Should you Swim Your Racehorses?

Swimming is a great therapeutic tool for injured horses, as well as a nice change of pace for healthy ones undergoing stressful trackwork – but it is not an activity that contributes significantly to an overall conditioning effect – here’s why:

The above chart is taken from a recent swim session where the horse in question was outfitted with an onboard heart rate device (click to enlarge). The red line is the HR in bpm and the x-axis is elapsed time in minutes.

Walking to the pool at the start of the chart; one can see a very relaxed HR of roughly 40bpm. But, at approximately the 3 min mark he finally enters the water – and his HR immediately jumps to 170bpm as excitement and apprehension sets in. At this point the HR is NOT a measure of aerobic exercise intensity, as it is artificially high due to the excitable nature of the thoroughbred. However by minute 5 this effect dissipates and we have an accurate number to discuss.

The blue shaded area of the graph represents a HR range of 140-160bpm, or 60-70% of maximum heart rate. This level of intensity is nearly 100% aerobic in nature, and essential to developing the foundation for later gains in stamina. On the track this horse slow gallops/canters at a 5min/mile pace to reach this same level of intensity.

But in the pool, a large percentage of the bodyweight is supported by the buoyancy of the water; making any effort to swim far less intense than most earth-bound exercise. Sure many muscles are being exercised as one swims; albeit in a non weight bearing environment. As a result, HR hovers around 125bpm, roughly 55% of maximum.

This lines up perfectly with what I find when I swim. As I run I can hit max HR values of 188bpm, but I can swim like a shark is chasing me and still struggle to reach 155bpm – as my 200lbs is greatly reduced by the water. I’m breathing heavily and my shoulders burn; but I’m not doing a ton to help my 800m race times on the track.

Look again as the horse exits the pool at the 11:30 mark, once more the change in activity excites him and his HR spikes to 185bpm for nearly 30sec – if a vet slaps a stethoscope on him now and sees this HR – he’ll proudly proclaim: “185bpm – he really got a lot out of that session!” But he’s wrong as the horse only hit a ‘true’ HR value of 125bpm on average during the whole exercise. (I’ve seen vets WAY smarter than myself make this elementary mistake at top rehab facilities.)

So, is swimming a waste of time? Of course not, but it’s far from an alternative to even the slowest of trackwork in building  a foundation of aerobic fitness. Now if yours is coming off an injury or is otherwise unsound, swim away until he’s ready to move forward – just know that the real work begins only when out of the pool.

The ideal use of the pool may be in the afternoons, giving the horse a break from the monotony of the track and allowing him to stretch his limbs in a cool setting.

EDIT: 2 readers alerted me to an Aussie trainer atop the Hong Kong standings named John Size who swims his twice a day, once after morning work, again in the afternoon before a long walk, and even swims on raceday mornings…here’s Mr. Size’s bio:

EDIT2: Magnificent tool in place at the barn of Niall Brennan in Ocala: an aquacizer that only fills up the water to just below the shoulder – allowing for walking/jogging in cold water and achieving heart rates well within the aerobic zone of intensity:



About bpressey

Equine Exercise Physiologist

Posted on January 27, 2012, in Uncategorized. Bookmark the permalink. 12 Comments.

  1. Bill

    One of the better papers written on swimming and changes in cardiac dimensions and response to training was written by Dr. Allan Davie for RIRDC ( in 2008. It basically had similar findings to what you have discussed here. They didn’t use heart rates for the exact reason you described above, they had to measure heart rates post exercise, but they used post-exercise whole blood lactate concentrations as an indicator of metabolic stress. They found lactate concentrations of 1 to 2.6 mmol/L, indicating that horses allowed to swim at their own rate are not producing a large metabolic stress on their system and certainly not enough stress to stimulate different cardiovascular adaptions than if the horse was given traditional training.

    Byron Rogers
    Performance Genetics LLC.

    • Thanks for the info Byron – boy a lactate reading of 1.5 mmol/l is quite low indeed. Heck half of that lactate could even be from stress rather than actual muscular contractions. That is why I favor HR, you can look at the graph and discount artifacts – but you cannot easily do that with a blood sample.

      I’m going to read over this tonight. I should be in Ocala in early February, where are you these days?

  2. This study makes another great point: 2 horses can swim and one can produce a negligible amount of lactate at 1 mmol/l, while another produces 2.6 mmol/l, that is a very significant difference.

    Likewise I see this on the track. A group of horses do the same ‘easy’ exercise, yet half produce 4 mmol/l of lactate, and the other half under 2. This ‘easy’ workout was not so easy on the first group.

  3. It was most interesting article about swimming I ever read. First of all I met in all articles before about swimming warnings that swimming can create bleeding because of a water pressure to the corpus of the horse. Is it true? if You compare a month of hand walking with a month of swimming after injury is it a different to bring a horse to basic condicion to start a real training? Do You think a water treadmill gives a horse more intensity of work comparing to swimming pool?
    Greg racehorse trainer

  4. Although I haven’t taken heart rate , I think by tying the horses tail and esentailly driving him (in the same place) in the pool , work the horse much more !
    IF I give a horse 5 minutes like that without getting him used to it , his lungs and muscles are so tired he has trouble walking coming out of our pool !

