Unrestrained Versus Vertically Restrained Loaded Countermovement Jumps: Are There Any Differences in the Components of Force Application?

The objective of this study was to compare a number of variables derived from the vertical and horizontal force components between loaded countermovement jumps performed in a Smith machine (SM modality; vertically restrained jumps) and with free weights (FW modality; unrestrained jumps). Twenty-three recreationally trained individuals, 6 women and 17 men, performed on a 3D force platform 5 maximal countermovement jump trials against 3 external loads (30%, 50%, and 70% of the SM 1-repetition maximum) using the SM and FW jumping modalities on separate sessions. The SM modality promoted greater values for virtually all the variables derived from the vertical force component (maximal force, maximal and minimum velocity, and impulse) and also shorter durations of the braking and propulsive phases. Regardless of the countermovement jump phase (braking or propulsive), the impulse directed toward the backward direction was always considerably greater for the SM compared with the FW modality. These results evidence that for recreationally trained individuals, the SM modality could be more effective to increase the general force capacity of the leg muscles due to increased external stability, while the FW modality is preferable when the orientation of force application is a crucial consideration, as it reduces the horizontal force component.

Effect of defence response time during lunge in foil fencing.

The aim of this study was to analyse the effect of stimulus change timing on reaction response time parameters, horizontal velocity of the centre of mass (CM) and precision during offensive actions in fencing. Twelve fencers from the Spanish National Foil Team were included in the study. Two 500 Hz force plates were used to register the horizontal component of the reaction force while a 3D video camera set at 250 Hz recorded the spatial position of 11 body markers and a projector connected to a programmed stopwatch projected a moving target (stimulus) on a screen. When the circle (target) appeared in the centre of the plastron, fencers had to execute a step-forward-lunge as fast as possible, trying to touch the circle with the tip of the foil. During the lunge, the position of the target could randomly shift or not to three different positions. The stimulus change was performed randomly at four different times with a progressive delay. The results show that target changes did not have any effect when they occurred at the beginning of the movement sequence. However, when the target change was delayed, reaction and movement times increased and the technical execution of the lunge changed, leading to more errors.

Time Required to Initiate a Defensive Reaction to Direct and Feint Attacks in Fencing.

The two-fold purpose of this study was to analyze the time required by a fencer to initiate a defensive action in response to a direct attack, which involves identifying when the defending fencer detects the just-noticeable difference, and, secondly, to assess the effect that an attacker's rapid armed hand movement (feint attack) has on the time required to initiate a defensive move. Twenty-four elite fencers and a fencing master were included in the study. Four adapted force plates were installed on a scaffold used as a fencing piste. A 3D video analysis system recorded the location of 2 markers installed on the fencing master's shoulder and sword. The results confirm that the defending fencer has a mean movement time of 0.353 ± 0.028 s to perform the defensive action, which provides an advantage over the attacking fencer. The velocity of movement in the peripheral visual field has no influence on the time required by elite fencers to initiate a defensive action. This confirms the crucial role that response inhibition processes play when nonrelevant actions are perceived. Kinematic analysis of markers suggests that the eye movements of elite fencers are not the only source of information used while observing an attack.

An analysis of two styles of arm action in the vertical countermovement jump.

The aim of this study was to determine the effect of two arm swing techniques, the simultaneous arm swing and the early arm swing, on vertical countermovement jump performance and on the contribution of the arms to vertical movement at the centre of mass (CM) during the propulsion phase. Participants were 28 athletes practicing sports in which the vertical jump constitutes a basic ability. Ground reaction forces were recorded by a force platform and the sagittal plane motion was recorded by a video camera. Although at take-off the vertical velocity (2.7 +/- 0.2m/s for simultaneous technique vs. 2.8 +/- 0.2m/s for early technique; p = 0.040) and position (1.18 +/- 0.06m for simultaneous vs. 1.17 +/- 0.05m for early; p = 0.033) of the CM were significantly different, no difference was observed in jump height (1.56 +/- 0.01m in both techniques). The arm action differed during the initial and final propulsion phases in both styles but the accumulated vertical contribution was similar. The practical implication in sports is that the use of the arm-swing technique to reach the maximum jump height should be determined by tactical demands instead of the technical execution of the arms.

Effect of uncertainty during the lunge in fencing.

