Chronic Cardio = Heart Damage?

Although the other negatives of selecting long-distance cardiovascular training as your predominant form of exercise are eye-opening, this one tends to hit home the most. Mainly because a good portion of the population starts running, cycling, and swimming in an effort to improve their heart health. I can’t help but think of someone running their ass off to go harder and further to strengthen their blood pumping muscle and prevent heart disease, when they’re actually damaging it and increasing their risk as they improve.

When it comes to exercise, the saying “you can never have too much of a good thing,” should be ignored.

This can be seen in the cardiovascular health of ultra-endurance athletes, who continuously put their bodies through a pounding. These guys, and girls, aren’t just running ‘further’ than everyone else, they’re running more consistently than everyone else, and faster!  Most (including me) would like to idolize these individuals as we can’t see ourselves doing 1 marathon, let alone 2. But, as I’ve already shown you, the duration and intensity of exercise has a profound effect on free radical production, cortisol secretion, lactate accumulation and inflammation. Despite the increase in antioxidant production to handle some of these elevations, the added protection quickly plateaus.

The stress-related damage from exercise is especially prevalent with increased distances.  Other than marathoners, triathletes, and ultra-endurance enthusiasts, the generation population commonly surpasses this threshold when they decide it’s time to ‘get fit.’ Not only because they’ve been misled into believing that losing ‘weight’ requires eating less and exercising more, but because the first thing the out-of-shape guy or girl at work comes out with this on January 1st:

“My goal this year is to run a marathon!”

As cardiologist, Dr. James O’Keefe, discusses in one of his research papers, endurance training causes ‘structural cardiovascular changes’ and ‘elevations of cardiac biomarkers’ that return to normal in the short term, but worsen when taken on as a regular activity and result in the development of:

“patchy myocardial fibrosis…an increased susceptibility to atrial and ventricular arrhythmias, coronary artery calcification, diastolic dysfunction, and large-artery wall stiffening.”

According to O’Keefe, it’s common to see abnormal test results for high-level endurance athletes, but recent evidence is suggesting as high as a 5-FOLD increase in the prevalence of atrial fibrillation.

“If we went out for a run right now and you ran hard… by 60 minutes something starts happening… the free radicals blossom, and it starts burning the heart. It starts searing and inflaming the inside of your coronary arteries.”

One study, from the European Heart Journal looked at marathon runners, triathletes, alpine cyclists, and ultra triathletes, who competed in races lasting 3, 5, 8, and 11hrs respectively.

Dysfunction in the right ventricle after the race was least in the marathon runners (3hrs), and highest in the ultratriathletes (11hrs).

Although the evidence is still emerging, and is still somewhat contradictory, there’s a considerable amount of research that long endurance training sessions performed frequently leads to cardiovascular damage over time:

  • Impaired Cardiac Contractile Function – left and right ventricle (1, 2, 3, 4, 5)
  • Decline in Peak Systolic Tissue Velocity (1, 2, 3)
  • Cardio Myocyte Damage – specifically, elevated cardiac troponin (1, 2, 3, 4, 5)
  • Myocardial Fibrosis (1, 2, 3, 4, 5)
  • Atrial Fibrillation (1, 2, 3)
  • Cardiac Arrhythmia (1)
  • Poor Left Ventricle Function (1)

As some of the research notes, these elevations and alterations could be the result of‘adaptive responses our body goes through in order to deal with the physically taxing and stressful workout. However, it’s clear that this adaptation is likely not favorable in the long-term, as heart damage and risk of heart failure rises beyond a certain threshold.  For instance, in April of this year (2014), the Journal of the Missouri State Medical Association published research showing that:

“Long-term male marathon runners may have paradoxically increased coronary artery plaque volume.”

The study compared a group of sedentary men to men that competed in at least 1 marathon annually for 25 years. Compared to the inactive group, the runners had nearly double the total plaque and calcified plaque volumes, and almost 1.5 times the non-calcified plaque volume.  Interestingly, this was despite lower resting heart rates, BMI (Body Mass Index) and triglyceride levels than the sedentary group.  Which suggests it’s likely the physical practice of marathon running that’s causing the arterial damage.

Other than the excessive stress, perhaps the increase in heart disease from chronic cardio has something to do with the prolonged drop in blood pressure (a sign of cardiac fatigue)?

Either way, it’s one more reason to Stop Jogging.

Stay Lean!
Coach Mike


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