Acid/Base Balance Part 5: Adapative phase

As we finished up last time, we touched on some strategies of the body to replenish fluid and elyte losses after exercise.  This is referred to as the “acute” stage. 

The secondary “adaptive” stage results in an “enhanced ability to cope with future systemic disturbances” - because exercise is in a nutshell a disturbance in fluid and elyte balance.  And the changes that occur during this adaptive phase are all about being able to do the same work better (less disturbance) than last time.

The more I research different topics related to exercise physiology, the more I realize that conditioning my endurance horse goes way beyond musculoskeletal and building better muscles, heart, and lungs. I’m conditioning their GENES (epigenetics), and the way the horse handles everything from water to electrolytes to what proteins (and how much protein) they produce as well as a million other small biochemistry and metabolic changes that add up to a horse that can do 50 or a 100 miles. A horse doesn’t just need to build a better musculoskeletal system to do the distance, they need to build a better biochemical environment. 

It turns out that the adaptive response to exercise is a lot like the adaptive response to heat training.

The number one adaption that occurs in response to training is......an increase in plasma volume. 

You will remember that heat training causes an increase in plasma volume.  And that getting old causes a reduction in plasma volume. In short, plasma volume seems to have a great deal to do with thermoregulation ability and performance.

Studies have demonstrated that the increase in plasma volume causes a total body water increase - the plasma volume isn’t increasing at the expense of “stealing” water from another compartment.

How does the plasma volume increase?

60% of the mechanisms are related to stimuli associated with thermoregulation.  Even if we aren’t technically “heat conditioning” our horses, you will remember from the heat posts that the TNZ of the horses is significantly lower than most of our competition temperatures, even in mild weather.  Thus, exercise in horses is about them being able to thermoregulate and the same factors that stimulate an increase in plasma volume during “heat training” are also playing a role in normal riding and training. 

40% of the mechanism is related to the actual exertion of exercise.  This includes a stimulation in the intake of water (caveat - mixed results in the literature on this point when it comes to long-term training), and a decrease in the loss of water and electrolytes in the kidneys. 

ie - the kidneys are actually retaining water and electrolytes (seems to be ALDO-related) to increase plasma volume so that the next time exercise occurs it will result in less disturbance of body water and elytes.

Just the increased intake of water and kidney retention doesn’t totally explain the entire increase in plasma.  So, the thought is that there is also an adaptive response in the gut to increase uptake of water and elytes that will contribute to the plasma volume increase. Not just sodium uptake is increased, other vital elytes are also retained.

Hinchcliff emphasized several times that the ALDO mediated retention of water/elytes in the kidney and the increased uptake in the gut of water/elytes occur BEYOND the acute phase of replenishing water/elytes lost in exercise and that this was truly an ADAPTIVE response of the body.

There is also an increase in plasma proteins.  Remember a couple of posts ago when I told you that the plasma and interstitial compartments, which make up the ECC, are almost identical?  Most things can freely pass through the barrier between the plasma and interstitium....except plasma proteins.  Mostly because of size, they are big enough that they are trapped on the plasma side. They act like a solute and will draw water into the plasma compartment side and trap it there. So, an increase in plasma proteins increases the total solute content of the plasma, which will draw water in and keep it there.

In horses (and humans) an increase in plasma proteins in the plasma is first because of proteins shifting into the plasma from other places (what those other “places” are I have no idea...). Later on during the adaptive phase, the protein increase is because more plasma protein is actually being produced!!!!!!  This warrents exclamation marks because.....anytime you have an increase or decrease in something like this, it’s a change at the gene level ==> which genes are being expressed, and to what degree.

How long does this extra plasma stick around if you aren’t continuing to exercise and condition the horse?  Ummm...no idea. Just like heat training (which seems to be very much dependent on the increase in plasma volume) the answer is unknown. 

We aren’t even sure HOW the body allows the extra plasma to exist.  We talked a bit about hypovolemia (low plasma volume) and how the body responds to correct it, and there’s mechanisms for the body to correct increases in volume too.  However, somehow extra volume that is created because of conditioning is allowed to exist.  Is it the receptors that sense plasma volume adapting so that they accept the increase volume as normal?  In humans training decreases ANP (that cardio hormone that has a secondary renal response that causes increased Na/K excretion) as well as other responses - perhaps as a way to support and keep that extra volume.

How long does it take for horses to increase their plasma volume to training?  REALLY REALLY FAST. In fact, the increase in plasma volume takes place so much faster than the increase in red blood cells to fill it up, you can end up with “sports anemia”.

Other adaptions that were cited in endurance training was the reduced rate of lactate and hydrogen ion accumulation in contracting muscles and the blood during the first week of training.  We will cover the issue of hydrogen ions and lactate (and postassium) in future posts, but as a side note “acidification” of the muscles because of lactate and hydrogen ions are NOT a major reason for fatigue in endurance horses. 

Aren’t these adaptations exciting?  Gene expression modification, increases in total body water, increases in plasma volume, changes in how electrolytes and water are extracted from the gut - all so the body can prepare itself better for “next time”.

We’ve just scratched the surface of how the body can adapt, and Hinchcliff emphasizes that the impact of training on acid-base balance especially has not been well studied.

There is evidence in the human field that giving iatrogenic substances can be detrimental to the adaptive process - look at the most current research on anti-inflammatories, antioxidant, and vitamin use in the human world.  As a general rule, the research seems to suggest that when you provide the body something to solve a problem (like taking high levels of antioxidants, or anti-inflammatories) the body decides it doesn’t need to upregulate it’s own pathways to create those substances - after all, everything produced biologically costs something in the body’s energy currency, so if it’s just going to “magically” be there from an outside source, it’s more efficient to use what’s given.  I’m not saying that if you have an injury, you shouldn’t use anti-inflammatories, and if you have a documented deficiency of an antioxidant (selenium and vit E comes to mind) you shouldn’t supplement.  The body has to have the raw materials. 

But in general, learning about the incredible changes in biochemistry that occur as a result of training, makes me incredibly leery about messing with it. For years the advice to marathoners was to take “vitamin I” (ibrophen) to reduce inflammation, and to even prophylaxily take it before running a marathon.  Now, we think that taking anti-inflammatories actually dampens the body’s response to training and mal-adpats the muscle to the work (and doesn’t even significantly relieve DOMS, which was a major reason it was recommended). What about giving my horse electrolytes during races or during conditioning?  By increasing the sodium content of the horses gut does that mean that less “transport channels” for sodium uptake will be created because they aren’t needed? No one knows the answer to that question.  Might there be value in giving some additional sodium/elytes during a ride because my horse hasn’t fully conditioned to the distance and made all those biochemical pathways/transport channels it needs to get the sodium out of the gut it needs?  Perhaps - but as time goes on, and the horse more fully adapts to the exercise biochemically perhaps the need for supplemental elytes decreases? There’s the rule of “nothing new on ride day” which suggests that if you use elytes during ride day, you might want to give it during conditioning rides too. I’m not sure this is the wisest thing.  Rarely do I ride as long or hard as I do on ride day, and by providing electrolytes on my shorter conditioning rides, am I shortchanging the adaptive process of sodium retention and uptake?  I’m not sure.  Will some horses never adapt biochemically to the task of going 50 or 100 miles and always require more sodium/electrolytes than what they can either get into their gut naturally in feed?  Maybe. 