The aim of this study is to determine the effect that uncertainty, in relation to the probability of error, exerts on the reaction response and speed during the lunge in fencing. The participants were 18 regional-level fencers with over five years' experience. Force platforms under the feet recorded the horizontal components of the reaction forces, from which the kinematic parameters of the center of mass were calculated. An electronic system to present stimuli, controlled by a programmable clock, projected a target onto a screen that represented a plastron. In situations without uncertainty, the fencers had to lunge as swiftly as possible when a circle (the target) appeared in the center of the plastron, trying to touch the center of the circle with the tip of the sword. In situations with uncertainty, the fencers had the same target as in the previous situation but they received the information that they had to change the lunge into a defensive move if the target disappeared from the plastron during the action. The results indicate that the reaction time and the movement time increased with uncertainty. Although there were no differences for the horizontal velocity of the center of mass at the end of the acceleration phase, the mean horizontal velocity of the lunge was reduced by the effect of the uncertainty. Prior knowledge of the opponent´s possible action implies a reduction in uncertainty, reducing movement time as well as meaning faster execution, thereby increasing the success of the lunge in fencing. Key PointsReaction time (RT) and the movement time (MT) increase when doubts arise about being able to reach the target as planned during the lunge.The horizontal velocity of the lunge decreases by the effect of uncertainty due to the possibility that the events might not occur as planned.These results highlight the importance that tactical intent has in fencing for successfully predicting the defensive movements of the opponent during the attack.

Effect of target change during the simple attack in fencing.

The aim of this study was to test the effect that changing targets during a simple long lunge attack in fencing exerts on the temporal parameters of the reaction response, the execution speed, and the precision and the coordination of the movement pattern. Thirty fencers with more than 10 years of experience participated in this study. Two force platforms were used to record the horizontal components of the reaction forces and thereby to determine the beginning of the movement. A three-dimensional (3D) system recorded the spatial positions of the 9 markers situated on the fencer plus the epee, while a moving target was projected on a screen, enabling the control of the target change. The results indicated that when a target change is provoked the reaction time (RT), movement time (MT), and the time used in the acceleration phase of the centre of mass (CM) increases significantly with respect to the attack executed with a straight thrust. The speed and horizontal distance reached by the CM at the end of the acceleration phase (VX(CM) and SX(CM), respectively) significantly decreased, while the errors increased. However, the temporal sequence of the movement pattern did not appreciably change.

Effectiveness of a Cognitive-Motor Training Program in Reducing Attentional Cost During Walking in Patients With Multiple Sclerosis.

The purpose of this study was to assess the efficacy of a combined training program (CTP) in reducing the effects of dual tasking on the temporal parameters and kinematics of gait, as compared with single-task gait. A controlled, randomized, intervention study was performed in an intervention group and a control group. The intervention group attended three weekly CTP sessions for 24 weeks. Gait pattern was evaluated prior to the baseline intervention, at 12 weeks, and at 24 weeks (Repost). The sample was composed of 22 subjects diagnosed with multiple sclerosis with an Expanded Disability Status Scale score of 0-5.5. A total of 12 patients were allocated to the intervention group and another 10 to the control group. A three-dimensional photogrammetry scanner was connected to a selective attention system designed to present a dual-task gait condition. Dual tasking had an impact on all spatiotemporal parameters of gait, and the most remarkable effect of dual tasking was on double-support time, which increased by 9% with respect to normal walking. In contrast, dual tasking had a trivial effect on single-support time. The CTP was effective in reducing the effects of dual tasking on stride length and velocity of the center of mass after Repost of training (p < .05). The CTP reduced time in double-support phase, whereas single-support time increased after Repost of intervention. The application of the CTP had no effect on the cost of the double task after 12 weeks of intervention. It is suggested to increase the application time over Repost.

Anticipatory strategies of team-handball goalkeepers.

This study seeks to discover whether handball goalkeepers employ a general anticipatory strategy when facing long distance throws and the effect of uncertainty on these strategies. Seven goalkeepers and four throwers took part. We used a force platform to analyse the goalkeeper's movements on the basis of reaction forces and two video cameras synchronised at 500 Hz to film the throw using 3D video techniques. The goalkeepers initiated their movement towards the side of the throw 193 ± 67 ms before the release of the ball and when the uncertainty was reduced the time increased to 349 ± 71 ms. The kinematics analysis of their centre of mass indicated that there was an anticipatory strategy of movement with certain modifications when there was greater uncertainty. All the average scores referring to velocity and lateral movement of the goalkeeper's centre of mass are significantly greater than those recorded for the experimental situation with bigger uncertainty. The methodology used has enabled us to tackle the study of anticipation from an analysis of the movement used by goalkeepers to save the ball.

