Environmental Factors as a Cause of Differences in the Feet of Ecuadorian Children and Its Relation to Their Footwear.

The objective of this study was to analyze the differences in foot measurements of Ecuadorian children according to their geographical location of residence, taking into account climatic differences (1). A total of 1662 children (2) participated in the study. Three groups were established: coast, mountains and amazonia. The type of footwear (3) used was recorded and the lengths, widths, perimeters, heights and angles of both (4) feet were analyzed with a 3D foot digitizer (5). The variable 'fitting of the foot to footwear' was also obtained. Children living in coastal areas presented greater lengths, widths, perimeters and heights compared to those living in the mountain (p > 0.001) and amazonia (p < 0.001) between ages 5 to 13. Mountain residents showed a greater first toe angle than coast residents (p > 0.001) aged 8 to 17. Children used shoes smaller than required by their foot length (p < 0.01). Ecuadorian children from the coast presented longer and wider feet with higher foot arches, whilst those from mountains presented greater first toe angle. The studied sample used footwear up to one size smaller than the size corresponding to their foot length. The fitting and type of footwear used according to climatic differences could be interfering with normal foot development.

The relation of foot morphology to performance in three vertical jumping tasks / Relación entre la morfología del pie y el rendimiento en tres saltos verticales

SUMMARY: The objective of this research is to relate the performance in three vertical jump events with morphological variables of the foot and stature. A total of 177 practitioners of 12 sporting events aged 24.5 ±8.0 years, with 71.01 ±13.00 kg of body mass, 1.71±0.09 m height, and BMI of 24.29±3.24 kg·m-2 were evaluated with an anthropometer in terms of foot length (FL), forefoot width (FW), navicular height (NH), and hindfoot width (HW). These variables were normalized to the height of the subjects. From the footprint record the arch index (AI) was obtained, which indicates the morphology of the medial longitudinal foot arch (MLFA). Performance was evaluated in three vertical jump events: countermovement jump (CMJ), squat jump (SJ), and drop jump (DJ), recording the height reached. FL, FW and HW show a weak positive correlation (r<0.4; p<0.05) with the heights achieved in the three types of jump. The stature is strongly associated with FL, FW and HW (r=0.8; r=0.7 and r=0.6; respectively; p<0.05) and with the height in CMJ, SJ, and DJ (r=0.37; r=0.41 and r=0.32, respectively, p<0.05). The only normalized morphological foot variable that maintained consistency in the correlations analysis was the normalized foot length (NFL) with CMJ (r = 0.2, p<0,05). The subjects whose left foot length was equivalent to 14 % of the stature jumped 27.94 ±6.63 cm, those with 15 % jumped 30.96 ±7.4 cm, and those with 16 % jumped 31.03 ±7.8 cm. FL, FW, HW, and stature are moderately correlated with performance in vertical jump events. However, after discarding the stature of the subjects, only the foot length maintained its relation with performance in CMJ.

RESUMEN: El objetivo de esta investigación fue relacionar el rendimiento en salto vertical con variables morfológicas del pie y estatura. 177 practicantes de 12 disciplinas deportivas de 24,5 ±8,0 años; 71,01 ±13,00 kg; 1,71 ±0,09 m, e IMC de 24,29 ±3,24 kg•m-2 fueron evaluados con un antropómetro obteniendo longitud de pie (FL), ancho de antepié (FW), altura navicular (NH) y ancho de retropié (HW). Estas variables fueron normalizadas a la estatura. Se midió la huella plantar obteniendo el índice del arco (AI), el cual indica la morfología del arco plantar longitudinal medial (MLFA). El rendimiento fue evaluado en tres pruebas de salto: salto con contramovimiento (CMJ), sentadilla con salto (SJ) y salto desde caída (DJ), registrando la altura alcanzada. FL, FW y HW mostraron una débil correlación positiva (r<0,4; p<0,05) con la altura alcanzada en los tres saltos. La estatura se asocia con FL, FW y HW (r=0,8; r=0,7 y r=0,6; respectivamente; p<0,05) y con la altura en CMJ, SJ y DJ (r=0,37; r=0,41 y r=0,32, respectivamente, p<0,05). La única variable normalizada del pie que mantuvo consistencia en el análisis de correlaciones fue la longitud del pie normalizada (NFL) con CMJ (r=0,2; p<0,05). Los sujetos cuyo pie tiene una longitud equivalente al 14 % de la estatura saltaron 27,94 ±6,63 cm, los que equivalen al 15 % saltaron 30,96 ±7,4 cm y quienes tuvieron un pie equivalente a un 16 % de la estatura saltaron 31,03 ±7,8 cm. FL, FW, HW y la estatura se correlacionan moderadamente con el rendimiento en salto vertical. Sin embargo, después de descartar la estatura de los sujetos, solamente la longitud del pie mantiene su relación con el rendimiento en CMJ.

A study of reproducibility of kinesiology tape applications: review, reliability and validity.

