The great muscle-to-fat myth: busted

Cathleen Kronemer, NSCA-CPT, Certified Health Coach, is a longtime fitness instructor at the Jewish Community Center. She is also a member of the St. Louis Jewish Sports Hall of Fame.

By Cathleen Kronemer, NSCA-CPT, Certified Health Coach

If you have ever seen professional athletes on television, perhaps 20 years after having retired from their sport, it is often easy to notice how their physiques seem to have changed from those glory days.   The most common deduction is that they have somehow allowed their muscle to turn into fat, heaven forbid.  However, nothing could be further from the truth.

Lean muscle tissue and adipose tissue (yes, there really is a technical term for the word “fat”) are fundamentally different in their metabolic make-up; as such, it is simply not possible for one to morph into the other, in either direction.  

When engaging in exercise, the body actually does not ‘create’ new muscles, although it gives the appearance of having achieved just that.  What is really occurring beneath the surface is that the existing muscle cells are becoming stronger and larger.  In addition, the number of blood vessels increases.  If exercise is a regular part of one’s lifestyle, muscle cells also begin to develop more mitochondria, the biochemical steam engine that drives cellular energy.  The result is what you observe in the mirror with great satisfaction: larger muscle mass with greater definition.

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Another contributing factor to this definition is that during exercise, adipose tissue will at some point be utilized as an energy source and get “burned off”, so to speak.  The less body fat, the more those muscles are going to be visible. Athletes who are still vigilant about a healthy meal plan will retain their muscular appearance, even during retirement years, especially if regular workouts are still incorporated into daily life.  Conversely, those individuals who have begun consuming a fair amount of empty-caloric foods while slipping into a sedentary daily schedule will see the body accumulating and storing fat, giving the outward appearance of significantly less muscularity.

What is really occurring when the former athletic superstar begins to adopt an inactive lifestyle? Since the increase in blood flow is no longer required to fuel the cells during bouts of intense exercise training and high-stakes competitive contests, the size of those blood vessels will begin to reduce.  Muscles don’t go away; they simply shrink and decrease in mass and density.  Couple this with a potentially different diet, one that takes in more calories than the body is burning, and fat will begin to get stored by the body.

One doesn’t need to immediately turn to Cross-Fit competitions upon retirement in order to stay in shape.  Basic exercises such as push-up’s, sit-up’s, recreational weight-bearing sports and cardiovascular activities will keep those busy little mitochondria chugging away.  It may be true: gone are the days of pre-season intensity and in-season workouts. Now it is time for the retired athlete to realize that while work is still needed, both in the gym and the kitchen, the time devoted to such exercise is not necessarily required.  Maintenance can be fun for a change, and your physique will continue to reflect a lifetime of athleticism.