General Cycling Discussion - Heart attacks and riders?

If anyone here has had heart attacks. Did they happen eventhough you have been riding for years? Did you start riding after the heart problems started?

I quit smoking, took up riding and lost 60 lbs. to help avoid heart problems. Surley I'm not wasting my time. I love to bike and I won't quit untill I'm forced to!:eek:

No heart attacks here but I'd say you're moving in the right direction to avoid one.

It was after I stopped riding and got out of shape that my heart problems developed. It's a common story.

The most recent findings tend to indicate that almost all cases of coronary artery disease (CAD) are caused by poor lifestyle choices, not genetics. This certainly tallies with my own experience and that of the patients and professionals in the field that I've talked to.

If you've returned to a healthy lifestyle without actually suffering a cardiac event, there's a pretty good chance you won't -- although if you haven't had a a cardiac workup and you're a middle-aged male who was once overweight and smoked, you probably should.

I had several years of heart problems (and other serious health issues) that developed after I let myself get sucked into the suburban-dad-with-career pit.

But in the last few years I've succeeded in actually reversing the CAD (as well as controlling my diabetes without medication) through cycling and diet.

So no, of course you're not wasting your time. What a silly idea!
:D

RichC

of course you're not wasting your time.

I thought not. I am a medical lab tech and I have been used as a test subject for the ultra sound machine that checks your heart and they said " I have a very good heart".
I have my blood preasure into the normal range now. My HDL is twice as high as before and my other lipids are better also. My resting HR was 54 this morning, it was around 78 less than 2 years ago.

Most of all I feel GREAT! I just got back from a little ride and I feel like crap if I don't get to ride atleast every other day.

My goal is to drop another 40 lbs. by the spring.

I'll have to agree with most of this. A vast majority of heart disease is due to lifestyle but much of it is due to old age. With the average lifespan in the upper 70's its double what it was 100 years ago. Thats twice as long for disease processes to work. Whats important is to watch your risk factors, diet, smoking exercise etc. Something you should have done, if this is bothering you, is to have a very thourough cardiac workup. I had a 12-lead EKG done not to long ago and gave me peace of mind to know it was OK. The 'ultrasound' machine you've been tested on is nice for diagnosing congenital defects or valvular disease but it does nothnig to diagnose coronary artery disease. Keep exerciseng, keep losing weight, have a stress test, see your cardiologist and WEAR A HEART MONITOR!!!

Jim.....cardovascular perfusionist

Rich,
I dot mean this in a negative way. However "recent studies" what exactly is this? Just over the past few months BRAIN did stories of avid cyclists well known in the industry droppiong dead while riding from heart attacks. One was a former trainer of Lance. I remember another well known runner named Jim Fixx while running dropped as well. I do not think these studies took people such as this into consideration. I also do not think their lifestyle choices were all to conductive to heart failure. If so thre would not be so many people posting here.

If you've returned to a healthy lifestyle without actually suffering a cardiac event, there's a pretty good chance you won't

Yes and no and heres why. Lets say you have a 75% blockage of one of the main coronary arteries, you eat like pig, smoke, and dont exercise. Now you assume a healthy lifestyle. I'm going to say your now at greater risk for a heart attack. If you dont do anything strenuous...i.e. your a couch potato your cardiac demand is almost always constant so that vessel with only 25% flow is flowing enough to get you up a flight a stairs. Now you start exercising. At first that vessel is flowing enough because you only walking around the block. What do you think is going to happen when you get yuor heart rate up and try to pedal up a small hill?? That vessel will no longer be able to supply your myocardium with the increased demand for oxygen. Your now going to have chest pain, if you lucky you wont have an MI.

CHEST PAIN is similar to the muscle pain you get climbing a hill. The pain you feel in your legs is a result of lactac acid build-up which is a result of not supplying enough oxygen to the tissues. The tissues become ISCHEMIC. When this occurs certain enzyme levels in your blood elevate. If the levels are within a certain range within a certain time after the onset of chest pain you've had heart attack. If a cetain enzyme is elevated you've had a myocardial Infarction (MI).

