A New Index to Evaluate Running Coordination Based on Notational Analysis.

The aim of this study was 1) to define a new index to describe running coordination, named % of coordination, and 2) to examine whether it could represent an order parameter in relation to running velocity. Twelve international middle-distance athletes (six males and six females) performed three trials at easy, 5000 m pace and sprint velocities while filmed from a lateral view at 240 Hz. Notational analysis of six lower-limb key events corresponding to touchdown, mid-stance and flight phases was performed with high values of intra- (maximum standard deviation = 7 ms) and inter-operator (maximum systematic bias = 6 ms) reliability. Running velocity manipulations resulted in substantial and progressive increases in stride length, stride frequency (all p's < 0.001) and % of coordination (p < 0.001; η²p = 0.77), while duty factor showed a progressive reduction (p < 0.001, R2c = 0.86). However, % of coordination depended on the stride phase (p < 0.001; η²p = 0.78), with greater time gaps between key events in touchdown and mid-stance than in the flight phase. Results confirmed that % of coordination can illustrate changes in movement organisation, representing an easy tool for evaluating the running technique of competitive athletes.

What is the Most Important Leg and Discipline in Triathlon Mixed Team Relays?

This study aimed to determine the importance of the different relay legs and sport disciplines in the overall result of the triathlon Mixed Team Relay (MTR) events. The study analysed the results of 80 Mixed Team Relay triathlon teams (n = 320 professional triathletes) corresponding to the top ten finishers at the World Championships in Hamburg from 2013 to 2020. Split times, average speeds, time behind the race leader (gap), partial and finishing positions, as well as the rank positions of every segment, relay leg, and overall race were computed. Decision tree analyses were conducted as a predictive method for the overall results, and correspondence analyses were conducted to examine the relationship between the different relay legs and segments and the finishing positions. Running was the variable with the greatest importance (32%) in the overall result, followed by female team members (17%) and the third relay leg (17%). The swimming segments (1%) and the fourth relay leg (1%) had the lowest relevance. Medallist relay teams were characterised by cycling and running faster than 10.99 m/s and 5.59 m/s, respectively, with time gaps of less than 43 seconds by the end of the third relay leg. A reliable and accurate prediction model for the medallists' and finalists' team positions in the Mixed Team Relay triathlon was obtained. The running disciplines and performance of female team members, especially in the third leg, were ascertained to be the most significant determinants for the overall Mixed Team Relay result.

Efectos del calor en el rendimiento en deportes de resistenciaen los diferentes dominios de intensidad-duración: artículo derevisión / Effects of heat on endurance sports performance in different intensity-duration domains: a review article

El ejercicio físico induce un aumento de la temperatura corporal que se ve influenciado por la intensidad de este, además de por las condiciones de estrés térmico en las que se realice. La relación potencia/velocidad-duración (PD/VD) muestra cómo el tiempo que un ejercicio puede ser mantenido depende de la potencia o velocidad producida, pudiendo diferenciarse 4 dominios de intensidad que estarán delimitados por el umbral láctico (LT), la potencia/velocidad crítica (PC/VC) y el consumo máximo de oxígeno (VO2max). Esta revisión tiene como objetivo analizar los efectos del estrés térmico sobre el rendimiento en los diferentes dominios de intensidad-duración, así como identificar los principales mecanismos fisiológicos responsables. En los dominios de intensidad moderado (por debajo del LT) y duro (entre LT y PC/VC), el calor perjudica el rendimiento en los ejercicios que comprenden duraciones de ~40 min hasta por encima de 3h, siendo los mecanismos centrales y la depleción del glucógeno los principales contribuyentes a esa fatiga. En el dominio severo (por encima de la PC/VC), el calor afecta negativamente al rendimiento de los ejercicios máximos que van de los ~25 a ~2 min de duración, siendo los factores cardiovasculares y periféricos los limitantes principales. Sin embargo, en el dominio extremo (por encima del VO2max), el calor se ha visto como un elemento clave en la consecución de mejores registros de rendimiento en esfuerzos máximos inferiores a ~2 min de duración, debiéndose estas mejoras a factores centrales y de disponibilidad energética. El calor influye en gran medida en el rendimiento de los deportes de resistencia, acelerando el fracaso de la tarea en aquellos que tienen duraciones superiores a los ~2 min, y favoreciendo aquellos de duraciones inferiores. Conocer estos mecanismos de actuación puede ayudarnos a identificar distintas estrategias para reducir o aprovechar sus efectos durante el entrenamiento y la competición.(AU)

Physical exercise induces an increase in body temperature that is influenced by the exercise intensity, as well as by the heat stress conditions in which it is performed. Power/velocity-duration relationship (PD-VD) shows how long an exercise can be sustained depending on the power output or the velocity output. Four intensity domains can be differentiated, which will be delimited by the lactic threshold (LT), the critical power/velocity (CP/CV) and the maximum oxygen consumption (VO2max). This review aims to analyze the effects of heat stress on performance in the different intensity-duration domains, as well as to identify the main physiological mechanisms responsible. In the moderate (below LT) and hard (between LT and CP/CV) intensity domains, heat impairs the performance of exercises ranging from ~40min to over 3h, with central mechanisms and glycogen depletion being the major contributors to this fatigue. In the severe domain (above CP/CV), heat negatively affects the performance of maximum exercises ranging from ~25 to ~2 min duration, with cardiovascular and peripheral factors being the main limitations. However, in the extreme domain (above VO2max), heat has been considered as a key element in achieving better performance records in maximum efforts of less than 2 min, associating these improvements with central and energy availability factors. Heat greatly influences the performance of endurance sports, accelerating task failure in those efforts longer than ~2 min, and favoring those with shorter durations. Knowing these mechanisms of action can help us to identify different strategies to reduce or take advantage of their effects during training and competition.(AU)