    • Interesting Greg – I love the massaging action of the water in the pool, and I like the idea of taking off SOME bodyweight, but just not as much as swimming does. In Florida this spring I am hoping to quantify some HR values depending upon varying heights of water fill; a unique way of increasing resistance by starting with the water at 2 foot of depth for instance, then adding another 6-12″ when HR improvement starts to stall out…

  5. Hi,

    I am new to racing and your blogs are a shining light in an otherwise dark and unfriendly industry.

    I am learning about conditioning my horses from an 83 year old farrier in Australia – an extremely successful pacing trainer.

    I swim my 16.3hh, 590kg 4yo unraced stallion twice a week for approx 6 minutes. 2 gentle laps, and I chase him the third lap. He exits the pool blowing like he has had a strong gallop. I walk him for 2 minutes, in which time his breathing has gone back to normal, and then enter the pool again.
    Another three laps, this time, I chase him the last two laps. I have to jog around the pool to keep up with him.

    Spending a bit of time down by the pool, I watch many trainers swimming their horses. Sometimes I have had to wait with my horse for 15 – 30mins to use the pool, while a trainer does 20 or 30 laps :O. When the horse exits the pool, it is not really blowing and the trainers are often gloating on how fit the horse is to have not blown after such a long swim.

    This is where my 83 year old mentor enlightened me.

    He does not believe in stop watches, heart rate monitors, GPS etc. Only ‘feel’ and horsemanship. I think their needs to be a balance between horsemanship and what modern science can give us in the form of cold hard data.

    ” they let their horses just cruise along and ‘bludge’ (Aussie lingo for being lazy and only doing what is required). What YOU do by chasing your horse is like finishing off a breeze with a blowout”.

    I was skeptical at first, and, being completely new to the racing industry, I listened and did as I was told by my old farrier. Low and behold, when doing fast work, the horse returns to the mounting yard almost not blowing at all. Very very sound wind, even after 600m dash ups.

    So I DO think that swimming has a place in maintaining fitness in racehorses – if done using common sense. Its like people who jog 10km every day and dont really puff when they finish. if they ran 400m at half pace and then sprinted 100m they would damned sure be puffing at the end 🙂

    I think when the horse is chased after their initial warmup lap, it DOES serve to increase the heart rate. I suppose what I have been taught is a kind of interval swim training; get him used to the water, let him warmup, chase him, let him walk and recover, then ask him to go in again, and chase him home.

    In all of the studies I have read on the net, not one uses a common sense methodology. There seems to be little horsemanship used. I think results would differ a lot if they chased the horses the last lap or two.

    Respectfully yours


    • Thanks for writing Rebecca.

      Surely chasing a swimmer will help get the intensity up. Everyone knows of a horse that swims and wins, or swims and loses – my point was that the intensity of exercise typically resembles that of a trot, not a gallop. When submerged in water, a horse weighs closer to 200lbs as opposed to 1000+lbs. Regardless, it’s wonderful cross-training.

      Be careful of using whether or not a horse is blowing as a sole means of fitness, respiration is highly individual and influenced by humidity and high temps.

      In terms of an old timer discounting any objective data in favor of ‘feel’, he is making the same mistake as a college boy who only uses science without experience, as you indicate – the best method encompasses both measures.

      Imagine two humans trying to lose weight. One goes by ‘feel’ and fails to count calories – the other counts calories and is careful to make sure he eats 500 cal less per day than he expends. The second guy will outperform the first every time.

      Why ‘horsemen’ seem to be insulted by stopwatches, HR/GPS, scales, etc. baffles me. These experts can eyeball if a horse has gained or lost 20lbs, but they cannot ascertain 2lbs. Likewise, human hands can feel a temperature difference of 2 degrees in a leg, but not 0.2 degrees.

    • Every sport has traditionalists who cling to the old ‘eyeball’ methods – even the fairly new Ultimate Fighting Championship:

      Tito Ortiz immediately traveled to Frank Shamrock’s gym in San Jose and trained with him for a month straight. Shamrock showed Ortiz that there was a science to fighting. Ortiz had never seen a heart rate monitor before Shamrock strapped one to his body. Ortiz learned how to read (and eventually control) his own body. His recovery time and endurance improved drastically. Six months later, Ortiz became a UFC champion.

      I watch the HBO 24×7 series here in the US that details conditioning regimens of top boxers, who are very old school in their thinking – one famously drank his own urine because he thought it gave him ‘energy’. Now all these guys have strength and conditioning specialists.

  6. Thanks for your reply.

    I understand the action is different in the water – trot vs the gallop action on the track. I suppose this is where one has to use experience to gather whether the horse is benefiting from regular swimming in replacement of track work.

    Would love to see a HR monitor on horses who are chased in the water to see if there is any evidence that chasing in the water will raise the heart rate to the rate required to be useful for training.

    Regarding your comments on respiration… noted 🙂

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