BACKGROUND: Literature addressing the mechanical properties of kinesiology tape is quite scarce. There are no studies which focus on the mechanical characteristics of kinesiology tape, its mechanical properties, nor its adherence following the ISO international standard test methods for tape elongation. METHODS: This study quantified the mechanical characteristics of 380 samples of kinesiology tape from 19 different brands and in 4 different colors using a dynamometer. Mechanical testing was controlled by UNE EN ISO 13934-1. RESULTS: Significant differences were found between tape brands in terms of grammage, maximum force tenacity, work, pre-elongation and percentage elongation (P < .001). Regarding kinesiology tape color, statistically significant differences were found between tape brands in terms of grammage, maximum force and tenacity (P < .001), work and pre-elongation (P < .05). When adherence was studied, statistically significant differences were found between tape brands in terms of maximum force and work (P < .001). CONCLUSIONS: The different kinesiology tapes presented different behaviors with regard to rupture and removal when applied to skin in dry state, wet state and after being submerged in artificial acidic sweat solution. Therefore, different kinesiology tape brands will produce different levels of strain even though the same elongation is used. Depending on the characteristics (body dimensions) and properties (skin elongation) of each subject in the sample, bandages with different elongations must be applied to achieve the same strain in all of the tapes and therefore produce the same effect. The absence of these data at this time limits the reliability of previous clinical studies, makes comparing their findings impossible and presents new challenges for research in this field.

Load-controlled moderate and high-intensity resistance training programs provoke similar strength gains in young women.

INTRODUCTION: While current exercise guidelines recommend progressive, high-intensity resistance training (RT) to promote muscle hypertrophy and strength gains, controversy exists regarding the efficacy of lighter-load RT. We compared 2 work-matched RT interventions that differed in training intensity. METHODS: Fifteen women underwent 10 weeks of unilateral knee extensor RT. One leg was trained at increasing intensity (intensity leg, InL, 50-80% 1-repetition maximum [1-RM]), and training progression in the contralateral leg (volume leg, VoL, 50% 1-RM) was based on increasing training volumes. Quadriceps muscle size (ultrasound, dual energy X-ray absorptiometry) and strength (isokinetic dynamometry) were assessed on 4 occasions. RESULTS: Both training programs induced significant, yet comparable increases in muscle size (InL: +4.6-12%, VoL: +3.1-11%) and strength (InL: +10-16%, VoL: +10-14%). CONCLUSIONS: Training at lower than commonly suggested intensities may be an equally effective alternative form of RT. Factors other than training intensity, such as the total mechanical work during training, may strongly affect the training response.

Effects of isometric training on the knee extensor moment-angle relationship and vastus lateralis muscle architecture.

PURPOSE: To analyse the muscle adaptations induced by two protocols of isometric training performed at different muscle lengths. METHODS: Twenty-eight subjects were divided into three groups: one (K90) performed isometric training of the knee extensors at long muscle lengths (90° of knee flexion) for 8 weeks, and the second group (K50) at short muscle lengths (50°). The subjects of the third group acted as controls. Isokinetic dynamometry was utilized to analyse the net moment-angle relationship and vastus lateralis muscle thickness at three different locations, and pennation angles and fascicle length at 50 % of thigh length were measured at rest with ultrasonography. RESULTS: Only subjects from K90 group showed significant increases in isokinetic strength (23.5%, P < 0.001), while K50 group showed no increases in isokinetic strength: (10%, P > 0.05). There was a shift in the angle of peak torque of the K90 group to longer muscle lengths (+14.6%, P = 0.002) with greater increases in isokinetic strength, while the K50 angle shifted to shorter muscle lengths (-7.3%, P = 0.039). Both training groups showed significant increases in muscle thickness, (K90 9-14% vs. K50 5-9%) but only K90 significantly increased their pennation angles (11.7%, P = 0.038). Fascicle lengths remained unchanged. CONCLUSIONS: Isometric training at specific knee angles led to significant shifts of peak torque in the direction of the training muscle lengths. The greater strength gains and the architectural changes with training at long muscle lengths probably come from a combination of different factors, such as the different mechanical stresses placed upon the muscle-tendon complex.

Foot morphology in Spanish school children according to sex and age.

The aim of this study was to analyse the differences in foot dimensions in a sample of Spanish school-aged children. A total of 497 boys and 534 girls from Spain participated in the study. Measurements of both feet were obtained using a 3D foot digitiser, and shoe sizes were recorded and then estimated based on foot length measurements. The variations in foot measurements underwent a gradual increase with age in both boys and girls. Gender differences appeared at the age of 8-9 years, when the girls in the sample were found to wear smaller shoes than those they should have worn. Most foot dimensions begin to differ between boys and girls at the age of 8 years. The girls in the sample studied used footwear that was too small for their foot length, probably because they looked for a better width fit.

