Often I see someone train, and I can’t help but ask, “Why are you doing things in that order?” Sometimes they reply with some bro-science, or they say that the order of exercises doesn’t matter; but more often than not, they simply have absolutely no idea why they do things they way they do.

I’m here to fix that. To get the most out of your workouts, you need to understand how your energy systems work.

Energy System Overview

The human body is fueled by two primary energy systems: the anaerobic (without oxygen) system and the aerobic (with oxygen) system. The anaerobic system is further divided into the ATP/PCR (alactic) system and the glycolytic (lactic) system, leaving us with three different ways our bodies fuel for our training and daily activities. Furthermore, these systems are tightly regulated and work in the following order.

ATP/PCR

The process of splitting up the body’s ATP, phospagens and phosphocreatine (PCR) to fuel exercise provides us with energy—why we supplement with creatine. This energy system provides rapid high energy fuel to working muscles, but the energy supploy lasts only seconds. Therefore, the ATP/PCR system best suited for fast explosive, low-rep movements.

Glycolytic

This system refers to the non-aerobic breakdown of carbohydrates (primarily muscle glycogen) into lactic acid thru glycolysis. The energy source is more abundant in providing ATP, but does so at a slower rate. The glycolytic system provides energy for short term bouts of exercise such as what one would normally encounter during a typical weight training session.

Oxidative

The oxidative system refers to the breakdown of fat and carbohydrates thru aerobic metabolism. Fat needs oxygen to break down; this fat can provide an enormous amount of ATP. However, this is accomplished at a much slower rate than the anaerobic systems, therefore serving as the primary fuel for endurance activities lasting longer than two to three minutes.

When quick energy runs out, the other systems kick in to provide longer lasting fuel. A percentage of each energy system is always at work. However, as the duration of the exercise increases, a gradual shift occurs from the left to right:

ATP/PCR > Glycolytic > Oxidative

Structuring Your Workouts

You must always try to get the most bang for your buck from your workouts. To do so, you need to perform exercises in an order that most efficiently uses your body’s energy systems. Here’s the best order to follow:

1. Non-Fatiguing Dynamic Warm-Up
2. Non-Fatiguing Speed Drills (Pro Agility)
3. Power Exercises (Power Clean)
4. Strength Exercises (Bench Press, Squat)
5. Isolation Exercise (Chest Fly)
6. Auxilliary Movements (Core or Mobility Work)
7. Endurance Exercise (Jogging, Stadium Stairs)

References

• Dr Paul B. Gastin. “Energy System Interaction and Relative Contribution During Maximal Exercise.” Sports Medicine. August 2001, Volume 31, Issue 10, pp 725-741.
• G. C. Bogdanis, M. E. Nevill, L. H. Boobis, H. K. Lakomy. “Contribution of phosphocreatine and aerobic metabolism to energy supply during repeated sprint exercise.” Journal of Applied Physiology. Mar 1996,80(3)876-884.