The Basics of Endurance Training

Whether you’re a seasoned pro or a newbie, learning the science behind the basics of endurance training and how to apply it to your own training schedule is helpful to us all! Find out more below.

Endurance Training Basics

Bioenergetics aka how the body transfers and uses energy

The cells in the human body utilize a molecule called ATP as energy. In order to get ATP to the muscle cells there are three main energy pathways.

Phosphagen System – This is the energy system we think of for short, high intensity bursts of exercise. However, it is the initial system used for all types of exercise, regardless of intensity. The body stores ATP in the cells at all times, when it is used up, which happens very quickly, the phosphagen system can replenish it immediately.

Glycolysis – Once the phosphagen system has replenished as much ATP molecules for energy as it can, glycolysis kicks in. It takes a bit longer than the phosphagen system, but it can provide more energy for a longer period of time.

Oxidative System – This is the system that keeps us going for long periods of time. It utilizes carbs and fats to make ATP. This system takes longer to produce energy and requires oxygen, but it produces the most amount of ATP molecules for energy.

System at Play Phosphagen






Work Time 0-10 Seconds


15sec-3min >3min
Work to rest Ratio 1:12 to 1:20 1:3 to 1:5 1:1 to 1:3

Why does this really matter? It’s helpful to better understand which system you want to improve the most and tailor your program to that goal.


In the simplest terms, speed is how quickly an object moves over a distance. Whereas acceleration is the rate at which the speed/velocity increases over time.

There are two main metrics when we think about speed, the length of each step, and the frequency of each step. These both rely on she speed of contraction of a muscle, because a stronger contraction can lead to a larger step, and a faster contraction allows a greater frequency of steps.

This is most applicable to sprinting, where acceleration plays a greater role because the event is so brief. In this scenario, it’s clear that incorporating strength training and plyometric training is important, because it helps develop stronger, faster muscle contractions.

Aerobic Endurance

With increasing event times, you must rely more and more on oxygen to produce muscular contractions. The ability to continue sustaining a given effort depends on a few things, one of which is VO2 max, which is the maximal amount of oxygen the body can take in and distribute to the muscles.

Another factor for improving aerobic endurance is your ability to exercise as close to the VO2 max without fatigue, this is known as the lactic threshold. Now lactate gets a bad rap, it actually is used to help produce energy, but if too much accumulates and it can’t be turned into energy fast enough, lactic acid builds up and fatigue becomes inevitable. All this to say, increasing your lactic threshold will improve performance.

How do we improve these?

1. Long distance running

This should be done at a moderate effort 60-70%. It improves tolerance to longer runs, muscles adapt to be able to improve use of oxygen as energy, and the body can work on using lactate as energy.

2. Tempo Training

This is performed at/near the lactate threshold in order to increase that threshold.

3. Interval training

Training near VO2 max with a 1:1 work- rest ratio. This helps to increase the VO2 max.

4. High Intensity Interval training

Training beyond VO2 max for 30-90seconds with 1:5 work-rest ratio. This can help improve running speed, an anerobic (oxygen free) energy use.

Additional Considerations

It’s important to progress gradually, this means not increasing milage, intensity, duration, frequency, etc. more than 10% from week to week. Additionally, incorporating resistance training can help improve recovery, mitigate injuries, and improve speed on hills.

Looking for more info? Check out our instagram, where we’re always posting fresh new content! If you’ve got some nagging pains that just won’t go away or have found yourself plateauing in your own endurance training, reach out to us here!

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