Diferencias de comportamiento del tobillo funcionalmente recuperado en test de salto monopodales / Behavioral differences of functional ankle sprain recoveries during single-leg jump test

Objetivo: Analizar las diferencias en las fuerzas de reacción verticales intra-sujeto entre una extremidad que presentó signo de bostezo articular en el tobillo frente a la extremidad sin bostezo. Métodos: Participaron 18 sujetos voluntarios (8 mujeres y 10 hombres), físicamente activos, con una media de edad, de20,4 ± 1,9 años. Con una plataforma de fuerzas se midieron las fuerzas de reacción verticales, el tiempo de estabilización yel desplazamiento del centro de presiones en las caídas y estabilización de 3 test de salto en apoyo monopodal: salto hacia delante, salto lateral desde un escalón y saltos laterales continuos. Resultados: En el test de salto hacia delante la extremidad sin bostezo presento un 2º pico de fuerza mayor (bostezo =1142,08 ± 242,50 N; no bostezo = 1213,39 ± 299,89 N) (p<0,05). El tiempo de estabilización en el eje medio-lateral fue mayor en la extremidad con bostezo en el test de caída lateral desde un escalón (bostezo = 12.83 ± 1,77 s; no bostezo = 11,42 ± 2,14 s) (p<0,05). Conclusiones: La extremidad con bostezo presentó menores impactos verticales en el segundo pico de fuerza en la caída del test de salto hacia delante, compatible con una mayor amortiguación que pudiera obedecer a un mecanismo de protección. Se vieron aumentos en el tiempo de estabilización en el test de caída lateral desde un escalón en los tobillos que habían padecido esguince. No obstante no se observaron incrementos en las áreas barridas por el centro de presiones en ninguno de los tests. Los tests dinámicos funcionales son capaces de detectar déficits en los ejes específicos en los que se realiza el test y detectar déficits tras un esguince (AU)

Objective: To analyze within subject differences in ground reaction forces. The tests were carried out by comparing the ankle with a previous lateral ligament injury (with permanent ligament loosening) and the one without ligament loosening. Material and methods: Eighteen volunteers were recruited for the study (8 women and 10 men), all of them physically active, with a mean age of 20.4 ± 1.9. The vertical ground reaction forces, the time of stabilization and the path of the center of pressures were measured during the landing and posterior stabilization in 3 single-leg jump tests on a force platform: jump landing test, lateral drop jump test and side hop test. Results: The second peak of the vertical force were greater in the uninjured limb during the jump landing test (injured= 1142.08 ± 242.50 N; uninjured = 1213.39 ± 299.89 N) (p<0.05). The medio-lateral time of stabilization was greater in the uninjured limb during the lateral drop jump test (injured = 12.83 ± 1.77 s; uninjured = 11.42 ± 2.14 s) (p<0.05).Conclusions: The injured limb presented lower vertical impact at the second peak force during the jump landing test, compatible with a softly landing which could be a defense mechanics. The injured limb showed an increased in the time of stabilization during the lateral drop jump test. However, there were no changes in any of the 3 tests in the excursion area of the center of pressure. The dynamic functional tests are useful to detect deficits in the specific axis where the tests are performed, as well as deficits after and an ankle injury (AU)

Foot morphology in normal-weight, overweight, and obese schoolchildren.

UNLABELLED: This study compared the foot morphology of Spanish schoolchildren based on their body mass index and age and analyzed whether body mass index affects the child's foot development at primary school. Cross-sectional study of 1,032 schoolchildren (497 boys and 535 girls), 6-12 years old. Height and weight were measured to calculate body mass index. Children were classified as obese, overweight, and normal-weight. Measurements of foot morphology were obtained with a three-dimensional feet digitizer in static standing. Significant differences were found between the feet of children with normal-weight and overweight (2.6 to 9.0 %) and among children with normal-weight and obese for all variables (3.9 to 17.3 %). Differences in width, ball height, and arch height (5.3 to 7.6 %) were only found among overweight and obese children. There were no changes in the foot morphology of children between 6 and 7 years and between 10 and 12 years. Obese children showed more gradual changes in the foot measurements. The average percentage increase by year in children with normal-weight and obese were similar (3.6 and 3.4 %, respectively); however, morphological measurements of the foot of overweight children increased at a faster rate (4.0 %). CONCLUSION: Excess weight affects the foot structure of children. The differences between age groups seem to indicate that the feet of children with overweight and obesity follow a different growth pattern than that of normal-weight children. With these results, the shoe manufacturers can design shoes for children depending on their age and weight.

Neuromechanical adaptation induced by jumping on an elastic surface.

Jumping on an elastic surface produces a number of sensory and motor adjustments. This effect caused by jumping on the trampoline has been called "trampoline aftereffect". The objective of the present study was to investigate the neuromuscular response related with this effect. A group of 15 subjects took part in an experimental session, where simultaneous biomechanical and electromyographic (EMG) recordings were performed during the execution of maximal countermovement jumps (CMJs) before and after jumping on an elastic surface. We assessed motor performance (leg stiffness, jump height, peak force, vertical motion of center of mass and stored and returned energy) and EMG activation patterns of the leg muscles. The results showed a significant increase (p ≤ 0.05) of the RMS EMG of knee extensors during the eccentric phase of the jump performed immediately after the exposure phase to the elastic surface (CMJ(1)), and a significant increase (p ≤ 0.05) in the levels of co-activation of the muscles crossing the ankle joint during the concentric phase of the same jump. Results related with motor performance of CMJ(1) showed a significant increase in the leg stiffness (p ≤ 0.01) due to a lower vertical motion of center of mass (CoM) (p ≤ 0.005), a significant decrease in jump height (p ≤ 0.01), and a significantly smaller stored and returned energy (p ≤ 0.01). The changes found during the execution of CMJ(1) may result from a mismatch between sensory feedback and the efferent copy.

