The seemingly healthy habit that can turn deadly

When I lived in the utopian, post-modern “paradise” of LA County between 1966 and 1971, I clearly remember how my lungs burned whenever I attempted even light exercise.

At the time, residents didn’t always make the connection to the poor air quality in LA. But as I learned more about the body’s respiratory process, it dawned on me that breathing polluted air was literally burning my lungs.

In fact, a new study, published in the prestigious scientific journal Lancet, shed some light on the very real dangers of exercising in a polluted environment. I’ll tell you all about that study in a moment. But first, let me give you a quick refresher on the dangers of excessive exercise…

Excessive exercise taxes joints, organs, and more

Excessive exercise can cause chronic joint disease, primarily to knee and hip joints. This epidemic clearly stems from excessive, episodic running on hard, man-made surfaces that wear down joints.

Unfortunately, the “natural-know-it-all” solutions of chondroitin and glucosamine just don’t work. Instead look for my “ABCs of joint health” — ashwagandha, boswellia, and curcumin — which also have numerous other health benefits.

More recent studies link excessive exercise to other types of long-term damage. For example, as I reported last summer, a whopping 75 percent of marathon runners suffer kidney injuries following a big race.

And as I reported in the October 2017 issue of my Insiders’ Cures newsletter, a recent review of eight studies examined the new phenomenon of “exercise-induced gastrointestinal syndrome,” which results from prolonged, vigorous endurance exercise, like running and cycling. (To access these archives, simply log in to the Subscribers Sign-In with your username and password on

Beware of sending your heart and lungs into overdrive

As for the heart, most people correlate exercise to its positive relationship to heart health. (And studies show clear heart benefits associated with sensible, light-to-moderate exercise.)

However, it’s important to be mindful that your heart can only beat so fast. Anything above its threshold won’t allow it to fill with blood in between beats. In fact, when you push the heart past its limit like this, you actually induce a well-known physiologic condition called “high-output heart failure.” Therefore, excessive exercise causes damage to the heart muscle and nerve conduction system over the long-term.

And the same type of issue with your heart can also happen with your lungs.

When you exercise excessively, your body needs more and more oxygen to burn more fuel (aka glucose or blood sugar) to meet the increased demands for energy.

Despite your lungs’ best efforts, they are not designed to deliver enough oxygen to meet increased metabolic demands from excessive exercise. You physically can’t breathe fast enough.

And when your body doesn’t receive enough oxygen, your muscles switch to a primitive mechanism called “anaerobic respiration,” which causes cells to break down glucose (blood sugar) without oxygen.

This incomplete breakdown of glucose produces toxic waste byproducts — like lactic acid, a common cause of muscle fatigue. It also results in an unhealthy state of lactic acidosis, which causes problems in your blood and organs, especially among people with diabetes.

In medicine, we typically associate this kind of anaerobic fermentation with dangerous, primitive, pathogenic microbes that dwell deep in oxygen-deprived soil. In short, excess exercise causes your cells to revert to the metabolic activity of a pathogenic microbe.

Add bad air into the mix

When you exercise and have to breathe faster to keep up with your muscles’ need for more oxygen, you should always consider the quality of the air around you.

Up to a point, your lung cells can protect themselves from pollutants in the air. But when you breathe too fast for your lung cells to respond, you set yourself up for both lung and heart damage, as demonstrated in the new Lancet study.

For this study, researchers randomly assigned participants, 60 years and older, into two groups.

The first group took a two-hour walk in Hyde Park, a large park in London, where amateur stump orators create their own brand of “air pollution” participating in the tradition of free speech­ — while it lasts.

The second group took a two-hour walk along London’s Oxford Street — a high-traffic urban nightmare.

The researchers’ aimed to assess the effects on respiratory and cardiovascular responses from walking in a traffic-free area with lower pollution levels versus walking down a busy street with high levels of pollution.

The Hyde Park walkers experienced better lung function, as measured by pulmonary tests. This group also experienced improved arterial flexibility, a sign of cardiovascular health. Best of all, these physiologic improvements lasted for more than a day after the nice walk in the park.

The walkers on Oxford Street didn’t fare as well. Healthy participants who walked on Oxford Street simply didn’t experience the same benefits as those who walked in Hyde Park. Plus, patients with prior heart disease experienced increased coughing when walking down Oxford Street. And patients with prior lung disease reported more coughing up sputum, as well as wheezing and shortness of breath.

This study confirms that light-to-moderate exercise confers lung and heart benefits — but only in unpolluted environments. On the other hand, the same exercise undertaken while breathing dirty, urban air causes significant short-term problems for heart and lung function.

This study didn’t measure the long-term effects of breathing polluted, urban air. But it’s not hard to imagine how bad they would be…especially in LA.

Of course, Los Angeles County is perhaps the ultimate example of an urban area with a major pollution problem. It’s more crowded than all but a few of the larger states in the U.S. And — despite all the government-mandated controls — the pollution is overwhelming, mostly because California’s physical geography, topography, and climate are all a disaster waiting to happen.

Plus, the recent massive fires in LA County and San Fernando Valley — which occurred ultimately as a result of too many people living in that natural, dry desert area — only exacerbated their longstanding air-quality problems.

Bottom line?

You now have even more reasons to avoid over-exercising — particularly in crowded, urban areas, and inside gyms. You’d be shocked to learn about the toxins and pollutants swirling inside gymnasiums — especially those with chlorinated, indoor pools. But that’s another story for another day…

As I always advise, it’s best to exercise out in Nature, away from crowds and pollutants. Next month, I will report on another study showing that any exercise in a polluted environment is unhealthy. In other words, there is no “safe” level of exercise if you are breathing bad air.

So, now we know that excessive exercise in any environment, and any exercise in a polluted environment, are unhealthy.

To learn more about how avoiding excessive exercise can save your life, refer to the January 2018 issue of my newsletter. If you’re not yet a newsletter subscriber, now’s the perfect time to get started.




“Respiratory and cardiovascular responses to walking down a traffic-polluted road compared with walking in a traffic-free area in participants aged 60 years and older with chronic lung or heart disease and age-matched healthy controls: a randomised, crossover study,” Lancet ( 12/5/2017