Maximum Oxygen Uptake

[Robert Vaughan]

Obviously, the horse's heartbeat and bloodflow levels increase as the level of sustained exertion increases ... the question is how fast do they and the oxygen uptake levels so do under racing conditions where the level of exertion is at its maximum from the outset ... that is, how long does it take for them to reach the maximum levels ... and does it increase linearly, exponentially or what?

Since I suppose the stride logically represents some sort of unit of work (exertion), answers in either strides or time would suit me just fine ... and since I figure it depends on the horse ... I'm just looking answers or opinions covering the "typical" situation.

I would appreciate any and all opines ... posits are fine too! Seriously, I would like to know what you think ... in yards or furlongs ... in strides or seconds!

Thanks!

Robert

[yak merchant]

It's definitely not about a stride unless it's strides per second. As that "unit" alone could be happening at completely different rates. It's more related to velocity/acceleration, and I'm sure you could get agreement that it's not linear, now getting agreement on the actual curve will take you a million years. Not much on this type of thing in horses, but I'd read up on VO2 Max calculations in human runners if it floats your boat.

[Robert Vaughan]

Thanks Yak! I wouldn't think that it's linear and while you may well be correct, neither would I suspect it to be a function of acceleration unless it's inversely related since the highest rates of acceleration occur at the start of the race and acceleration is more closely associated with anaerobic rather than aerobic based energy. For some reason I suspect that VO2 Max is typically reached in less than 4 furlongs but really have no basis for that conclusion.

That's why I was hoping for some estimates, ideas and/or opinions.

As an aside, I tend to agree with the notion that the duration of the stride is relatively constant while the length of the stride reflects velocity.

[robert99]

Main variance issues are the extent of warm-up before racing, the ambient temperature and the type of horse ie front runners have high rates of early energy production (with heart and lungs at full capacity right from the explosive start), whereas closers stoke up more gradually during the race. Sprinters, middle and long distance horses have very differnt energy production profiles. VO2 measured from a treadmill is relatively high in thoroughbreds averaging at about 180ml/min/kg but there are two other energy sources going on at the same time ie from muscle chemical stores and anaerobic energy production. The heart rate and lung capacity is vitally being also used to expel waste products including heat from that energy production to maintain the optimum cruising rate. Once the horse slows toward the finish that capacity is no longer adequate so you can see from the horses total pace shape where things are happening or changing. Most horses cannot maintain their top speed for more than 2 (low class)-3 (top class) furlongs so ideally need to be rated down to a high and even cruising speed that gets them to the line fastest.

[Tom]

Check your email for some info.

[Robert Vaughan]

front runners have high rates of early energy production (with heart and lungs at full capacity right from the explosive start), whereas closers stoke up more gradually during the race.

Robert, thanks, as always for the valuable input! However, I can't imagine it being true that any horse's oxygen uptake is at "full capacity from the start" .... though I agree that the warmup should have an impact on the starting V02 level.

Pardon my throwing around these dollar words without really knowing what they mean ... I would think that most of the energy in the beginning comes from the two anaerobic energy sources you mentioned.

Methinks that if the horse had reached it's VO2Max at the start of the race, it would be able to expel the anaerobic energy production waste products efficiently so that there would be no significant fatigue in races under 1 1/2 miles ... logically, the speed horse would decelerate as it's anaerobic stores emptied but from my easy chair, it would tend to level out.

It does trigger an additional question in my mind ... does the buildup of anaerobic waste equally affect aerobic and anaerobic energy production? I would tend to so think since what's in the blood is in the blood, regardless of how it got there ... but, you mentioned "in the muscles" as well, prompting my question.

Any additional insights would be appreciated!

Thanks Tom, for the Wellman Link! For some reason, my Outlook Express doesn't like my FoxFire and it took a few tries to get it to work ... I found those to be interesting though I had a bit of difficulty in fully understanding them on a first read; I think primarily due to his syntax.

He suggests that VO2Max isn't reached in races under 1 1/2 miles ... which I also find surprising though I have no planes of reference from which to draw. What's your thinking?