ISCHEMIA...a lack of proper oxygen delivery to the tissues. Either caused by to much demand for oxygen or lack of proper oxygen delivery. Regardless its an im-balance in supply/delivery. Tissues can become ischemic without causing injury. If and injury occurs to the tissues you have had a MYOCARDIAL INFARCTION. Once na infarction thats it....in most cases the tissue is permanently damaged.

Hunter and miamijim, please note that I was specifically discussing CAD, and not other cardiac problems that may cause heart failure.

miamijim, I agree with what you're saying, which is why I also suggested that a cardiac workup is a good idea for someone returning to exercise after getting out of shape. However, even after an MI that causes tissue death, revascularization can and does occur, and the CAD itself can be reversed. The heart can be strengthened, and even someone with 25% tissue damage can become fully fit again (as I know from personal experience).

Hunter, here's a report on a recent study indicating that lifestyle-related risk factors are likely to be the overwhelming cause of CAD. There may have been other sorts of heart problems that led to the deaths of those athletes, and there are always exceptions (90% may be an overwhelming majority, but it's not everyone; yet's it's a mistake to pick an exception and try to generalize backwards from it).

"Most people with heart disease do have at least one risk factor

"Reported by Susan Aldridge, PhD, medical journalist

"An analysis reveals that the vast majority of those with heart disease have been exposed to at least one known risk factor.
Allthough it is known that diabetes, smoking, high cholesterol, and high blood pressure increase the risk of heart disease, it is commonly believed that many heart attacks occur for other reasons. There could be genetic factors, say, or risk factors still be to discovered.

"However, a new analysis from researchers at Northwestern University, Chicago, now reveals that conventional risk factors do play a major role in heart disease. They looked at three major studies of risk factors and heart disease and found that where fatal heart attacks were concerned, 87 to 100 per cent of those affected had at least one risk factor. For non-fatal heart attack, the figures were slightly lower, This suggests that heart disease may be more preventable than previously realised. If you want to avoid having a heart attack, a healthy lifestyle is a great investment.

"Source
Journal of the American Medical Association 19th August 2003"

RichC

Rich, a majority of the patients we operate on do in fact have at least one of the risk factors you mention. One risk factor you failed to mention is old age. Its just like anything other plumbing, with time your going to get build-up in the pipes. You say that coronary disease is reversable. In what way are you reffering to? Coronary revascularization? Ballon Angioplasty? Coronary endarterectomy?

Revascularization of an area that has had an MI occurs as soon as the oxygen supply/demand ratio has been corrected. The trick is to keep the tissue from becoming ischemic again. The tissue can recover from the damage but its realtive to the extent of the infarct and how soon intervention takes place.

Originally posted by miamijim
You say that coronary disease is reversable. In what way are you reffering to? Coronary revascularization? Ballon Angioplasty? Coronary endarterectomy?


I mean without surgical intervention, or in addition to it.

When you look at a CAD patient's tapes, you can see lots of plaque deposits. They'll ballon and stent the worst ones, but there will still be a Number of deposits -- 50, 60% blockages -- that they'll leave alone because too much intervention is risky.

Most patients eend up coming back to the cath lab eventually to get those repaired, if they're lucky enough to avoid bypass.

But sometimes those blockages can be seen to reduce, or even disappear, in patients that truly change their lifestyles. The plaque goes away, revascularization takes place, the heart muscle strengthens, and the patient is in bettr shape than he was before the initial MI. Dean Ornish has documented a number of these cases, and while I don't follow a regime as extreme as the one he espouses, I've experienced similar results, as confirmed by a cardiogram done about two years ago.

I can't argue with old age being a statistical risk factor, but I'm not quite ready to accept it as causal. I don't think there's enough data. But people from cultures that generally get a lot of aerobic exercise, eat low-fat diets, and don't smoke do tend to die of other things, and there's some evidence from autopsies that CAD isn't a factor as it is in First World cultures.

