Pass me the salt. And shut up about stroke risk.

They say, statistics lie.

That's a bad rep for a science, which has no other aspiration than that of making sense from data, of discovering an association between salt intake and stroke, of proving that the former causes the latter. Statistics is above lies. Those who interpret it are not. 

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To hell with exercise

Who says that exercise is medicine? For one, the American College of Sports Medicine (ACSM) of which I'm a professional member. Then, how can I say it isn't?

Let's look first at the conventional view of the benefits of exercise. There is a large and increasing amount of evidence which clearly tells us that exercise prevents today's number 1 killer: cardiovascular disease. That is, heart attack, stroke and peripheral vascular disease. Mind you, what is common knowledge today emerged only some 50 years ago when Morris and colleagues discovered that UK bus conductors, the guys climbing up and down the double-decker London buses, had better fitness and fewer heart attacks than their all-day-seated driver colleagues [1].

In the years since then our knowledge about the effects of physical activity on cardiovascular, metabolic and mental health has virtually exploded. From this evidence the U.S. Dept. of Health and Human Services (HHS) concluded in 2008 that the most active people of the population have a 35% reduced risk of dying from cardiovascular disease compared to the least active people [2]. The WHO lists insufficient physical activity (PA) as the 4th leading cause of death world wide after high blood pressure, tobacco use and high blood glucose. What's wrong with this picture? High blood pressure and high blood glucose are known consequences of a sedentary lifestyle. So is obesity, which ranks 5th place on the WHO killer list. Which is why physical inactivity deserves top spot on that list.

What most people don't know is the way lack of physical activity causes all those diseases, from insulin resistance and diabetes to arterial dysfunction and atherosclerosis, and from there to heart attack, stroke, kidney failure. The mechanisms are extremely complex, and, while we have untangled quite some of them, there are probably a lot more to discover. I'll try to make this the subject of one of the next blog posts. 

Now you are probably asking yourself, how the hell, with all this evidence, will I ever be able to make my point that physical activity is not a medicine. Ok, here it comes: it's a matter of viewpoint. The one I'm taking is the one of evolutionary biology. Let me play its advocate and present as evidence a couple of insights.

First, our human ancestors, who had roamed this Earth as hunter/gatherers for the most part of human existence, had, by necessity, a much more physically active lifestyle. A lifestyle which required at least 1.7 to 2 times the normal resting energy expenditure [3]. [To get an idea about resting energy expenditure and physical activity levels and how they are calculated, simply follow the links to the videos.] Those ancestors' genes are what we have inherited. And these genes are exposed to a lifestyle which is vastly different from the ones under which these genes evolved. Specifically with a view to physical activity, which brings me to evidence no 2:

What we typically observe today are physical activity levels with factors of somewhere between 1.2 and 1.4 of our resting energy expenditure. That's true for most people.

Even if you were to follow the ACSM's recommendation of 30 minutes of moderate to vigorous exercise on at least 5 days per week, would you NOT reach the level of 1.7 if you are working in a typical office job or doing house work. Which means, the physical activity levels which we recommend today, do not add a behavioral type of medicine into our lives, they merely reduce the extent of a "poisonous" behavior called sedentism. It's like cutting down from 2 packs of cigarettes per day to 1 pack. Would you call this a "medicine"? Would the ACSM call that a medicine? With respect to exercise they do.

So, OK, if you had been attracted to this post in the hope of finding some excuse for not doing exercise, or some argument to get those exercise evangelists, like myself, off your back, I'm sorry to have disappointed you. No, actually, I'm not sorry. And neither will you be, if you get your physical activity level above those 1.7. Then you may just start calling exercise a medicine. Until then, chances are you will still go to hell with exercise, because you get too little of it. Certainly too little to stay out of that hell of heart disease, stroke, diabetes and many cancers.

1.           Morris, J.N. and P.A. Raffle, Coronary heart disease in transport workers; a progress report. Br J Ind Med, 1954. 11(4): p. 260-4.

