"Energy Systems" Made Simple

You every notice, depending on what kind of activity you're doing, the way you perform, and the way it makes you feel is different? Jumping with all your might for a handful of seconds probably leaves you feeling different than lifting weights for thirty. Or benching for a set of 10 leaves you feeling different than jogging a 5K? While the science of why can get complex very easily...let's keep it simple and relevant for the 99.999% of us NOT trying to major in advanced exercise science. It'll get mildly science-y, but I promise it'll be digestible and uncomplicated. If interested in learning more, let us proceed:

You've got 3 energy systems: Phosphagen, Glycolytic, and Oxidative.

• Your body uses all of them to a degree with any activity you do, but favors one over the others based on what type of specific work is at the forefront.

• All utilize a molecule called ATP (short for adenosine triphosphate) as a source of energy. How this ATP is produced differs.

• Phosphagen & Glycolytic Systems are anaerobic (doesn't require oxygen), while the Oxidative System is aerobic (does require oxygen).

Phosphagen System: Think of this as your "immediate" energy source. Used during high-energy, explosive, demanding actions. Short bursts of energy. For literally just a handful of powerful seconds (upwards of a mere 10s). A molecule called Phosphocreatine (PC) already stored in your muscles is utilized. You don't ever have a lot of this to go around, hence such a short time frame of use is available at any given time.

Examples: Sprinting, Jumping, Throwing a ball, Swinging a bat/club, etc.

Glycolytic System: Your "short-term" energy source. Used during moderately intense-to-intense work. For 30s to 3 minutes of work. Also utilizes fuel already stored in your muscles, but in the form of glycogen/carbohydrates. Breaks down slower than PC.

Examples: Lifting weights, Boxing, Carrying or hauling something for 100 ft., etc.

Oxidative System: Your "long-term" energy source. The only one that uses oxygen to make ATP. Used during lower intensity, more extensive activities. Anything lasting over 3-5 minutes. Energy isn't created as quickly, but because the energy demand is so much less, endurance endeavors are able to be performed for longer (sometimes VERY long), since the rate of energy produced is comparable to the rate at which it's being used.

Examples: Steady state cardio, Marathons, Soccer, Rowing, etc.

What the heck can I do with this info?

Knowledge is power. With these insights, you can understand how to better/more confidently fuel yourself depending on what activity you're doing (i.e. getting solid carbs in for a lifting session might be a pretty good idea; or: I might be able to go on a fasted, 30 min. steady jog with no problem). It also explains why it makes smart sense to welcome a few minutes of earned rest after a bout of 10 seconds of highly explosive, energy-zapping work. Lastly, but importantly -- it helps you get specific with conditioning for specific goals and tasks, and that means appreciating, training, and improving specific energy systems.

About the Author

Jacob is multi-certified fitness coach who specializes in strength, muscle, and functional movement. From Team USA athletes to those who have never lifted a weight, Jacob has personally helped hundreds of people improve their health and habits, while providing valuable tips and strategies for continued independent strength and development. While he upholds steadfast principles that apply to everyone, they are always thoughtfully adapted to the individual's specific goals, fitness level, and needs. He is currently accepting new clients on his all-inclusive 1:1 Online Coaching Platform, as well as select availability for live session training. Serious inquiries, please reach out through his website.

Like, Comment, or Share! Thank you!

follow on instagram