The Three Energy Pathways in the Body and how they Function.

. Everyone wonders about the best way to train your body, and everyone has different goals. Let's explain the three energy systems to understand how the body functions.

First, we have the ATP-PC ( ATP= adenosine triphosphate, PC=phosphocreatine) or phosphagen system. This is what the supplement creatine helps replenish fuel. Examples of ATP-PC exercises are weight lifting, sprinting, HIT (high-intensity training) training, and anything else you expend maximum effort in a short period. This is anaerobic, meaning without oxygen, and anaerobic exercise tends to be anabolic or muscle building.

Next, we have the glycolysis energy system, which can be anaerobic or aerobic as it gets prolonged. Weight training in the 5-8 rep range. Circuit training with 45 seconds on each station and a short rest. Due to lactic build-up, we could use a 1:6 ratio to train the body's capacity and a 1:3 ratio if we wanted to teach the body to clear lactate. We could use a 1:1 ratio if we tried to prepare the body to tolerate lactate (warning, this ratio is not for someone new). What I mean by ratio is time. So 30 seconds lifting or running followed by 180 seconds resting is a 1:6 ratio, or 30 seconds lifting, and 90 seconds resting is a 1:3 ratio. I recommend newcomers to use a 1:6-1:3 ratio for the first couple of months.

Lastly, we have the aerobic energy system. This energy system gets a little more complicated to understand. During aerobic respiration, the heart and lungs supply the muscles with oxygen. Carbon dioxide is breathed out while water is lost as sweat. As long as muscles are provided with enough oxygen, exercising aerobically can be carried out for an extended time. Step 1)Glucose and oxygen are carried in the red blood cells, step 2) glucose and oxygen pass into all muscle cells to help muscular contraction, and step 3) aerobic respiration produces carbon dioxide and water as waste. As you can see, the result is the production of ATP.

So now that we know the three types of energy systems, we can see what produces more energy and force and what depletes fastest. This becomes important for our training methods.

If we are concerned with strength gains, which energy system do you think we would want to use? Of course, the ATP-PC system. So, for example, lifting 1-5 reps and then waiting 3 minutes or more to do it again. We need to wait a long time to give our muscles time to replenish the ATP system. As you can see above, the ATP-PC system depletes fast. If we wanted to get strength and hypertrophy (the enlargement of an organ or tissue from the increase in the size of cells), we would lift 6-12 reps and wait 1-2 minutes for another set. As muscles keep contracting without rest, we build up lactic acid in the cells, turning into aerobic exercise. Fifteen reps would be an example of endurance training and resting for 30 seconds to a minute. This is a short time when the muscle fibers do not get enough time to relax fully.

Resources:

NASM, (2012) Essentials of Personal Fitness Training: 4th Edition.

Ptdirect, (2010). The Anaerobic glycolytic System. https://www.ptdirect.com/training-design/anatomy-and-physiology/the-anaerobic-glycolytic-system-fast-glycolysis