We are going to talk about this further in the next couple of posts when we talk specifically about acid/base balance, but here’s an interesting thing.  During endurance exercise, by the end of a 100 mile ride, horses slowly develop a metabolic alkalosis.  Horses that are “properly electrolyted” according to one study, do not.  They maintain their acid/base balance. But is this slowly developing metabolic alkalosis a bad thing?  When horses eat, they actually become metabolically ACIDIC for a time period post eating. Should we electrolyte to prevent the alkalosis?  It could be argued that 100 miles is not natural for a horse and thus require “metabolic support” in the form of elecrolytes.  Or, is a perfectly stable acid/base balance NOT as constant as we thought.....because the simple act of eating can change it?  I also find it fascinating that while exercise produces alkalosis, eating produces acidosis.  A natural adaptation? 

In thinking about how best to support a horse through 50 or a 100 miles it is wise to keep the following things in mind:

1. Acid/base balance and other adaptations to exercise have NOT been well studied.
2. Iatrongenic substances are not benign and DO have an impact on response to exercise (good? bad? detrimental? helpful?)
3. Exercise causes changes at the genetic (epigenetics!!!!) level through expression and regulation of genes.

My bottom line for elyte supplementation after going through all my reading?  Elyte supplementation may be needed for a horse that is under-conditioned for the task at hand - a hot ride that we didn’t heat condition for, or a bump up in distance that we’ve never gone before (like moving from 50’s to 100’s).  A “well-conditioned” horse is more than musculoskeletally ready for the distance, they are biochemically ready too.  But just like some horses can adapt better on the cardioresp or musculoskeletal systems for the distance, there are probably some horses that biochemically adapt better to, and some horses may need that elyte support for longer distances......I’ll just be doing my best to make sure that I’m not providing iatrogenic support to the detriment of the adaptive process- which means until proven otherwise, I probably will administer only minimal amounts of iatrogenic "support". Like anything else in this sport, it’s a balance.

Solstice really is the perfect saddle

By some miracle I find myself with about 30 minutes of free time, with no school stuff to review, study, or prepare, and without my notes for the next installment of our acid base discussion. 

Which means you get a quick personal update instead. 

I sat in a Solstice saddle for the first time since I sold mine 2 years ago....and realized why I never had problems with it and why all the other saddles I have tried to date have. 

If I’m being completely honest, it was really emotional to sit in that solstice and realize that it WAS and STILL IS possible for me to do long rides without pain, and it was no longer a mystery of why that Solstice worked so well for me.

You know that saying that sometimes you don’t know how good you had it until you lose it?  Yeah.......

When I bought my Solstice, it was sight unseen. I had done my research, decided that I wanted a Solstice. Found one in my price range, bought it, put it on my horse and rode Tevis 4 weeks later in it, which was my first 100. Continued to ride 100’s in it successfully with no issues with my or my horse that were saddle related, until I sold it to help pay for a car when I started vet school.

That was the extent of my great saddle hunt. 

I laughed at all those posts and those people who bought saddle after saddle only to not have it work for them or the horse. 

I didn’t have any qualms about selling it because, based on my experience, it wasn’t really THAT hard to find a saddle that was going to work for me and Farley.

I’ve never sat in a bunch of different saddles before, so what I didn’t realize was how differently the flap on the Solstice was constructed compared to other saddle options......

Fast forward to now.  I’ve had debilitating knee pain for the last 5 rides I’ve done.  I won the RnT scholarship and have decided to devote the award to buying a saddle. 

I’ve been sitting in a LOT of saddles.  Every saddle that I think might work for endurance - but none of them actually felt right. 

Then, at the last saddle shop I went to I saw a Solstice on the wall.

Honestly, I wasn’t even going to try it.  It was the wrong width for my horse and the leather wasn’t in the best condition, and so I knew it wasn’t one I was interested in, and since I already knew what they felt like, I almost didn’t take it off the rack.

But then, after trying (not exaggerating) every single other endurance suitable saddle in the store, I decided to take it down and see how it felt.

I kid you not, sitting in that saddle put tears in my eyes.

It was like slipping into the embrace of your dearest friend. 

It was the perfect twist and the perfect rise.

And more importantly - the knee roll and flap does not start to gain thickness until it is completely PAST my knee cap.  It’s totally flat under my knee and in no way displaces my knee or leg outward.

THAT is the difference between the Solstice and every other saddle I’ve tried. There’s still support for my knee and leg, but it’s there without displacing my knee - which apparently my IT bands cannot handle at ALL. 

The actual shape of the flap is a perfect fit for my funky short-but-with-abnormally-long-femur legs.  My leg is most comfy in a more straight up and down “dressage” position for my upper leg, which puts my leg and knee really behind where it feels like it should be in an AP style saddle.

Most of the western style endurance saddles have a twist that’s too wide.  Every single English style saddle had a flap that started increasing in thickness way before the actual knee roll. 

I had wondered whether my recollections of my Solstice were by the benefit of rosey colored “hindsight” glasses, but it was such a relief that it was just as I remembered.  

I’ve already contacted the person I sold my Solstice to, to see if it was up for sale again, but she loves it.  Which I’m totally OK with - I would be happier in a slightly larger seat anyways. 

So, I’m on the lookout for a 17.5” medium width solstice. I don’t care about color, billet length etc. I have a $1000 to spend.  Let me know if you can help :).

As for the rest of my life? 

School is going GREAT.  I think I was made to do Herd management and health.  It just “clicks” so much better for me than individual animal focus.  I’ve given up trying to predict where my career is going to go, and whatever happens, rest assured equine exercise physiology will remain a passion and whether or not I’m getting paid for it, I’ll continue to write articles that only obsessive horse people could enjoy. 

Tess is fat.  I had one side of the equation figured out - I hadn’t been running as regularly, and because of the heat she wasn’t invited on my conditioning rides.  However, I was confused on the “intake” side because she hadn’t been eating her kibble. 

I had a suspicion she was reducing the small rodent population on our property.

But, in addition to reinstating the standing invitation to go on rides and runs with me, I duely reduced her kibble.

Tess was.....not happy.  She was diving into her food again, which made ME happy (Tess is a labrador in disguise), but I got confirmation last night that Tess fully embraces the notion of being fat and has no intentions of going on a diet.

It’s one thing to therotically know that your dog is most likely crunching little rodents into little rodent bits. It’s quite another thing to actually dig a half eaten gopher out of her mouth (and stepping on random gopher parts BAREFOOT, in the DARK, in the GRASS) .  EWWWWWWWWWW.

(I have to admit I shrieked for Matt to get me a flashlight and refused to move until my path through the grass was FULLY illuminated from where I was, to the porch).

I’m slated to move, AGAIN.  Probably sometime mid-September.  I’ll keep you’all posted. The good news is that I’ll be 5 miles from my horse, 1 mile from the dog park in the area, and less than a mile from the levee/river bottoms for days I want to run in nature with my dog off leash, but don’t want to take the horse along.  It’s a good move. Still doesn’t get me close enough to campus to satisfy the “within 30 min” rule for clinics, but that’s what campers and backs of trucks are for right?????????  (mom and dad - if you are reading this, I’ll notify you of moving plans when they are official, they are processing our application now).

Off to class!

Acid Base Balance Part 4: Continuing with Exercise

I find this post incredibly confusing. So, the bottom line is this: various hormones increase in the body at different points during exercise.  Each thing has it’s own unique action on body water balance and sodium AND different actions of a molecule/hormone may be emphasized over others during exercise. And just because something is reported to do X, Y, and Z doesn’t mean it actually does X, Y, and Z during exercise.

To recap from previous post, immediately after starting exercise, blood that was being stored in the capacitance vessels returns to circulation along with fluid from the interstitium.  This contributes to cardiac/heart function. Minutes later plasma volume decreases as fluid is pushed out of the vasculature/plasma into the interstitial space and cells where it performs really important functions such as delivering nutrients, taking away waste, and being converted to sweat for thermoregulation. 

