Comparación del consumo máximo de oxígeno predictivo utilizando diferentes test de campo incrementales: UMTT, VAM-EVAL y 20m-SRT / Comparison of the maximal oxygen uptake predictive using different incremental fi eld test: UMTT, VAM-EVAL and 20m-SRT

Introducción: El principal objetivo de nuestro estudio fue establecer comparaciones en la predicción del consumo máximo de oxígeno (VO2máx) en 3 test de campo; Test de Pista de la Universidad de Montreal (UMTT), Test VAM-EVAL y el Test Course Navette de 20 metros (20m-SRT). El objetivo secundario fue comparar las velocidades finales alcanzadas, las distancias recorridas y la duración entre los test. Material y métodos: 41 sujetos (24 hombres y 17 mujeres), estudiantes de educación física participaron voluntariamente. Fueron evaluados en 4 ocasiones, en primer lugar se realizó la evaluación antropométrica en laboratorio. En las siguientes tres oportunidades fueron evaluados aleatoriamente en campo con el UMTT, VAM-EVAL y 20m-SRT. Las diferencias y relaciones entre el VO2máx predictivo y otras características cuantitativas entre los test fueron analizadas aplicando ANOVA a 1 factor y el coeficiente de correlación de Pearson respectivamente. Resultados: En ambos grupos no se observaron diferencias en el VO2máx predictivo entre el VAM-EVAL y el UMTT, siendo para el grupo de los hombres 48,5±4,7 versus 49,1±4,6 ml•kg-1•min-1 (p< 0,05), y para las mujeres 41,8±3,4 versus 42,3±3,2ml•kg-1•min-1. El VO2máx predictivo del 20m-SRT, fue inferior significativamente con respecto a los otros test, siendo para los hombres 43,8±5,3 y para las mujeres 34,2±4,5 ml•kg-1•min-1 (p< 0,05). Conclusión: En estudiantes de educación física el VO2máx predictivo obtenido desde el 20m-SRT fue inferior significativamente con respecto al UMTT y al VAM-EVAL, en ambos sexos. No se encontraron diferencia estadísticamente significativas en el VO2máx predictivo entre el UMTT y el VAM-EVAL. En ambos sexos, se observo una tendencia en alcanzar mayores velocidades en el VAM-EVAL (AU)

Introduction: The main objective of our study was to establish comparisons in the prediction of the maximum consumption of oxygen (VO2máx) in 3 field test; Universite de Montreal Track Test (UMTT), VAM-EVAL test and the 20m Shuttle Run Test (20m-SRT). As secondary objective it was to compare the speeds, the running distances and the duration among the test. Material and methods: 41 individuals (24 men and 17 women), students of physical education participated voluntarily. They were evaluated in 4 occasions; in the first place he was carried out the evaluation anthropometric in laboratory. In the following three opportunities they were evaluated aleatorily in field with the UMTT, VAM-EVAL and 20m-SRT. The differences and relationships between the VO2máx predictive and other quantitative characteristics among the test were analyzed applying ANOVA respectively to 1 factor and the coefficient of correlation of Pearson. Results: In both groups differences were not observed in the VO2máx predictive between the VAM-EVAL and the UMTT, being for the group of the men 48,5±4,7 versus 49,1±4,6 ml•kg-1•min-1 (p <0,05), and for the women 41,8±3,4 versus 42,3±3,2 ml•kg-1•min-1. The VO2máx predictive the 20m-SRT, was inferior significantly with regard to the other test, being for the men 43,8±5,3 and for the women 34,2±4,5 ml•kg-1•min-1 (p <0,05).Conclusion: In students of physical education the VO2máx predictive obtained from the 20m-SRT was inferior significantly with regard to the UMTT and to the VAM-EVAL, in both sexes. They were not difference statistically significant in the VO2máx predictive between the UMTT and the VAM-EVAL. In both sexes, one observes a tendency to reach high speeds in the VAM-EVAL (AU)

Neuromuscular characteristics of drop and hurdle jumps with different types of landings.

