The relationships between the decline of running speed and changes of running economy, running mechanics and muscular strength and power in a marathon race

Abstract

The purpose of this study was to examine the relationships between the decline of running speed during a marathon race and the changes in running economy, running mechanics and muscular strength and power expended in the race. Thirteen healthy males were measured for oxygen consumption (VO_2), respiratory exchange ratio (RER) and running kinematics (stride frequency, stride length, support time and non-support time) during treadmill running (200 m/min, 3 min), maximal force and rate of force development (RFD) of isometric knee extension (ISO), and jumping height (JH) of counter-movement jump (CMJ) and 5-rebound jump (5RJ) before and after a marathon race (42.195 km). 1) In all of the subjects VO_2 during treadmill running tended to increase. RER was significantly decreased, and non-support time was significantly shorter after the race. Maximal force and RFD of ISO and JH of CMJ and 5RJ were significantly lower after the race. Contact time of 5RJ was also significantly longer. 2) There were no relationships among the changes in running economy, running mechanics and muscular strength and power. 3) When the subjects were divided into two groups according to relative change in running speed due to the race, the KEEP group (n=6, %change: 0.44 +/-2.6%) showed a significantly different RER, non-support time, maximal force and RFD of ISO and contact time of SRI, whereas the DOWN group (n= 7, %change: -21.8 +/-16.8%) showed a significant increase in VO_2 during treadmill running, and significantly different RER, and muscular strength and power measurements. These results suggest that the decreases in running economy and muscular strength and power, and the changes in running mechanics may cause the decline of running speed during the race. However, because the interrelations among these parameters remain unclear, further research will be required to develop training methods that can minimize these changes.