Introduction

It might be observed at the end of a horse show, event or trail ride. A horse is lathered, huffing and looks exhausted. Is the horse exercise-intolerant?  No, most likely it just has not been properly conditioned. Conditioning is defined as getting one’s muscles into better shape through graded exercise. Age, genetics, and nutrition play major roles in conditioning.    

Age of the horse is an important factor when considering a conditioning regimen.  Younger horses have less blood volume, resulting in fewer red blood cells, and thus less oxygen carrying capacity, than mature horses. Additionally, new bone must be laid down in response to not only exercise, but also growth in the young horse, which often causes a higher degree of stress placed on a young (age four or younger) performance horse’s skeletal system. As a consequence, injuries to the bones of immature horses can and do occur.  

There is good news for older, trained horses. Horses retain basic fitness even after six to eight weeks of rest, although the equine skeletal system does not stay in form after several weeks of rest.    

Genetics also play a role in conditioning.  Some horses are naturally more athletic (capable of quicker, more coordinated maneuvers) than others. Feeding and conditioning can be adapted to achieve the maximum genetic potential of any horse.  

Body condition scoring (BCS) can be useful when preparing a horse for conditioning.  These scores range from one (very emaciated) to nine (very fat). Recent research indicates that a body condition score of five is the most desirable in helping a horse realize its maximum performance. At this score, a horse’s topline or backbone is level (has the normal dip of the back but does not lack definition or muscling and is not sunken in), the ribs cannot be seen but can be easily felt, the withers appear slightly rounded, and the shoulder starts to blend smoothly into the body. Horses with this body condition score can store more energy than thinner horses. Thinner horses (body condition one-four) must rely on energy drawn from the daily diet rather than on body stores. A horse with a BCS below 3.5 or 4 should not be put into a conditioning program until their BCS is increased.  

A horse needs to have sufficient muscle and fat over the topline to make it easier and more comfortable to carry a rider. Additionally, it is possible that a low body condition score could result in lack of stability in the joints, leading to dysfunction, and some joint damage.  

On the other end of the spectrum, a fatter horse will need more energy to remove heat that provides a cooling effect. Therefore, moderately (a moderate amount of muscle/fat) conditioned horses (body condition score=five) will have improved thermal regulation and delayed onset of fatigue.  

Thin horses, or horses that will compete at a moderate to intense level, can be gradually introduced to a fat-supplemented diet. It takes about one week for the horse to adapt to digestion of fat supplements and three weeks to one month before they can be utilized for energy.  Grain mixes can contain up to 10% added fat or up to three cups of canola oil can be gradually added to the diet. Fat spares the use of glycogen (stored carbohydrates) and provides twice the amount of energy as carbohydrates. It can also aid in thermal regulation.    

A horse’s weight should be monitored on a regular basis, using the condition scoring system to determine if weight is being gained or lost during the conditioning process.   

Use this equation to calculate body weight:   

[(Heart girth in inches)2 x Body length in inches]/330 = weight (pounds). This will be + 25 pounds of the actual weight. Feed intake should vary from 1.5% - 3% of body weight daily, with horses doing intense work on the upper end of feed intake.   

Start early on a conditioning program with specific goals in mind. In general, initial conditioning should consist of long distance at a lower speed; long, slow distance work. This does not mean that a horse travels a long distance, but that the horse is exposed to aerobic exercise resulting in a low working heart rate, usually for 30 days.  This consists of walking, slow trotting, introduction of extended trot, loping or cantering and some galloping. These activities are aerobic because the horse’s heart rate is always less than 150 beats per minute (bpm) (see chart below). During this time, fatter horses will mobilize stored fat and burn it as a fuel source.     

Table 1. Heart rate for horses participating in common activities.

^a From Snow and Vogel,  ^bFrom Scott et. al.

Horses that have not exercised throughout the cooler months should start with aerobic exercise as the weather warms. The next fact sheet discusses the pre-ride check that can be used when conditioning your horse, the benefit of heart rate monitors, anaerobic conditioning (the next step), the importance of the warmup and cool down periods, and how to recognize fatigue. Implementing some of the changes can lead to a positive change in the horse. 

Resources

New American Medical Dictionary and Health Manual, 1992. Penguin Books USA, Inc. NY.  

