Exercise Science

Workouts Sculpt Heart As Well As Muscles

Exercise can cause structural changes in the heart — and the changes can vary depending on the type of exercise.

Researchers found that endurance athletes showed an increase in the size of both their left and right ventricles after 90 days of team training. However, athletes who only did strength training had excessive growth in their left ventricles, but no change at all in their right ventricle size.


In addition, the ability of the left ventricle to fully relax between beats (diastolic function) was enhanced in the endurance athletes, but it worsened in the strength trainers.


It is possible that this could point the way towards tailored recommendations for rehabilitation and recreational exercise for people with heart problems.












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Dr. Mercola Dr. Mercola’s Comments:

This is an interesting study in that it shows how various types of exercise affect the structure of your heart in different ways.


It also shows that you’re not necessarily “born” to be a good athlete because you were born with a bigger or stronger heart, but that it’s the type of training you choose that has the most influence on your performance by building an “athletic heart.”


Athletes are Built Not Born

In this study, the endurance group consisted of long-distance rowers, whose exercise regimen consisted of daily running, cycling, swimming, rowing or using an aerobic machine with sustained effort for at least 20 minutes a day.


The strength training group was American-style football players doing weight lifting, plyometric exercises (explosive movements to develop muscular power) and sprint running drills.


After three months of organized team training, they found there were significant training-specific changes in the athletes’ heart structure and function.


While left ventricle mass increased in both groups, the endurance athletes had better diastolic function in their left ventricle, and enlargement and more efficient contraction and relaxation in both sides of the lower chambers of the heart (atria).


The strength-trained athletes, on the other hand, actually had hypertrophy, or excessive growth, in the muscle of the left ventricle, and reduced diastolic function, with no other structural changes.


Is Your Exercise Prescription Up to Date?


For a change, I agree with the idea to use this type of research to influence and fine-tune your “exercise prescription.” Exercise is a critical component of good health, especially as you age, and a good way of looking at it is to view it as a drug that needs to be precisely prescribed for maximum benefit.


Most Americans suffer from an “exercise deficiency,” which contributes to two-thirds of the U.S. population being overweight, and tens of millions of others with high blood pressure, high cholesterol and diabetes; all of whom desperately need more exercise to control their underlying condition.  


Exercise is simply one of the most powerful tools available to drop your insulin levels, and elevated insulin levels are one of the primary drivers for these types of illnesses and weight gain. It is my belief that properly performed exercise is far more powerful for controlling these symptoms than any drug yet developed. 


What Type of Exercise Regimen Do YOU Need? 


A TRULY effective, well-rounded exercise program must involve all three types of exercise, taking into account exercise intensity and duration for your individual fitness level and goals: 



  1. aerobic, endurance workouts (lowers blood pressure)
  2. strength training (helps ease muscle and joint pain)
  3. interval-type training that includes short bursts of activity at very high intensity that is individualized for your specific fitness level (burns fat) 

Interval training — where you break your exercise session into segments with a rest period in-between — has been proven especially effective at burning greater amounts of fat than one single hour-long session. Newer studies on the specific benefits of interval training also suggest that it may actually provide MORE protection against heart attacks than long durational aerobic type exercises. So, I wouldn’t trade in interval training for endurance-style training only. 


Even though it wasn’t mentioned or included in the study above, high-intensity interval exercises have been shown to DOUBLE the endurance in 75 percent of test subjects, compared to those who did traditional endurance training only! (So just imagine the benefits of interval training compared to doing nothing but pumping iron.) 


My personal experience would support that as I have been a long distance runner for the last 40 years, and my heart is so large I have left ventricular hypertrophy on EKG and chest X ray evaluation.  This is not pathological in my case but a healthy response to exercise.


I now incorporate interval training in the form of sprints, and strength training through pull-ups, push-ups and dips, rounded out with a game of singles tennis whenever I can. Tennis has become one of my passions. I’m now taking lessons twice a week, working my way up to a 3.5 player, and hope to be a 4.0 someday. It’s just great fun; something I look forward to each week. 


Avoid This Common Pitfall When Starting a New Exercise Routine 


Now, if you are overweight or out of shape, you can start with walking. Most heavy people start with walking and it’s an excellent choice, as it is low-risk and inexpensive.  


The major problem with walking, however, is that many people become fit relatively rapidly but don’t increase the intensity of the workouts as they become more fit.  


Remember that once you become comfortable with your routine, you need to increase the intensity in order to continue reaping the benefits. 


Push the intensity of your workouts so you are going just hard enough to where it’s difficult to carry on a conversation with someone next to you. If you can easily talk to someone you simply are not going hard enough to give your body the benefits it needs. An additional benefit of this technique is that you don’t need to monitor your heart rate to make sure you’re exercising at peak intensity.


Remember to Listen to Your Body


One of the key principles I teach and believe in is to listen to your body.


If your body will not allow you to exercise, either due to pain or worsening of your underlying condition, then you have no practical option but to honor your body’s signals and exercise less or not at all.


Even though your body desperately needs the exercise to improve, you will only get worse if you violate your current limitations. So you may have to start with as little as just minutes a day. That’s okay.


Apply the Take Control of Your Health Program and as your body gradually improves so will your tolerance to exercise, so continue to push yourself until you reach the daily 90-minute level.


Need Inspiration? Remember All the Benefits!


Even if you have no aspirations of becoming a professional athlete, the benefits of even small amounts of exercise are far too valuable to ignore. Aside from developing a stronger “athletic heart,” exercise will also help you: 



  • Sleep better
  • Lose weight, gain weight, or maintain weight, depending on your needs
  • Improve your resistance to fight infections
  • Lower your risk of cancer, heart disease and diabetes
  • Help your brain work better, making you smarter 

Do You Need Help Getting Motivated?


If you are having trouble motivating yourself to exercise, the Emotional Freedom Technique (EFT) can help. EFT is a form of psychological acupuncture treatment I recommend in order to optimize your emotional health.


It can help you remove the mental or emotional blocks that prevent you from successfully implementing your program. You can learn the technique with my free manual and discover more about the connection between your emotional well-being and your overall health.


You can also combine EFT with Medical Hypnosis to create an unconscious desire to exercise every day. This is session six on the hypnosis program I recommend for long term weight loss.



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