Pierre Samozino

Université Savoie Mont Blanc | UdS · Sciences et Technologies des Activités Physique et Sportives (STAPS)

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...

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...

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 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...

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 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...

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...

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...

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...

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...

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...

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,...

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 conditio...

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 crosscountry skiers (6 national and 6 regional level) skied at 4...

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 8-week in-season resisted or assisted sprint train...

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...

This study aimed to compare the reliability and magnitude of the force-velocity (F-V) relationship parameters between the squat jumps performed from the 90º (SJ90) and self-preferred knee angle (SJpref). A secondary aim was to explore the effect of the analysis procedure (force platform [FP] and Samozino's [SAM] method) and the number of loads test...

Lower limb external maximal power output capacity is a key physical component of performance in many sports. During squat jump and countermovement jump tests, athletes produce high amounts of mechanical work over a short duration to displace their body mass (i.e. the dimension of mechanical power). Thus, jump height has been frequently used by the...

Measuring the ground reaction forces (GRF) underlying sprint acceleration is important to understanding the performance of such a common task. Until recently direct measurements of GRF during sprinting were limited to a few steps per trial, but a simple method (SM) was developed to estimate GRF across an entire acceleration. The SM utilizes displac...

AimsWe analysed the changes in force-velocity-power variables and jump performance in response to an individualized training program based on the force-velocity imbalance (FVimb). In particular, we investigated (i) the individual adaptation kinetics to reach the optimal profile and (ii) de-training kinetics over the three weeks following the end of...

The majority of studies have routinely measured neuromuscular (NM) fatigue with a delay (~1–3 min) after cycling exercises. This is problematic since NM fatigue can massively recover within the first 1-2 minutes after exercise. This study investigated the etiology of knee extensors (KE) NM fatigue and recovery kinetics in response to cycling exerci...

The assessment of horizontal force during overground sprinting is increasingly prevalent in practice and research, stemming from advances in technology and access to simplified yet valid field methods. As researchers search out optimal means of targeting the development of horizontal force, there is considerable interest in the effectiveness of ext...

Objectives: To provide a comprehensive overview of what is known about injury prevention in the 14–19-year-old competitive alpine skier following the 4-step injury prevention sequence from van Mechelen et al. (1992). Method: A systematic review was conducted in November 2018 using two database (“Pub Med” and “Science Direct”) and the following keyw...

While fatigue can be defined as an exercise-related decrease in the maximal power or isometric force, most studies have assessed only isometric force. The main purpose of this experiment was to compare dynamic measures of fatigue [maximal torque (Tmax), maximal velocity (Vmax) and maximal power (Pmax)] with measures associated with maximal isometri...

Measuring the ground reaction forces (GRF) underlying sprint acceleration is important to understanding the performance of such a common task, but until recently, direct measurements of GRF during sprinting were limited to only a few steps per trial. A simple method (SM) based on displacement- or velocity-time data fitted by an exponential model an...

Objective: To investigate the relationship between the perception of cushioning and variable measured using tibia acceleration in heel–toe running. Method: Ten rearfoot strikers’ runners ran at 3.9 m.s⁻¹ on a stiff treadmill in seven footwear conditions presenting different mechanical properties through midsole geometries and/or materials. The perc...

In the published article, there was an error in the affiliation for Zoran Grgantov. Instead of affiliation 6, “Faculty of Psychology, eCampus University, Novedrate, Italy,” the correct affiliation for Zoran Grgantov should be affiliation 7, “Faculty of Kinesiology, University of Split, Split, Croatia”. The authors apologize for this error and state...