Horses That Can Run Longer Distances

Posted by Heather Smith Thomas on 03/27/2017
Bill & Susan Casner won the 2010 Kentucky Derby with their colt Super Saver.
Skeletal muscle is a genetically determined mixture of both slow and fast twitch fiber types.
A race horse with little lateral or medial deviation will have more speed since the legs do not swing out of line much and there is no wasted motion. Fractions of a second can be made up with each stride over the course of the race.
Correct conformation can help determine whether a horse can withstand race training. A horse is less likely to have problems if the front angles are correct, and a strong hind end with efficiency of motion will help deliver speed.
It’s popular to have young horses evaluated at sales with a vet check, scoping, and an ultrasound of the heart. A horse's heart during exertion will beat around 230 times per minute.
1973 Triple Crown winner Secretariat (above) had a heart that weighed 22 pounds, while 1998 Belmont Stakes winner Victory Gallop had a small, powerful heart.
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What is it about a horse that enables him to be a winner, especially on the race track? It takes a combination of strength, speed, good conformation, the “heart” and will to run, and sheer determination. It all comes in a package that isn’t necessarily easy to recognize in a foal or a young, untried adolescent just starting training or being evaluated at a yearling sale. Can he run? Will he be a sprinter or a distance runner? Every breeder of racehorses and every buyer at a sale are hoping to find that perfect combination. 

The next question we should ask, then, is where is that horse’s sweet spot for distance.

Bill Casner of Flower Mound, Texas, has some observations about the traits and talents that differ between sprinters and distance horses. Casner has been working with racehorses all his life—both Quarter Horses and Thoroughbreds. He still breeds and buys some Thoroughbred racehorses, but also owns some good Quarter Horses that he uses for team roping.

“Some horses’ best distance is the quarter mile (440-yard) versus 350, and some will stretch out to 550, and some may run 870, as well. The basis of this question (the distance a particular horse can run) is mainly genetics,” says Casner. What a horse inherits for talent, conformation, and muscle type makes the biggest difference in what distance he can run.

Some horses excel at continuous athletic effort because their muscles work aerobically, depending on sustained oxygen supply. Others excel at quick bursts of speed, utilizing whatever oxygen and fuel is already stored in the muscle cells. This is the difference between a sprinter (anaerobic) and a distance runner (aerobic). Sprinting is an all-out effort for a comparatively short period, while a distance runner must put forth sustained effort.

“Some Quarter Horses can almost run their race without even breathing. They can almost hold their breath that long! A horse generally takes a breath at every stride, in and out, as a natural action and because of the mechanics of the lungs. But some of the sprinting Quarter Horses can go into oxygen debt and sustain their exertion during their run and catch their breath later. They can sustain shorter breathing patterns for that sprint,” he says.

There is also a difference in skeletal muscle fibers between sprinters and distance runners. Horses (and humans) have two basic types of muscle fibers—slow twitch (type I) or fast twitch (type II). Slow twitch muscle fibers facilitate endurance feats, such as distance running. Fast-twitch muscle fibers fatigue faster, but are used in powerful bursts of movement like sprinting. “There are also some fibers that, with careful training, can go either way,” Casner explains.

Skeletal muscle is made up of bundles of individual muscle fibers called myocytes. Each myocyte contains many myofibrils, which are strands of proteins (actin and myosin) that can grab on to each other and pull. This is what shortens the muscle and causes muscle contraction. Most horses and humans have a combination of slow twitch (Type I) muscle fibers and fast twitch (Type II) muscle fibers. Fast twitch fibers can be further categorized into Type IIa and Type IIb fibers.

These differences influence whether a horse is a natural sprinter or a distance horse, and also influence how the muscles respond to training and physical activity since each fiber type is unique in its ability to contract in a certain way. The muscles contain a genetically determined mixture of both slow and fast fiber types. The slow Twitch (Type I) are more efficient at using oxygen to generate more fuel for continuous, extended muscle contractions over a long period of time because they fire more slowly than fast twitch fibers and can go for a longer time before they fatigue.

Every good athlete is a combination of natural ability and training (nature and nurture).  “The type of muscle fibers a horse inherits is the genetic (nature) part of what that horse can do and how we train him is the nurture part—assisting or modifying his ability,” explains Casner. We can help a horse with good training, but it is difficult to make a natural sprinter into a distance horse or vice versa.

