11 research outputs found
Influencia de los parĂĄmetros biomecĂĄnicos en el rendimiento y la economĂa de corredores de fondo aficionados
Los objetivos de este estudio son analizar la relaciĂłn entre las variables biomecĂĄnicas, la economĂa de carrera y el rendimiento en corredores de fondo aficionados. AdemĂĄs, determinar si existe algĂșn cambio en los parĂĄmetros biomecĂĄnicos coincidente con el umbral anaerĂłbico ventilatorio. Participaron 10 corredores de fondo aficionados realizando: AntropometrĂa, baterĂa de saltos verticales, prueba de economĂa de carrera y prueba de consumo mĂĄximo de oxĂgeno. Estas Ășltimas realizadas en tapiz rodante, registrĂĄndose parĂĄmetros fisiolĂłgicos (ventilatorios y frecuencia cardiaca) y biomecĂĄnicos (tiempos de contacto y de vuelo, frecuencia y amplitud de zancada, âduty factorâ). Por primera vez, se ha observado una relaciĂłn entre parĂĄmetros biomecĂĄnicos espacio-temporales de la carrera (frecuencia y amplitud de zancada), el rendimiento y la economĂa de carrera. AdemĂĄs, se ha comprobado que la apariciĂłn del umbral anaerĂłbico ventilatorio se encuentra relacionada con cambios en la biomecĂĄnica de la carrera (fundamentalmente âduty factorâ y amplitud de zancada). Las relaciones encontradas entre las variables antropomĂ©tricas y de salto, economĂa de carrera y rendimiento estĂĄn en consonancia con las mencionadas en estudios previos, asĂ como que la relaciĂłn entre la economĂa de carrera y el rendimiento. Futuros trabajos deberĂan realizarse en corredores de mayor nivel para contrastar estos hallazgos.The aim of this study is to analyze the relationship between running biomechanics, running economy and performance in recreational long distance runners. Additionally, determine if there is any change in running biomechanical parameters that coincides with the anaerobic threshold. Ten recreational runners performed an anthropometric evaluation, a battery of vertical jumps, a running economy test and a maximal incremental test. Both running tests were performed in a treadmill, registering simultaneously physiological (ventilation and heart rate) and biomechanical (contact and flight times, stride length and rate, âduty factorâ) parameters. A relationship between running biomechanics (step length and rate), running economy and performance was obtained. Furthermore, the appearance of the ventilatory anaerobic threshold was related with changes in running biomechanics (mainly with âduty factorâ and step length). The relationships between anthropometry and vertical jumpsâ parameters, running economy and performance still consistent with those identified in previous studies, as well as the relationship between running economy and performance. Future studies should be done with a higher level sample to contrast these findings.Peer Reviewe
Influencia de la longitud de la biela en la eficiencia y biomecaÌnica del pedaleo submaÌximo
El principal objetivo de este estudio es analizar el efecto de pequenÌos cambios en la longitud de la biela en el gasto energeÌtico y la teÌcnica de pedaleo submaÌximo. Participaron 12 ciclistas de fondo en carretera bien entrenados, que realizaron pruebas de pedaleo a tres potencias con cadencia estable, utilizando tres longitudes de biela (en orden aleatorio). Sus bicicletas fueron exactamente reproducidas en un ergoÌmetro que mediÌa el torque ejercido sobre la biela izquierda y derecha de forma independiente. SimultaÌneamente se registroÌ cinemaÌtica 2D de la pierna derecha y el gasto energeÌtico al pedalear (eficiencia gruesa). Los resultados muestran que los cambios en la longitud de la biela no tuvieron efecto en la eficiencia gruesa, pero siÌ en las variables biomecaÌnicas. Una biela de mayor longitud provocoÌ una peÌrdida de eficiencia mecaÌnica y un aumento en la flexioÌn y el rango de movimiento de la cadera y la rodilla, sin cambios en el tobillo. Aunque estos cambios no fueron lo suficientemente importantes para alterar la eficiencia gruesa, siÌ que podriÌan tener implicaciones negativas a largo plazo (peor teÌcnica de pedaleo y riesgo de lesioÌn). En conclusioÌn, el efecto de pequenÌos cambios en la longitud de la biela, que seriÌan asumibles por ciclistas de competicioÌn, producen alteraciones en la biomecaÌnica de pedaleo, pero no en su eficiencia gruesa. Futuros estudios deben abordar los efectos a largo plazo de estos cambios.The main purpose of this study was to analyze the effects of small changes in crank length on gross efficiency and pedaling technique during submaximal cycling. Twelve well-trained road cyclists participated. They pedaled at three power outputs and steady cadence with three crank lengths (in a randomized order). Their bicycles were exactly reproduced on an ergometer where crank torque of the left and right legs were independently registered. 2D kinematic of the right leg and energy cost (gross efficiency) were recorded. The results showed that changes in crank length had no effect on the gross efficiency, but had effect on the biomechanical variables. A longer crank caused a decreased in mechanical efficiency and an increase in the flexion and range of movement of the hip and the knee, without changes in the ankle. These alterations were not significant enough to alter the gross efficiency, but they could have negative long-term implications (worse pedaling technique and possible injuries). In conclusion, the small changes in crank arm length which are feasible for competitive cyclists affected cycling biomechanics, but not gross efficiency. Future studies should study long-term effects of these changes.Peer Reviewe