Dual-Task Cost of Discrimination Tasks During Gait in People With Multiple Sclerosis.

PURPOSE: The aim of the study was to assess dual-task cost to spatio-temporal gait parameters in people with multiple sclerosis and a matched control group. METHOD: The multiple sclerosis group was composed of 17 participants with a diagnosis of multiple sclerosis and an Expanded Disability Status Scale score of less than 6. A total of 17 healthy participants were allocated to the control group by stratification. Controls were matched on the basis of age, sex, sociocultural habits, and body structure. Dual-task cost was determined by within-group repeated-measures analysis of variance. Participants were instructed to ambulate under normal conditions and perform a discrimination and decision-making task concurrently. Then, between-group analysis of variance was used to assess differences in mean dual-task cost between groups and determine dual-task cost differential. Testing was performed using three-dimensional photogrammetry and an electronic walkway. RESULTS: Based on dual-task cost differential, gait cycle time increase (-5.8%) and gait speed decrease (6.3%) because of multiple sclerosis-induced impairment. CONCLUSIONS: During single- and dual-task conditions, gait speed was lower in multiple sclerosis participants, because of a shorter step length and increased swing time. Increased gait time might be the result of compensatory mechanisms adopted to maintain stability while walking specially during the double-support phases.

Effect of a Combined Program of Strength and Dual Cognitive-Motor Tasks in Multiple Sclerosis Subjects.

This study investigated the effects of a 24-week combined training program (CTP) based on strength exercises and cognitive-motor tasks performed concurrently in participants with multiple sclerosis. A randomized, controlled intervention study was carried out. In total, 31 subjects with a confirmed diagnosis of multiple sclerosis (14 men and 17 women) were stratified and randomized into an intervention group (17 subjects) and a control group (14 subjects). The intervention group completed three weekly training sessions for 24 weeks, while the control group pursued their normal daily activities. In this program, cognitive-motor tasks were completed at once (dual tasking). A 3D photogrammetry connected to a selective attention system designed for dual tasking while walking was used. Ground reaction forces were measured using two force plates, one for sit-to-stand testing, while the other was used for static force measurement. Postural equilibrium was examined using a stabilometric plate based for Romberg test assessment. The 24-week training program for multiple sclerosis patients improved their static peak force by 11% (p < 0 .05), their rate of force development by 36% (p < 0.05), and their balance (p < 0.05). Performance in daily activities such as walking or sitting-to-standing improved significantly in multiple sclerosis participants. CTP training was effective in reducing the dual-task costs of step length (48%) and walking velocity (54%), as compared to a matched control group.

A comparison of two landing styles in a two-foot vertical jump.

In team sports, such as basketball and volleyball, the players use different takeoff styles to make the vertical jump. The two-foot vertical jump styles have been classified according to the landing style and identified as hop style, when both feet touch the ground at the same time, and step-close style, when there is a slight delay between the first and second foot making contact with the ground. The aim of this research is to identify the differences between the two styles. Twenty-three subjects participated in the study, of whom 14 were volleyball players and 9 were basketball players. The jumps were video recorded and synchronized with two force platforms at 250 Hz. Two temporal periods of the takeoff were defined according to the reduction or increase in the radial distance between the center of gravity (CG) and the foot support (T - RDCG and T + RDCG, respectively). The findings produced no specific advantages when both styles were compared with respect to takeoff velocity and, consequently, to jump height, but takeoff time was significantly shorter (p < 0.001) in the hop style takeoff. However, this reduction was compensated for by the greater time employed in the last step of the approach run (p < 0.001). When the step-close style was used, the vertical velocity of CG at the beginning of the takeoff is significantly lower. Moreover, the mean vertical force developed during T - RDCG was reduced by -627.7 +/- 251.1 N, thus lessening impact on landing. Horizontal velocity at the end of the takeoff is less when the step-close style is used (p < 0.005), suggesting that this style is better for jumps where it is necessary to move horizontally during the flight against an opponent.

Components of attack response inhibition in fencing: Components of attack response inhibition in fencing.

