The Role of Exercise in Overcoming a Bad Diet

Dr Glenn McConell chats with Professor Benjamin Levine who has the best global research track record in Sports cardiology/cardiovascular physiology and exercise. He is the founder and Director of the Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas, Professor of Internal Medicine/Cardiology and Distinguished Professor of Exercise Sciences at the University of Texas Southwestern Medical Center.  He has published over 400 journal articles with a very high H-index of 109.   

We enjoyed a broad ranging discussion including: 

- how the main determinant to be an endurance athlete/ to have a high VO2 max (aerobic capacity) is the maximum stroke volume (how much blood pumped per beat). Their heart and pericardium stretch more (more compliant) which allows a large stroke volume. 

- Athletes big hearts: Which comes first, the training to increase the heart size or need to have a big heart first?  

-Genetic component to being a great endurance athlete? Can’t use genetic profiles, it’s a gene-environment interaction.  

-Eccentric hypertrophy (volume load) with purely long slow distance exercise, concentric hypertrophy (pressure load) with purely strength training. But many activities are a combination of volume load and pressure load. Eg Rowers have the biggest hearts, thick walls and large volumes (they have a combined strength and endurance type training stimulus): they have mean arterial pressures of 250mmHg during exercise!    

-Resistance trained people do not have a thick walled hearts like one might expect because they only have the high pressure loads during the exercise, unlike people with hypertension that have pressure loads 24/7. 

-Dallas bed rest study from 1967 then followed up with the same participants 30 years later. Found that 3 weeks of bed rest was worse than 30 years of aging for the body’s capacity to do physical work! Aging leads to atrophy and stiffening of the heart and reduced compliance of the blood vessels and life long training prevents this.  

-Four to five days a week of exercise the sweet spot for optimizing cardiovascular health  (one fun easy 60+ min, 2-3 moderate to vigorous, 1 intense plus sone strength training).  

-If been sedentary for a life time (eg 70 year olds) exercise can’t reverse the hearts lack of compliance etc. Starting exercise before the age of 55 is important.  

-Walking not hard sufficient load to maintain the hearts function. Endothelial function and exercise training: greater dilation of blood vessels after exercise training.  

-For the vast majority of people competitive levels of exercise is good for heart health. In a small amount of people that do an extraordinary amount of exercise, exercise-induced right ventricular cardiomyopathy can occur (this will be discussed more in a later podcast by the expert on this, the Cardiologist Dr Andre La Gerche).  Genetic cardiomyopathies and exercise. Higher calcium/calcification in coronary arteries in some athletes but this doesn’t increase mortality and appears to reduce mortality. Higher rate of atrial fibrillation with high levels of exercise training but not greater heart disease risk.  

-Exercise can’t be expected to overcome a bad diet.

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