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How Your Cardio Workout Could Kill You

October 31, 2013
Photo credit: Thinkstock

Photo credit: Thinkstock

It’s a tired truism that there can always be too much of a good thing.

Take too many vitamin pills and you could suffer from iron poisoning. Drink too much water and you could drown from the inside.

Over-indulging in beautiful women can be bad for your bank account as well as your health. Pretty much anything can kill you in sufficient quantities.

The same holds true for exercise. If you overstress your body, you can damage joints, tear muscles, and pull tendons.

That’s why it’s wise to pay attention to pains beyond normal muscle burn when exercising, and to take it easy the day after a strenuous workout. It’s also a good idea to keep cardio to an hour a day or less: benefits dramatically fall off above that threshold as you cross the point of diminishing returns.

Bigger Dangers

At the extreme end of the workout bell curve, there are bigger, weirder dangers to watch out for.

For those who seriously overtax their bodies every day, the stress on their system can trigger everything from hormonal imbalances to sleep disturbances. It can also cause your body to produce abundant cortisol, which triggers weight gain, particularly around the stomach.

There’s also the strange phenomenon of overtraining: weird backslides in capability that occur when your exercise outpaces your supply of metabolic energy and your body is not allowed to recuperate from damage.

In cases of extreme overtraining, a condition called rhabomyalisis can result, in which the muscle tissue, over-worked to the point of damage, suddenly begins to die off. This can lead to permanent muscle damage and loss of tone, and the materials your muscles shed when dying can damage the kidneys. In extreme cases, severe rhabdomyalsis can necessitate the amputation of a limb.

The Dangers of Cardio Training

Training for a triathlon or ultra-marathon? Then you’ve almost certainly stepped up your cardio training. That can be a good thing. But studies show that if you push the cardio workouts too far, you will eventually find yourself at increased risk of heart disease.

The increased risk is not negligible. Studies show that, while regular cardio decreases your risk of heart disease about threefold, repeated over-stressing of your heart can actually increase your risk of heart failure up to seven times.

That’s a serious and surprising result for those looking to exercise for their health.

How Exercise Damages the Heart

Photo credit: Thinkstock

Photo credit: Thinkstock

How does this happen?

Exercise is primarily directed at skeletal muscle – that’s the tissue that moves your body around. However, exercise also effects smooth muscle tissue such as your heart and the lining of your throat.

You know how your thighs and abs feel after overtraining? The same thing happens to your heart.

Your heart muscles get taxed, which is good, but, if they are overworked for too long, the muscles bulk up.

That reduces the volume of blood the heart can hold and pump. It also decreases the flexibility of heart tissue.

Worse yet, the micro-tears that appear in skeletal muscle when it’s stressed also form in the smooth muscle of your heart when it’s pushed to its limit.

Micro-tears usually heal themselves in a few days. But if your heart isn’t given time to heal, and if you repeatedly indulge in vigorous cardio training, your heart can become riddled with patches of scar tissue.

This scar tissue creates places for collapses and ruptures later.

The result of all these factors is that extreme endurance athletes are at high risk of developing serious cardiac scarring that can lead to sudden heart failure.

The Silver Lining

The good news is that you are probably in no danger. Unless you are doing two hours or more of intensive cardio training every day, you are not at risk. So keep jogging – exercise is still good for you.

If you are doing extensive cardio training, more than two hours per day, then considering more rest days to your routine. Consult your doctor and find out if your workouts could be doing more harm than good.

If you’re training seriously for a triathlon or marathon, it might be worthwhile to get an EKG every now and then, just to be on the safe side. Nature has an ugly sense of humor.

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