Efectos del ejercicio continuo e intermitente sobre la huella plantar / Effects of continuous and intermittent exercise on the footprint record

Introducción: Este estudio buscó comparar los cambios producidos en la huella plantar por los desplazamientos intermitentes en el fútbol sala y la carrera continua, y estudiar las diferencias en la respuesta entre hombres y mujeres. Material y métodos: Participaron 10 hombres (edad: 20.4±1.4años) y 10 mujeres sanos y moderadamente activos. Realizaron3 sesiones distintas: un circuito dentro de un campo de fútbol sala con distintas direcciones y velocidades de carrera, una sesión de carrera continua con el mismo volumen del circuito (2500 m) y 30 minutos de carrera continua. Antes y después de las pruebas se analizaron las longitudes de la huella plantar y las áreas y anchuras de antepié, mediopié y retropié. Resultados y conclusiones: Las tres sesiones provocaron cambios significativos en las dimensiones de la huella plantar (0.1-9.1%) aunque sólo la anchura del mediopié fue sensible al número de apoyos en los 30 minutos de carrera (8.0%, P < 0.01).En el resto de parámetros analizados no hubo diferencias entre sesiones, lo que indica que a partir de un determinado número de apoyos, la huella plantar no cambiaba más, independientemente del volumen o la intensidad del ejercicio. La mayoría de estos cambios fueron similares en hombres y mujeres (AU)

Introduction: This study aimed to analyze the changes in the footprint record produced by a simulated futsal course and continuous running. A secondary purpose was to analyze theresponse differences between men and women. Methods: Ten active and healthy men (age: 20.4±1.4 years)and 10 women (age: 19.9±1.4 years) volunteered for the study. They performed 3 exercise sessions: an interval running course into a futsal pitch, a continuous running task with the same distance of the course (2500 m) and 30 minutes of continuous running. Before and after the exercise sessions the foot lengths, widths and areas (forefoot, midfoot, rearfoot) were analyzed from the footprint record. Results and conclusions: All the exercise sessions led to significant changes the footprint parameters (0.1-9.1%).Nonetheless, only the midfoot width changed differently by the greater number of steps performed (+8.0%, P < 0.01). The rest of the parameters showed no differences among sessions, this it seems that, from a given number of steps, the footprint dimensions did not show greater changes, despite the differences in exercise volume or step intensity. Most of these changes were similar between men and women (AU)

La estimulación eléctrica neuromuscular del tibial anterior vs superficie viscoelástica en la reeducación de la propiocepción del tobillo. Un estudio piloto / Neuromuscular electrical stimulation on the tibialis anterior vs viscoelastic surface in the re-education of ankle proprioception. A pilot study

Objetivo: Analizar las diferencias en el recorrido del centro de presiones durante la realizaciónde 3 tests de equilibrio estáticos, en que se incluyen dos de las técnicas usadas en lostratamientos de la rehabilitación del esguince de tobillo.Material y método: Participaron voluntariamente 14 sujetos sanos, sin signo de bostezo articular(8 hombres y 6 mujeres), deportistas, con una media de edad de 19,9±3,8 años. Se midióel recorrido del centro de presiones durante tests de equilibrio monopodal sobre plataformade fuerzas (duración de 60 s), en tres condiciones: sobre superficie estable (plataforma), sobresuperficie viscoelástica, y aplicando estimulación eléctrica neuromuscular en el músculo tibialanterior.Resultados: La amplitud de desplazamiento del centro de presiones en el eje anteroposteriorfue mayor en el test con estimulación eléctrica neuromuscular que en el realizado sobre superficieestable (p < 0,01) y viscoelástica (p < 0,05). La posición media del centro de presiones sesituó más lateral (53,00±7,60mm) y anterior (128,40±10,70mm) en el test sobre superficieviscoelástica. Las mayores áreas barridas por el centro de presiones se obtuvieron en el testcon estimulación eléctrica neuromuscular (1.115,96±411,40mm2).Conclusiones: Con la electroestimulación se obtuvieron mayores amplitudes de desplazamientodel centro de presiones en el eje anteroposterior, una posición media más retrasada, y mayoresáreas barridas. Con la superficie viscoelástica se obtuvo un mayor recorrido y velocidad, y unaposición media del centro de presiones más lateral(AU)

