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  • Writer's pictureDoug Joachim

Obese Marathoners: Cardio Overkill

Updated: Jun 29, 2023

Many years ago I trained a type-A Wall-Streeter who enjoyed indulging in back to back spin classes 4-5 days per week and a ‘short’ 50-mile bike ride on the weekends. In addition, he took 2 resistance training sessions per week with me, though cardio was his true love.  He was a glutton for the pain. The more the better, or so he thought.  But no matter how much cardio he crammed in, he was 15 pounds overweight. He did like to eat and enjoyed his vino, maybe a little too much, but with that amount of exercise, he shouldn’t have been overweight, right?  So what’s the deal?  After months of cajoling and begging, I got him to slow down and exercise less.  He purchased a heart rate monitor and dropped the double spin classes. During his cardio sessions, I limited his anaerobic exposure and kept him in the aerobic work zone for the majority of the time. Without changing his diet, in 4 weeks he dropped 10lbs.  We both felt better.

Chronic stress makes you fat. Although, ask any biologist worth her salt and she’ll tell you humans need stress because it is essential for life.  Good stress helps our bodies/brain react more positively to situations of danger and or risk by stimulating serum levels of many hormones.  These fight or flight hormones enable the human animal to perform better, faster and more precisely.  “Stress is a burst of energy,” says psychiatrist Dr. Lynne Tan of Montefiore Medical Center in New York City. “It’s our body telling us what we need to do.” There is good stress and then there is chronic stress – aka bad stress. Exercise can be both.

Moderate exercise is usually a good stressor for the body.  Excessive exercise is deleterious stressor.  Just like food, we need exercise to live, but too much food or exercise and it can be fatal.  Yes, it’s rare for ‘athletes’ to drop dead in the middle of a race, but many are running around with damaged cardio-pulmonary systems. The dose-response relationship is critical in determining safe and effective exercise levels. How much exercise can your body handle, how much exercise do you actually need to achieve your goals?  Most people will be surprised to find that body composition goals can be achieved with very little exercise coupled with a simple yet smart nutrition plan. It is imperative for athletes and competitors to be aware of their daily stressors and take steps to mediate all three kinds:

3 Types of Stressors:

  1. Physical: bodily strain, prolonged sitting or driving, exercise, dental ailments, bad footwear, improper clothing etc.

  2. Chemical: exposure to pollutants in the home and at work, chemical off-gassing of furniture, paint and carpeting, smog (and air quality), hormones and chemicals in the food supply, dehydration and poor nutrition

  3. Mental: Tension, anxiety, and depression

These stressors are cumulative in nature and affect all aspects of physical and cognitive performance.  It is critical for all endurance athletes to assuage as much of this stress as possible.  Living and working in the 21 century may certainly be less physically taxing than prior generations but our chemical and mental stressors are clearly much higher.  Triathlons, Tough Mudders, Cross Fit Games and such have become wildly popular in recent years and are typically attracting those type-A individuals who are already stressed to the tee. Not being able to manage all these stresses will leave the body vulnerable to a plethora of injuries, ailments and the preservation of fat.  When stress is constant and excessive the serum levels of stress hormones, specifically cortisol, tend to malfunction. In turn, this directly affects the storage of fat and decreases the amount of adipose tissue your body will use for energy.

Factoid: Too much stress will speed up the aging process.

Chronic stress has been shown to trigger the body’s abdominal fat storage response (stress belly). It has also been connected to a host of other pernicious effects:

  1. Impaired cognitive performance

  2. Suppressed thyroid function

  3. Blood sugar imbalances (insulin)

  4. Decreased bone density

  5. Decrease in lean muscle tissue

  6. Higher blood pressure

  7. Lowered immunity and inflammatory responses in the body

  8. Lower white blood cell count

  9. Disruptive sleep

  10. Lower testosterone

  11. Decrease healthy bacteria in gut

  12. Lower libido

I hope we can all agree that too much stress is unhealthy.  But that’s only one of the complications facing chronic exercisers. Research has shown the risk of atrial fibrillation is significantly higher in endurance athletes than with the gen pop. This is likely the result of scar tissue formation in the heart and excessive amounts of inflammatory markers brought on by the high volume of endurance training. Furthermore, according to data presented at the American College of Cardiology 59th Annual Scientific Sessions“long-term endurance running in marathon runners was associated with significantly increased calcified coronary plaque volume compared with non-marathon runners”. In recent years we have seen the unfortunate and premature deaths of many world-class endurance athletes due to these and other heart conditions.  Certainly, these athletes are fit, more so than 99% of the American public, but are they healthy?  Sadly, many are fit but unhealthy and don’t even know it until it is too late.


J-curve of cardiovascular disease risk as a function of training volume with respect to years. Under-training has been known for many years to substantially increase the risk of heart disease and is represented by the steep line. The lower slope of excess training volume represents the slow development of heart disease risk over many decades of intense endurance training.

Another major issue with chronic aerobicizes is joint deterioration, injury and/or pain.  Have you ever noticed the foot traffic wear pattern on the carpet between your TV room and kitchen?  Over time chronic repetitive motions will wear down joints just like that carpet. Lack of proper rest and recuperation between bouts of exercise can lead to deterioration of the cartilage around your joints and eventually result in painful osteoarthritis. Working out is only productive and positive for the body when you get enough rest, otherwise, it might be better not to train at all.  You can be sure our great ancestors moved all day long and even sprinted occasionally.  It is unlikely they ‘jogged’ or swam for hours at a time. If they did, you can bet they rested in between and did not overtax their bodies…or they died!

As a small footnote, I’d like to mention, chronic weight training can be just as dangerous and fattening as chronic cardio.  Didn’t your mom tell you, everything in moderation? Find your sweet spot and swim in its beauty.

Bottom Line: Exercising beyond a certain threshold will make you unhealthier and fatter. Limit your miles and minutes of intense cardio per week. Jog less, walk more and sprint a little.  

Emerging medical evidence about the dangers of too much cardio -TEDX:


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