Different Approach to Assessing Training Adaptation

Dutch researchers report that a different technique for assessing adaptation to training gives a more accurate picture than the usual approach of measuring muscle enzyme levels. In the study, researchers instead used "quantitative needle electromyography" (QEMG) to evaluate adaptations in skeletal muscle in athletic horses.

A horse's performance can be improved by gradually increasing the duration and intensity of its exercise sessions. If the training load is balanced with the horse's exercise tolerance, then an increased athletic performance will ensue within a few days.

"In contrast, sustained, vigorous exercise can result in incomplete recovery and a decreased performance level," explained Inge Wijnberg, DVM, PhD, Dipl. ECEIM, of the department of equine science, faculty of Veterinary Medicine at Utrecht University, and lead researcher on the study.

This incomplete recovery is referred to as overreaching and can progress to a more severe and chronic stage called overtraining.

To detect this early, Wijnberg and colleagues evaluated adaptations in skeletal muscle in athletic horses using QEMG and measured muscle enzyme levels in muscle biopsies in horses undergoing either normal or intensified training programs.

Twelve Standardbred geldings were trained for 32 weeks in a normal, intensified, or control groups. Researchers performed QEMG and muscle biopsies prior to a standardized exercise tests, which were performed periodically throughout the study.

"Horses in the intensified training program exhibited stronger adaptation, potentially due to synchronization of the nerve signals going to the muscles, which resulted in a more coordinated muscle contraction," said Wijnberg.

Additional, detailed analysis of the relationship between QEMG and muscle enzyme levels revealed that QEMG is a more sensitive tool for monitoring training adaptation, but it is not capable of discriminating between normal training adaptations and overreaching.

Wijnberg continued, "While the suitability of QEMG for detecting these early signs of overtraining remains to be established, it can be used to identify even small improvements in muscle fitness levels in athletic horses. More research is certainly needed."

The study, "(Over)training effects on quantitative electromyography and muscle enzyme levels in Standardbred horses," will be published in an upcoming edition of The Journal of Applied Physiology. The abstract is currently available on PubMed.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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