And it can't be controlled anyway, so I'm not going to worry about it!

RichC

ther are many risk factors for CAD (atherosclerotic)...and many are genetic

hypertension, diabetes, elevated cholesterol, being male or old, obesity, cigarette smoking being the biggies...family history is also included in a risk stratification by most physicians

when one discusses risk factors one must remember that the "risk factor" concept does not neccessarily imply direct causation...ie you can have bad diabetes and cholesterol and not have any coronary disease...other people will have no risk factors and have terrible disease...there is still a lot more to learn

the three that have the clearest predictive value for having an increased risk of atherosclerosis are high blood pressure, high cholesterol, and smoking.

saying it another way....modifying these 3 factors will most likely benefit the patient and his coronary arteries



yes a healthy lifestyle helps

sometimes the way you were made also has an influence

Originally posted by bandaidman
sometimes the way you were made also has an influence

I think this is turning out to be dangerous thinking. That's what I was glad to see the results of the Northwestern study indicating that genetics is a much smaller contributor than we've been fooling ourselves into believing.

There a re a lot of people who will use an excuse if it's offered to them. For years, there's been this prevailing "wisdom" that half of all heart attacks were caused by inherited factors... that half of the patients would have had the MI even if they didn't smoke, overeat, constantly lose emotional control, never exercise, etc.

And that gave a lot of those folks all the excuse they needed not to change, to blame their genes and not themselves.

Family history doesn't necessarily mean genetic predisposition. Usually it means a family history of eating lots of sausage and a house full of cigarette smoke. My father was a diabetic, but he was also an alcoholic. Certainly those things are risk factors for me (for becoming a diabetic or an alcoholic), but mostly because we learn how to behave -- and what to eat -- from our parents.

I'm not denying the existence of genetic predisposition as a possible contributor in some cases of CAD. But I'd like to see it de-emphasized, because it's too convenient an excuse. Most people can avoid CAD -- and Type II diabetes -- by making intelligent choices. And although it's harder, these diseases can be controlled and even reversed by taking personal responsibility for one's health and making those same choices.

RichC

WEAR A HEART MONITOR!!!

What will this do for me?

I would also like to share what my old mentor pathologist told me when I was just wet behind the ears. He came here from Cuba due to the political climate and his first jobs where doing autopsies on mental health folks. It was his firm conviction that heart diease was caused mostly by stress. He said he had never done an exam on one of these patients that had heart diease and atributed it to the total lack of stress. I don't know how true this is, but he swore to it.

WEAR A HEART RATE MONITOR!!!!

Wearing a heart rate monitor is relevant to supply/demand of oxygen. As heart rate increases cardiac output (how many liters of blood per minute) your heart pumps, increases to a certain point. Once your heart rate reaches a certain level CARDIAC OUTPUT DROPS. Now, if your body needs a certain amount of blood flow (oxygen carrying capacity) and your heart rate enters the zone in which cardiac output drops you've just exceeded the supply of oxygen. That is a heart attack. A monitor will keep you in your target zone.

PTCA...ballon angioplasty....its not that intervention is to risky. Occlusions in vessels do not become hemodynamicly significant untill there is a 50% blockage or more. If you ballon or stent something like that your treating something that doesnt require treating. Vessels become operable/treatable when blockages reach 70-80%. The same holds true for the carotid arteries in your neck.

How many references do you want to verify genetic pre-disposition? Do you want the one from my friend who had bypass at the age of 40? When his blood pooled in his chest and in my heart lung machine you clould see the lipids glistening in the blood. High cholesterol or lipids at the age of 20 when you have a healthy diet is a genetic pre-disposition.

Now, if your body needs a certain amount of blood flow (oxygen carrying capacity) and your heart rate enters the zone in which cardiac output drops you've just exceeded the supply of oxygen. That is a heart attack. A monitor will keep you in your target zone.