Reagardless, Wellman is a worthwile read ... and I wish he had provided more detail; general equations etc. Is the link you provided the only available Wellman source? He made reference to his "derby list" ... what's that?

Regards,

Robert Vaughan

[Tom]

Check also Carrol's book on speed. He goes into a discussion about this topic.

[Cratos]

Main variance issues are the extent of warm-up before racing, the ambient temperature and the type of horse ie front runners have high rates of early energy production (with heart and lungs at full capacity right from the explosive start), whereas closers stoke up more gradually during the race. Sprinters, middle and long distance horses have very differnt energy production profiles. VO2 measured from a treadmill is relatively high in thoroughbreds averaging at about 180ml/min/kg but there are two other energy sources going on at the same time ie from muscle chemical stores and anaerobic energy production. The heart rate and lung capacity is vitally being also used to expel waste products including heat from that energy production to maintain the optimum cruising rate. Once the horse slows toward the finish that capacity is no longer adequate so you can see from the horses total pace shape where things are happening or changing. Most horses cannot maintain their top speed for more than 2 (low class)-3 (top class) furlongs so ideally need to be rated down to a high and even cruising speed that gets them to the line fastest.

Would not the horse's bodyweight and the amount of weight on its back have to be taken in considersation in an energy calculation?

[robert99]

Robert, thanks, as always for the valuable input! However, I can't imagine it being true that any horse's oxygen uptake is at "full capacity from the start" .... though I agree that the warmup should have an impact on the starting V02 level.

Pardon my throwing around these dollar words without really knowing what they mean ... I would think that most of the energy in the beginning comes from the two anaerobic energy sources you mentioned.

Methinks that if the horse had reached it's VO2Max at the start of the race, it would be able to expel the anaerobic energy production waste products efficiently so that there would be no significant fatigue in races under 1 1/2 miles ... logically, the speed horse would decelerate as it's anaerobic stores emptied but from my easy chair, it would tend to level out.

It does trigger an additional question in my mind ... does the buildup of anaerobic waste equally affect aerobic and anaerobic energy production? I would tend to so think since what's in the blood is in the blood, regardless of how it got there ... but, you mentioned "in the muscles" as well, prompting my question.

Any additional insights would be appreciated!

Thanks Tom, for the Wellman Link! For some reason, my Outlook Express doesn't like my FoxFire and it took a few tries to get it to work ... I found those to be interesting though I had a bit of difficulty in fully understanding them on a first read; I think primarily due to his syntax.

He suggests that VO2Max isn't reached in races under 1 1/2 miles ... which I also find surprising though I have no planes of reference from which to draw. What's your thinking?

Reagardless, Wellman is a worthwile read ... and I wish he had provided more detail; general equations etc. Is the link you provided the only available Wellman source? He made reference to his "derby list" ... what's that?

Regards,

Robert Vaughan

Robert V,

A horse is quite different from a human in that a horse is forced to breath once per stride as the weight coming onto the forelegs expells the air from the lungs. At the start, the muscle demand is explosive and the stride length is short. The muscles can always use up more oxygen than the heart can actually push around and with so many muscles in explosive action at the start (4 legs, back, chest, neck, tendons etc etc) as compared to a human runner or cylist, the heart rate has to climb to stop the blood pressure falling as all the muscle "taps" are turned on at once. The short stride increases the oxygen delivery per second - this gives a high VO2 from the start. (This cannot be measured on a treadmill as the horse for its safety has to gradually build up to its cruising speed). The reference Tom points out gives information on the relatively flat speed / distance curve for thoroughbreds (requiring a range of horses suited to the actual distances) this also indicates that VO2 remains high even up to point of fatigue. Quarter horse races flat out below 5f have different characteristics. ( My meaning for VO2 is that level which can actualy be utilised for locomotion rather than the amount that is inhaled/ exhaled each stride).

