The Marathon Myth: Is It the Quickest Way to a Heart Attack?

Running a marathon is often seen as the epitome of fitness and the ultimate show of endurance. As a former sub 3-hour marathon runner myself, I understand the drive that pushes many athletes and weekend warriors to compete in these strenuous events -- but when you examine the research it becomes clear that doing so may put your heart at risk.

You've likely heard the stories about fit marathon runners who die suddenly in the middle of a race. Though rare (one study put the rate of sudden cardiac deaths during a marathon at 0.8 per 100,000 participants), it is certainly not unheard of, and it seems no one is immune to this risk. Even Olympic athletes have died in the middle of training.

This is because in the case of exercise, more is not always better.

Excessive cardio like that performed during marathons or triathlons is likely not much better at improving longevity than being sedentary. In fact, according to a study presented at the Canadian Cardiovascular Congress 2010 in Montreal, regular exercise reduces cardiovascular risk by a factor of two or three. But the extended vigorous exercise performed during a marathon raises cardiac risk by seven-fold!

This is a powerful lesson to anyone who engages in large amounts of cardio exercise, because as it turns out, excessive cardio may actually be counterproductive.

What Makes Marathon Running So Dangerous?

To put it simply, it puts an extraordinary stress on your heart, one that your body was not designed for. In the study mentioned above, researchers found that during a marathon more than half of the segments in your heart lose function due to an increase in inflammation and a decrease in blood flow.

Research by Dr. Arthur Siegel, director of Internal Medicine at Harvard's McLean Hospital, also found that long-distance running leads to high levels of inflammation that may trigger cardiac events, and a separate study published in Circulation found that running a marathon lead to abnormalities in how blood was pumped into the heart.

Even if you don't end up dying from sudden cardiac death during a race, years of marathon running can take a toll on your health. Research emerging over the past several years has now given us a whole new understanding of what your body requires in terms of exercise, and many of our past notions have been turned upside-down. It's now clear that exercising too much is a blow to your health.

For example, two recent studies showed:

• Heart damage after lifelong cardio: In a study published in the Journal of Applied Physiology in February, researchers recruited a group of extremely fit older men. All of them were members of the 100 Marathon club, meaning athletes who had completed a minimum of 100 marathons. If running marathons provided cardiovascular benefit this would certainly be the group you would want to seriously examine. So what did they find?
  
  Half of the older lifelong athletes showed some heart muscle scarring as a result, and they were specifically the men who had trained the longest and hardest.
• Heart scarring after elite cardio training: Recently published in the journal Circulation, this animal study was designed to mimic the strenuous daily exercise load of serious marathoners over the course of 10 years. All the rats had normal, healthy hearts at the outset of the study, but by the end most of them had developed "diffuse scarring and some structural changes, similar to the changes seen in the human endurance athletes."

Separate research published in the journal Progress in Cardiovascular Diseases also recently concluded that the best fitness regimen is actually one that mimics the movements of our hunter-gatherer ancestors, which included short bursts of high-intensity activities, but not long-distance running such as is required to complete a marathon.

The point is, too much of something that is normally good for you can have the reverse effect. So, although most people who read this are not exercising nearly enough, it's still important to understand that it is indeed possible to over-exercise -- especially if your primary focus is on traditional cardio or aerobics.

Are You Still Spending an Hour on the Treadmill?

Even if you're not a marathon runner, you may still be cheating your body of the optimal exercise benefits if you are focusing your workouts on long periods of cardio. According to fitness expert Phil Campbell and author of Ready Set Go, getting cardiovascular benefits requires working all three types of muscle fibers and their associated energy systems -- and this cannot be done with traditional cardio.

Here's a quick review:

• Slow twitch (red muscle): Activated by traditional strength training and cardio exercises
• Fast twitch (white muscle): Activated by Sprint 8 exercises
• Super-fast (white muscle): Consists of fast twitch AND super-fast fibers, activated by Sprint 8 exercises

Unfortunately, most traditional cardio and strength training exercises work only red muscle fibers, completely missing your white muscle fibers, which then atrophy. If your fitness routine doesn't work your white muscle, you aren't really working your heart in the most beneficial way.

Your heart has two different metabolic processes: the aerobic, which require oxygen for fuel, and the anaerobic, which do not require any oxygen.

Traditional strength training and cardio exercises work primarily the aerobic process and the slow twitch (red) muscle fibers. On the other hand, Sprint 8 exercises work your aerobic AND your anaerobic processes, which is what you need for optimal cardiovascular benefit.

This is why you may not see the results you desire even when you're spending an hour on the treadmill several times a week. You're only working HALF of your muscle fibers!

In the case of Sprint 8 exercises, less is more, as you can get all the benefits you need in just a 20-minute session performed twice a week. In fact, you should not do Sprint 8 exercises more than three times a week, as if you do it more frequently than that you may actually do more harm than good -- similar to running marathons. 

Your body needs regular amounts of stress like exercise to stay healthy, but if you give it more than you can handle you will actually lose your health. So it is really crucial to listen to your body and integrate the feedback into your exercise intensity and frequency. When you work out it is wise to really push as hard as you possibly can a few times a week but you need to wisely gauge your body's tolerance to this stress.

How to Perform Sprint 8 Exercises

The key to performing Sprint 8 exercises properly is to raise your heart rate up to your anaerobic threshold. Keep pushing at maximum effort for 30 seconds, and then rest for 90 seconds. Repeat this cycle for a total of eight repetitions. In other words:

1. Warm up for three minutes
2. Exercise as hard and fast as you can for 30 seconds. You should be gasping for breath and feel like you couldn't possibly go on another few seconds
3. Recover for 90 seconds, still pedaling, but at slower pace and decreased resistance
4. Repeat the high intensity exercise and recovery 7 more times

In the video below, Phil Campbell and I demonstrate how it's done.

Total Video Length: 22:16

When you perform Sprint 8 exercises properly it also helps increase your human growth hormone (HGH), which increases your muscle growth and effectively burns excessive fat. It also plays an important part in promoting your overall health and longevity.

I've been exercising for over 43 years, but for much of it I focused on running, or cardio. Adopting the Sprint 8 exercises instead has made a HUGE improvement in my exercise program and has boosted my level of fitness.

The take-home message here is that one of the best forms of exercise to protect your heart is short bursts of exertion, followed by periods of rest.

By exercising in short bursts, followed by periods of recovery, you recreate exactly what your body needs for optimum health. Heart attacks don't happen because your heart lacks endurance. They happen during times of stress, when your heart needs more energy and pumping capacity, but doesn't have it. So rather than stressing your heart with excessively long periods of cardio, give Sprint 8 a try.

I suspect you'll find the benefits to be as outstanding as I did.

Most importantly, during any type of exercise as long as you listen to your body you shouldn't run into the problem of exerting yourself excessively. And, with Sprint 8, even if you are out of shape you simply will be unable to train very hard, as lactic acid will quickly build up in your muscles and prevent you from stressing your heart too much.