Hard To Tell By Looking At Him

“What we see on the outside is not indicative of what that horse’s true potential is. There are some general differences between Quarter Horses and Thoroughbreds, but you still can’t tell by looking at a horse what his natural talent will be for running. Everyone wants to pick a pretty horse at the sale and has an idea in their mind of what that perfect horse will look like. They have an imaginary picture of the type of horse they like and generally select that kind of horse. This picture is based on their own experience over the years regarding what has worked for them,” Casner says.

“But when horses go through the yearling sales, it becomes a beauty contest. There are always some not-so-pretty horses that are overlooked by astute horsemen and expert horse selectors, yet end up being very good racehorses. It’s a gamble at a sale picking out horses you think will run, but that’s where the market is and this is a person’s resource for young horses unless they breed the horses themselves. A person just has to combine a knowledge of pedigree, evaluation of conformation, etc., and scope the horses and look at their throats,” says Casner.  

“At the sales, we vet them to the extreme sometimes, and it could help tell us whether a horse might be able to hold up to training. Correct conformation is important. In the front end, correct angles help determine whether the horse can hold up. We’ve all seen some horse with poor front end conformation that sure could run, but they also have to be able to stay sound,” he says. A horse is less apt to break down if the front legs are correct.

“The law of physics comes into play. Poor angles put more stress on joints and certain parts of the feet and legs. If they can’t hold up, it doesn’t matter how fast they can run. I’ve had a lot of fast horses that had less than ideal conformation. Well Armed was extremely fast, but pigeon-toed. We were able to keep him sound by running him on synthetic surfaces, which are more forgiving,” says Casner.

“You see some horses in a Quarter Horse race that are able to get out in front and sustain that effort for a full quarter of a mile. Those have the potential to win futurities, but it’s not always easy to select those athletes. For much of my career I’ve been more involved with Thoroughbreds than with running Quarter Horses, but in my early days I was involved with Quarter Horse racing. Breeders have infused a lot of good, fast Thoroughbred blood into the Quarter running horses—Thoroughbreds that had the ability to create a fast Quarter Horse that could sustain that speed for a distance. The horses that can run 870 tend to be that type of horse,” he says.

“I recently had a big 17-hand Quarter Horse that looked just like a Thoroughbred. A friend of mine at El Paso wanted to buy the horse and make him into a dressage horse. So, I ended up having that horse at my place in Texas and ran him. He broke his maiden and won, running 350 yards, which really amazed me (because he looked like a distance horse) and I think he won four races—including some at 550 yards, and he might have won at 870 as well. But when I looked at that horse, it seemed like he was registered in the wrong breed because he looked a lot more like a Thoroughbred than a Quarter Horse. He was fast at short distances (winning at 350 yards), but I am sure he could have carried that speed for three-quarters of a mile,” Casner says.

“The Quarter Horse breed has had Thoroughbred blood infused into it from the very beginning. Many of the early foundation horses were Thoroughbreds and a lot of them were from the Army Remount program. They were big, rugged horses and could carry a big person all day long on those Texas ranches. They were big-country horses,” he says.

When selecting a running horse, people generally study pedigrees and look for the Thoroughbred influences and speed. “If that element in the pedigree matches what you see with your eye when evaluating a horse, this gives an idea about what that horse might be able to do. The smaller Quarter Horse may not run as far as the horse with more stretch and leg,” he explains.  

“I also believe that the biomechanics of the rear end are absolutely paramount because the racehorse is rear-wheel drive! That horse needs a strong hind end with efficiency of motion. When I look at a young horse, it’s the rear end that I am most interested in; I want to see a horse that is very efficient, with no lateral or medial deviation that will diminish speed.” If the legs swing very much out of line, it can cost fractions of a second at each stride, and that time lost adds up over the course of the race.

“Angles of the hip and hind leg are probably the most important aspect in whether or not a horse will be successful on the racetrack. Some horses can overcome bad angles and still run well, but at the very highest level for speed you won’t find horses that don’t have a good hip angle,” says Casner. If there is any wasted motion—wherever it might be in that leg—it takes more time to straighten that leg and move it forward again. Inefficiency will catch up with that horse, adding more fatigue as well as reducing the overall speed. 

