#140 – The Science of Conditioning: Energy Systems Explained with Santana and Christy Alexon, PhD
We all know that some level of fitness, or aerobic conditioning, is necessary for life. Whether it’s for sport, physical activities (like hiking, biking, or throwing the frisbee), or simply to minimize the risk of cardiac and metabolic disease, conditioning must play a role in our training program.
Of course, as discussed in previous episodes barbell training satisfies the criteria for “conditioning,” being a form of short, intense exercise similar to the high intensity interval training (HIIT) employed in circuit training, Crossfit, and the like. But why? Robert Santana and fellow Registered Dietician and PhD Christy Alexon join us today to explain.
The body utilizes ATP, adenosine triphosphate, to do stuff like stand up, walk around, climb a tree, pick up a box, etc. ATP is readily available in our muscle cells but in small amounts — enough for 10-15 seconds of strenuous activity, but no more. Obviously many physical tasks involve strenuous activity lasting much longer than 15 seconds, so why don’t we keel over once the initial ATP is used up? The answer lies in bioenergetics, that is, the network of energy systems the body uses to deliver ATP to the muscle cells.
There are three major types of energy systems:
- “Anaerobic” or phosphocreatine — ATP stored directly in the muscle cells; high energy output, very short duration
- Anaerobic glycolysis — the breakdown of glycogen (a blob of glucose molecules, or carbohydrate, stored in the muscles and liver) into ATP; medium energy output, medium duration
- Aerobic (oxidative) glycolysis — the use of oxygen as fuel to breakdown carbohydrate and fat into ATP; low energy output, long duration
These systems do not work independently, but rather concurrently; as you lift a heavy set of five, the phosphagen system dominates, but glucose is being broken down and the aerobic glycolytic cycle is upregulated in anticipation of more activity. Therefore, weight training provides a conditioning effect because it trains the aerobic energy systems, albeit indirectly. After all, that is what conditioning is: the capacity for sustained aerobic activity, typically measured by VO2 max in the lab.
Many novices wonder whether they should be doing “conditioning work” in addition to the main barbell lifts. The answer, for a novice, is no (though exceptions may apply to morbidly obese trainees who require additional calorie burn for emergency weight loss). The barbell training alone constitutes enough conditioning work to satisfy general health needs, and any additional work would simply interfere with recovery… and as Barbell Logic has made the case repeatedly, getting stronger will make a bigger impact on performance and health than any other fitness attribute at this point. For intermediates and beyond, the answer varies. For general health, i.e. minimizing the risk of heart disease and metabolic disorders like diabetes, strength training combined with regular physical activity (walking, hiking, biking) is sufficient. Sports with an endurance component will require more conditioning, which may interfere with the acquisition of strength. It’s rare to see a marathoner with a big squat.
Christy has a PhD in Nutrition and Wellness and currently works as both a Registered Dietician for Rennaisance Periodization and as a Clinical Associate Professor of Nutrition at the Arizona State College of Health Solutions where she teaches macronutrient metabolism.