Editor’s note: This article is part of TheHorse.com’s ongoing coverage of topics presented at the 2012 American College of Veterinary Internal Medicine Forum, held May 30 – June 2 in New Orleans, La.

Many equestrians, at one time or another, have dismounted after a long or strenuous ride and thought, "Boy, are my legs are going to be sore tomorrow!" Your horse has probably experienced a similar sensation, and as one researcher recently explained, a variety of muscle problems can cause a decrease in athletic performance in horses.

At the 2012 American College of Veterinary Internal Medicine Forum, held May 30 – June 2 in New Orleans, La., Erica C. McKenzie, BSc, PhD, Dipl. ACVIM, ACVSMR, associate professor of large animal medicine at Oregon State University, gave an overview of some common muscle problems that affect equine athletic performance.

"Equine athletes have proportionally greater muscle mass than comparably athletic species, with muscle tissue comprising approximately 45% of body weight in most equine breeds, and up to 55% of body weight in the Thoroughbred," she explained. Thus, muscle problems can have a profound impact on performance quality.

Muscle Soreness and Strain

McKenzie explained that the degree of muscle strain and soreness horses experience, and the muscles affected, often depends on the activity in which they compete or train.

"Athletic horses may participate in brief, intense athletic events; prolonged endurance events; events that require a combination of activities (such as jumping and dressage); or events that require the h