What is Stamina? (or the myth of the 2 minute lick)

Just 24 extra seconds of stamina is worth $50 million dollars in an American 3 year old colt.

How is that?
Consider that dozens of American 3 year olds can go 8F in 1:36, but ZERO can go 10F in 2:00 come the first Saturday in May. I don’t care how many of them can rip off a first quarter in :22 or a half in :45, speed doesn’t matter – it’s the ability to hold 95% of top speed that wins at classic distances and creates thoroughbred legends. The great Secretariat’s Belmont victory consisted of 12 furlongs in 12sec/furlong pace – a full 48 seconds of additional stamina that today’s equine athletes fail to possess, do you think he ever breezed a 10sec furlong at age 2 like the Green Monkey?

Let me state that again: Peak speed doesn’t equal success in classic distance American races. The fastest workers at two year olds in training sales routinely bring the highest hammer prices, and just as routinely disappoint on the race track. An analysis of one particular Barrett’s sale over the years shows that fast workers typically return about 20% of their sales price in race earnings – and at least one top consignor shows better racetrack results from his RNA’d stock in these same sales. Interesting, to say the least.

Obviously pedigree plays a role in stamina, but genetics merely sets the blueprint for stamina development, the training environment dictates how much of that blueprint is achieved in the real world.

At least one world class trainers has figured that out:
Dubai and South Africa based Mike de Kock: “When your horse may not have the bloodlines or ability of their opponent, fitness is the one area in which you can beat them.”

Poker is a perfect example of the age-old ‘nature vs. nurture’ question.

As a trainer, you may either play Texas Hold ‘Em Seven Card Stud or you play the much less popular Seven Card Draw. In stud, you get 2 cards of your own (genetics) and everyone plays off of the 5 community cards (environment). However, in Seven Card Draw there are no community cards – every player gets the chance to trade in up to 4 of his cards (genetics) received from the dealer. You can’t trade them all in, but you are not forced to play the hand you are dealt, nor are you forced to play the community cards (environment) that others are bound to in Texas Hold ‘Em. You may trade in some cards and get poorer ones in return, or you may improve your hand significantly. In Stud that is purely a game of chance, but in equine training/conditioning you can literally ‘stack the deck’ in your favor.

Confused yet? Maybe that was a clumsy analogy, but as a horseman you are not stuck playing the genetic cards dealt to you by breeding in terms of stamina, you can better your hand by altering the conditioning stimulus for each individual horse. To do this properly, you need to know exactly how stamina is developed on a physiological level.

In thoroughbred race horses, stamina is the ability to hold 95% of top speed for a longer period of time. This differs from endurance horses, who like human marathoners, must run all day long at a slower pace. Thoroughbreds must deal with holding speed in the presence of lactic acid, therefore training paces must take this into account.

Stamina is not some mythical quality, it is measureable.

Stamina consists of actual physiological structures inside of a horse’s body. Again, pedigree dictates what quantity and function the animal is born with – as well as its rate of development through age and training – but targeted conditioning itself improves this scenario.

For simplicity’s sake we’ll first focus on just one of these structures: mitochondria. You can see these things in a muscle – although you need a very powerful microscope. This is the powerhouse of the muscle cell: where nutrients from the diet and broken down in the presence of oxygen to produce aerobic energy and eventually movement down the track. (By the way, all the mitochondria in a horse’s body are inherited from the mother, which again points to the genetic importance of the female lines in breeding theory.)

Heck, let’s add one more physical component of stamina: capillaries. Horses are born with a set number of arteries and veins with which to transport blood to and from the working muscles during exercise. Capillaries are the very small vessels that run between these arteries and veins. The surface area of these blood vessels is where gaseous exchange takes place – the taking in of oxygen from the blood and the release of waste products such as carbon dioxide back into the environment. Most importantly, although the number of arteries and veins are set at birth, the number of capillaries is not. Exercise increases capillarization – and therefore increases the surface area for gaseous exchange which results in more aerobic energy output.

Very simply put, the quantity and quality of mitochondria in the muscles and capillaries in the circulatory system dictate the presence or absence of stamina in a thoroughbred racehorse.

Now training an endurance horse, or human, is simple – miles upon miles of slow exercise to build these structures. Thoroughbreds cannot do this – else they will simply be able to run forever, albeit slowly. Thoroughbreds race mainly in 120 seconds or less at high speeds – and with great buildups of lactic acid in the process.

So, we must discover the intensity of exercise, or pace/speed, that allows a horse to build the precursors of stamina, while at the same time introducing enough lactic acid into the bloodstream so that fast twitch muscles are not ignored. That pace is called V200 – or velocity at 200 beats per minute, which roughly corresponds to 85% intensity of effort in the average thoroughbred.