After this initial drop in plasma volume (minutes after exercise started) all the later decreases in plasma are due to the losses in overall body water because of sweat. Initially the water that forms sweat comes from the plasma, but later the cells (ICC space) get progressively more and more dehydrated.

Remember that beautiful way that the kidney increase plasma volume by retaining more sodium than usual, that then drew water into the plasma compartment because of the increased number of solutes?  (This was the result of ALDO, which was the first example I gave you of how water and solute changes could occur in the body to address low plasma and add water back into that compartment).

But during exercise sodium is actually EXCRETED by the kidney, along with potassium.  This excretion (losing) of sodium was called both “significant” and “minimal” with one paragraph in Hinchcliff so I’m not really sure what to think...... this was my first reality check that in the exercising animal the biology is really complicated.

So what is causing this exodus of Na from the body, when theoretically it should be retained so that it can pull water into the plasma?

It’s probably a secondary response to another hormone that is increased in the exercising horse, called Atrial Natriuretic Peptide (ANP).

ANP is the body’s answer to the rapid fluid shift that happen during the beginning of exercise. 

Imagine the cardio system as a closed fluid system.  There’s a pump at one end that can pump more or less fluid through the system.  The diameter of the pipes can change, the number of pipes in use can change, and the total amount of fluid within the pipe system can change.  During the beginning of exercise with the sudden changes of fluid shifts in and out of the system, and the pump engaging faster, you can imagine how difficult it would be to control blood pressure and blood flow and make sure you are getting the right amount of fluid to the right places at the right pressures.

ANP is a hormone produced by the heart that fills this job description.  It regulates blood flow and blood pressure during exercise.  In doing it’s job it inhibits vasopressin, renin (which starts the whole aldosterone cycel), ALDO, and others and is cited by Hinchcliff as the reason sodium is actually excreted by the kidneys during exercise.  It’s a “secondary” effect of ANP doing it’s primary job of regulating the cardio system.

Vasopressin is a defender of plasma volume, fluid and elyte balance.  Although it is initially supressed by ANP at the beginning of exercise, eventually it is able to overcome ANP. In one study, ANP steadily increased to a peak at 40 min and then remained elevated through 60 minutes, but didn’t continue to rise.  However exercise causes an increase in plasma vasopressin that is correlated with both duration and intensity.  ie - the longer and harder the exercise is, the more vasopressin that is in your plasma.

Side note: Vasopressin = AVP (arginine vasopressin) = ADH (anti-diuretic hormone).  I chose to use the name “vasopressin” over my other choices since I already had a bunch of “A” acronyms floating around in this series. But if I accidentally call it AVP or ADH, now you know it’s the same thing. :)

Increased vasopressin during exercise is VERY good during exercise because it causes the body to retain water, and the same things/receptors that signal for more vasopressin to be release also increase thirst.

So.....what would you think if I told you that horses that are over hydrated at the beginning of exercise had high ANP concentration compared to under hydrated horses? Does that make sense now that you know ANP inhibits vasopressin and vasopressin makes you thirty and retain water? 

Vasopressin does more than just retain water, it also affects the cardio system, and does other helpful stuff during exercise like prevent re-sequestration of blood cells into the spleen (horses have a “splenic reserve” of blood cells within their spleen that are released during exercise. Vasopressin makes sure they stay out into the circulation instead of going back into the spleen). 

I have to mention that I did find something that said while vasopressin does increase during steady state submaximal exercise (ie endurance....) it doesn’t affect water clearance.....and the body is using vasopressin during exercise mainly for it’s cardio effects and without changing the water clearance.  But then the next thing I saw a mere page later was “Increase in AVP during exercise stimulates thirst and drinking after exercise causing a decreased in free water clearance by the kidneys (water retention), may influence uptake of Na and water from colon”.....which demonstrates how confusing researching this topic was.

Overall the body tries to protect plasma volume and blood pressure. Sometimes it seems like its contradicting itself - like excreting Na, or suppressing thirst in the first hour of exercise....but in the end water everything works together to make sure that volumes and pressures are maintained.

Urine flow

Urine flow INCREASES during exercise.  This happens in horses AND humans.  Maybe I have an excuse for why I need to use the bathroom so many time during a marathon?

It’s a significant increase in urine production - 45%.  However it’s important to remember that the total extra volume lost in urine is small compared to the loss of water the horse is experiencing in its sweat.

The increase in urine confuses me because this is at odds with the increased level of vasopressin during exercise, which retains water. No idea.  But wanted to throw this out there just because it was mentioned. 

Post exercise urine flow remains increased for about 30 minutes and results in the increase excretion of water, sodium, and potassium.

Post exercise

Post exercise is the ACUTE phase of exercise recovery.  There is also a secondary “Adaptive” phase where the body is actually changing itself to be able to respond to exercise better the next time around.  The two phases are completely different things. 

The acute phase is concerned with replenishment of fluids and electrolytes.  The body doesn’t just replace the fluids and electrolytes and then “hope for the best”.  It actually makes proactive CHANGES in the hormones and body water so that it does better next time.

This was a revelation for me - while it’s natural to think of muscles getting stronger and adapting to training, I hadn’t thought about similar changes happening to the actual water, electrolytes, and exercise hormones that are also working hard during exercise. 

The specific adaptions the body makes in the secondary “adaptive phase” will be the topic of the next post. 

Even though horses can be moderately dehydrated after 50 or 100 miles (moderately dehydrated 1000 pound horse could be missing almost 11 gallons) they can replace this fluid loss overnight on their own! ALDO remains elevated for several hours post exercise and (along with vasopressin) increases the uptake of water and elytes from the gut.  ANP also remains elevated post exercise, probably to help continue regulating the cardiovascular system.


But....
But what about sodium and solutes and what they are doing in exercise?  Wasn’t that the point of these post.  Errr......yes.  But it’s really hard to talk about sodium without introducing ANP, vasopressin, ALDO and all those other “big picture” things that are happening during exercise that are affecting water because in the end THAT’s what is affecting Na.  Remember that Na and water are best friends.  Where one goes, so goes the other.

Even with all these hormones floating around and moving water and sodium around, remember that overall concentration of sodium within the ECC changes relatively little, even after riding 100 miles.  The TOTAL amount of sodium is lower.....because the horse has lost water/sweat and the sodium contained in it.  To replace this water and salt lost during exercise, the body is pulling water in through a increase in thirst and increased absorbtion from the gut, and is pulling in sodium from increased absorbtion from the gut. And voila!  You maintain enough plasma volume to thermoregulate and not have your cardiovascular system crash (hopefully).

Here’s a summary of Na and Water movement during exercise

1. When vasopressin is increased during exercise (remember that it is initially supressed by ANP) it increases WATER and SODIUM uptake from the gut.

2. More water and sodium is needed from the gut because water and sodium is being lost from the interstitial compartment as sweat.

3. Losing water from the interstitial compartment decreases overall water content from the ECC, which includes the plasma.

4. Low plasma pisses the body off and activates all those hormones we just talked about in the last section.......ANP to protect cardiovascular function, vasopressin to help cardiovascular function, increase thirst signals, and continue to demand more water and sodium from the gut.

5. Initially there is an increase (described as “small” “minimal” “not insignificant”) in sodium loss by the kidneys because of the increase of ANP.  ALDO would decrease this loss and actually retain more sodium - but it doesn’t have a significant effect during exercise, just for a couple of hours afterwards (maybe even 24 hours when you are doing the first couple of training rides). Whether or not sodium continues to be secreted at a higher rate past the acute stage of exercise (when ANP reaches it’s peak) is not something I could get a consensus on.

6. Vasopressin should be helping the body to retain water, but the jury seems to be out whether during exercise it actually does this.......