2.           Physical Activity Guidelines Advisory Committee, Physical Activity Guidelines Advisory Committee Report, 2008, U.S. Department of Health and Human Services: Washington, D.C.

3.           Eaton, S.B. and S.B. Eaton, An evolutionary perspective on human physical activity: implications for health. Comp Biochem Physiol A Mol Integr Physiol, 2003. 136(1): p. 153-9.

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MORRIS JN, & RAFFLE PA (1954). Coronary heart disease in transport workers; a progress report. British journal of industrial medicine, 11 (4), 260-4 PMID: 13208943
Eaton, S., & Eaton, S. (2003). An evolutionary perspective on human physical activity: implications for health Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology, 136 (1), 153-159 DOI: 10.1016/S1095-6433(03)00208-3 PrintPDF

When risk scores for heart attack really suck!

When risk scores really suck.

If you are a man aged 55 or younger, or a woman aged 65 or younger and have had your risk for heart attack and stroke profiled recently, chances are your doctor told you that you have a low risk. So you probably walked out of her clinic, seeing no reason to change your lifestyle. Now here I am, the party pooper, who is going to rain on your parade. How so?

Well, first off, those risk scores, like the Framingham score used in the US and the PROCAM score used here in Germany, typically look at things like cholesterol, blood pressure, blood sugar, smoking status, age and gender. From these values the scores determine your 10-year forward risk. Conventionally, if your chances of suffering a heart attack, stroke or any other of the cardiovascular diseases endpoints is less than 10% for that 10-year period, yours is categorized as low-risk. If it was in excess of 20%, you would be considered a high-risk person, and anything in between is called moderate risk. Now here is the problem: of the women who are hospitalized for their first heart attack at an age younger than 65, typically none would have scored as high-risk even a day before the event [1].  In fact, 95% of these women would have flown under the risk radar in the low-risk altitude.

How come, you may ask. To understand the reason you need to know how heart attacks and strokes happen. Most of them are the result of a blood clot being formed at the site of a ruptured plaque (those fatty streaks) in one of your arteries. Traveling downstream these clots may be dissolved or they may be not. If they get stuck some place downstream, blocking the supply of blood, and thereby of oxygen, to your heart or brain tissue, a heart attack or stroke occurs. But most plaque ruptures do not cause a heart attack or stroke. There is a large element of chance involved. Fact of the matter is, we can't really predict which plaques will cause a heart attack or stroke. We can't even say whether a stable or a so-called vulnerable plaque will still be stable or vulnerable in a few months down the line. They can change their status. Which means, even if your doctor was able to map all the plaques in all the arteries throughout your body, he still wouldn't be able to tell you exactly your risk. How much less accurate will his risk prediction be when he uses risk factors which just correlate somewhat with plaque burden, such as cholesterol? There you go.  

Which is why you should not look at 10-year risk, but at lifetime risk. For a woman that risk stands at roughly 40% once she has reached the age of 50 [2]. Men, by the way have a 52% risk at that age. But here is the kicker: being free of any of the risk factors (those of the Framingham or PROCAM variety) at that age, means a dramatically lower lifetime risk of 8% and 5% for women and men respectively.

So here you are. Your doctor has just sent you off with a low-risk assurance for the next 10 years, even though 2 of your risk factors are elevated. You walk out of his clinic with a strong sense of invulnerability and no real motivation to change your lifestyle and to get those two risk factors back into the green zone. That's why risk scores really suck. When they rain on your parade later on it's a lot worse than if I, the party pooper, do it right now. Don't you think?

1.           Akosah, K.O., et al., Preventing myocardial infarction in the young adult in the first place: how do the National Cholesterol Education Panel III guidelines perform? Journal of the American College of Cardiology, 2003. 41(9): p. 1475-9.

2.           Lloyd-Jones, D.M., et al., Prediction of lifetime risk for cardiovascular disease by risk factor burden at 50 years of age. Circulation, 2006. 113(6): p. 791-8.

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