Applying the Go/No-Go paradigm to fencing, we investigated the relationship between the moment at which the No-Go signal appeared after a movement had been initiated and the time required by fencers to suppress the motor execution of a step-lunge. Secondarily, we determined a time threshold from which movement inhibition results in an error. The No-Go stimulus was represented by a real attack movement. 18 elite fencers and a fencing master were included in the study. Four force plates measured the horizontal components of the fencer's and master's reaction forces, which were used to calculate the time components of the attack and the response inhibition process. Also, the velocity and displacement of the master's and fencer's respective centres of mass were estimated using inverse dynamics. In all cases, cognitive inhibition processes were completed after the onset of movement. Movement time was calculated using four time components (muscle activation, muscle deactivation, transition and braking time). The results obtained revealed that cognitive processes were not significantly affected by the timing of the appearance of the No-Go signal. In contrast, movement time and its time components tended to decrease when the time delay between the No-Go stimulus and the onset of the fencer's movement increased. In conclusion, any attempt to withhold an attack movement when it has already started leads to an error that increases the risk of being hit by the opponent, especially when attack is inhibited within 150 ms after the movement has started.

Effect of dual-attention task on attack and defensive actions in fencing.

The objectives of this study were to investigate the effect that the presence of two stimuli that require two different responses (dual-attention) has both, on offensive reaction-response time to a light stimulus, and on defensive response time when the stimulus is a real fencing attack. Twenty-five elite fencers and a fencing master were included in the study. The equipment included four force plates adapted to a scaffold that served as a fencing piste. Two force plates were placed, at the start position, under the fencer's feet and another two plates were placed under the master's feet. The results demonstrate that choice reaction time to visual stimuli increases in dual-task conditions with respect to simple reaction time, whereas the mean horizontal force tends to decrease in dual-task. However, when the stimulus was an opponent's movement, dual-task conditions did not have any effect on the time required to initiate a defensive action. The changes in reaction time when real movements were used as stimuli challenge the validity of the reaction time to visual stimuli paradigm as a predictor of performance in fencing. Also, the results obtained demonstrate that perceptual and attentional processes play a major role in fencer performance in real competition.

Motoneuron loss associated with chronic locomotion impairments after spinal cord contusion in the rat.

Information on the nature of deficits and adaptive mechanisms occurring after spinal cord injury is essential to the design of strategies for promoting functional recovery. Motor impairments and compensations were quantified by three-dimensional kinematic analysis in freely walking rats, 6 months after mild cervical (C7) or moderate lumbar (L2) spinal cord contusion. After C7 contusion, the animals showed reduced elbow extension and wrist movement, whereas reduced knee extension was the main impairment after L2 contusion. In both cases, the duration of the walking cycle increased and forward velocity was reduced due to a longer stance phase. Histology revealed reproducible lesions extending approximately to one spinal cord segment. In the transverse plane, the lesion involved the central gray matter and adjacent axons, including the dorsal corticospinal tract, but partially spared the ventrolateral tracts. Retrograde motoneuron tracing by nerve exposure to HRP or intramuscular injection of aminostilbamidine demonstrated that C7 contusion caused the loss of approximately 40% of triceps brachii motoneurons, whereas approximately 30% of quadriceps femoris motoneurons were lost after L2 contusion. These results demonstrate permanent deficits after incomplete lesions at the spinal cord enlargements and suggest that motoneuron loss contributes to their production.

Response timing in the lunge and target change in elite versus medium-level fencers.

The aim of the present work is to examine the differences between two groups of fencers with different levels of competition, elite and medium level. The timing parameters of the response reaction have been compared together with the kinetic variables which determine the sequence of segmented participation used during the lunge with a change in target during movement. A total of 30 male sword fencers participated, 13 elite and 17 medium level. Two force platforms recorded the horizontal component of the force and the start of the movement. One system filmed the movement in 3D, recording the spatial positions of 11 markers, while another system projected a mobile target over a screen. For synchronisation, an electronic signal enabled all the systems to be started simultaneously. Among the timing parameters of the reaction response, the choice reaction time (CRT) to the target change during the lunge was measured. The results revealed differences between the groups regarding the flight time, horizontal velocity at the end of the acceleration phase, and the length of the lunge, these being higher for the elite group, as well as other variables related to the temporal sequence of movement. No significant differences have been found in the simple reaction time or in CRT. According to the literature, the CRT appears to improve with sports practice, although this factor did not differentiate the elite from medium-level fencers. The coordination of fencing movements, that is, the right technique, constitutes a factor that differentiates elite fencers from medium-level ones.