7. There is minimal changes in sodium concentration in the plasma during long term exercise

8. There is a substantial decrease in total sodium CONTENT in the body.  10-20% of the body’s sodium is in the gut.  Which is why #1 and #4 occur.

9. Horse sweat, having the same sodium content as the ECC that it’s being lost from means that there aren’t huge osmolality changes in the plasma because of sweat loss, which means that I’m finding less information on how swings in sodium concentration affect water intake etc. in horses, compared to the human literature.

10. We haven’t discussed potassium in detail yet because it is intimately associated with acid base and electrical activity, kind of like sodium is linked with water, however overall potassium is secreted as a result of all these mechanisms.

11. there are lots of vague “sodium needs to be replaced” and “effective electrolyte replacement” to address the loss of sodium in sweat but the how’s are lacking.  Post exercise intake and the “substantial gut reserve”, as well as the adaptive phase changes we will talk about next time seem to be the natural mechanisms for replacing sodium.

Coming up next: long term adaptation to exercise, potassium and acid-base balance.


A couple of warnings about evaluating literature on this topic
In case you want to do your own digging around.....When looking up literature on the subject of endurance and how electrolytes and water respond it’s really important that you understand what the authors are classifying their different exercise types as.  In general endurance exercise = submaximal or low intensity exercise. The body responds really differently to maximal (thoroughbred racing) exercise, so aren’t appropriate to use if you are researching endurance.  But endurance/submaximal means different things to different studies.

For example, one review I came across listed “submaximal exercise in trained horses”. Sounds perfect eh?  Except when you came across their definition.  Sampling was taken 15 post exercise because that’s after all the initial fluid shifts occur.....but was also chosen because it was 10 minutes before the horses started to become fatigued. 

Ummm.....not as close as I thought.

And then I came across a section that was actually labeled as “endurance” and “submaximal”.  Yeah!........except it was measured in drafts pulling heavy loads on consequetive days. Again, different from what we are looking for.  The lesson here is that you cannot just take titles and abstracts and assume that something with the right key words are going to be relevant to competing a horse across 25 or 50 or 100 miles. 

Acid Base Part 3: Continuing with plasma volume and exercise

Quick update on me:
Third year is so far, much more awesome than previous years. Mostly because they split the class up into large and small animal.  Any guesses of how many large animal people there are from a class of 140?

About 25. 

That’s AWESOME!!!!!!!!!

Turns out I’m much more motivated to study and learn and prepare when I’m sitting in an itty bitty room with just a few other people and an instructor that doesn’t have to use a mike, and can write on the board instead of droning through powerpoints (powerpoints are a way for instructors to shove way more information than should be presented in 50 minutes at students - akin to having someone read every 3rd sentence out of a text book for 50 minutes (x8 a day) and is about as interesting.  Having to talk and write on the board provides a much more reasonable pace/amount of information and forces instructors to interact with their students as we ask them to decode their handwriting and whimsical drawings.

Anyways.  I’m pretty sure that was a tangent.

The second half of this year will be even more cool as out of that 25 students....there are only 4-5 food animal students.  Talk about individual attention!!!!!!  (which is nice considering the bill I’m paying for my education). 

So, I’m writing bits and pieces of these blog posts as I can squeeze them in.

I had some reader questions on the last couple of posts.

I said in the previous post that when Na is lost in sweat, Cl follows it. It’s not because Na and Cl are stuck to each other like they are in a NaCl salt compound.  It’s because Na has a (+) charge and Cl has a (-) charge. All the body fluids want to remain “electroneutral” - ie the same amount of negative charges to positive charges.  When Na leaves at a high rate in the sweat, the ECC is losing a lot of (+) charge.  The loss of an equal number of (-) charges keeps the body fluid close to electroneutral. 

This was sort of a side point to the main topic, which is why I skipped over it.  However, electroneutrality is an important concept :). 

The other question had to do with what a blood vessel wall was actually composed of, as opposed to tendon sheaths etc.  Are the all the same thing? 

Nope. All blood vessels contain a cell layer called “endothelium”. Depending on the exact type of blood vessel (artery versus vein versus arteriole versus capillary) there are more or less additional layers to the vessel such as a elastic fibers made of protein and protein.  Capillaries are the smallest blood vessels are are just made up of the endothelium.  Think of endothelium as a layer of cells, like skin, that make up a sheet, that happens to form a round tube. 

Here is some excerpts from my Histo book (Bacha, William J.. Color Atlas of Veterinary Histology, 3rd Edition. Wiley-Blackwell (STMS), 01/2012. p. 77), because they explain it so well, BUT I vainly don’t want delete what *I* wrote....so including both.

“Vessels of the cardiovascular system are lined by an endothelium, which is typically a single layer of squamous cells. The smallest of the blood vessels, capillaries, are tiny endothelial tubes.

The walls of arteries and veins are arranged into concentric layers: the inner tunica intima, middle tunica media, and outer tunica adventitia. The composition and thickness of these layers vary with the size and type of vessel. The tunica media is not always present.

Small arteries can be defined, arbitrarily, as possessing up to eight or nine layers of smooth muscle cells in the tunica media. The smallest of these vessels is usually termed an arteriole. Its wall is comprised of an endothelium (tunica intima), one or two layers of circularly arranged smooth muscle cells (tunica media), and a bit of surrounding loose connective tissue (tunica adventitia). Some of the larger small arteries have an internal elastic membrane (a sheet-like membrane forming the outer surface of the tunica intima). Small arteries are accompanied by small veins. The smallest veins are called venules. These are similar to arterioles, but have relatively thin walls and lack a tunica media of smooth muscle. An internal elastic membrane is not found in small veins.

As the diameter of a vessel increases, the tunics become larger and more elaborate. For example, the tunica intima of a medium artery contains connective tissue interspersed between the endothelium and internal elastic membrane. The thick tunica media, with varying proportions of smooth muscle and elastic fibers, comprises the bulk of the wall. The connective tissue of the tunica adventitia contains collagenous and elastic fibers, small blood vessels (vasa vasorum), and nerves. A medium vein, in contrast, has less smooth muscle and fewer elastic fibers in the tunica media and possesses a thicker tunica adventitia.”

Part 3 official start: Continuing with plasma volume and it’s response to Exercise

To recap, we’ ve talked about solutes and their ability to push and pull water in the various body compartments.  We’ve talked about a mechanism that the body uses to correct low volume in the plasma or vascular compartment....and then followed up with a statement that ALDO is actually not that involved DURING exercise, even though it is elevated after exercise for a couple of hours.  We know that during exercise, water leaves the ECC (of which plasma is a part of......) as sweat, which the body has to react to because “hypovolemia” (low plasma volume) makes for a very very very unhappy horse (or human for that matter). 

So, let’s talk about exercise and the fluid shifts that occur. 

Veins are also referred to as “capacitance vessels”.  There’s your fancy vet word of the day that I just couldn’t resist :). Basically, the vessels can hold a lot of blood volume and can return more or less of it to the heart depending on the body needs.  When the demand for lots of oxygenated blood is (low - for example when I’m standing at a library study desk typing this blog post) blood sorta pools into the veins, which expand (they are loose and flopping and can stretch to accomodate lots of blood). 

When a loose, rabid dog barrels into this room and my body decides it needs to run like hell, the net result of a lot of different physiological responses is that the blood in the veins will decrease because it’s no longer pooling - it’s being pushed though the system as fast and furious as possible. No longer is it sluggishly making its way through my veins. 

Bottom line, the immediate response is the redistribution of fluid from “capacitance vessles” and interstitial spaces and plasma volume increases.  This allows the increase in cardiac parameters needed for that fight/flight response - it creates an increase in “cardiac output”.

