I spent five and one-half years getting my Bachelor’s degree, and four semesters getting my Master’s degree. In that time, my philosophy toward exercise and exercise prescription was formed, based on what I learned by reading and sitting in lecture halls and labs. I’ve been applying those principles in my practice for well over 20 years, and until fairly recently, thought I was on the right track. The first whiff of a change in the wind occurred about two years ago, after reading about a study done in 1998, which showed that cardiac fitness, muscle strength, and fat loss, could be achieved by more intense and much shorter exercise sessions. I began looking into cracks in the status quo of exercise prescription. More recent studies have corroborated the earlier work, with some of the findings really rocking my world. For instance:
A study of marathon runners showed that they had left ventricular hypertrophy, akin to persons suffering from high blood pressure or other heart problems. If you’re going to have a heart attack, this is an area of prime concern. They also had a decrease in bone mineral density, a decrease in lung volume of Fe1 and FeV (Fe1 is the amount of air one can forcibly exhale in one second, FeV is the total amount of air one can evacuate), and they also showed signs of atherosclerosis. All of these effects are completely opposite of what one would want for health. At first I thought this was strange. Most of us think of marathoners as very healthy persons. But, as the authors pointed out, “if the body is trained to have to endure long periods of physical stress, it needs to downsize.” I didn’t learn this in graduate school.
A study using a pair of female identical twins, both of whom had body fat levels of 22%, were put on two different exercise protocols. One was given a program of distance running (starting with a mile and gradually increasing it to 6.5 miles at the end of the study), the other short sprints (starting with 2 sprints of 50 yards with 2 minutes of rest in between and progressing to 8 with 2 minutes rest between). After six months, the endurance woman had lost five and a half percent body fat and had gained 1.5 pounds of muscle. The sprint woman lost 11 &1/2% body fat and gained 5 &1/2 pounds of muscle. Plus, the woman with the sprints had a higher lung capacity and increased cardiac ejection fraction (the amount of blood pumped with each beat, which is a good thing).
Why the favorable results for doing things short and fast and not long and slow? Because we, as human beings, are designed that way. It is in our nature to be able to do things quickly and recover. Occasionally, we can also do long duration things, but only occasionally.
One of the decades-old tenets of weight loss is to do exercise at a low intensity for a long duration. True, you do burn a higher percentage of fat during low intensity exercise (and you burn almost all fat when you sit on the couch), but you burn a higher total number of calories during moderate or high intensity exercise. In addition, what you are looking for from your exercise routine is adaptation; whether it’s muscle hypertrophy, fat loss, and heart and lung improvement. You want to prompt your body to do this adaptation with the stimulus of exercise. Since you burn more fat during low intensity exercise, you are telling your body you need more fat stores because they’re needed-quite the opposite effect people want. With moderate to high intensity exercise, you are telling your body the opposite. Since you can’t use much fat during these types of exercise protocols, your body is being told the opposite: increase muscle glycogen stores, creatine, and ATP, the fuels needed for higher intensity work. Many people who started walking to lose weight 20 years ago are either still walking to lose that weight or have given up!
One more note about long duration exercise. There is no relationship between long duration exercise and all cause mortality, meaning it has no effect on your lifespan. Short-burst, high intensity exercise shows an inverse relationship with all cause mortality, meaning the more you engage in it, the better health you will have. To my knowledge, no one has died running a 50 meter sprint, whereas many long distance runners die each and every year.
My personal routine involves 15-20 minutes of short duration (30-45 seconds with a 30 second rest), doing mostly body weight exercises and also using resistance bands. I do some sprinting, jumping, sideways hops, jump rope, etc. I can do it 5 x/wk because it takes so little time, and it is much more enjoyable. My blood work looks great, body fat is normal, blood pressure and heart rate are excellent. And, I have time to enjoy other things.
For more info on a workout plan, email me at firstname.lastname@example.org
Stay well, John R Blilie, M.S.