Effect of uncertainty on the reaction response in fencing.

PURPOSE: The objective was to determine the way in which the level of uncertainty produced during the execution of a lunge attack with target change (two or four possible responses) affects reaction-response time parameters and kinematic factors involved in the technical coordination of the attack. METHOD: Seventeen fencers from the Spanish National Men's Fencing Team participated in the study, which involved performing a lunge attack against a moving circle as fast as possible, while attempting to place the tip of the sword inside the circle that appeared in the plastron's center of symmetry. Two force platforms were used to record the anteroposterior component of force and the initiation of movement. Kinematics were measured with a three-dimensional motion-capture system that recorded the spatial positions of 11 markers. An electronic signal was used to time-synchronize all of the systems. RESULTS: The results demonstrate a significant increase in reaction time, p < .01, and choice reaction time, p < .001, when uncertainty increases, while movement time, precision, and segmental participation sequence during movement are not affected when uncertainty increases. CONCLUSION: It is worth stressing the importance of uncertainty-reduction strategies for fencers' performance to reduce the reaction-response time. Although increased uncertainty has little influence over precision and segmental participation sequence of the movement pattern used in attacks executed by elite fencers, caution should be used when generalizing these results for fencers of a lower technical level than that of the participants in this study.

Biomechanical analysis of anticipation of elite and inexperienced goalkeepers to distance shots in handball.

The objective of this study was to evaluate the anticipation time and kinematic factors in the movement of goalkeepers' center of mass when making a long-distance throw in handball. The sample group was composed of 14 goalkeepers and field players. A force platform was used to measure the force of the goalkeepers' reaction movements, while the throwers' movements were recorded with high-speed cameras. The expert goalkeepers began to move 193 ± 67 ms before the ball was released, with a 67% success rate of interception. The inexperienced goalkeepers began their movement 209 ± 127 ms with a 24% success rate. The time taken by expert goalkeepers to begin a vertical movement of their CM, relative to the moment of the ball's release, was less than the time taken by inexperienced goalkeepers (77 ± 70 vs. 141 ± 108 ms respectively). The analysis of the velocity and movement indicates that expert goalkeepers wait longer before moving than do inexperienced goalkeepers.

Prediction of distance in hammer throwing.

The aim of this study was to determine how much the predicted distance of a hammer throw is affected by (1) ignoring air resistance and (2) assuming that the centre of mass of the hammer coincides with the centre of the ball. Three-dimensional data from actual throws (men: 72.82 +/- 7.43 m; women: 67.78 +/- 4.02 m) were used to calculate the kinematic conditions of the hammer at release. A mathematical model of the hammer was then used to simulate the three-dimensional airborne motion of the hammer and to predict the distance of the throw. The distance predicted for vacuum conditions and using the ball centre to represent the hammer centre of mass was 4.30 +/- 2.64 m longer than the official distance of the throw for the men and 8.82 +/- 3.20 m longer for the women. Predictions using the true centre of mass of the hammer reduced the discrepancy to 2.39 +/- 2.58 m for the men and 5.28 +/- 2.88 m for the women. Predictions using air resistance and the true centre of mass of the hammer further reduced the discrepancy to -0.46 +/- 2.63 m for the men and 1.16 +/- 2.31 m for the women. Approximately half the loss of distance produced by air resistance was due to forces made on the ball and the remainder to forces made on the cable and handle. Equations were derived for calculation of the effects of air resistance and of the assumption that the centre of mass of the hammer coincides with the centre of the ball, on the distance of the throw.

Efecto de la restricción segmentaria en los test de salto vertical CMJ / Effect of segmental restriction in the vertical jump test CMJ

