LaFlore, you did read that right. A HRM can be used to keep you from overtaxing the heart. Lets say you set off the upper limit alarm, maybe you can alter your pedal cadence from a low cadence hard push to a higher cadence spin to bring your heart rate down while keeping the same speed (or vice versa). It is very possible to overtax the heart before you feel 'the burn' from lactic acid builup in your legs. For some people all it takes is walking up a flight of stairs and I can gaurantee you they didnt fell 'the burn'.

Is this something only people with pre-existing heart need worry about? To be honest with you, I dont know. Think of a HRM as a tool that has several functions. Choose the function that best serves you purpose. Maybe you should try it in a crit.....perhaps your HR isnt getting high enough!?!?!?

One thing that may or may not be a factor here is blood doping. This is something that has happened in sport to give athletes an edge, and up to a point, is undetectable.

Basically, an athelete either transfuses his own blood or takes Erythroprotien to increase his Hematocrit level or count. What this does is give your blood more red cells like you are living at a super high altitude. having more red cells gives you an advantage over competitors on getting oxygen to muscles. Lance does something similar but legal where he sleeps in an oxygen deprivation tent to natually raise hematocrit.

The drawback, when blood gets this thick (hemtocrit over 50%), if you get dehydrated, the blood can turn to jelly and BAM instant heart attack.

Not saying this is what happened to these particular atheletes, but it is certainly possible that this or something similar contributed so when dealing with elite atheletes, perhaps a) sometimes we dont have all the facts and b) regular causes of heart attacks don't nececarily apply.

peas,

Jester

P.S. not an expert, just repeating what I read on this during TDF.

Personally I've always sworn by the old "listen to your body" adage. It's pretty effective, even in temperatures exceeding 45 degrees C where the old heart rate can be a little volatile.

voodoo alert voodoo alert

Although Hct's above .50 are rare although the normal range for adult males is from the mid 40's to the lower 50's. If the TDF riders are limited to a maximun HCT. of .50 I can tell you they arent going to dehydrate themselves to the point of sludging thier blood. I'd have to do some math but you'd have to loose alot of circulatory volume.

Cant argue with that....

Dont fight what you body is telling you.

When you body overheats your vasculature dialates. This vaso-dilation cause a decrease in blood pressure. Baro-receptors in your carotid arteries sense this then send a message to your brain telling it blood pressure is low. The brain now sends a message to the heart telling it to pump harder to get your blood pressure up. But theres a problem. Your so dialted up you have no blood returning to your heart. Its all pooled up in your dialated venous system. Passing out will occur from the lack of blood pressure in yuot brain.

What do you do? Raise the persons legs to transfer volume to the heart. This is a nasty viscious cycle.

When it's that hot, I watch the feelings very, very carefully. I'm also prone to finding a shady spot to rest for a minute or two if necessary.

I hear that. This summer has been a real scorcher in my area.

I went on a few rides where the temperature was approaching 45 degrees C.. very hot. Better believe I was paying close attention to sensations going on in my body. Well, that and stopping for a good drenching at every running sprinkler I saw.. fun stuff.

Well,

When they first started testing for hematocrit levels Riis was over .60, FWIW.

In any event, I wasn't neccecarily saying that was the case or not, just something i'd read. Guess that example may have been wrong. But thicker blood has to be harder on the heart, even if it doesn't turn to sludge?

take care,

Jester

What makes the heart work harder from a 'thickness of blood' standpoint is your systemic vascular resisitence (SVR). SVR increases the afterload (resistence the heart is pumpimg against). As blood becomes more viscous (a higher HCT.) SVR increases which in turn forces the heart to work harder. This isnt that crucial because our bodies have the ability to auto-regulate SVR thus keeping the afterload of the heart within a certain range.

Coincidence I'm sure, but road by a dead, or dying guy on the bike path yesterday. It looked like a stroke or heart attack. He was a regular older (70 or so) rider I see from time to time. I hope he is OK, but he looked bad.

Edited to add: He was in the company of police and EMS.

I hope he was being helped by somebody. I hope you offered assistance if there was none already present.

British Medical Association report showed that riding as little as 4miles/day reduces your chance of heart disease by 50%

The notion of using a heart rate monitor to keep out of the "danger" zone is rather new to me.

I have pushed my heart rate right up there and I have never ever had a chest pain whilst cycling.

In our fast group in the local club, the riders launch nearly constant attacks until virtually everyone has been dropped. It gets intense. I have seen people crash because their brains were not getting enough blood to function - it isn't common but it happens a couple times a year easily. I have even known a few people who have passed out while riding! Virtually all of the riders are over 45 too. So if you can get a heart attack by overdoing it, these guys are sure trying to do it! And so far even after years of trying by dozens of people, no one has succeeded.

Now I have heard that people die pretty often on those mass marathons. I mean, they don't drop like flies, but a fair number of marathons lose 1 person to a heart attack. So aerobically fit people can die from heart attacks. So it might just be a numbers game. Fast cyclists and marathoners tend to be careful with their diet, they tend to be thinner then the normal population, they tend to not smoke, and they tend to get lots and lots and lots of exercise. So they are doing a number of things right. But I suppose if the numbers are big enough and in those big marathons you are talking thousands well someone is going to get unlucky.

One of the guys, started to slow down a while back. And he was one of the more intense riders. Turned out his arteries were clogging up. He went to a cardiologist. He discovered that he was genetically inclined to heard problems. He had a triple bypass and feels much better and is back at it (with his physician's approval). The cardiologist told him that his cycling increased his circulatory function and probably saved his life. He did not have a heard attack but I guess that is saying that he would have had one except for his excess circulatory capacity gained from years of intense riding. Of course, I might have misheard what he said, or HE might have misheard what the cardiologist said, or the cardiologist might have been all wet.

Be that as it may, I think the biggest risks facters are smoking and diet. Most cyclists don't smoke so they get that as a freeby. If you look at human populations where saturated fats are extremely low in the diet, deaths by heart attack are nearly unheard of. So if you indulge in food on the "cardiac special" routinely, exercise probably won't overcome it. But if your diet is prudent, exercise will help improve your situation and lower your risk.

Of course, for any of us, it is a good idea to go out have the blood test to determine your cholesterol levels (LDL and HDL) so you have a handle on what your personal risk is. Some people can have a pretty spartan diet and still have a high level and other people can have a marginal diet and be fine.

Pat, once your heart reaches a certain rate its efficiency decreases (cardiac output drops). Using a HRM can keep you from getting into that zone. When cardiac output drops the amount of blood being pumped to your myocardium drops as well. If you dont get onto the wrong side of the supply and demand balance you will not have a heart attack. Those guys passing out on the intense rides are obviously suffering from a supply/demand imbalance of oxygen to the brain. Lets just say they get into into that zone where cardiac output (supply) drops but thier demand is constant or increasing. If demand (oxygen consumption) is high, and cardiac output drops your oxygen saturation will gradually fall. Perhaps their oxygen saturation is dropping to a level thats causing them to pass out.