Low blood pressure and Chicago Marathon?

Hi Coll div

Very interesting, and don't defer on anything, please!! You sound as though you have a different, but equally valuable take on the subject, so I'm quite happy to defer to you in that regard! the theory of ALL THE WAY AROUND is a good one, but not been studied yet, as far as I can tell. And the papers I'm familiar with all look at the increase in temperature as the main factor precipitating the 'leakiness' of the cells. I did a search for articles a moment ago and found only those again.

I still wonder about how powerful the effect of cytokines would be - enough to heat a man who is sitting in a bathtub full of ice water? That level of heat production, enough to overcome the cooling of cold water, is not seen during exercise, when this cytokine cascade is happening. And then more than this, it happens so rarely that I suspect there has to be more to it. If the cytokines alone explained the rise in body temperature, then most people would overheat, yet hardly anyone does. So there's still a "missing link" in the puzzle.

ANd lastly, there's not much evidence that acute dehydration does compromise sweating responses. Only in lab studies, where athletes are hypovolemic before exercise and then not able to drink, in the presence of zero wind cooling, has this ever been observed. As soon as you provide wind cooling the body's ability to lose heat is more than adequate, even with the 2 to 4% body weight loss that one sees during exercise. I will concede that if you lose more than about 6 to 8% of body weight (from fluid that is, this is a proxy, and sometimes a clumsy one, just for the record), then your sweat response begins to be compromised. But not at 2 or 3%, in normal exercise.

But anyway, as I said in a previous post, feel free to email me at

if you want to chat further!

Cheers

Ross

Wile E. Coyote wrote:

Again, thank you for your replies and for turning what was from me a somewhat rude post into an open discussion. As a medical student, I take the dispersion of medical information over the net and in the media very seriously. I see that you can appreciate that. I have thumbed through The Lore of Running several times, and now plan on picking it up, as this thread has sparked some new curiosities. Also, I would not be too concerned with having an extended intellectual conversation over this forum; Lets Run could use more of the same. Cheers,

Wile E.

No worries! I'm delighted to discuss things. I have seen (particularly in this subject and area of physiology of the fluid debate: Noakes vs Gatorade) how failure to openly discuss matters and listen can lead to even more problems. So the debate is fantastic. And yes, I do take the dispersion of information seriously - that was in fact the reason for the creation of the Science of Sport blog I share with Jonathan - we wanted to use news events to push the science into the public and make it more relevant, withe a focus on valid, accurate data - truth, not politics. Of course, people will disagree, but that's fine, provided it's discussed sensibly, it's great.

So thanks and don't worry. And good luck with the read, and I'm always up for a conversation!

Regards

Ross

Ross is exactly right. I instantly felt better when they laid me down and gave me water (which is what I craved). By the time I got to the medical tent, I didn't need much else as I wasn't overheated and didn't feel dehydrated.

Might I ask-- what would be the circumstances for giving someone an IV? I saw lots of runners getting these.

Top 100 at Chicago wrote:

Might I ask-- what would be the circumstances for giving someone an IV? I saw lots of runners getting these.

I suspect these runners were in more critical conditions. Giving fluid IV will replenish blood volume more rapidly than by ingestion, because it takes time for water to be absorbed by the gut.

Hi Top 100

The IV is a rapid way to restore blood volume. The jury is out as to whether this is even needed. From my experience of research in the medical tent, the people who come into the tent as collapsed runners are NOT more volume depleted than the people who don't. So in our 89 km long Comrades ultra marathon, there are 13000 participants, and 150 of them (about 1%) come into the medical tent, and 12850 don't. But the studies have shown that there is no difference in the level of 'dehydration' in these people - they lose the same amount of weight, which is really interesting. So why do some collapse, and does the restoration of blood volume help??? Don't know, but it's being researched.

one thing that has happened is that we've evolved this idea that if they collapse, you have to throw an IV in. That has actually contributed to more deaths than it prevents, in my opinion, because what happens now is that an athlete may actually OVERDRINK on the course - we discussed this before. For this reason, SOME of the athletes who come into a medical tent are hyponatremic, and the LAST thing they would need is an IV. Remember that the IV is hypotonic, which means it is only going to dilute the blood even more. There was a famous case a few years ago of a young woman who came in having had too much water, and she was misdiagnosed as being "dehydrated" because of the perception that dehydration causes collapse. The treating doctors gave her an IV and over the course of the new few hours, put EVEN MORE fluid in her. She died the next day, and I have little doubt that her treatment contributed to it.

So the reason it's such a big issue that people perceive dehydration as the cause of collapse is because this belief costs lives. The only way to know then, whether a person should NOT receive an IV is to measure the sodium content of the blood - this is now standard practice in the big marathons here in SA. Every person who comes into the tent has blood drawn, it's analyzed and within 5 minutes the doctors know. If it's too low, they don't give hypotonic or isotonic saline, but rather a specially formulated HYPERTONIC saline - this is to correct the sodium level. If the blood sample comes back normal, then the doctors make a call on the IV. They often give it anyway, but it doesn't seem to actually predict time to discharge of the patient, in that the people who receive an IV leave at around the same time as the people who don't, so it's interesting that way

But the incorrect use of IV can kill people.

Ciao

Ross

Dear Ross,

Can you give me your thoughts on this one ?

I ran extremely well as a kid. I started running at the age of 10 after 5 years of competitive swimming. My training was very hard and I ran fast as a 800-meter runner. I also ran a spontaneous marathon when I was 12 and was age-group cross country champion with 4 Jr. Oly metals. The short story….I stopped running at age 17 and started running again at 30 after a grueling career working 12-16 hour days.

When I started to train again …my coach and I noticed this bizarre situation that was happening with my legs.

I would train hard…and my legs felt great. Then I would taper for a race and my legs would become very, very heavy…..my coach sent me to doctor after doctor and we could not figure out what was the problem. He sent me to all of these herbalists. Then I went to a cardiologist and he said my veins needed to be stripped….I was not interested in that and not sure that stripping my veins would help.

After speaking with someone at a health store, he suggested that I raise my feet up for 15 minutes a day. That made my legs felt better. In fact, a lot better.

A month ago I had a check up with a hematologist….my blood count is good and I told her about my leg situation. The only thing she said she could think of is that my blood is moving to my feet good, but it is not pumping back up to my heart they way it should.

Do you have any suggestions?

Want to run great again..

When you exercise your body responds in various ways to the stress. One of the ways is to turn your arteries from "garden hoses" into "fire hoses". This reduces the resistance that the blood must face as it pumps its way through you. The alternative would be a heart rate of 370 or a BP of 300/200 -- something like that. So it is a healthy adjustment. Your lowered blood pressure is most likely the direct consequence of this arterial dilation.