Jones, W.E.  1989.  Blood volume and the performance horse.  In Equine Sports Medicine News.  8(6):  81-82.  

El Shorafa, W.M., J.P. Feaster, and E.A. Ott. 1979.  Horse metacarpal bone: age, ash content, cortical area and failure stress interrelationships.  J. Anim. Sci 49: 979.  

Lawrence L.A., E.A. Ott, G.J. Miller, P.W. Poulos, G. Protrowski and R.L. Asquith.  1994. The mechanical properties of equine third metacarpals as affected by age.  J. Anim. Sci. 72: 2617.  

Coffman, J.R. 1989.  Heart rate and cardiac output in the athlete.  TAMU Equine Symposium, College Station, TX.  

Moyer, W., and J.R.S. Fisher. 1991.  Bucked shins: Effects of differing track surfaces and proposed training regimes.  In Proc. AAEP: 541.  

Sellnow, L. and L.J. Fisher. Nov. 1991. Bucked shins. (An interview with J. Fisher, D.V.M., Fair Hill Training Center, MD) Blood Horse. pg. 5194.  

Gibbs, P.G., Potter G.D., Nielsen B.D., Householder D.D., and W. Moyer.  1999. Scientific Principles for Conditioning Race and Performance Horses.  Horse Industry Handbook, p. 851-1-13.  

Scott, B.D., G.D. Potter, L.W. Greene, M.M. Vogelsang, and J.G. Anderson.  1993.  Efficacy of a fat supplemented diet to reduce thermal stress and maintain muscle stores in exercising thoroughbred horse.  Proc 13th Equine Nutr. Physiol. Symp., Gainesville, FL, p. 66.  

Henneke, D.R., G.D. Potter, J.L. Kreider and B.F. Yeates.  1983. A scoring system for comparing body condition in horses.  Equine Vet. J. 15: 371.  

Carroll, C.L. and P.J. Huntington.  1988. Body condition scoring and weight estimation of horses.  Equine Vet. J. 20 (1): 41-45.  

Milner, J. and D. Hewitt. 1969. Weights of horses: Improved estimated based on girth and length. Can. Vet. J. 10(12): 314.  

Gillespie, J.R. 1989. Thermal regulation in the equine athlete. TAMU Equine Symposium, College Station, TX.  

N.R.C. 1989. Nutrient Requirements of Horses. 5th revised edition. National Research Council. Washington, DC.  

Vogelsang, M.M. and S.P. Webb. 1988. What the horse trainer needs to know about exercise physiology. Proc. Connecticut Horse Short Course, Storrs, CT, p.1.  

Snow, D.H. and C.J. Vogel. 1987. Equine Fitness: The Care and Training of the Athletic Horse. A Trafalgar Square Farm Book. David and Charles, Inc. North Pomfret, VT.  

Scott, B.D., G.D. Potter, L.W. Greene, P.S. Hargis and J.G. Anderson. 1992. Efficacy of a fat supplemented diet on muscle glycogen concentrations in exercising Thoroughbred horses maintained in varying body condition. J. Equine Vet. Sci. 12(2): 105.  

Meyers, M.C., G.D. Potter, J.W. Evans, L.W. Greene and S.F. Crouse. 1989.  

Physiological and metabolic response of exercising horses fed added dietary fat. J. Equine Vet. Sci. 9:218.  

Oldham, S.L., G.D. Potter, J.W. Evans, S.B. Smith, T.S. Taylor and W.S. Barnes. 1990. Storage and mobilization of muscle glycogen in exercising horses fed a fatsupplemented diet. J. Equine Sci. 10(5):1.  

Potter, G.D. 1989. Dietary manipulation in the equine athlete.  TAMU Equine Symposium, College Station, TX.  

Webb, S.P., G.D. Potter and J.W. Evans. 1987. Physiologic and metabolic response of race and cutting horses to added dietary fat. Proc. 10th Equine Nutr. and Physiol. Symp, Ft. Collins, CO, p. 115.  

Julen, T.R., G.D. Potter, L.W. Greene, and G.G. Stott. 1995. Adaptation to a fat supplemented diet by cutting horses.  Proc. 14th Equine Nutr. Physiol. Symp. Ontario, Canada, p. 56.  

Personal communication, 2001, with Dr. Laurie Lawrence, University of Kentucky.  

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