Objective: To analyse the differences in the path of the centre of pressures during the performanceof 3 static balance tests, which included two of the techniques used in the rehabilitationof ankle sprain rehabilitation.Material and method: Fourteen healthy subjects, without ligament loosening in the ankle wererecruited for the study (8 male and 6 female) voluntary participated in this study, all of themphysically active, with a mean age of 19.9±3.8 years. The path of the centre of pressures wasmeasured during monopodal balance tests on a force platform (60 s last), in three different conditions:on stable surface (force platform), on a viscoelastic surface, and during the applicationof electrical stimulation on the tibialis anterior muscle.Results: The anterior-posterior path of the centre of pressures was greater in the test with electricalstimulation than in the tests on the stable surface (P < .01), and on the viscoelastic surface(P < .05).The mean position of the centre of pressures was more lateral (53.00±7.60mm) andmore posterior (128.40±10,70mm) in the test on the viscoelastic surface. The greatest excursionareas of the centre of pressures were found in the test with neuromuscular electricalstimulation (1115.96±411.40mm2).Conclusions: Greater anterior-posterior path length and excursion areas and a more posteriormean position of the centre of pressures were found in the neuromuscular electrical stimulationtest. We also found greater total excursions and velocity, and a more lateral mean position ofthe centre of pressures in the viscoelastic surface tests(AU)

Revisión de las repercusiones de los esguinces de tobillo sobre el equilibrio postural / Review of the repercussions of ankle sprains on postural balance

El esguince lateral de tobillo es una de las lesiones más comunes ocurridas en deporte, pudiendo afectar a diferentes componentes del control postural. Esta revisión bibliográfica analiza los estudios en los que se evalúa el control postural a partir de tests de equilibrio estático, dinámico y dinámico funcional en personas que han sufrido un esguince y personascon tobillos sanos utilizando metodologías cuantitativas. Los tobillos lesionados presentan mayores rangos de desplazamiento del centro de presiones y mayores tiempos de latencia de la musculatura. También presentan mayores tiempos de estabilización en el eje anteroposterior y menor alcance en las posiciones extremas que puede adoptar el centro de presiones. Sin embargo, algunos de los trabajos encontrados usan métodos poco objetivos en la selección de los sujetos con esguince de tobillo y otros utilizan tests y variables poco sensibles para el estudio de las secuelas de déficits de control postural después de un esguince(AU)

The lateral ankle sprain is one of the most common injuries in sports and can affectdifferent components of postural control. This literature review analyses the studies that evaluatethe postural control through static balance tests, dynamic balance tests and dynamicbalance functional tests in subjects who have suffered an ankle sprain and healthy subjectsusing quantitative methods.Injured ankles lead to a greater total path of the centre of pressure and an increased musclelatency time. Furthermore, the antero-posterior time of stabilisation increases and decreasesthe reach distance that can be taken by the centres of pressure. However, in some of the studiesfound, less objective methods are used in the selection of the subjects with an ankle sprain, and in others, non-sensitive tests and variables are used to study the consequences of posturalcontrol deficits after an ankle sprain(AU)

Reliability of squat and countermovement jump tests in children 6 to 8 years of age.

The aim of this study was to determine the reliability of the squat jump test (SJ) and countermovement jump test (CMJ), in fifty-six children (30 girls and 26 boys) with ages ranging from 6 to 8 years. Each subject performed two evaluation sessions (T1, T2) with seven days between tests. The results show that the CMJ test has a high intratrial reproducibility in T1 and T2 measured through intraclass correlation coefficient (ICC ≥ 0.95). The ICC for the SJ test had a high value (0.99) only in T1. The variability for both tests among children under 9 years of age is higher than those reported for adult subjects in other studies. The intersession reliability was questionable with a high methodical error (ME= 9.86-15.1%, for the SJ and CMJ, respectively) and a significant worsening of the results of CMJ in T2 (p < .05).

Diferencias en test de equilibrio estático entre las extremidades con y sin bostezo articular de tobillo / Between limb differences during static balance tests with and without permanent ligament loosening

ObjetivoAnalizar las diferencias intrasujeto entre una extremidad que presentó signo de bostezo articular en el tobillo, fruto de una lesión previa de esguince lateral, frente a una extremidad sin bostezo.Material y métodosTomaron parte en el estudio 14 sujetos voluntarios (6 mujeres y 8 hombres), deportistas, con una media de edad de 19,9±3,8 años. Se midió el rango de movimiento del tobillo de manera estática y pasiva, y el desplazamiento del centro de presiones durante un test de equilibrio monopodal sobre una plataforma de fuerzas (duración de 60s), en tres condiciones: sobre plataforma, sobre espuma y aplicando estimulación eléctrica neuromuscular en el músculo tibial anterior.ResultadosEl rango de desplazamiento del centro de presiones en el eje anteroposterior fue mayor en la extremidad con bostezo en el test sobre espuma (bostezo=60,9±14,3mm; sin bostezo=51,8±9,5mm) (p<0,05). La posición media del centro de presiones de la extremidad con bostezo se situó significativamente más medial en los 3 test (p<0,05) y más posterior en el test con espuma (p<0,01). En el test con electroestimulación, el recorrido total (bostezo=3.097,4±899,3mm; sin bostezo=3.329,3±996,6mm) y la velocidad media (bostezo=51,6±15,1mm/s; sin bostezo=55,1±17,0mm/s) fueron mayores en la extremidad sin bostezo (p<0,05).ConclusiónAl aumentar la dificultad de los test, aumentaron las diferencias entre ambas extremidades. La extremidad con bostezo modificó la posición del centro de presiones situándolo de forma más medial y posterior(AU)