I thought a heart attack was when one of the vessels supplying blood to a portion of the heart became occluded and shut off the oxygen to that part of the heart! This muscle dammage is how an ECG picks up a heart attack, when a certan area of the heart muscle stops firing. Also when the cells of the heart die this is where the enzymes that the lab picks up come from, not just because you exceded the oxygen supply your body was asking for.
I thought when my cardiac output droped below what my skeletal muscle system was begging for is what causes me to get dropped on the hills by fellas in better shape than myself. I was under the impression a heart monitor was so I can train more effectively, not avoid a heart attack.

uci, I wasnt to clear with that.....if your bood supply to the heart muscle isnt delivering enough oxygen to supply the heart muscles demand you have a heart attack....

a heart monitor can help you train train more effectively by getting you in your maximum cardaic output zone and it can keep you from having a heart attack by preventing you from exceeding that range....

On hills you get dropped because your muscles use all of the oxygen being supplied to them not because your cardiac output decreases....your leg muscles become ischemic...the burn you feel is acid build-up..this is just like having a heart attack except its in your legs.....chest pain/leg pain....basicly the same

You are right about the enzymes and EKG changes...just remember you can have EKG changes due to ischemia (lack of oxygen) without damaging the heart muscle (infarction)

You do not need to have occlusions in any of your coronary arteries to have a heart attack...without 'getting into it' if you have severe aortic stenosis (a tight aortic valve) and your blood pressure drops your heart muscle can get ischemic and you have all the symptoms of a heart attack....because you just had one...

If old age is a risk factor for a heart attack, it seems the only remedy for this one particular risk factor is to commit suicide at a younger age so you won't die of a heart attack.

Listing "old age" as a risk factor seems absolutely silly and oxymoronic to me. Old age is a natural and inevitable progression. To me, a "risk factor" is something over which I might have some control. I have no control over my age.

Also, in regarsd to Jim Fixx and other intense athletes, I do believe that there was a study sometime back on free radicals and the damage they inflict and that they are more often produced by folks involved in intense physical activity.

Originally posted by miamijim
How many references do you want to verify genetic pre-disposition? Do you want the one from my friend who had bypass at the age of 40? When his blood pooled in his chest and in my heart lung machine you clould see the lipids glistening in the blood. High cholesterol or lipids at the age of 20 when you have a healthy diet is a genetic pre-disposition.

One more time, because I refuse to be painted into a corner: I'm not suggesting that there are no genetic factors that can contribute to heart disease. There's good data that something like 2 or 3% of lipid disorder cases are inherited, and that certainly sounds like your friend's sad situation.

But other factors are more slippery. Are some people genetically predisposed to higher percentage of body fat? Yes, apparently, maybe so. Does that mean those people can't avoid having their tendency end up causing a heart attack? Absolutely not. Maybe that have to work hearder than some other people, but that's the hand they were dealt.

Indeed, that's what the research into the genetic factors that contribute to heart disease is focusing on: enabling people to identify their particular genetic risk factors so that they can take the necessary steps to obviate them.

But those are the same steps everyone should take anyway. Diet. Exercise. Stress reduction. Not smoking. You don't really need to know that you're genetically predisposed to accumulating abdominal fat to know that you need to take steps to lose weight. And for some people, knowing that would just become an excuse for not trying.

RichC

See "1OLDROADIE"

Or to translate "shut up, ride, when it happens - ride, when it won't stop happening - wait till it kinda stops, then RIDE!

Make love as often as you can, love your kids and parents, insult a teen for something to do...and enjoy the day God has given you!!

Originally posted by miamijim
With the average lifespan in the upper 70's its double what it was 100 years ago.

The life span is so high now mainly to the successes in the containing the infectious diseases.

Please, note that this is the life span of the generation, which grew up in the first half of the twentieth century, when the ecology was close to perfection.