The objective of this study was to compare drop (DJ) and hurdle jumps using a preferred, flat foot (FLAT) and forefoot (FORE) landing technique. Countermovement jump height was used to establish the hurdle and the DJ heights. The subjects performed forward hurdles and vertical DJs on a force plate. Measures included vertical ground reaction force (VGRF), contact time, leg stiffness, and rate of force development (RFD). Electromyographic (EMG) activity was measured in the rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius during 3 phases: preactivity, eccentric phase, and concentric phase. All the kinetic variables favored hurdles over DJs. Specifically, hurdle-preferred technique and FORE exhibited the shortest contact time and DJ FLAT the longest. The VGRF was higher in hurdle preferred and FORE than in DJ preferred, FLAT, and FORE. For stiffness and RFD, hurdle preferred and FORE were higher than DJ preferred and FLAT. Hurdle jumps showed higher rectus femoris EMG activity than DJ did during preactivity and eccentric phases but lower activity during the concentric phase. Considering the type of landing, FLAT generally demonstrated the greatest EMG activity. During the concentric phase, DJ exhibited higher rectus femoris EMG activity. Biceps femoris activity was higher with hurdles in all the phases. Gastrocnemius showed the highest EMG activity during the concentric phase, and during the eccentric phase, hurdle preferred and FORE showed the highest results. In conclusion, the hurdle FORE technique was the most powerful type of jump.

Training specificity of hurdle vs. countermovement jump training.

The objective of this study was to compare bilateral and unilateral hurdle jumps with traditional countermovement jumps (CMJs). Thirteen athletes were tested during continuous forward bilateral and unilateral hurdle jumps and single CMJ. Countermovement jump height was used to establish the hurdle height. Subjects jumped forward over 4 hurdles with the force plate positioned after the second hurdle to measure vertical ground reaction force (VGRF), contact time (CT), and rate of force development (RFD). For bilateral jumps, hurdle height was established at maximal (100%) CMJ height and at 120, 140, and 160% of the CMJ height. The athletes were instructed to jump as fast as possible to mimic a training session drill. For unilateral jumps, hurdle height was set at 70, 80, and 90% of the CMJ height. Bilateral 160% jumps showed a significantly longer CT than bilateral 100, 120, and 140% jumps. The bilateral 100, 120, and 140% jumps had significantly shorter CT than the unilateral jumps and CMJ. The VGRF during bilateral jumps was higher than unilateral jumps and CMJ. Bilateral 160% jump RFD was significantly higher than CMJ and unilateral jumps but significantly lower than the other bilateral jumps. In conclusion, the characteristics of the bilateral jumps were substantially different from those of the CMJ and unilateral hurdle jumps. As bilateral hurdle jumps with a height between 100 and 140% of the CMJ provide similar CTs and VGRF as many reported sprint or jump actions, they may be considered a more training-specific power training drill than the CMJ.

Short-duration massage at the hamstrings musculotendinous junction induces greater range of motion.

Massage for the purpose of health dates back to early civilization and more recently has been used in the management and prevention of sport injuries. Massage has also been used as part of a warm-up to help increase acute flexibility. However, the physiological benefits and mechanisms of massage are not well known. The purpose of the present study was to investigate the effectiveness of 3 massage conditions on hip flexion range of motion (ROM). This experimentation involved a novel massage technique, which focused the massage on the musculotendinous junction for a short duration. Ten recreationally active women ranging from 21 to 36 years in age participated in this study. Participants were subjected to 3 massage conditions (no massage, 10-second massage, and 30-second massage) in a random order on separate days. Hip flexion angle, passive leg tension, and electromyography (EMG) were measured thrice before and within 10 seconds after the intervention. A main effect for conditions was found with the 30-second massage providing a 7.2% increase in hip flexion ROM that was significantly greater than the control condition (p < 0.05). Significant interactions occurred with an increased ROM (p < 0.05) from pre to posttests of 5.9 and 7.2% for the 10- and 30-second massage conditions, respectively. There were no significant differences in passive tension or EMG for any conditions or time. With a significant increase in hip angle and no associated increase in passive tension or EMG, there is a suggestion that 10 and 30 seconds of musculotendinous massage induces greater ROM through a modified stretch perception, increased stretch tolerance, or increased compliance of the hamstrings. Musculotendinous massage may be used as an alternative or a complement to static stretching for increasing ROM.

Entrenamiento de sobrecarga en niños / Resistance training in children

La presente revisión tiene como objetivo actualizar y establecer parámetros válidos para el entrenamiento con sobrecarga durante la prepubertad. Se revisaron los antecedentes bibliográficos como así también la opinión de instituciones líderes en salud y prevención. También se revisaron los tipos de ejercicio utilizados, la intensidad y las recomendaciones básicas para profesionales de las ciencias de la salud (AU)

The objective of the present review is to establish valid rules for resistance training during puberty. It reviews the past literature and the opinion of important leaders in health and fitness. In addition, it reviews the basic recommendations for health professionals of the type and intensity of exercises that should be used (AU)