After this immediate response, MINUTES later, plasma volume DECREASES. This is because of hydrostatic pressure (the pressure of water pushing) driving water and elytes etc OUT of the vascular compartment into the intersitium.

Notice that so far all the shifts in water are occurring between the ECC “subcompartments”.

At first this seems counterintuitive......having all that fluid in the vasculature is good for performing exercise right?  That’s why there’s initially an increase....so why would there be a decrease? 

Because the fluid in the ECC has more functions than just to participate in cardiac output. Remember that the interstitial compartment of the ECC is the body water that is bathing the cells, delivering nutrients and taking away waste products. This push of fluid out of the plasma into the instersitium allows the working muscle cells (and other cells) to take up the fluid.  It can either be turned into sweat for thermoregulation (extremely important), or returned to the vasculature compartment. 

Remember that we are talking about the first couple minutes of exercise. 

Going to class now, so will pick up from here next time.

Acid Base Balance Part 2: Sodium and Intro to Plasma Volume

Low plasma volume is called “hypovolemia”. Losing body water to sweat during exercise causes a SIGNIFICANT loss of plasma volume. Plasma volume is protected by the body, because in the presence of hypovolemia the cardiovascular (to put in a very non-vet way) crashes. 

No bueno.

Plasma volume expansion is one way the body adapts to exercise and to heat conditioning.  Decreasing plasma volume that occurs in the older horse is cited as one reason older animals can’t thermoregulate as well as their younger counterparts.

In summary, how much fluid is in the plasma ECC body water compartment is REALLY important. 

Remember how I said water follows solutes?  More precisely, in the body, water follows sodium.  So, if the body wants to add water to the ECC/plasma compartment, it needs to increase the amount of sodium in the plasma.

And it turns out, that is exactly what happens. 

If plasma volume goes down, sodium increases in the plasma. 

If sodium increases, the solute content of the ECC increases. Sodium cannot pass through the barrier between the ICC and the ECC, so water moves instead.  Water redistributes across the body water compartments and moves into the plasma/ECC, drawn there because of the sodium. 

How does the sodium increase in the plasma? 

The answer to that question in most of my “general” text books is “Aldosterone acting on the kidneys (and the gut).”

Kidneys filter plasma and depending on what the body needs at that moment, will either retain stuff (like elytes and water) or remove it.  For example, it removes or leaves more water depending on the balance between how much you drank, and how much you sweated, making your urine more or less concentrated.

Aldosterone (ALDO) is a biological molecule that is released when the body senses that there is low plasma volume (such as during exercise because of sweat losses) or high potassium in the plasma.  ALDO causes the kidney to reabsorb more sodium than usual, and secrete more potassium.  Voila!  Result: more sodium in the plasma that will attract water.

Side note: ALDO also causes the kidneys to produce more bicarb and dump it into the plasma.  As we will talk about later, Bicarb is one of the very important buffers in maintaining acid base balance.  So tuck this away in the back of your brain, and we will come back to this later.  
ALDO also acts on the intestine.  Along with vasopressin (ADH), ALDO increases the uptake of water and elytes from the gut!!!!!!   

Several sources observed that a horse, especially those on a high roughage diet, have an enormous fluid and elyte reserve in their gut.   In the presence of ALDO, this reserve becomes even more available.

Unfortunately, when I started looking at ALDO in the exercising horse, it turns out that ALDO is considered to have a “limited” response in “acute” exercise (ie sudden, short term), although it remains elevated in the body for HOURS post exercise - helping the body to recover in the acute phase to replenish water and elytes lost.

There are other more major factors that are moving water and adjusting solute concentrations during exercise.  However, let’s finish talking about the equine gut reserve before moving on.

This reserve in the gut was cited as a possible adaption to make up for their simple sweat glands and the amount of elytes lost in the sweat and this “gut reserve” can be utilized during exercise.

You might recall from the thermoregulation posts that there is a difference between horse and human sweat. There is a LOT more elytes in horses sweat.

As humans sweat they lose water, but since their sweat glands filter out sodium, there is less sodium per water than in plasma.  Less sodium lost means, less chloride is lost (Cl has a negative charge, and thus follows Na - which has a positive charge - in the sweat to maintain “electronuetrality”).......Bottom line: there is a relatively low concentration of sodium and chloride in human sweat.

Equines are different.  They lose sodium in their sweat in the same concentrations as what is in plasma.  They are also losing tremendous amounts of Cl because like in humans, it’s negative charge is matching sodium’s positive charge.

How does this matter?

In the human, as they sweat and water is lost from the ECC, very little sodium leaves with the sweat.  So, even though the total amount of sodium in the ECC is relatively unchanged, the decrease in water means that the ECC is more “concentrated”.  Remember what happens where one body compartment has an increase concentration of solutes?  Water moves to the area where there are more solutes, restoring plasma volume.

In the equine, sodium and water are leaving as sweat in the same concentration as they exist in the plasma.  So, even though your plasma volume decreases and the total amount of sodium decreases.......the concentration of sodium remains relatively unchanged.  In fact, horses can lose up to 30 liters of sweat OR MORE before sodium concentrations in plasma change.  In endurance horse studies, there are minimal changes in plasma concentrations of sodium, even though the total sodium content has significantly decreased. Because of the large amount of sodium lost in sweat and the chloride that is accompanying it, horses also experience tremendous losses of plasma chloride - which decreases in both concentration AND content.

To recap:

Sweating Humans:
Sodium plasma concentration: increases
Plasma volume: decreases (because of water loss in sweat)
Total amount of Na: unchanged (or slightly decreased)

Sweating Equine:
Sodium plasma concentration: unchanged
Plasma volume: decreases
Total amount of Na: decreases

As you can see - because of these differences it can be very difficult to extrapolate from one species to another on the topic of exercise and electrolytes!

Next up: If ALDO doesn’t fully explain how a horse supports plasma volume during exercise, than what does?

Acid Balance Part 1: Important concepts

References - for this post and the following posts.......I will probably add more, but these are the main sources that are a good starting point if you want to do your own reading.

Faubel, S., & Topf, J. (1999). The Fluid Electrolyte and Acid-Base Companion (1st ed.). Alert and Oriented Publishing Co.
- Note: just like Hinchcliff, with some searching on the internet it *may* be possible to find the book for free in an e-version. 

Hinchcliff, K., & Geor, R. (2008). Equine Exercise Physiology: The Science of Exercise in the Athletic Horse. (1st ed.). Saunders Elsevier.

Reynolds, G. (2012). The First 20 Minutes - Surprising Science reveals how we can exercise better, train smarter, live longer. Hudson Street Press.

And now to get started!

I have put more hours into researching this topic than any other subject I have introduced on the blog to date.  And yet, I feel like my understanding is barely sufficient for me to compose a post on it.

In my experience, the more confusing the literature is, the less we actually know about the subject. 

I tend to avoid those subjects on the blog. Because it’s a lot of hard work to sort through the literature, read expert opinions and reviews on the literature since the studies all contradict each other, and then come up with something concise, interesting, and accurate to post here.  But this is an important subject that enough people expressed interest in me doing so, here it goes.

Turns out that acid-base balance, especially in the exercising endurance horse... especially if you are looking at how it changes in response to conditioning..... and especially if you are looking for real world applications to the research is, well.......not exactly clear.  And everyone is contradicting everyone else, and there’s lots of caveats to everything, and it’s quite confusing.

So, here it is.  My best guess at acid and base balance (along with the intimately connected topic of body water) in an exercising horse, and hopefully enough information that you can make your own informed decisions on managing your own endurance horse. 