ObjectiveThe purpose of this study was to analyse within subject differences in a number of static balance tests, performed during monopodal stance.Material and methodsThe tests were carried out comparing the ankle with a previous lateral ligament injury (with permanent ligament loosening) and the one without ligament loosening. Fourteen volunteer subjects were recruited for the study (6 women and 8 men), all of them physically active, with a mean age of 19.9±3.8 years. The measurements included the ankle range of motion (static and passive), and the path of the centre of pressures during a monopodal balance test on a force platform (60s last), in three different conditions: on the platform, on a foam pad and during the application of electrical stimulation on the tibialis anterior muscle. All the measurements and tests were applied on both legs, injured and uninjured.ResultsThe anterio-posterior path of the centre of pressures was greater in the previously injured limb in the test on the foam pad (injured=60.9±14.3mm; uninjured=51.8±9.5mm) (p<0.05). The mean position of the centre of pressures in the injured limb was more medial during the three tests (p<0.05) and more posterior in the test on the foam pad (p<0.01). In the test with electrical stimulation, the total path of the centre of pressures (injured=3097.4±899.3mm; uninjured=3329.3±996.6mm) and its average velocity (injured=51.6±15.1mm/s; uninjured=55.1±17.0mm/s) were significantly greater in the uninjured limb (p<0.05).ConclusionsWhen the tests became more challenging, the differences between injured and uninjured limbs were greater. The position of the injured extremity was more medial and posterior during the static tests(AU)

The trampoline aftereffect: the motor and sensory modulations associated with jumping on an elastic surface.

After repeated jumps over an elastic surface (e.g. a trampoline), subjects usually report a strange sensation when they jump again overground (e.g. they feel unable to jump because their body feels heavy). However, the motor and sensory effects of exposure to an elastic surface are unknown. In the present study, we examined the motor and perceptual effects of repeated jumps over two different surfaces (stiff and elastic), measuring how this affected maximal countermovement vertical jump (CMJ). Fourteen subjects participated in two counterbalanced sessions, 1 week apart. Each experimental session consisted of a series of maximal CMJs over a force plate before and after 1 min of light jumping on an elastic or stiff surface. We measured actual motor performance (height jump and leg stiffness during CMJ) and how that related to perceptual experience (jump height estimation and subjective sensation). After repeated jumps on an elastic surface, the first CMJ showed a significant increase in leg stiffness (P < or = 0.01), decrease in jump height (P < or = 0.01) increase in perceptual misestimation (P < or = 0.05) and abnormal subjective sensation (P < or = 0.001). These changes were not observed after repeated jumps on a rigid surface. In a complementary experiment, continuous surface transitions show that the effects persist across cycles, and the effects over the leg stiffness and subjective experience are minimized (P < or = 0.05). We propose that these aftereffects could be the consequence of an erroneous internal model resulting from the high vertical forces produced by the elastic surface.

Prophylactic ankle taping: elastic versus inelastic taping.

BACKGROUND: The ankle is frequently injured in sporting activities, and therefore it is frequently protected with prophylactic ankle taping. This study aimed first, to compare the mechanical fatigue of two types of prophylactic ankle taping after 30 minutes of intense exercise, one made with elastic tape (ET) and the other with inelastic tape (IT), and second, to investigate the subjects' perception on the tape restriction and comfort. MATERIALS AND METHODS: Twenty-seven active women (mean age, 20.6 +/- 4.1 years), without previous ankle injuries volunteered for the study. The participants were tested on three different conditions: with elastic ankle taping, with inelastic taping, and without taping, before and after 30 minutes of intense exercise. The ankle passive ranges of movement (ROMs) were measured before and after exercise, and a subjective scale on taping comfort and restriction was completed by the subjects. RESULTS: Both types of ankle taping showed less ROM restriction after 30 minutes of exercise in inversion (IT = 27% and ET = 21%), and plantarflexion (IT = 8% and ET = 6%). The IT showed more loss of restriction than the ET, with significant differences in inversion (p < 0.05). The participants perceived the ET as more comfortable and less restrictive. CONCLUSION: We would recommend the use of ET as the first choice for prophylactic ankle taping because it produces the same restriction in the ROM as the IT with less taping fatigue, and is perceived as more comfortable and less restrictive by the users.

Ankle taping does not impair performance in jump or balance tests.

This study aimed to investigate the influence of prophylactic ankle taping on two balance tests (static and dynamic balance) and one jump test, in the push off and the landing phase. Fifteen active young subjects (age: 21.0 ± 4.4 years) without previous ankle injuries volunteered for the study. Each participant performed three tests in two different situations: with taping and without taping. The tests were a counter movement jump, static balance, and a dynamic posturography test. The tests and conditions were randomly performed. The path of the center of pressures was measured in the balance tests, and the vertical ground reaction forces were recorded during the push-off and landing phases of the counter movement jump. Ankle taping had no influence on balance performance or in the push off phase of the jump. However, the second peak vertical force value during the landing phase of the jump was 12% greater with ankle taping (0.66 BW, 95% CI -0.64 to 1.96). The use of prophylactic ankle taping had no influence on the balance or jump performance of healthy young subjects. In contrast, the taped ankle increased the second peak vertical force value, which could be related to a greater risk of injury produced by the accumulation of repeated impacts in sports where jumps are frequently performed. Key pointsAnkle taping has no influence on balance performance.Ankle taping does not impair performance during the push-off phase of the jump.Ankle taping could increase the risk of injury during landings by increasing peak forces.

