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Manic Monday: Chronic Cardio

February 28, 2011

Manic Monday is a feature I hope to run every Monday(ish) – provided folks out there in the “mainstream” keep supplying the fodder.

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I had another “Manic Monday” post all cued up and ready to go (The Diabetic Climber), but that can wait until next week. As I was leaving class this evening, I got into a discussion about the merits of “cardio” (mostly me whining about how silly I think it is). This is a topic that has come up quite a bit lately, so without further ado, we’re off and running. (I warned you about the puns.)

It’s supposed to be a heart made of running shoes. Clever, right? I’m no Spaniard, but I think it means “Run With Heart”. Read on.

What is “Cardio”?

The “Cardio” page on wikipedia forwards to “Aerobic Exercise,” which I imagine is the common usage. Safe to say, most people picture treadmills and stationary bikes when they hear cardio – and they hop on these modern marvels of exercise technology for marathon “Cardio” sessions because they believe it will burn fat or improve heart health.

Why don’t I engage in “Cardio”?

I don’t find it fun, and it would be counterproductive in the pursuit of all six of my listed goals. Oh yea, and all that stuff I’m about to lay out about how it is bad for you. You know, the heart disease and such. In visual form, courtesy of MDA:

Let’s get into the hard hitting stuff.

“Cardio” Causes Heart Disease

The brilliant Kurt Harris of PaNu has hit this issue twice (first and second). The first is very technically involved and doesn’t get into the actual relevant study results until about halfway down the page. The cliffs notes version: 204 people with no symptoms or history of heart problems were subjected to “cardiac MRI with LGE imaging.” Half of them were marathon runners (3+ in the previous 5 yrs), and half had “no history of vigorous exercise.” 12% of the runners had evidence of myocardial damage vs 4% of the couch-surfers. They also found evidence of previous heart attacks, 5 “classics” in the runners to 2, and 7 “non-classics” to 2. That totals out to 12 vs. 4, if it’s fair to sum in that manner. He goes on to list more results from this subject group (be sure to check his post for greater detail): “Cardio” results in coronary atherosclerosis. (Coronary Artery Calcium score median 192 vs. 26) (Yikes), and among the subjects, more marathons meant more heart disease.

His second post references an article with a real gem of a quote:

A group of elite long-distance runners had less body fat, better lipid profiles, and better heart rates than people being tested for cardiac disease, but, paradoxically, the runners had more calcified plaque in their heart arteries

This set off alarms for me because they were comparing asymptomatic runners with people who had reason to test for heart disease (and the runners still lost!), and the good Dr. Harris had a similar response:

So the controls came from a population that has (Bayes theorem here) a much higher a priori probability of having coronary disease than average, and yet the runners still beat them in having more evidence of coronary atherosclerosis. That is really very impressive, and not in a good way.

Not looking very good for “Cardio” as far as heart health is concerned.

“Cardio” Still Burns Fat Though, Right?

I’m going to skip right to body composition here because most people care more about their abs than their heart anyway. I imagine this is especially true of all the treadmill-treaders in gyms across the country. For more reading on “Cardio” and health, check out MDA’s long line of wonderful posts (1,2,3,4,5,6).

I’m going to get a little more anecdotal here, please forgive me. Jogging for hours doesn’t burn fat unless it absolutely has to. Your relatively high work load (compared to walking) depletes muscle glycogen until it is all gone, then you will resort to whatever else is on hand. The only problem is that once you deplete all that glycogen, your body will start breaking down muscle and using the amino acids that used to be biceps for gluconeogenesis (making amino acids into glucose) because it really wants glucose. Admittedly, you’ll burn some fat too, mostly to power the breakdown of all that muscle. That’s why you end up looking like the marathon-runner above.

The Bottom Line

Ask yourself honestly – do you enjoy your “Cardio”? I suspect most of you don’t (I know I never did, even when it was a big part of my routine). If you do enjoy it, is it worth the heart damage and “skinny fat” look? If so, keep hitting that treadmill.

If not, use your time in the gym for resistance exercises. The heavier the better. I think you’ll find that gets your heart pumping just fine. Make your sessions short and intense, and you’ll feel supercharged afterward instead of beat-down and heaving. Then go take a nice slow walk with all the time you have left over.

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