Frédérique Hintzy

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

Introduction Soft tissue vibrations (STV) have been extensively researched for their effects on muscle fatigue and damage, but their influence during running remains unclear. As compression garments are known to lower STV, they have shown benefits on acute neuromuscular responses to downhill running. However, an in-depth analysis of changes in STV...

We compared neuromuscular fatigue induced by cycling at a fixed perceived effort in normoxic condition (NOR) and three purported hypoxia modalities: systemic hypoxia (SyH, FiO2 = 0.13), blood flow restriction (BFR, 50% arterial occlusion pressure) and airflow restriction mask (ARM, calibrated to ~3500 m). Seventeen healthy young participants cycled...

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...

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...

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...

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....

The purpose of the study was to assess the influence of a preceding mountain ultramarathon on the impact between the foot and the ground and the resulting soft tissue vibrations (STV). Two sessions of measurements were performed on 52 trail runners, before and just after mountain trail running races of various distances (from 40 to 171 km). Triaxia...

Cyclists are exposed for a long period to continuous vibrations. When a muscle is exposed to vibration, its efficiency decreases, the onset of fatigue occurs sooner, and the comfort of the cyclist is reduced. This study characterised the vastus lateralis (VL) soft tissue vibrations for different input frequencies and different pedalling phases. Ten...

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,...

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...

Hintzy, F, Gregoire, N, Samozino, P, Chiementin, X, Bertucci, W, and Rossi, J. Effect of thigh-compression shorts on muscle activity and soft-tissue vibration during cycling. J Strength Cond Res 33(8): 2145-2152, 2019-This study examined the effects of different levels of thigh compression (0, 2, 6, and 15 mm Hg) in shorts on both vibration and mus...

The purpose of this study was to investigate the evolution of ground reaction force during alpine skiing turns. Specifically, this study investigated how turn phases and slope steepness affected the whole foot normal GRF pattern while performing giant slalom turns in a race-like setting. Moreover, the outside foot was divided into different plantar...

Background: Ankle movements can be partially encoded by cutaneous afferents. However, little is known about the central integration of these cutaneous signals, and whether individual differences exist in this integration. The aim of this study was to determine whether the effect of cutaneous stimulation at the ankle would differ depending on the p...

External ankle supports, such as ankle braces, may improve postural stability by stimulating cutaneous receptors. It remains unknown whether these supports have an effect on the posture central regulation. The aim of this study was to determine the effect of wearing a soft ankle brace on soleus H-reflex amplitude and presynaptic inhibition during s...

Non-circular chainrings have been reported to alter the crank angular velocity profile over a pedal revolution so that more time is spent in the effective power phase. The purpose of this study was to determine whether sprint cycling performance could be improved using a non-circular chainring (Osymetric: ellipticity 1.25 and crank lever mounted ne...

Sporaltec, Cluster de la région Rhône-Alpes, a comme stratégie d'être un accélérateur d'innovations pour toutes les entreprises du secteur Sport & Santé. A ce titre, il fédère toutes les typologies d'acteurs de ce secteur (mais aussi des secteurs complémentaires) : entreprises, laboratoires, fédérations, ... Sporaltec travaille aussi en partenariat...

Le but de cette expérimentation était d’étudier l’effet d’un cuissard compressif sur l’évolution de l’activation musculaire et du transfert vibratoire au cours d’un pédalage avec vibration induisant une fatigue neuromusculaire. Quinze sujets ont réalisé un exercice d’un pédalage (20 min, 85 rpm avec vibrations 33 Hz et 2 mm d’amplitude) avec un cui...

Non-circular chainrings alter the crank velocity profile over a pedalling cycle. The aimof this study was to investigate the effect of this altered crank velocity profile on the aerobic performance compared to a circular chainring (CC). Ten male non-cyclists performed two incremental maximal tests at 80 rpm on a cycle ergometer: one with a circular...

Abstract The aim of this study was to investigate the effect of using poles on foot-ground interaction during trail running with slopes of varying incline. Ten runners ran on a loop track representative of a trail running field situation with uphill (+9°), level and downhill (-6°) sections at fixed speed (3.2 m.s(-1)). Experimental conditions inclu...