Class                                                  V200/ideal stamina building pace

2yo start of training                         3:30-2:30 min/mile
claimer                                               2:30-2:15
allowance                                           2:15-2:00
stakes                                                 2:00-1:50
graded stakes                                    1:50-1:40

In terms of lactic acid, these V200 paces are equivalent to VLA4, which is the gallop speed that results in a blood lactate level of 4mmol/liter in an exercising thoroughbred. Lactic acid is not all bad – at this intensity/pace the horse can actually teach himself to use lactate as an energy source, as well as teach his blood to buffer the increased concentration of hydrogen ions – this V200 pace is nature’s TCO2 milkshake.

We get close to building ideal stamina when we speak of a Two Minute Lick, a mile galloped in 2:00 flat, or 15 sec/furlong. This is indeed an ideal stamina builder, but only for one specific class of horse, basically an allowance type runner, perhaps a non graded stakes competitor. If you throw 2 minute licks at your 2yo or your claiming stock – you are not building stamina, this is essentially speedwork for them. Plus, the fact that they ‘can’t blow out a candle’ 10 minutes after such a workout means little, but that is another story for another day. Surely, you trainers out there have had many such instances where you thought your horse would stay based on a few 2:00 lick gallops, only to be surprised otherwise on raceday-

I have seen traditional 1.5-2 mile gallops in many horses over the years, from $4k claimers at Beulah Downs on up to stakes winners at Churchill. 99% of these works average around a 2:15 to 2:30 pace, and only for a mile or so in the middle of the session. That intensity of work during a gallop is only good for stamina in a small range of athlete (see above chart) and does little to build stamina in a quality horse. Should you take your stakes horses and gallop them faster than a 2:00 mile every day? Of course not. But it would be wise to begin with one day each week targeting conditioning for optimal stamina development.

Americans, by necessity, must train for speed due to our race tactics, but why ignore stamina in the process?  We do a fantastic job of conditioning to withstand the rigors of speed during a fast opening quarter or half – but we sort of ignore the stamina end of the equation. And with no real reason, by definition training for stamina is sub-maximal in nature and easy on both the minds and the bodies of today’s thoroughbred. V200 is often referred to as ‘cruising speed’ by Todd Pletcher and others.

Stamina and Published Works

Except for our very top graded stakes competitors, stamina workouts are too slow to be timed and will not show up in the worktabs of the DRF or Equibase. Therefore, it remains difficult to figure out which trainers, if any, utilize these types of exercise in their daily regimen. American trained horses who are stabled trackside will rarely get enough track time to knock out many 2:15 miles, but I would suspect that horses trained off the farm, or at a private training center such as Fair Hill in Maryland, would be more likely to have some exposure to stamina building exercise. Surely the European turf stars are trained in such a manner – as exercise riders over there tell me these horses get an hour a day of exercise on average at a variety of paces.

Despite selectively breeding the best to the best for dozens of generations, here in the US our classic Triple Crown races are being won in times roughly equal to those in the 1940’s:

http://thoroedge.wordpress.com/2010/11/29/triple-crown-times-have-not-improved-in-70-years-why/

Perhaps it’s time to address the conditioning angle in an effort to stretch our horses out a bit further?

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About bpressey

Equine Exercise Physiologist

Posted on April 1, 2011, in Uncategorized. Bookmark the permalink. 6 Comments.

  1. Bill, here’s a question from a forumite at the Oz forum TBV:
    “Can I gather from that article there is no point in breeding a stayer unless you are training it to stay and doing it from a young age ?”
    http://forum.thoroughbredvillage.com.au.websitelive.net/training-for-stamina_topic39209.html

    • Breeding/genetics merely set the blueprint for stamina, speed, etc. In the case of stamina, to keep things simple, let’s focus on the density of mitochondria in the muscles and the amount of capillaries between blood vessels. Breeding will dictate the numbers of each, but targeted aerobic conditioning increases both. You may very well breed a superior stayer who doesn’t improve maximally through conditioning, but odds are you will not (97% of the time).

      After the mating is planned, genetics is done. Conditioning to improve mitochondrial and capillary density is the only facet you can control, so why not maximize it? Of course, stamina is multi-factorial, and things like the size of the trachea are genetically determined and un-changed by conditioning.

      Conversely, you may condition it perfectly, but if the genetics aren’t there – you will also get submaximal results.

      So convoluted, but my main point is that conditioning is the only factor subject to human control, genetics is simply a roll of the dice. Why spend countless hours worrying about a ‘coin flip’ and next to no time structuring workouts to influence stamina?

  1. Pingback: Racehorses: Make Lactic Acid Your Friend, not Foe | ThoroEdge Equine Performance

  2. Pingback: Pedigree is Merely Potential on Paper, Lactic Acid Dictates Class on the Racetrack | ThoroEdge Equine Performance

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