El vendaje funcional elástico VS inelástico en saltos y amotiguaciones / Elastic VS inelastic tape in jumps and landings

El propósito de este estudio ha sido analizar la influencia de dos vendajes funcionales preventivos de tobillo en diferentes tests de salto y amortiguación mediante el estudio de las fuerzas verticales de reacción del suelo. Participaron 27 mujeres jóvenes, sanas y activas (edad=20.6±4.1 años).Se realizaron dos tipos de vendaje funcional preventivo de tobillo, uno con vendas inelásticas (VI) y otro con vendas elásticas (VE), que limitaban la supinación y la extensión. Se analizó su influencia en cuatro tests; (1) buscando la máxima amortiguación desde 0.75 m, (2) lo mismo desde0.30 m, (3) buscando máxima altura de salto sin ayuda de brazos desde parado (CMJ) y (4) lo mismo con ayuda de brazos y 3 pasos de aproximación. Ambos vendajes restringieron, sin diferencias significativas entre ellos, la supinación (restricción respecto a la situación sin vendaje: VI=40.74% y VE=41.77%) y la extensión del tobillo (VI=14.54% y VE=11.15%). No se encontraron diferencias en las alturas de los saltos ni en las potencias mecánicas en la batida entre los vendajes. Tampoco se encontraron diferencias en el segundo pico de fuerza vertical durante la amortiguación de la caída. Sin embargo, con el vendaje inelástico, en los tests donde se buscaba máxima amortiguación, el segundo pico de fuerza sucedía antes que con el vendaje elástico o sin vendaje. Como conclusión del estudio se aconsejaría la utilización del vendaje elástico, siempre que la economía lo permitiera, debido a que no ha modificado ningún aspecto de la biomecánica del salto y la amortiguación, produciendo una limitación en la movilidad del tobillo similar al vendaje inelástico y creando una barrera de restricción progresiva, similar a la situación fisiológica de la articulación (AU)

This study aimed to analyze the influence of two types of prophylactic ankle taping on the vertical ground reaction forces during different jump and landing tests. Twentyseven active and healthy women volunteered for the study (age = 20.6 ± 4.1 years). Two types of prophylactic ankle taping, designed to limit supination and plantar flexion, were applied to the subjects. One of them was done with inelastic tape (VI) and the other with elastic tape (VE). The influence of these ankle tapings was analyzed in four tests;(1) Land from 0.75 m as soft as possible, (2) land from0.30 as soft as possible, (3) jump as high as possible with hands on the hips (CMJ) and (4) jump as high as possible with a 3 m run-up and arm swing. Both types of ankle taping restricted, without significant differences between them, the supination (percentage of restriction compared to the tests without taping: VI = 40.74% and VE = 41.77%)and the plantar flexion (VI = 14.54% and VE = 11.15%).There were no differences between taping conditions in the jump heights or power outputs during the push off phase. There also were no differences in the second peak vertical force value during the landing phase of the jump. However, the peak vertical force value during the landing phase of the tests where a soft landing was required appeared before with the inelastic taping than with the elastic tape or without taping. In conclusion, the results of the present study suggest the use of elastic taping if cost is not a limitation, because it did not modify any biomechanical parameter from the push off or landing phases of the jumps. Additional advantages were that the limitation in the ranges of movement was similar to the inelastic taping and that the restriction was more similar to that performed by the joint complex (AU)

Capacidad de salto y amortiguación en escolares de primaria / Jumping and landing perfomance in school-aged children

Objetivo: El propósito de este estudio ha sido analizar las diferencias en un grupo de escolares según el sexo, la edad y el peso, en la cinética de la amortiguación del test de salto con contra movimiento y ver si guardan relación con la altura del salto y potencia en la batida. Metodología: Se analizaron los saltos de 57 niños (edad =9.3±0.9 años) y 45 niñas (edad = 9.2±1.0 años) de 3º, 4ºy 5º de primaria mediante plataforma de fuerzas. Resultados: Se encontraron diferencias significativas entre cursos en la altura del salto (3º = 15.9±2.5 cm; 4º =17.0±3.1 cm; 5º = 20.9±4.1 cm) y en el pico de potencia (3º = 33.2±3.9 W/kg; 4º = 34.7±3.9 W/kg; 5º = 41.5±5.0W/kg), sin diferencias significativas entre sexos. Los sujetos sin sobrepeso obtuvieron mayores alturas de salto y picos de potencia en la batida (p<0.001). No se encontraron diferencias significativas en el segundo pico de fuerza de reacción vertical durante la amortiguación de la caída (F2)entre los sujetos sin sobrepeso y el resto de sujetos, probablemente porque los primeros saltaban más que quienes tenían sobrepeso u obesidad (18.9±3.9 cm y 15.5±2.7 cm, respectivamente). No aparecieron correlaciones entre altura del salto y F2, lo que indica que independientemente de la altura desde la que se caiga, se podrían conseguir valores bajos en F2.Conclusiones: La ausencia de relaciones significativas entre la potencia en la batida y el pico de fuerza en la fase de amortiguación sugieren que la habilidad para amortiguar correctamente en escolares es independiente de la fuerza explosiva. Las diferencias en fuerza explosiva entre niños con sobrepeso y sin él no se tradujeron en diferencias en la fase de amortiguación, probablemente por las distintas alturas desde las que caían (AU)

