(NaturalHealth365) How many of us know someone who spends hours and hours on the cardio machine every week and view this time like a badge of honor? In one respect, we have to applaud their exercise commitment.  But, as you may already intuit, “chronic cardio” can present some negative health consequences.

In fact, overtraining seems to hurt more than it helps – and it’s not simply a matter of increasing injury risk. According to research, overtraining may actually disrupt several physiological systems, elevate levels of the stress hormone cortisol, and hurt the heart – creating (for many people) anything but the picture of health.

Your excessive exercise training could be harming your heart and making you sick

It’s tough to come up with a comprehensive list of all the ways exercise benefits the human body. But the age-old warning against “too much of a good thing” is perfectly exemplified by physical activity. Just look to the research on chronic cardio to see why!

For example, a 2012 review published in the Mayo Clinic Proceedings endorses exercise as “one of the cornerstones of therapeutic lifestyle changes for producing optimal cardiovascular and overall health.” But the authors also warn that individuals who participate in extreme endurance events may expose their hearts to acute physiological stress including volume overload (so much blood in the heart that the heart can’t pump efficiently), elevated cardiac biomarkers (indicative of heart muscle damage), and reduced ejection fraction (the percentage of how much blood a heart ventricle pumps out with each contraction).

While these adverse effects tend to resolve within a week after an extreme event (such as an ultramarathon or Ironman race), longer-term damage can occur over months to years of repetitive injury (aka, excessive exercise).

In other news, a 2003 paper from Sports Medicine found a correlation between excessive exercise, overtraining syndrome (where, despite vigorous training, a person’s performance declines), and an increased risk of upper respiratory infections. The authors concluded that this was due to the way overtraining suppressed immune function and mediated by the production of cytokines in response to exercise-induced tissue damage.

Additional research from Journal of Endocrinological Investigation published in 2008 shows that moderate to vigorous research temporarily increases levels of cortisol in the blood. Since cortisol is a hormone released during stress—and, when chronically elevated, is correlated with inflammation and accelerated aging – we can conclude that doing too much exercise, even at a moderate intensity, can cause long-term damage.

Overall, we know that lifelong vigorous exercisers tend to enjoy good functional capacity and lower mortality rates – but this isn’t counterintuitive nor contradictory. Here’s the crucial reason why: 

According to the U.S. Department of Health and Human Services (HHS), vigorous exercise is not the same thing as “excessive exercise.”

So, how much is too much? Here’s a good exercise goal for the typical American

To be clear, excessive exercise isn’t a problem for MOST of us – quite the opposite actually. Just look at these stunning statistics from the HHS:

• Only 1 in 3 adults achieve the minimum recommended amount of physical activity every week.
• Less than 5% of adults get 30 minutes of physical activity every day.
• More than 80% of adults and adolescents do not meet the minimum guidelines for aerobic activity.

So, how much exactly should you be working out every week? According to the Physical Activity Guidelines for Americans published by HHS, the typical adult should aim for 150 to 300 minutes per week of aerobic exercise performed at a moderate intensity (50 to 70% of max heart rate). At a minimum, this works out to about 30 minutes of exercise on most days of the week.

Want to save on time?  Up the intensity!

It’s also within the recommendations to aim for 75 to 150 minutes per week of exercise performed at vigorous intensity (70 to 85% of max heart rate). Notice that this vigorous exercise does not have to take more than 15 to 30 minutes of your day on most days of the week.

In other words, sure it’s high intensity – but it’s also low volume, and that’s good for avoiding overtraining.

And, last but not least, add in some strength training at least twice per week and avoiding sitting too much – then you’re well on your way to better health.

Sources for this article include:

Health.gov
HHS.gov
NIH.gov
NIH.gov
NIH.gov
Mayoclinic.org
Springer.com