Variables antropomeÌtricas, fisioloÌgicas y bimecaÌni- cas determinantes del rendimiento en corredores de media maratoÌn
El objetivo es analizar la influencia de los factores antropomeÌtricos, fisioloÌgicos y biomecaÌnicos en el rendimiento de carreras de fondo. Participaron 48 corredores clasificados en 4 niveles seguÌn rendimiento en media maratoÌn (hh:mm:ss): Grupo 1 (n=11, <1:10:00), Grupo 2 (n=13, <1:20:00), Grupo 3 (n=13, <1:30:00), Grupo 4 (n=11, <1:45:00). Realizaron una valoracioÌn antropomeÌtrica, prueba submaÌxima de economiÌa de carrera y prueba maÌxima de VO2max. Estas uÌltimas realizadas en tapiz rodante, registraÌndose paraÌmetros fisioloÌgicos y biomecaÌnicos (anaÌlisis espacio-temporal). Se observaron diferencias entre grupos y correlaciones con el rendimiento en ciertas variables ligadas al entrenamiento (anÌos de experiencia y kiloÌmetros semanales), antropomeÌtricas (masa, IMC y sumatorio de pliegues), fisioloÌgicas (VO2max, umbral anaeroÌbico y economiÌa de carrera) y biomecaÌnicas (tiempos de contacto en prueba submaÌxima; tiempos de contacto y amplitudes de zancada en prueba maÌxima). Las diferencias en los tiempos de contacto podriÌan explicarse por los distintos patrones de pisada de los corredores (talonadores vs planta entera/antepieÌ), velocidad a la que se obtuvieron las variables fisioloÌgicas (umbrales y VO2max) y, en menor medida, por el nivel de rendimiento. AsiÌ, a excepcioÌn de la amplitud de zancada, el resto de variables biomecaÌnicas han mostrado ser poco sensibles al rendimiento obtenido en esta disciplina.The aim of the study was to analyze the influence of anthropometric, physiological and biomechanical factors on long-distance running performance. Forty-eight runners participated in the study and were classified into 4 groups according to their performance level in half-marathon (hh:mm:ss): Group 1 (n=11, <1:10:00), Group 2 (n=13, <1:20:00), Group 3 (n=13, <1:30:00), Group 4 (n=11, <1:45:00). They performed an anthropometric evaluation, a submaximal running economy test and a maximal incremental test. Both running test were performed on a treadmill, registering simultaneously physiological and biomechanical (spatio-temporal) parameters. Significant differences between groups and correlations with performance were obtained with training-related variables (experience and km/week), anthropometrics (mass, BMI and sum of skinfolds), physiological (VO2max, anaerobic threshold and running economy) and biomechanical (contact times in submaximal test; contact times and step length in incremental test). Differences in contact times could be explained by the different runnersâ foot strike patterns (rearfoot vs midfoot/forefoot), speed where physiological variables were obtained (thresholds and VO2max), and to a less extend, to performance level. Thus, except from step length, the rest of biomechanical variables have shown to be not very sensitive to long-distance running performance.Peer ReviewedAward-winnin
Influencia de la longitud de la biela en la eficiencia y biomecaÌnica del pedaleo submaÌximo
El principal objetivo de este estudio es analizar el efecto de pequenÌos cambios en la longitud de la biela en el gasto energeÌtico y la teÌcnica de pedaleo submaÌximo. Participaron 12 ciclistas de fondo en carretera bien entrenados, que realizaron pruebas de pedaleo a tres potencias con cadencia estable, utilizando tres longitudes de biela (en orden aleatorio). Sus bicicletas fueron exactamente reproducidas en un ergoÌmetro que mediÌa el torque ejercido sobre la biela izquierda y derecha de forma independiente. SimultaÌneamente se registroÌ cinemaÌtica 2D de la pierna derecha y el gasto energeÌtico al pedalear (eficiencia gruesa). Los resultados muestran que los cambios en la longitud de la biela no tuvieron efecto en la eficiencia gruesa, pero siÌ en las variables biomecaÌnicas. Una biela de mayor longitud provocoÌ una peÌrdida de eficiencia mecaÌnica y un aumento en la flexioÌn y el rango de movimiento de la cadera y la rodilla, sin cambios en el tobillo. Aunque estos cambios no fueron lo suficientemente importantes para alterar la eficiencia gruesa, siÌ que podriÌan tener implicaciones negativas a largo plazo (peor teÌcnica de pedaleo y riesgo de lesioÌn). En conclusioÌn, el efecto de pequenÌos cambios en la longitud de la biela, que seriÌan asumibles por ciclistas de competicioÌn, producen alteraciones en la biomecaÌnica de pedaleo, pero no en su eficiencia gruesa. Futuros estudios deben abordar los efectos a largo plazo de estos cambios.The main purpose of this study was to analyze the effects of small changes in crank length on gross efficiency and pedaling technique during submaximal cycling. Twelve well-trained road cyclists participated. They pedaled at three power outputs and steady cadence with three crank lengths (in a randomized order). Their bicycles were exactly reproduced on an ergometer where crank torque of the left and right legs were independently registered. 