Important Concepts

We are going to start with “important concepts”.  These are concepts that will probably be familiar if you took chem and bio in school, but you might need a refresher on.  It is very very very important that you are comfortable with these concepts because EVERYTHING that relates to body water and acid base balance are based on these concepts. My hope is that all my upcoming posts are accessible to anyone, no matter what their background, so if this all seems rather simple to you than feel free to skim....

Important Concept 1 - Compartments

Body Water is kept in compartments. 

(All drawings blow up if you click on them)

There are 2 compartments - the intracellular compartment (ICC) which represents all the water inside cells and the extracellular compartment (ECC) which represents all the water outside cells.  The ECC has two “sub compartments” - the interstitial and plasma.  Interstitial is the fluid surrounding cells, that is outside of the blood vessels.  Lymphatic fluid is a type of interstitial fluid.  Plasma is water inside of blood vessels.  Plasma is NOT cells - it is the liquid that all the cells and other “stuff” is dissolved in.  Red blood cells are IN the plasma, but not part of the plasma.  Plasma proteins are IN the plasma, but not part of the plasma. 

Important Concept 2a - Barriers

There are 2 barriers
1. The cell membrane divides the ICC from the ECC. 
2. The blood vessel (BV) wall divides the interstitial fluid from the plasma.  The blood vessels that are represented in the diagrams and that are most relevant to this discussion are mostly capillaries - the really small vessels. 

A simplified diagram that shows the 2 compartments and the 2 barriers looks like this (yes, I know I’m calling the cell membranes “walls”, but once I got it done, I really didn't want to redo it):

 

The two barriers have very different properties. 

Think about the blood vessel membrane as a decorative fence and the cell membrane as a chain link fence.  The decorative fence allows much more stuff to flow back and forth than the chain link fence. 

The cell membrane and the BV membrane both allow water to flow across them.  So, water moves freely from the ICC to the ECC (both areas) and back and forth as it needs to. 

Important Concept 2b - Barriers and Solutes
Solutes are the “stuff” that is dissolved in the fluid of each body compartment.  This “stuff” is electrolytes (elytes), proteins, non-elytes etc.

Some stuff can go through the dividers, and some can’t. 

Water can go through both dividers. (notice this is the second or third time I’ve mentioned this.  This is because it’s IMPORTANT).

Potassium and Sodium cannot go through the divider between ICC and ECC.  Most of the potassium is trapped in the ICC (99%), most of the sodium is trapped in ECC. 

The sodium and potassium in the ECC can move between ECC compartments (plasma and interstitial). 

Although the “decorative fence” that splits the ECC into plasma and interstitium let’s a lot through.....there are some things like plasma proteins that can’t get through and are trapped in the plasma. 

So, to recap:

ICC: High in Potassium, Low in Sodium
ECC: High in Sodium, low in potassium
ECC/plasma: High in Plasma protein
ECC/interstitial: Low in plasma protein

WATER: can move through ALL barriers and distribute to ALL compartments.  How much water ends up in each compartments depends on how many solutes are in each compartment. 

Which brings us to “important concept 3”

Important Concept 3: Solutes and Water movement

The number of solutes dissolved in the water is called “osmolality”.  Think about this as the “concentration of solutes”. 

Water will follow solutes and distribute in such a way that the concentration of solutes will be equal in the different compartments.

Don’t worry if that hasn’t completely sunk in.  We are going to go over the concept in small bites with pictures. 



 

Imagine you have 2 containers with the same amount of water.  To each container you try to add the same amount of a substance - we will call our substance “solute”. 

To your horror, you accidentally add TWICE as much to one container as the other one.  The second container has way more solute in it, and thus is more concentrated.  :(

How are you going to fix it? 

You have 2 options.

Option 1 - Move the solute around so that each container has the same number of solutes. 

Option 2 - Move the water around so that each container has the same number of solutes.

































In both options, the ending concentration of solutes per water ends up equal!!!

Instead of 2 separate containers, imagine them joined together, and instead of having to “transfer” water and solutes between them, imagine a divider or membrane between the containers that will allow water+solutes or just water through. 




 

Can you see that water follows solutes?  Water goes where there is a greater concentration of solutes. 

Whenever there is an imbalance, the solutes try to move first.  However, remember that the cell membrane divider between ECC and ICC doesn’t allow K and Na (which are solutes) to pass between freely.  So, the body uses the movement of water to correct concentration imbalances between compartments.

During exercise we aren’t usually adding solutes to the compartments - the problem is that water and solutes are leaving in the form of sweat!!!!!

Here is a simplified example that brings together all the concepts in this section
a. solutes try to equalize across the dividers if they can get through
b. water can move across both dividers to try and equalize concentrations of solutes in all compartments.




Of course, this is simplified, and we will talk later about how elytes and fluids move through the different compartments during exercise.  But hopefully this illustration helps cement the important concepts we have discussed so far. :). 

PS - to EnduranceGranny and anyone else who is having trouble searching the blog - I have no idea what is wrong with the widget on the sidebar.  It used to search the blog and now it doesn't.....I've tried removing and reinstalling it to no avail.....So unless anyone has any bright ideas, it looks like my blog search function will only do that last couple months or so :(, until I have the time to devote to a fix, which doesn't seem likely since school starts Monday.........

Your regular scheduled programming will return

Why the long silence?  I'm researching the body water/electrolyte/acid base topic, which is IMMENSE and requiring quite a bit of brain power to break it down into something I can understand, much less explain here!  I start school next Monday and would really like to have some posts put together for you on the electrolyte topic before starting up. So I've been pouring my energy and time into those posts between traveling for work, hanging out with my horse, and getting my runs in - leaving little time to write on other stuff.

So, go away and read some of the awesome blogs on my side bar and I'll see you in a couple of days or less :).

Edit update: just finished the research on the topic (acid-base) and now to compile 50 pages of notes into interesting and understandable bite size chunks.  Oh my oh my oh my.  Good thing I already covered thermoregulation with you, My Dear Reader.  If I had gotten to my "muscle" and "magic spleen" posts that are currently in drafts it would have helped, but I think we can tip toe through the tulips well enough for now, and as a bonus -  "filling" in the horses legs will be answered through this discussion of body water, fluid shifts, and acid base.  Whew! 

What did I accomplish this year?

Before we get into the post today, just wanted to say that I actually took a good look at Farley’s feet yesterday, ~10 days post Tevis and DANG they look good.  I think that’s my favorite part of riding a 100 in strap ons - the hooves just look incredible afterwards (in glueons they are always feel a bit soft and are smelly).  There’s a ton of growth, and the retained sole that I’ve been glaring at for the last couple months is falling out, and the hoof that is the “High” of the high/low is actually wearing heel and the hoof that is the “Low” is actually wearing toe.  So Cool!!!!!!!!!  If an argument could be made of riding a 100 miles being beneficial to a part of the horse, hooves would definitely be the winner.

Since Farley got hurt and I started vet school in 2011, I haven’t posted my normal “goal” posts.  It’s hard to have exciting goals that I feel like striving towards when both time AND money is severely limited, and I didn’t know whether Farley would hold up under a 50 mile effort, never mind a 100 miler.  But, it turns out I’ve had quite the successful season.

This year was all about tying up loose ends and being a part of endurance in a bigger way than just riding the rides.

1. Farley’s 1,000 miles: Complete
2. Get Cougar rock pics: Complete
3. Start Tevis (and feel good about my horse): Complete
4. Crew for the first time: Complete
5. Go to a ride just to volunteer (as opposed to finishing and then volunteering): Pending.....haven’t decided which ride, although I have some 2014 rides on the list.
6. Go to a trail maintenance day: Pending.  Haven’t quite figured out where to start on this one.

I think as far as doing rides my season is done, but as you can see, I still have an item or two to check off the list. 

