Lactate response to maximal exercise on the track: relation to muscle characteristics and kinematic variables

Abstract

Fourteen 2‐year‐old Standardbred trotters, born, raised and trained at the same establishment performed maximal exercise on a track over a distance of 1000 m. Blood samples for plasma lactate (PLA) analyses were obtained from the jugular vein immediately after exercise. Muscle biopsies from m. gluteus medius were taken and analysed for fibre type composition (I, IIA, IIB) and enzyme activities representing oxidative (citrate synthase (CS), 3‐OH‐ acyl‐CoA dehydrogenase (HAD)) and glycolytic (lactate dehydrogenase (LDH)) capacity. Stance time (ST), stride length (SL) and velocity were determined from high speed films (250 frames/s). Simple linear regression analysis was used to describe relationships between lactate response, muscle characteristics and basic kinematic variables. Significant positive correlations were found between PLA/IIB and negative correlations between ST/IIB, SL/PLA, ST/PLA. No relationships were observed between CS, LDH or HAD and PLA, IIB or the kinematic parameters. The results indicate that young Standardbred trotters with a low percentage of type IIB fibres perform maximal trotting with a low lactate production and long stride length and stance time. © 1995 EVJ Ltd