Purpose: The purpose of this study was to analyze the differences in the kinetics of the landing phase of a counter-movement jump in a group of school-aged children, according to their gender, age and level of over weight. A secondary purpose was to analyze the relationships between the landing phase and the jump height and peak power during the push-off phase. Methodology: We analyzed the jumps of 57 boys (age =9.3±0.9 years) and 45 girls (age = 9.2±1.0 years) from the 3rd, 4th and 5th courses of the primary school with force platform. Results: There were significant differences among courses in the jump height (3rd = 15.9±2.5 cm; 4th = 17.0±3.1 cm;5th = 20.9±4.1 cm) and in the peak power (3rd = 33.2±3.9W/kg; 4th = 34.7±3.9 W/kg; 5th = 41.5±5.0 W/kg), but not between genders. The children without overweight showed greater jump height and peak power (p<0.001). There were no significant differences in the second peak vertical force value during the landing movement (F2) between the subjects without overweight and the others, probably because the children without overweight performed higher jumps than those with overweight and obesity (18.9±3.9 cm and15.5±2.7 cm, respectively). There were no significant correlations between jump height and F2, which would point out that the children, can perform landings with low F2 values regardless of the landing height. Conclusions: The lack of significant relationships between the power during the push off phase and the peak force value during the landing phase suggest that the ability to perform soft landings does not depend on the explosive force. The differences in explosive force in the children with and without overweight were not found in the landing phase, probably because of the lower jump heights reached by the children with overweight (AU)

Diferencias de sexo durante la amortiguación de caídas en tests de salto / Gender differences during landings after jumping

Objetivo: Analizar, en una población de aspirantes al ingreso en una Facultad de Ciencias del Deporte, la cinética de la batida, vuelo y amortiguación de sus saltos y estudiar las diferencias entre los subgrupos de hombres y mujeres. Metodología: Se analizaron los saltos de 180 sujetos, 132 eran hombres (edad= 19.8+/-3.0 años) y 48 mujeres (edad = 19.6+/-3.3 años). Se utilizó una plataforma de fuerzas Quattro Jump de Kistler. Se analizaron las fuerzas de reacción verticales y la posición del centro de gravedad en un salto con contramovimiento. Resultados: Los hombres lograron mayores alturas del centro de gravedad en el vuelo (hombres = 35.77+/-4.55 cm, mujeres = 26.08+/- 3.33 cm; p<0.001) y mayores segundos picos de fuerza en la amortiguación (F2) (hombres = 7.41+/-2.20 BW, mujeres = 5.72+/-1.82 BW; p<0.001) (BW = veces el peso corporal). Las mujeres mostraron un mayor recorrido del centro de gravedad durante la amortiguación (hombres = 10.21+/-2.26%, mujeres =10.84+/-2.21%; p<0.05). Los valores obtenidos en F2 en el conjunto de la población estudiada han sido superiores a los registrados por otros autores en alturas de caídas mayores, en las que el objetivo era lograr la máxima amortiguación. Conclusiones: Los resultados de este estudio justifican la necesidad de intervenciones profilácticas para enseñar a amortiguar correctamente las caídas de saltos. El mayor valor obtenido en F2 por los hombres podría ser debido a que caían desde mayor altura que las mujeres y al mayor recorrido del centro de gravedad registrado por las mujeres que les protegía de valores altos en F2

Purpose: To analyse, in a population of applicants to a Faculty of Sports Sciences, the kinetics of the push off, flight and Lansing phases in a jump test, and to study the differences between men and women. Methodology: The jumps of 180 applicants to a faculty of Sports Sciences (132 men, mean age: 19.8+/-3.0 years, and 48 women, mean age: 19.6+/-3.3 years) were recorded with a Quattro Jump Kistler force plate. Vertical ground reaction forces and the position of the centre of gravity in a counter movement jump were analysed. Results: The men´s group reached higher heights of the centre gravity during the flight phase (men= 35.77+/-4.55 cm, women = 26.08+/-3.33 cm; p<0.001) and greater vertical forces in the second peak of the landing phase (F2) (men = 7.41+/-2.20 BW, women = 5.72+/-1.82 BW; p<0.001) (BW = body weight). Women showed greater vertical displacement of the centre of gravity during the landing phase (men = 10.21+/-2.26% of subject´s height, women = 10.84+/-2.21%; p<0.05). The values of F2 in the population studied have been greater than those found in other studies performed with higher landing heights, but with the aim of maximal softening. Conclusion: The results of the present study support the necessity of prophylactic interventions to teach proper landing techniques among specific populations. The greater values of F2 in the men´s group could have be caused by the higher landing heights and the shorter vertical displacement of the centre of gravity during the landing phase, compared to the women´s group