The fatigue issue depends on pace and the horse. (At the point where the toxins build up faster than they can be expelled all the muscle cell chemical activities tend towards shutting down and the stride length shortens). In UK the same 6f flat horses can carry large weights up to 12 stone over 2 miles in national hunt hurdle races but the pace is 2 seconds per furlong slower. That same 6f horse may not be able to race effectively over 8f on the flat without fading, let alone 12f. Conditioning for the type of race the horse is competitive at, maximises the O2 supply to the muscles and keeps the heart rate relatively low to still be able to pump the blood supply around the system, oxygenated in and carbonated out.

[robert99]

Would not the horse's bodyweight and the amount of weight on its back have to be taken in considersation in an energy calculation?

Cratos,

Yes.
The thread started more as a discussion about the energy "production" side but that of course has to exceed or equal the locomotion energy "demand" side of raising the horse body weight and jockey weight each stride, wind resistance, cornering, accelerating from stalls etc. If it does not, the horse runs "relatively" slowly - closers often exhibit that trait in the early stages of a race but the opposite towards the finish. Any horse tiring in the closing stages also.

[Wiley]

The fatigue issue depends on pace and the horse. (At the point where the toxins build up faster than they can be expelled all the muscle cell chemical activities tend towards shutting down and the stride length shortens). In UK the same 6f flat horses can carry large weights up to 12 stone over 2 miles in national hunt hurdle races but the pace is 2 seconds per furlong slower. That same 6f horse may not be able to race effectively over 8f on the flat without fading, let alone 12f. Conditioning for the type of race the horse is competitive at, maximises the O2 supply to the muscles and keeps the heart rate relatively low to still be able to pump the blood supply around the system, oxygenated in and carbonated out.
So at slower paces and thus lower heart rates, aerobic (with oxygen) condition dominates and lactic acid buildup (that feeling in your gut when you are running fast like you are going to throw-up if you continue) is diminished so a genetic sprinter can continue on if the pace is slow enough, think Bold Forbes in the '75 Belmont. I think most of this has to be looked at on the individual basis meaning some horses are in better condition and have bigger engines, the ability of the heart to pump higher volumes of blood, so their VO2max, lactate threshold, heart rate limits are higher and they are able to run father at a faster pace then others.

I assume training conditioning can certainly help improve these levels VO2max, etc., in horses, within their genetic limits, just as in human runners and improve the horses fitness level. As a runner myself and knowing what helps me prepare for a race, if I trainined horses I would use heart rate monitors - which I have read are now available for horses - to maximize a horses fitness level.

I wonder if the Pletcher's of the world do this now whereas the average trainers use old school observational methods to determine fitness levels? IMHO, this type of improved training could make a dramatic difference in performance, along with improved nutrition. I liked what Tim Ritchey did with Afleet Alex a couple of years ago with the stamina building 'long run' training method in his use of long gallops with AA, paid off nicely in the Belmont.

[Robert Vaughan]

The short stride increases the oxygen delivery per second - this gives a high VO2 from the start. (This cannot be measured on a treadmill as the horse for its safety has to gradually build up to its cruising speed). The reference Tom points out gives information on the relatively flat speed / distance curve for thoroughbreds (requiring a range of horses suited to the actual distances) this also indicates that VO2 remains high even up to point of fatigue.


Robert, 'twas the difference between the gradual buildup associated with sustained exersize/treadmill studies ... and the immediate maximal effort associated with actual races that prompted the initial question.

While I can't imagine the horse reaching VO2Max immediately out of the gate, regardless of warmup, methinks the rate of VO2 acceleration is probably much greater than most would think, for reasons similiar to those reasons you have well articulated ... the big difference is that your level of understanding is much greater than mine ... that is, you understand it and I don't.

My thinking has always been that the weight carried by the horse had an exponential impact over time which would suggest that it would impact the time required to reach VO2Max and energy demands but until I get a better handle on the basics, that seems rather insignificant.

Tom's other suggested reference ... Charles Carroll's book seemed to indicate that VO2Max was probably reached after 4.5 furlongs ... though his levels of thought rival the layers of an onion and I need to reread it before reaching the conclusion that he was so indicating.

I think my understanding of VO2 and VO2Max is consistent with your usage and certainly everything, including fatigue, is horse specific.