Farley’s 1,000 miles is probably the achievement that means the most to me.

I can’t bear to put it away, so it may be the first thing that has ever lived on my rear view mirror. 

Of all my riding related goals, this was the one I knew was the most doable, and it was the one I cared the most about.  When I started the season, I was 3 50’s away from Farley having 1,000 career endurance miles.  When she got injured at 20MT in 2011, that was the goal I most regretted possibly never being able to achieve, and it was on the top of my priority list if we ever did endurance together again. 

When I got lost on the first day of Wild West I was so pissed at myself and kept telling Farley how sorry I was that she had a moron for a rider.  I knew there was a good chance we were doing Tevis that year, and the odds are not “ever in your favor” for finishing Tevis, so I couldn’t count on the miles there.  After Tevis we were done for the season, and so by having to RO at WW I was letting that 1,000 mile achievement slip away for yet another year.  A lot can happen in a year and there are no guarantees that me and Farley will have another season, or a season after that - sh*t happens.  Of course, we know the ending to the story - I was convinced to go on after learning the trail was short, went out the next day and Farley had her 1,000 miles.

But, the point is: as much as this award means to me, I was willing to let it go this season if I couldn’t do right by my horse in the process.  And I think that’s what I’m most proud of.  I earned this award, even while being determined to pull Farley at the *hint* of NQR in any of the last 155 miles.  That wasn’t always true over the course of these 1,000 miles - Before I was willing to manage through minor issues, and thought many of my less than “A” scores were “normal”.  But, my perspective and goals are different now, and while I know I’m a competent horseperson enough to managing issues during a ride, now I realize that I don’t want to if I can’t feel 100% good about what I asked my horse to do  when I look back over the ride.

Tevis Details IV - (Boots and Gear lists)

My ride and tie essay is submitted!!!!  And....I had a revelation.

Did you know that the scholarship award is exactly the amount of a used Solstice saddle?  Which, as of 2 years ago, did not hurt my knees when I rode.  And it fit Farley well enough. 

Of course, it’s also the same price as a lot of other endurance saddles that *might* work too - and who knows if the Solstice even still fits Farley.....but at least now I can borrow saddles from friends to try without the awful feeling that if I like it, I can’t ever afford one. 

The issue is my lack of rides of course.  How am I suppose to test out a saddle if I’m not riding 50’s every month? 

But the point is, I think it would be ENTIRELY appropriate to use money of this sort to buy a saddle.  Does my Dear Reader agree? 

*sigh* I don’t even know if I agree. There’s all sorts of more responsible things to use the money for.  Like.......tires for the trailer.  Or.....rent and groceries when no one hires me out of vet school because I have no practical talents beyond obsessive research on equine performance topics. 

Moving onto Tevis! Yet more details about the big race that everyone but me is sick of hearing about :). 

Boots!

I could not have done Tevis this year if it wasn’t for the generous sponsorship of Renegade hoof boots.  And I’m not just saying that - With a $450 entry fee (and I actually paid $550 because I waited until after Wild West to enter) there’s is absolutely no way that I can even afford to ENTER Tevis as a very very poor vet student. So, in the interest of full disclosure, Renegade paid for my ride entry and gave me some very spiffy orange tack and boots.  Additionally, I’m a dealer for the boots. 

You should know me well enough by now to know that if I can’t be honest and say what I believe here on the blog, than I won’t post it.  I’m not good at the “smile and nod” game .  Nope.  I’d rather lay it all out for you and have you, my Dear Reader make your own decisions. So you can rest assured that when I post something here on a subject like boots or anything else, it really is the whole story, not a version that I’ve “prettied” up because I have a financial or personal incentive to do so.

So, here’s the bottom line: I would ride Tevis in strap on boots again even if there was no financial incentive to do so.

Of all the options available today, I truly believe that the strap on boot - specifically the Renegade, since as far as I know is the only strap on boot to have complete the Tevis without modifications multiple times - is the best.  Not perfect....but the best.

I’ve ridden Tevis three times in three different hoof protection options. 

The first year I did it in shoes with pads.  Compared to the synthetic options, predictably the steel shoes did not have as good a traction.  I had pads so it was a comparable to boots over the rocks. I didn’t like the pads under the shoes and how it changed the angle and height of the hoof, she didn’t seem as sure footed as usual, and I was not thrilled with how her feet looked 6 weeks later when the shoes were removed.  I only shoed for races and didn’t have any races coming up, so I didn’t put shoes back on right away......by sheer coincidence those were the last shoes I ever put on Farley.  I switched to Renegades shortly after.

For the second attempt I used glueons.  I’ve expressed my views on glueons, but if they had stayed on I would have considered the hoof prep acceptable for a once a year “big ride”.  They didn’t.  I started losing glueon boots around mile 15 and they came off one by one as I rode and finished 100 miles. That year at Tevis I rode a lot of miles in the strap ons not by plan, and completely barefoot.  Some of it was my errors in prep......HOWEVER, even when professionals from boot companies glue them on they come off at Tevis.

The glue ons perform well when they stay on....but honestly, if I’m going to ride in strap ons anyways when the glueons fall off, I’d rather just start the race with them and skip the whole “sand off the outer wall” of my horse’s hoof. And, there’s the removal of the glueons -  if the glueons do stay on ‘til after the ride is finished, I struggle to take them off in the first few days after a ride, when me and my horse hate each other :) [I spend a lot of time in disbelief at how awesome my horse is DURING the ride, but AFTER a ride we both need our alone time - she’s not a pony that enjoys pampering and while she deals with the fussing during a ride as part of her job, afterwards she needs her space and I need mine].

So let’s talk about the strap ons. The strap ons were GREAT.  I put them on the morning of the ride, I took them off (or maybe my crew did?) after we were done that same night.  Her hooves looked great before and after. I also got all the benefits of the glueon over steel - increased traction, significant concussion absorption and protection from rocks - without the downsides of a sanded hoof wall or time spent prepping or removing boots.

Also, unlike the glueons, if I was concerned there might be an issue with the boot - such a rock or debris - I could take the boot off and make sure everything looked good.  Removing a glue on to see whether you got some glue under the sole that is making your horse sore is not quite so easy.....

What about losing boots?  Yes, I lost strap on boots this year.  But....I lost less strap on boots this year than I did glueons in 2010.  I did less miles barefoot this year than I did the year I wore glueons.  So, not perfect.....but I really felt like strap ons are the best option for tackling that trail at this point. I could chose a nail on option and likely not to have to any of the trail barefoot....but I think the consequences of going back to steel for this ride are worse than the possibility I might have to go a couple of miles with my horse (that is sound over rocky terrain without boots) barefoot.

Will I ride next year in strap ons?  I hope so. So much of it depends on her hooves - while there is flexibility designed into the boot to adapt to a hoof that isn’t quite perfect, the Tevis trail is HARD on boots and demands the best performance out of boots, which is achieved by a hoof that is ideally trimmed according to a “natural barefoot” trim, with relatively normal biomechanics.  I’ve had some challenges with Farley’s hooves over this year - thrush in a hind bad enough to make her look like she had an abscess, high/low syndrome in the fronts that I let get out of hand that takes time to correct, and a hoof landing that wasn’t quite as solidly heel first as I’ve seen in the past.  I still chose to go with the strap ons because of the 3 options available to me (nail, glue, or strap on) I still felt like it was the best way to support my horse’s hoof health, and I felt like even if I did have issues, she could go significant distance barefoot if we had too without an issue.  If I did glueon in the future because of a hoof issue, it would likely be the hinds, since because of the additional stress and thrust going up the heels, it seems like if my hind feet are not in ideal shape, they punish the boots the most.

