Cardio? Energy Systems? Whats the difference?

We hear terms "aerobic" and "anaerobic" being mentioned every time we talk about conditioning, but what do they really mean?  Understanding energy systems used for specific activities or a sport can give you valuable insight on how to design effective training programs. This can also help with structuring workouts that are fun, creative and functional. Here is a bit of an oversimplification of energy pathways to help you understand.

Aerobic conditioning is the use of continuous, rhythmic movement patter at heart rate below the lactate threshold, generally 50%-70% of maximum heart rate. This means endurance running, cycling, swimming and any other event that is completed by mostly constant pace for longer periods of time.  There are some great benefits of aerobic workouts: increased stroke volume, increased VO2max, improve capillary system, and burn calories.  Aerobic system can use fats, glucose, carbohydrates (CHO), protein, plus O2.  Circulatory system is used to transport oxygen to muscles before it creates ATP. This is the energy system that is mostly recommended for “healthy” workouts due to the low intensity and application to wide range fitness levels.

Anaerobic conditioning is your ability to perform at a rate faster than can be met by the incoming oxygen. Byproduct is lactic acid (note: hydrogen ion is what causes muscle burn).  This includes: HIIT training, boxing, MMA, intervals, and bootcamp workouts. Benefits of anaerobic conditioning are: greater caloric expenditure than aerobic training, mostly fast twitch muscle work (will cover why this is beneficial in another post), EPOC and improvements in VO2max. Anaerobic system uses glycogen stored in muscles and liver for energy (without O2).  

Creatine Phosphate (or Phosphocreatine) is used in short bursts of energy lasting up to ~10sec. This is also considered anaerobic since it doesn't require O2.

There are other differences: anaerobic energy pathway is much faster (glycogen is stored in muscles and liver), and each molecule of glucose can yield ~4 ATP. Aerobic pathway goes through many more steps (Krebs cycle), and yields ~34 ATP. Even though aerobic system seems more efficient on paper, they have different applications.

So what should you do for a specific sport?  

Dominant Energy System Based on Activity Duration (NSCA, 2012)

Dominant Energy System Based on Activity Duration (NSCA, 2012)

Different sports have different energy requirements.  Lets take a sport like basketball.  In a game of basketball there are a lot of explosive movements, jumps, sprints that last on average of 40 sec, followed by a stoppage of play for 20 sec. So in basketball we use all energy systems with emphasis on ATP-CP and Anaerobic (for most positions and body types).  To train a basketball player, we would have to figure out how to train all 3 energy systems in the specific ratios.  This is where things get complicated as players may excel at one energy system (genetically or through training) and goal would be to add to the area that they may be missing (without compromising other qualities).

While one energy system will predominate over the other, both aerobic and anaerobic energy systems are always working, regardless of intensity or type of activity
— (Brooks, 1999, p. 103).

In long distance runners, 85%+ of energy comes from aerobic system, and 15% from anaerobic. For distance running majority of the workouts should focus on aerobic system.

The relative contributions of each energy system are dependent upon both the exercise intensity and duration (McArdle, et. al., 2007; Newsholme, et. al., 1994).

Training the correct energy systems can help you excel at your sport, and training incorrect can ruin an athlete (create a shift in muscle fiber type, etc.). It is important to understand the sport or activity that you are training for, and your individual needs. There are also some great tools out there which we utilize for some of our individualized programming, including HRV/HR training, velocity based strength training, and structuring it in a workout model that will bring consistent results. For general health applications, there are great benefits to training all of the energy systems (as long as you are healthy and with approval from your physician). If you have any questions, don't hesitate to contact us 

Srdan Lukic