“At the end of the day, however, what makes a good racehorse (whether Quarter Horse or Thoroughbred) is what we can’t see. It’s that intangible aspect of talent. You can have two horses standing side by side and one might be knock-your-socks-off beautiful and the other one you can pick apart with some faults, yet that second horse might be faster. There are no perfect horses and there are a lot that are close to perfect that never do run well. They sell big because they look good, but they can’t run.” 

Some of the plainer horses may surprise you because they put it all together. “They have the talent, the proper physiology, and the gumption—that try. They want to run and want to be at the head of the pack. Many horses will run, but don’t really try to be at the front. The safest place to be in a herd is in the middle, and a lot of horses are content to do that; they have no interest in getting out in front. It doesn’t matter how much talent they have.  I’ve had dozens of horses that were incredibly talented, but they just didn’t have the gumption to want to be ahead of the pack,” he explains.

“There are superior individuals that have great talent, good biomechanics, and great cardiovascular attributes, but the most important thing is that they have the desire to run at the front of the pack,” says Casner.

Heart Scans

It’s become popular to have young horses evaluated at sales, not only with a vet check and scoping but also doing an ultrasound of the heart. “Checking hearts is part science and part art; it takes a lot of experience. When people first started doing it, they thought it would be the Holy Grail and that all you had to do was find a horse with a big heart. We’ve all heard the story about Secretariat’s 22-pound heart, or the big heart of the Australian racehorse Phar Lap,” he says.

“The people who are really good at doing heart scans have done thousands of horses and have a pretty good idea about them. Racehorse hearts come in all sizes. Victory Gallop had a small, powerful heart and he could run a mile and a quarter and really put on the afterburners when his rider moved his hands on the far turn. That horse would work exceptionally fast in the morning,” says Casner.

“Generally, horses that have small, powerful hearts are sprinters and they are typically precocious. Their best races may be at two or three years of age. When you start asking them to go longer distances, they may not be able to do that. But, you sometimes find a few that break that model,” he explains.

“Then there’s the AP Indy type of heart, which is a great big heart with thinner walls—more like a bellows. It takes a lot of training to strengthen that heart. Generally, it’s the middle-of-the road kind of heart that does well. There are so many things that are involved in what makes an efficient heart besides the size. There’s stroke volume, and the ability to sustain its effort for a long period,” he says.

The horse’s heart, beating at full tilt during exertion, will beat about 230 times per minute. “To put that into perspective, just try to open and close your hand four times in a second and keep doing it. It’s difficult to sustain that action. Training can certainly have an effect on a horse’s endurance muscle-wise, including the heart,” says Casner.

The Racehorse Is An Amazing Animal

“When we evaluate horses, we can ultrasound the heart, scope them (some have smaller throats and don’t take in as much air), etc. The horse is a tremendous athlete and has evolved from running away from predators in order to survive. The horse used speed over a fair distance of ground to outrun the varmints that wanted to eat him.” Now, we’ve fine-tuned that ability with selective breeding to create very fast horses.

“It is amazing what some of these good horses can do, and the things they can overcome. You can have a horse like Distorted Humor that looks like a running Quarter Horse because he was a big, strong horse with a big hip and he was fast! He won going a mile and 1/16th, but he had the ability as a stallion to sire horses that can run 1 1/2 miles and win the Belmont or the Kentucky Derby (1 1/4 miles). He sired countless horses that could carry their speed that far. There was something in those genetics that came through for distance speed in spite of the way he looked,” says Casner.

“Northern Dancer was a small horse and looked like a 15-hand Quarter Horse, but he broke the mold. He looked like a horse that you’d love to make a heading horse out of for team roping or to use as a barrel horse. He was small and catty with a great hip, yet he could run 1 1/4 mile and he could sire horses that ran that distance. It’s hard to tell by looking at a horse what he can do. This is one of the most difficult things in the business—predicting how fast a horse will be and for how far. When we look at a horse, we cannot see how much speed he will have or how far he will run. We think we can see things that might help him do that, but we really don’t know,” he says.

“Speed is the toughest thing in the world to see in a horse. You really don’t know until you train them and try them. I’ve come to the realization that it doesn’t matter if it’s a Quarter Horse, Thoroughbred, a dressage horse, a 3-day eventer, a bull-dogging horse or a calf-roping horse—every one of them has a certain talent in a certain area. What you hope is that the horse you pick for a certain career has a talent for what you want him to do. If he doesn’t, he’ll need a change of career!” 

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