Was Tevis the hardest ride on the boots themselves I’ve ever done?  Nope.  American River was much harder because of the presence of mud and water combined with erosion ditch single track and hills.  There are some boot eating parts of Tevis, but I’ve done worse trails in the boots. If you are thinking about doing Tevis booted, I would encourage you to think about your strap on options. It’s doable and the boots just keep getting better and better. There would have to be SIGNIFICANT reasons for me to chose to NOT ride in strapons next year. 

Let’s end our Tevis discussion with some more lighthearted topics!

Things my crew did that absolutely made a difference

1. Washing my girth at each check.  My sensitive, thin-skinned arab really appreciated this and because this detail was meticulously attended to, Farley doesn’t have ANY girth sensitivity or rubs.  Incredible. (adding the crupper was a factor too - but a clean girth was key).
2. Getting my leg boots really really clean
3. Icing Farley’s legs post ride (I always have good intentions...)
4. Replacing straps on the boots every time I took them off for some reason
5. Glow bars - putting them on, convincing me it was a good idea. It made me so much more visible on the trail and how they expertly placed them I couldn’t see them at all (I HATE catching the light out of the corner of my eye).
6. feeding me at vet checks, and bringing me a delicious hot meal at Foresthill, and making me fill out my food charts.
7. Getting the best crewing area EVER at Robinson Flat
8. Not laughing at me when I was butt naked in the middle of Foresthill taking a sponge bath and for the life of me, couldn’t figure out what parts of me was suppose to go through what holes in my shirt
9. Keeping me accountable to my rider plan.  What’s a rider plan you ask?......

The rider plan

One of the pieces of advice on the new100milers yahoo group list was to make a rider plan for nutrition and elytes and stick to it. I developed a plan from doing my 50’s at the beginning of the year, and seeing this advice on the email list solidified my resolve that I would ABSOLTELY STICK TO THE PLAN. 

1. Every hour take a mouthful of goop (nutella+almond butter)
2. Every hour until noon take 1 elyte capsules. Every hour from noon until 6 take 2 elyte capsules.  After 6pm, take 1 elyte capsule until done with race. 

This food and elyte protocol worked PERFECTLY.  At no point during the ride was I ever nauseous or had a headache, or didn’t feel good.  My adherence to the chore of popping elytes and goop every single hour without exception totally worked.  I actually came into each vet check ready to eat instead of nauseous.

I’m not sure why I believe in elytes for myself and will literally fall apart in a ride just a couple of hours in if I don’t take them....but I’m really hesitant about putting my horse on an elyte schedule. 

I haven’t done a lot of research into human elyte supplementation so maybe it’s just as haphazard and confusing as the horse research....but my horse just doesn’t seem like she’s suffering from a lack of elytes during these rides, as long as she’s eating and drinking and is heat conditioned.  I can’t get my elytes solely from food during a ride, so why should my horse be expected to?  I’m not sure.  However, there’s no correlation between how she looks and feels based on differences of I’m supplementing her with elytes. 

I just don’t know. 

There’s a lot of similarities between horses and humans and how they sweat etc but there’s a ton of differences too.  And I don’t know which ones may be significant to the elyte question and which ones aren’t.....and caution has to be used when extrapolating from human studies and applying to our horses. 

The acid-base balance post is on the draft list and maybe I’ll have some giant revelation about horse versus human elytes during my research for it, but for now, I have to just live with the hypocrisy of the fact I need regular elytes during physical activity, but my horse does not.  Stay tuned, I’m sure my views on this will continue to evolve and change.  

Next up!

I’m posting my gear list in case anyone is interested in the specific equipment I used or what I carried.

Gear List

• Equipedic pad - got this pad used and only use it during rides to try and make it last.  Really like this pad.
• Wintec saddle - Didn't work out so well :(
• webbers - continue to use and like these.  They wear out faster than other options, and I get nervous about them coming undone inside my fleece covers, so I electrical tape them.  But over all best no-bulk leathers I've found.
• Fleece over stirrup leathers/webbers - Sleeves without velcro.  If I had to do it over again, I might get the ones that velcro. 
• American Trail caged stirrups - LOVE the cages.  Don't like the stirrups as much as my composite fillis irons, but love the cages.  And I'm so glad I went with the blue and green instead of orange or black.  Although orange and purple is quite tempting don't you think?
• mohair string girth - this type of girth rubs Farley the *least* but if anyone else has a magic no-rub girth, I would love to hear it.
• American trail crupper - Best crupper on the market that I've found.  Love it. 
• American trail breast collar
• 4 snugpax boot bags - Used 2 for boots, one to hold my platypus water bottle, and one for my misc small stuff.
• American Trail halter bridle - absolutely gorgeous :)
• Myler kimberwick double joint bit - Decided on this bit so that she could absolutely not pull on me going down hill, which kills my knees and back faster than anything else. 
• round rope reins - with sisscor clips.  Really like these reins and have used them for years.  Perfect length.  Do wish I had a way to easily secure to the saddle when I'm dismounting and running or tailing so they won't slip to one side or the other.  Maybe a ring in the middle?
• Renegade boots - :) I wore vipers on the fronts, and the standard model on the hinds with viper captivators.
• Griffins leg boots - all around.  I only do that at Tevis and I was so glad I did.  There's so many rocks and stuff that are just waiting to bang up the legs.  Griffins were recommended to me early on and I've used them ever since. 
• Grittins large sized velcro ditty bag - This is how I carried my ride card, data sheet (with cut off times and list of checks), my elytes, horse elytes, and goop.

Pack contents

• 1 front spare boot - in a snugpax boot bag
• 1 rear spare boot - in a snugpax boot bag
• platypus 1 liter bottle - with a hose, turned upside down in a snugpax boot bag on the front of my saddle.
• elyte pills in mento gum container
• squeeze bottle of goop
• datasheet with checks and cutoff times
• sunscreen stick - used coppertone sport, which is a brand I've used for years in the lotion.  LOVED this stick.  Didn't melt, putting on was a breeze, more waxy and less greasy and I didn't notice that my skin felt as oily or collected dirt as much. 
• gloves (never wore)
• 2 feminine pads (for rubs or bruises)
• Ace bandage
• 2 half doses of elyte in syringes with wire cap tops
• Platypus water bottle with a hose.
• ????????? I’m sure I’m forgetting something, but this is the bulk of the items. 

Picture of the platypus set up as requested by Ashley: (click to make it larger).

 Here's the platypus bottle (1 Liter): http://www.rei.com/product/849826/platypus-softbottle-water-bottle-34-fl-oz

Here's the hose: http://www.rei.com/product/768135/platypus-drinking-tube

This is what I would buy if I was going to buy something particularly for this purpose because it fills from the top easily with a wide mouth - the reason I use the more normal bottle is because I use these primarily for my backpacking: http://www.rei.com/product/798147/platypus-big-zip-sl-18l-reservoir-60-fl-oz.  This way I wouldn't have to remove the platypus from the bag and screw off the hose - I could just unzip the top and pour water bottles in the top at the gate and goes.

If you want to see a real life picture of how this looks from the outside in real life, look at this picture.  See that blue hose by my right knee/thigh?  That's the hose from the platypus outside of the black boot bag which contains the platypus bottle. The hose is long enough for me to drink from the bottle while trotting, but short enough that if I drop it, it doesn't reach the ground or interfere with the horse if it dangles.  I use the included alligator clip on the hose to clip it to anything handy (tack, breast collar, the boot bag etc.) when I'm not drinking.

OK folks - that’s it for now.  I’m working on a Tevis Tips post that won’t go up for a while - a collection of tips that I want to both remember for myself, and what I would share with other riders that want to do Tevis.  But in the short term we will move on to other topics :).