Purpose To quantify the net energy expenditure and the respective implications of the aerobic and lactic energy sources over a giant slalom (GS) performed in the field in young ski racers. Methods Seven young alpine skiing competitors (14.0 ± 0.5 years) volunteered to participate in the study. An inclusion session consisted of an evaluation of the...

A theoretical integrative approach is proposed to understand the overall mechanical characteristics of lower extremities determining jumping ability. This approach considers that external force production during push-off is limited by mechanical constraints imposed by both movement dynamics and force generator properties, i.e. lower extremities cha...

Il s’agissait d’analyser les modifications perceptives, musculaires et physiologiques induites par l’utilisation d’une selle ergonomique sans appui périnéal et permettant les pivotements médiolatéraux du bassin.

Our aim was to clarify the relationship between power output and the different mechanical parameters influencing it during squat jumps, and to further use this relationship in a new computation method to evaluate power output in field conditions. Based on fundamental laws of mechanics, computations were developed to express force, velocity and powe...

Purpose. - The purpose of this study was to examine the relationships of VO2 during unloaded arm cranking and leg cycling exercises to respectively relevant upper and lower limbs anthropometrical characteristics. Method. - Fifteen males completed a 5-min unloaded bout on an arm crank ergometer (60 rpm) and a cycle ergometer (90 rpm). VO2 correspond...

The aim of this study was to describe elliptical cycle locomotion by muscular, kinematics, physiological and perceptual parameters during submaximal and maximal exercises. Seven men performed an incremental test until exhaustion. Pulse rate, ratings of perceived exertion (6–20 Borg's scale), muscular activity of 8 muscles (higher and lower limbs mu...

This study analysed muscular, mechanical and physiological parameters using a circular chainring (CC) and a non circular Osymetric chainring (OC). OC was characterized by the use of a lower radius during top and bottom dead center and a higher radius during downstroke and upstroke phases. Twelve triathletes performed (i) an 8 min submaximal test a...

The aim of this study was to evaluate the stabilisation of the wrist joint and the ad hoc wrist muscles activations during the two principal phases of the freestyle stroke. Seven male international swimmers performed a maximal semi-tethered power test. A swimming ergometer fixed on the start area of the pool was used to collect maximal power. The e...

The purpose of the present experiment was to investigate the immediate effects of a cycling exercise on postural control during quiet standing in healthy young adults. To this aim, 12 university students were asked to stand upright as immobile as possible, with their eyes closed, prior to and following a 15 min cycling exercise performed at a power...

The objective of this study was to partly explain, from electromyographical (EMG) activity, the decrease in power output beyond optimal pedaling rate (PRopt) during sprint cycling. Eleven cyclists performed four 8-s nonisokinetic sprints on a cycle ergometer against four randomized friction loads (0.5, twice 0.75, and 0.9 N x kg(-1) of body mass)....

The purpose of this study was to investigate the interactions between cadence and power output effects on cycling efficiency. Fourteen healthy subjects performed four constant power output-tests (40, 80, 120 and 160 W) in which the cadence varied in five bouts from 40 to 120 rpm. Gross efficiency (GE) was determined over the last ten respiratory cy...

The purpose of this study was to investigate the interactions between cadence and power output effects on cycling efficiency. Fourteen healthy subjects performed four constant power output-tests (40, 80, 120 and 160 W) in which the cadence varied in five bouts from 40 to 120 rpm. Gross efficiency (GE) was determined over the last ten respiratory cy...

The present study aimed to investigate the effects of a high-intensity swim test among top-level swimmers on (i) the spatial and temporal parameters of both the stroke and the 3-D fingertip pattern and (ii) the mechanical, muscular, and physiological parameters. Ten male international swimmers performed a 4 x 50 m swim at maximal intensity. Isometr...

Introduction. – The aim of this study was to analyse the evolution of neuromuscular fatigue in vastus lateralis and gastrocnemius medialis muscles during all-out cycling test at 100% maximal aerobic power.Fact synthesis. – Mean EMG increased from the beginning of the test and then decreased after have attained its maximum for all subjects and for b...

The aim of this work was to analyse the effect of a non-circular chainring during sub and supra-maximal cycling conditions on physiological, mechanical and muscular data. Results showed that the use of the non-circular chainring was beneficial during top and bottom dead centres by decreasing the effective force for a same external force for sub-max...