From my simplictic arm chair, lay perspective ... it seemed that aerobic energy contributions were present contrinuously throughout the race and that anaerobic production was triggered when the aerobic energy contribution was inadequate relative to the demand ... with the level of anaerobic production being a function of that inadequacy, the level of waste product buildup, and the availability of such resources.

Others seem to think that at the start of the race there is no direct aerobic contribution ... which may well be true because of the immediacy of the demand relative to the time required fot aerobic production ... as I previously indicated, you understand it and I don't.

But, truth is truth and I do so want to know!

[robert99]

Robert, From my simplistic arm chair, lay perspective ... it seemed that aerobic energy contributions were present continuously throughout the race and that anaerobic production was triggered when the aerobic energy contribution was inadequate relative to the demand ... with the level of anaerobic production being a function of that inadequacy, the level of waste product buildup, and the availability of such resources.

Others seem to think that at the start of the race there is no direct aerobic contribution ... which may well be true because of the immediacy of the demand relative to the time required fot aerobic production ... as I previously indicated, you understand it and I don't.

But, truth is truth and I do so want to know!

Robert V,

These are advanced topics and are not researched holistically so you can get confusing bits and pieces of information. Perhaps to condense things:

Aerobic takes time and oxygen. It is for actions requiring endurance and heart rates below 150 beats per minute. It is efficient in that fats burned have 3 times the energy of carbohydrates. There are ample supplies of stored fat fuels. In itself, if 100% efficient, it does not produce lactate toxins.

Anaerobic is for short, intensive, flight actions of up to a minute duration and heart rates greater than 150, where there is not time for the muscles to burn sufficient energy from stored fats (as you have stated). Limited supplies of glycogen fuels are available for anaerobic action. Produces high levels of lactate toxins causing severe fatigue if not quickly removed by the circulation.

Conditioning aims to boost the more efficient aerobic component so that the anaerobic part can last over longer than one minute, say. So particualrly in a fit racehorse both aerobic and anaerobic actions take place together. In sprinters, anaerobic dominates. (A human can probably run 100m without taking a breath, for example, but if running on further hits "the wall" sooner, when energy production changes to full aerobic).

[Robert Vaughan]

Robert V, ... you can get confusing bits and pieces of information.


That, my friend, is on the mark ... however, "have" rather than "can" is the operative word!

Methinks the Lost in Space robot would concur that your summary does indeed compute ... and remarkably, I think I understand and at least directionally accept same. Thanks!

That said, it's still a good thing that my primary interest is in understanding while arriving at an artifice for projecting performance is secondary ... as I would have otherwise already given up in despair.

Horses obviously have to accelerate to get velocity but I would think doing it in such as way so as to minimize the accumulation of performance inhibiting waste products would be the preferred route to take ... and it makes me ponder why closers don't win all but the shortest of races.

I know that sounds ridiculous to those of sound mind and acumen but it's a road down which I've been lately travelling.

Since anaerobic raw materials are in short supply and/or their accessibility diminishes with utilization, I'm led in the direction that the function describing maximum expendable anaerobic energy on demand might well be a decreasing exponential based on what was "left in the tank" while aerobic energy production would probably become relatively constant as VO2 approaches VO2Max; the level of which depending on the buildup of waste products.

Regarding the aforementioned artifice ... were the above to be true and I better understood when VO2Max was reached, I thought I could then resolve relative aerobic and anaerobic capacity measures for the horses based on past performances ... I still so think but, unfortunately, while my understanding may have increased, the nut still hasn't been cracked. Perhaps, the best approach would be to make different assumptions ... from what I'll call Robert99 to Wellman and see where it leads.

As I often say ... the poorly prepared student usually thinks the test is easier than does the well prepared one ... at least until he gets the results.

No I've never taught ... just took a lot of tests that I thought were easy.

Thanks again ... to you, Tom and all!

Regards,

Robert Vaughan ... decendant of Henry Vaughan the English poet and not The Man from U.N.C.L,E. ... though I wouldn't mind having some of his residuals.