your muscles - the only "window" into your body

I first came across the idea that “muscle is the ‘window’ into your body” in Ken Hutchins’ SuperSlow Technical Manual. He attributes the quote to a former employee of Nautilus, Ed Farnham. It’s a brilliant metaphor. The idea is that essentially all physical improvements that can be stimulated by exercise are fundamentally caused by loading your muscles. Making your muscles work is the way you “get at” and stimulate not just your muscles, but the rest of your body’s systems too. Your muscles are a pathway to improving your cardiovascular system, lungs, endocrine system, immune system, general metabolism, and more.

For example, suppose somebody is climbing stairs for the purpose of exercise. This person’s body will temporarily burn more calories during the stair climbing session. It’ll also make her heart beat faster, and by doing so potentially place positive stress on her cardiovascular system to improve. And if the stair climbing is challenging enough, her leg muscles will fatigue somewhat as well. If her body isn’t already used to a more demanding stress than stair climbing (such as high-intensity strength training), her body will be stimulated to improve the cardiovascular system, her muscles might get slightly stronger, and other positive adaptations may occur in such places as the immune system and the endocrine system.

Note that each of those effects from stair climbing (burning calories, positively stressing the cardiovascular system, potential strength increases, and positive changes in the immune and endocrine systems) are caused by making the muscles work. Extra calories are burned only because the leg muscles are working harder from the activity. The heart starts beating faster to supply nutrients to the working muscles, as well to remove waste products from them. If an increase in strength is stimulated, it would be because the muscles have been loaded, fatigued, and stressed sufficiently. All the physical benefits are fundamentally caused by making the muscles work.

Demanding muscular loading is the fundamental cause for triggering a cascade of positive changes throughout your body. Even for the cardiovascular system, the stimulus is making the muscles work, and the cardiovascular system kicks into higher gear simply as a support system for the working muscles. (In other words, the heart and lungs can’t jump out of your body and hop on the stair climber to exercise themselves. The only way to “get at” your cardiovascular system through exercise is by making the muscles work.)

A big advantage of effective strength training when compared with other exercise methods (like stair climbing) is that strength training gives you the opportunity to make your muscles work much harder than stair climbing or other exercise choices. If you’ve ever trained your leg muscles to “momentary failure” on the leg press machine in slow-motion form, you know firsthand how strength training works your muscles hard! Since strength training can make your muscles work harder than other activities (like stair climbing), you can stimulate as good or better benefits in all of the body’s systems (including the muscles, cardiovascular system, lungs, endocrine system, immune system, and general metabolism) than you can with other activities.

In a previous article I mentioned that studies show that effective strength training produces positive benefits in the cardiovascular system. This is why. In some studies with very high-intensity strength training, the changes in the cardiovascular system from strength training are superior to even so-called “cardio” activities like stair climbing. The reason is you can only address your cardiovascular system by making your muscles work, and strength training gives you the opportunity to really challenge your muscles, and as a result many other systems in your body improve in addition to the muscles.

Making your muscles work hard during strength training triggers a “total body response,” including:

  • More strength
  • Greater endurance
  • More calorie-burning lean muscle tissue to your body
  • Reversed age related muscle loss (sarcopenia)
  • Increased metabolism and how many calories you burn even while you’re resting
  • Greater fat loss
  • Stronger bones
  • Reversed aging of muscle cells (expresses younger DNA in the nuclei)
  • Improved cardiovascular fitness
  • Improved cholesterol levels
  • Lowered blood pressure
  • Improved low back pain
  • Better control of blood sugar
  • Improved immune system
  • A number of other benefits


When done properly strength training loads the muscles (your “window into your body”) much more effectively than other activities because strength training can load the muscles more efficiently, more intensely, and in a safer manner than other activities can.

The slow-motion, high-intensity strength training that we teach at The Perfect Workout is as good of a way as you will find at stimulating this “window” into your body, and as a result your whole body improves, not just your muscles. And all it takes is just 20 minutes, twice a week.