2D kinematic of the right leg and energy cost (gross efficiency) were recorded. The results showed that changes in crank length had no effect on the gross efficiency, but had effect on the biomechanical variables. A longer crank caused a decreased in mechanical efficiency and an increase in the flexion and range of movement of the hip and the knee, without changes in the ankle. These alterations were not significant enough to alter the gross efficiency, but they could have negative long-term implications (worse pedaling technique and possible injuries). In conclusion, the small changes in crank arm length which are feasible for competitive cyclists affected cycling biomechanics, but not gross efficiency. Future studies should study long-term effects of these changes.Peer Reviewe
Predictive Variables of Half-Marathon Performance for Male Runners
The aims of this study were to establish and validate various predictive equations of half-marathon performance. Seventy-eight half-marathon male runners participated in two different phases. Phase 1 (n = 48) was used to establish the equations for estimating half-marathon performance, and Phase 2 (n = 30) to validate these equations. Apart from half-marathon performance, training-related and anthropometric variables were recorded, and an incremental test on a treadmill was performed, in which physiological (VO2max, speed at the anaerobic threshold, peak speed) and biomechanical variables (contact and flight times, step length and step rate) were registered. In Phase 1, half-marathon performance could be predicted to 90.3% by variables related to training and anthropometry (Equation 1), 94.9% by physiological variables (Equation 2), 93.7% by biomechanical parameters (Equation 3) and 96.2% by a general equation (Equation 4). Using these equations, in Phase 2 the predicted time was significantly correlated with performance (r = 0.78, 0.92, 0.90 and 0.95, respectively). The proposed equations and their validation showed a high prediction of half-marathon performance in long distance male runners, considered from different approaches. Furthermore, they improved the prediction performance of previous studies, which makes them a highly practical application in the field of training and performance
Joint kinetics in rearfoot versus forefoot running: Implications of switching technique
PURPOSE: To better understand the mechanical factors differentiating forefoot and rearfoot strike (RFS) running, as well as the mechanical consequences of switching techniques, we assessed lower limb joint kinetics in habitual and imposed techniques in both groups. METHODS: All participants performed both RFS and forefoot strike (FFS) techniques on an instrumented treadmill at 4.5 m·s while force and kinematic data were collected. RESULTS: Total (sum of ankle, knee, and hip) lower limb work and average power did not differ between habitual RFS and FFS runners. However, moments, negative work and negative instantaneous and average power during stance were greater at the knee in RFS and at the ankle in FFS techniques. When habitual RFS runners switched to an imposed FFS, they were able to replicate the sagittal plane mechanics of a habitual FFS; however, the ankle internal rotation moment was increased by 33%, whereas the knee abduction moments were not reduced, remaining 48.5% higher than a habitual FFS. In addition, total positive and negative lower limb average power was increased by 17% and 9%, respectively. When habitual FFS runners switched to an imposed RFS, they were able to match the mechanics of habitual RFS runners with the exception of knee abduction moments, which remained 38% lower than a habitual RFS and, surprisingly, a reduction of total lower limb positive average power of 10.5%. CONCLUSIONS: There appears to be no clear overall mechanical advantage of a habitual FFS or RFS. Switching techniques may have different injury implications given the altered distribution in loading between joints but should be weighed against the overall effects on limb mechanics; adopting an imposed RFS may prove the most beneficial given the absence of any clear mechanical performance decrements. Copyright © 2014 by the American College of Sports Medicine