No one has the slightest idea what the life span of the generation, which was born in 60s, or 70s, etc. will be.

The Aids, cancer epidemic (pollution), obesity may cause the life span decrease significantly.

But we will know it only in some decades.

The current life span figures are exploited nowadays as an argument against the environmentalists, but this life span does not reflect the dangers of pollution and climate change, as we will see the results of these calamities decades later.

Commuting by bicycle, however, reduces the risks of pollution, loss of bio-diversity, and climate change. And if done by the large number of people, it will contribute to the improvement of health.

1oldRoadie, I'm with you!:p

I'm hoping to not be dropped on the hills next summer, by dropping 40lbs. of lard by the side of the county roads around here over the rest of the summer, fall, and winter.

Is a heart rate monitor going to help you that much unless you push yourself to the point of chest pain? I may look into getting one if it will help me push harder. Mostly what I have to keep in check is how hard I push my muscles and tendons and practice good form.

Looks like I'm moving in the right direction, I'll just keep on strokin!

Originally posted by uciflylow
Is a heart rate monitor going to help you that much unless you push yourself to the point of chest pain? I may look into getting one if it will help me push harder. Mostly what I have to keep in check is how hard I push my muscles and tendons and practice good form.

I think it depends somewhat on why you're training, but I find my HRM quite useful in maximizing the amount of time I spend "in the zone" when I'm riding. Since for me aerobic fitness is the training goal, I try to stay around 75-85% of my maximum heart rate pretty much all the time.

Of course, you have to know what your max rate actually is, and that has to be tested empirically. In other words, you have to go there. It's another worthwhile reason to get a cardiac workup including an exercise stress test. If you've been overweight, out of shape, a smoker, then determining your MHR by climbing a hill until you fall over and then checking your pulse (if any) is probably not the best strategy!

I'm continuously surprised by how frequently my perception of how hard I'm working doesn't match my heart rate. It's always lower than I think it is when I'm riding into a headwind, for example, and I have to push harder to get it higher. On the other hand, I can be cruising along on the flats feeling relaxed and enjoying the breeze when the damn thing starts beeping at me.

RichC

Rich has hit the heartrate monitor concept.....if you wait untill you have chest pain its too late. Remember a heart rate monitor will serve at least the following two functions..1. it gets you 'in the zone' as Rich has noted to maximize your workout and 2. it will keep you from going 'overboard'. Its important not to let your body use more than your heart can supply...staying within you target zone will limit what you body uses because you'll take it easier when you hit the upper rate alarm.

Supply and demand.... keep the balance in your favor.

I didn't use my HRM once this year. Guess I ought to start using it; especially now that I'm training harder than I have in years.

This is an interesting discussion.. I've always known that a HR monitor is a useful tool for helping one get 'in a zone' to maximize training, as well as for possibly detecting the onset of overtraining (i.e. low heartrate per perceived effort). I still occasionally use one for both these reasons, as well as for pacing in TT's or on long climbs.

However, the idea that one should use one to consciously hold back to keep from overtaxing the heart is a new one (to me). Did I read that right? I mean, I purposely forego using a HR monitor in criteriums because I don't want to know how sky-high my HR is! I was always under the impression that acid buildup in the legs would be a limiter well before the load on the heart reached dangerous levels. Or does this only apply to folks with known heart conditions?

This year I've relied more on RPE than on a HRM in my training - and I've had better results.

Go easy on me, I'm clueless in this area.. but always willing to learn something new. :D

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!?!?!?

Originally posted by Hunter
Just over the past few months BRAIN did stories of avid cyclists well known in the industry droppiong dead while riding from heart attacks. One was a former trainer of Lance. I remember another well known runner named Jim Fixx while running dropped as well.

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.

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.

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.

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.

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.

Originally posted by miamijim

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.

Originally posted by Chris L
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. :)

Originally posted by miamijim
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.

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

But thicker blood has to be harder on the heart, even if it doesn't turn to sludge?

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.