compared the goodness of fit from single all-out sprints performed against the traditional (TRAD...