Endurance.Net Ridecamp Archives

Title: Re: [RC]   Heart Rates and Fitness

Yes, several variables, and as in humans, the gold standard indicator 
is the the VO2 max—Uptake of O2 (Oxygen Gas) at maximum exercise.
Just found a terrific article from the Tufts vet school at
http://www.tufts.edu/vet/sports/oxygen.html

Resting heart rate, max heart rate, and recovery HR are just a few indicators, and relatively indirect ones, of aerobic fitness.

Some excerpts [emphasis mine]:

“Horses are considered to be elite athletes. This means that, pound for pound, the horse is a better athlete than any of our domestic species, including man. One of the most useful ways of measuring an individual's aerobic capacity - which is in turn a measure of athletic capacity - is to determine the body's maximal capacity for oxygen consumption, or the VO2max.”

“How can I help my horse to improve his VO2max?

The major improvements are made in the [variables:] capacity of the heart to pump blood, the density and size of the blood vessels in the muscles, red blood cell mass, the size of the muscles themselves, and the density of mitochondria within the muscles. Interestingly, the lungs are the one link in the chain that do not have the capacity to improve, unless they were diseased in the first place. Thoroughbred racehorses are born with more of these attributes than are, for instance, Shetland ponies, and they will always be faster, no matter how hard the pony trains.”

There is an interesting, slightly bizarre, photo of a horse on a treadmill w/ breathing apparatus. 



On 9/12/06 10:35 AM, "Bruce Weary DC" <bweary@xxxxxxxxxxxx> wrote:

>    Hi Dave--
>  That is a very good question, and I think there are several variables to consider. First, what is your gelding's RHR? If his is naturally higher, it will likely be higher during similar work and during a CRI, even if he's fitter. He may have a smaller heart and his stroke volume requires more beats to move the same amount of blood as your mare. The rest of his tissues are, no doubt, fitter than hers--better bone and ligament density and joint stability. Denser muscle, better water and electrolyte metabolism, sweating mechanism and heat tolerance. He is likely better able to shift fluids to different body compartments than your mare can right now. The heart rate, although it is influenced by the other factors I mentioned previously, gives a relative view of the horse's tolerance to work, not an absolute one. In other words, your gelding by be feeling better at a pulse of 60 than your mare will at 50, given her present level of conditioning and naturally low heart rate. Your mare may indeed be a better overall candidate once she has had the time to adapt to the demands of exercise that your gelding has. Anyone else have any insight on this? I am just guessing and could be wrong. Dr Q, often wrong,  but always sincere.