Efecto de la coactivación muscular sobre la economía de carrera en corredores de fondo entrenados

Introduction: Muscle coactivation is a key factor in running economy. Objectives: The aim of this study was to analyze the relationship between muscle coactivation and running economy in trained distance runners. Methods: Twelve trained runners (age: 32.1 ± 4.7 years) completed two treadmill running tests at speeds of 12 km/h and 20 km/h, each lasting 5 minutes. Gas exchange data and electromyographic activity of lower limb muscles were recorded during the tests. Coactivation indices were calculated for the following muscle pairs: rectus femoris/biceps femoris, rectus femoris/gastrocnemius, rectus femoris/gluteus medius, tibialis anterior/gastrocnemius, and tibialis anterior/peroneus longus. These were evaluated during the last 100 ms of the swing phase and the first 50 ms of the initial stance phase. Associations between variables were analyzed using Spearman’s correlation. Significant correlations were considered at p < 0.05. Results: A significant inverse correlation was observed during the stance phase between rectus femoris/medial gastrocnemius coactivation and energy cost (r = –0.599, p = 0.043). Likewise, a significant inverse correlation was found between peak activation of the biceps femoris and energy demand (r = –0.629, p = 0.031). Both correlations were observed at 20 km/h. Conclusion: Coactivation and peak activation of biarticular muscles (rectus femoris, gastrocnemius, and biceps femoris) were associated with energy cost. These findings may represent a neuromechanical strategy that enhances energy transfer between lower limb joints, thereby improving running economy in trained distance runners.Introducción: La coactivación muscular es un factor determinante en la economía de carrera. Objetivos: El objetivo fue analizar la relación entre la coactivación muscular y la economía de carrera en corredores de fondo. Métodos: Doce corredores entrenados (32.1 ± 4.7 años), realizaron dos carreras a velocidades de 12 km/h y 20 km/h, con una duración de 5 minutos cada una. Durante las pruebas se registraron datos de intercambio gaseoso y actividad electromiográfica de los músculos de la extremidad inferior. Se calcularon índices de coactivación entre los siguientes músculos: recto femoral/bíceps femoral; recto femoral/gastrocnemio; recto femoral/glúteo medio; tibial anterior/gastrocnemio y tibial anterior/peroneo lateral. Estos se evaluaron en los últimos 100 ms de la fase de oscilación y los primeros 50 ms de la fase inicial de apoyo. Las asociaciones entre las variables se analizaron mediante la correlación de Spearman. Las correlaciones significativas fueron aquellas asociadas con valor p