7 Chapter 7: Interval training

Melissa Markofski


Interval training for CRE

Interval training is a common technique used to increase a person’s CRF. Often the goal is to increase lactate threshold or lactate tolerance. It can be a very effective method of training, in part due to the participant pushing themselves to a high level of work. They are able to do this because it is a relatively short amount of time that they need to sustain the high level of work.

Interval training is also a currently popular fitness trend. One of its appeals is that it can be successfully completed by people with a wide range of fitness. This is because interval training often uses an intensity relative to a person’s fitness. Many people find exercise in intervals with instructions such as “run or walk at a pace that you cannot hold a conversation at for one minute, then a one minute recovery” more obtainable than “run for three miles”.

In class, we discussed three approaches for prescribing interval intensity. Two of these methods involved lactate threshold, and one is an estimation based on percent of total power. The intensity guideline is usually set so that the last repetition is difficult but doable. This means that it is likely that the first few repetitions will feel easy to the participant.

For any of the three methods we discussed, the intensity is selected based on the energy system we want to stress. For example, if we want to stress the phosphogen energy system the exercise duration will be about 5-10 seconds (usually 50-100 meters).

System stressed Percent of
maximum power
Typical work interval Typical work
to rest ratio
Phosphogen 90-100 5-10 seconds 1:12-1:20
Fast glycolysis 75-90 15-30 second 1:3-1:5
Fast glycolysis and oxidative 30-74 1-3 minutes 1:3-1:4
Oxidative 20-30 >3 minutes 1:1-1:3


Depending on which case study you select, you may find the lab this week very useful 


Class activity

Activity 1: Designing a CRE interval training session

Equipment: Area to run, timer, tape measure, cones

Participant: Everyone will participate in the design



  1. What system you want to train
  2. The length* (distance or time) the work intervals need to be to train this system
  3. The length** (distance or time) the rest intervals need to be to recover while training this system
  4. The number of repetitions


*Hint 1: For this class, distance works better for shorter intervals and time for longer intervals
**Hint 2: For this class, time works better for rest intervals to keep everyone on the same set


Virtual Lab Activity 1
Design a CRE interval training session:
1.  Follow the instructions above and design an appropriate interval training session to stress one of the four energy systems.
2. Include the energy system stressed, the work and time intervals, and the number of repetitions.



Activity 2: Participating a CRE interval training session

Equipment: Area to run, timer, tape measure, cones

Participant: Everyone who does not have an orthopedic or medical limitation will participate

Instructions: Execute the interval training session designed in “activity 1”


Virtual Lab Activity 2
Participate in a CRE interval training session:
1. Perform the interval training session that you designed in Activity 1.


Test your understanding of the four energy system’s work/rest intervals


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