Metabolic conditioning simply refers to structured patterns of work and rest periods to elicit a desired response from the body. This desired response is usually to maximize efficiency of a particular energy system and/or elicit a particular physiological adaptation such as increased strength or muscle size. Metabolic conditioning can reference all forms of exercise.

The body has several different methods of getting energy. Different ratios of work to rest periods call upon different energy systems and cause specific adaptations. Research has concluded that a metabolic conditioning workout should be based on desired outcomes and an individual’s level of fitness. For instance, someone looking to add size should have a different work to rest ratio than someone looking to get leaner or run farther. Pairing difficult exercises together and blowing through a circuit with no regards to timing, intensity and recovery on this micro-cycle isn’t nearly as beneficial as a programmed and objectively observed training session.


There is no perfect metabolic training program. You must use the guidelines shown in this manual to design an appropriate metabolic training program to ensure long term progress, avoid injury (to either the musculoskeletal or the endocrine system), and provide guidance and motivation to maintain and improve client interest and adherence to your program (through intelligent program design). These guidelines follow the FITTRR principle, where F stands for Frequency (sessions per week), I stands for Intensity (% of maximum capacity), T stands for Time (duration of workout), the second T stands for Type (mode of exercise), R stands for Rest/Recovery, and the second R stands for Rate of Progression.

Exercise Metabolism: The Basics

Metabolism simply refers to how we break down food for energy and for cellular activity (also cellular repair and “cleaning” of metabolic waste). Everything we ingest must be broken down into smaller particles in order to be used by the body. There are three primary pathways for metabolism that each has their own place and purpose.

The Immediate System:  Phosphagen

Commonly referred to as the creatine phosphate pathway, think of this system as the fastest and most powerful method of getting energy. It’s mainly utilized when performing power exercises that last less than 15 seconds (think Olympic lifts and sprinting). More important than the duration is the recovery time. This system (since it’s so quick and powerful) takes around three to five minutes to fully recover.

The Intermediate System:  Glycolytic

Call the Glycolytic pathway, this is an intermediate system that provides energy for activities lasting between one to four minutes. It’s primarily used in shorter duration, intense activities including weightlifting and mid-distance running intervals (400-800m). the Glycolytic pathway takes between one and three minutes to recover.

The Long-Duration System:  Aerobic

This long-lasting energy system can go for hours upon hours of easy to moderate intensity work. Since we have almost limitless amounts of fuel for the aerobic system in the form of fat, it can recover in a matter of seconds.

With the three major pathways outlined, keep in mind that there is always interplay. No on sole pathway is working at a time. Throughout a workout, each system is contributing to some degree. However, certain work-to-rest ratios call upon one primary system. For example: The hardest the Aerobic System can work is while facilitating recovery from an Anaerobic bout of exercise. This is why such big muscular & cardiovascular endurance benefits are observed with HIIT training.