En esta investigación se han pretendido tres objetivos: a) evaluarla contribución segmentaria en la altura alcanzada por el Centro de Masas (CM) en el salto vertical contramovimiento, b) proponer ecuaciones que nos permitan predecir la altura del salto a partir del protocolo propuesto en el test de Bosco CMJ y c) Investigar los efectos de diferentes métodos para el cálculo de la altura del salto vertical. Han participado 29 deportistas con experiencia en el salto vertical. Las fuerzas de reacción se obtuvieron a través de una plataforma de fuerza Dinascam/IBV a una frecuencia de 500 Hz, sincronizada temporalmente a una cámara de alta velocidad que registraba el plano sagital de los saltos realizados sobre la plataforma. Los sujetos realizaron dos tipos de saltos verticales máximos: con acción de brazos (CMJ+b) y usando el protocolo del test Bosco (CMJ). Los registros de las componentes rectangulares de la velocidad y la posición del CM, se determinaron mediante integración, a partir de las respectivas componentes de la fuerza de reacción. Los resultados han puesto de manifiesto que con acción de brazos, la altura alcanzada por el CM se incrementa un 12%.El 39% de este incremento se debió a la posición del CM en el despegue y el 61% restante al desplazamiento vertical del CM. El desplazamiento vertical del CM se debió al tiempo de impulso y no al incremento de la fuerza media. Cuando se incrementa el desplazamiento vertical del CM para los saltos sin acción de brazos, también se incrementa para los saltos realizados con acción de brazos (r =0.79; p<0.001). No se han encontrado diferencias entre los dos sistemas de registro para los saltos CMJ+ b, mientras que cuando se utiliza el "test de Bosco" (CMJ) han existido claras diferencias (p<0.001) (AU)

This research had three main goals: a) to assess the segmental contribution to the reached height by the center of mass (CM) during countermovement vertical jump, b) to propose equations that allow us to predict the height of the jump from the proposed protocol Bosco in the CMJ test and c) to investigate the effects of different methods to calculate vertical jump height. Twenty-nine athletes with experience in vertical jump took part on the study. Ground reaction forces were obtained from a Dinascam/IBV force platform at a sampling rate of 500 Hz, a time-synchronized to a high speed camera that recorded the sagittal plane of the jumps performed on the platform. The subjects performed maximum vertical jumps with arm action (CMJ + b) and using the test protocol Bosco (CMJ). The records of the rectangular components of the velocity and position of the CM were determined by integration, from the respective components of the reaction force. The results have shown that action of the arms, the height reached by the CM is increased by 12%. This increased was 39% due to the position of the CM at takeoff and 61% because of the vertical displacement of CM. The increase of the vertical displacement was due to the pulse time and the increase in average strength. When the vertical displacement of CM for action jumps without arms was increased, it was also increased for the action jumps performed with arms (r =0.79, p <0.001). No differences were found between the registration systems for jumps CMJ + b, whereas when there was used "test of Bosco" (CMJ) there were found clear differences (p <0.001) (AU)

Efecto de la superficie de contacto sobre los factores biomecánicos en el golpeo de fútbol / Effect of contact surface on biomechanics factors in the football kick

El objetivo general del presente estudio es el análisis e identificación de los parámetros biomecánicos discriminativos entre el golpeo con el interior del pie y el realizado con el dorso-interior. Para ello se han utilizado técnicas cinematográficas tridimensionales (3D), las cuales nos han permitido cuantificar ciertos factores que inciden en la técnica del golpeo de fútbol con trayectoria frontal del balón. Se han utilizado dieciocho jugadores de fútbol pertenecientes a equipos universitarios, con una talla media de 1,74 m (ñ0,043 m) y un peso de 71,88 Kg (ñ5,69 Kg). A cada uno de ellos se le filmó un total de cuatro golpeos de balón, dos de ellos con el dorso-interior del pie y otros dos con el interior. Para su análisis se seleccionó el golpeo donde se había conseguido una mayor velocidad de salida del balón para cada jugador y superficie de contacto. En general, se han encontrado diferencias significativas importantes en la velocidad tangencial del pie de golpeo en el instante de tomar contacto con el balón (p<.001), distancia comprendida entre el CG y el talón del pie de golpeo, en el instante de tomar contacto con el balón (p <.00 1) y en la distancia comprendida entre ia perpendicular dei CG y el talón del pie de apoyo en el instante de tomar contacto con el suelo (p<0,001). Los datos han puesto de manifiesto que existen diferencias en la secuencia de participación segmentaria, confirmando la teoría general de las cadenas cinéticas implicadas en los golpeos, realizándose dicha acción de forma más simultánea cuando el golpeo se realiza con el interior del pie. Aunque con diferente secuencia temporal, en los dos casos se ha encontrado una gran participación de las caderas en rotación a través del eje vertical, lo que nos confirma la importancia que tienen los músculos rotadores del tronco para un jugador de fútbol (AU)