The purpose of this study was to evaluate different efficiency indices, i.e., gross (GE: no baseline correction), net (NE: resting metabolism as baseline correction), and work (WE: unloaded exercise as baseline correction), to reveal the effect of endurance training on mechanical efficiency. Nine healthy sedentary women undertook an incremental tes...

This study proposed a non-invasive method to determine the gross (GE, no baseline correction), net (NE, resting metabolism as the baseline correction) and work (WE, unloaded cycling as the baseline correction) efficiencies during cycling at an intensity higher than the maximal aerobic power (MAP). Twelve male subjects performed two exercises consis...

The effects of endurance training in normoxia or in hypoxia on time to exhaustion (T lim) at the work rate corresponding to peak oxygen uptake (V̇O2peak) were examined at sea level in 13 healthy subjects. Before and after training the subjects performed the following: (1) incremental exercises up to exhaustion to determine peak oxygen uptake in nor...

Objective: The purpose of this study was to compare four methods of calculating the mechanical efficiency of hand-rim wheelchair propulsion. Methods: After completing a maximal incremental test, 18 untrained able-bodied males (mean age 22 years) performed four 4-min bouts of exercise (0%, 40%, 55%, and 70% of peak power output) on a wheelchair-e...

The aim of this study was to determine the relationship between force and velocity parameters during a specific multi-articular upper limb movement--namely, hand rim propulsion on a wheelchair ergometer. Seventeen healthy able-bodied females performed nine maximal sprints of 8 s duration with friction torques varying from 0 to 4 N x m. The wheelcha...

Without Abstract

The purpose of this study was to compare work efficiency values (WE = work accomplished/energy expenditure above exercising with 0 load) among different unloaded base-line correction techniques for different power outputs. Twelve healthy men performed 6 5-min steady-state exercises of 0 (unloaded), 40, 80, 120, 160 and 200 W at a pedalling rate of...

To determine the optimal pedalling rate that minimises both the oxygen consumption (f V˙O2,min) and the energy cost of cycling (f Cr,min), 22 male subjects were asked to cycle on an ergometer on five occasions of 4 min each at a constant power output of 150 W and at pedalling rates of 40, 60, 80, 100 and 120 rpm. The oxygen consumption (V˙O2 in mil...

The present study was performed to compare various individual muscular efficiency indices, i. e., gross (GE), net (NE), work (WE), and delta (DE), during arm cranking ergometer (ACE) and wheelchair ergometer (WERG) exercise at the same relative exercise intensities. Following a maximal test on both the ACE and WERG, 15 able-bodied subjects complete...

Purpose – Since wheelchair propulsion involves both arms working in a simultaneous cyclic motion with an active and a recovery phase, the frequency of arm pushing can be varied without affecting the velocity of the wheelchair when the power output remains constant. The purpose of this study was to analyse the effects of frequency and timing charact...

Purpose – The purpose of the present study was to examine the relationships between mechanical values (maximal velocity, force and power) generated on a cycle ergometer and sprint performance during the acceleration phase of a sprint start, using starting-blocks in trained male athletes.Methods – 7 male athletes volunteered to perform in a randomis...

The purpose of this study was to investigate the effects of endurance and sprint training on the perception of the optimal pedalling rate during a submaximal cycling exercise. Six subjects specialized in endurance activities and 6 subjects trained in sprinting activities used the model of bicycling at various pedalling rates with the same power out...

The aim of this study was to develop and validate a scale rating the perceived exertion of young children (RPE-C) who do not read. This scale presents seven pictures showing a man who becomes progressively fatigued. In order to evaluate this scale, we examined its reliability and sensitivity. Thirteen children (aged 5 to 6 years) completed two iden...

Purpose. The purpose of this study was to compare the mechanical parameters measured on a non-isokinetic cycle ergometer equiped with or without toe-clip pedals during sprinting. Methods. Two groups of subjects (international-national and regional cyclists) performed four sprints of 8 seconds with two different friction forces applied to the belt...

The aim of this study was to compare optimal pedalling velocities during maximal (OVM) and submaximal (OVSM) cycling in human, subjects with different training backgrounds. A group of 22 subjects [6 explosive (EX), 6 endurance (EN) and 10 non-specialised subjects] sprint cycled on a friction-loaded ergometer four maximal sprints lasting 6 s each fo...