HIIT Session Design - How Long Should HIIT Workouts Be?

Designing your own HIIT sessions can be challenging, especially with all the mis-information on this effective training style on the internet. This article will help you understand how long your HIIT workouts should be and how you can design them effectively yourself.

4 min read
Sean Klein
Written by
Sean Klein
Published on
Last updated
In This Resource
  • Designing You Own HIIT Workouts
  • Rules of Thumb
  • What is HIIT
  • How Long Should A HIIT Workout Be?
  • HIIT Session Design
  • Sample 1:
  • Bike Intervals (Mono-structural)
  • Sample 2:
  • Session 3:
  • Integrating HIIT into Strength Workouts

Designing You Own HIIT Workouts

As a general rule of thumb a well designed HIIT workout should involve 5-15 minutes of workload at a high heart rate.

Rules of Thumb

  • Work for 5-15 minutes of output
  • High Movement Virtuosity (movements where you have good technique)
  • High heart rate, high difficulty. (These are challenging sessions mentally)
  • No high levels of muscular fatigue (if your doing HIIT for cardiovascular adaptations)
  • What is HIIT

    Before we can dive into HIIT session design and come around to how long HIIT sessions should be, we need to define HIIT. HIIT is an acronym for high intensity interval training, it involves repeated bouts of activity performed at a intensity which is considered challenging by the individual performing them, often with a very high heart rate and unsustainable pacing (anaerobic). This is performed with the goal of improving cardiovascular characteristics, through increases in VO2 max. It is also done for weight loss, but that is not the desired adaptation of a HIIT workout, as weight loss is so linked to nutrition and lifestyle.

    How Long Should A HIIT Workout Be?

    If a HIIT session requires both a high heart rate and unsustainable pacing then it should not be surprising that HIIT workouts are not performed for a long time. In order to reach the high levels of intensity (high heart rate) we cannot perform these outputs for a long time, so HIIT workouts should be performed from between 8-15 minutes of work. HIIT was originally designed to be done at interval, hence the name, but for me it is related much more to the intensity of the activity, hence why some examples below will be continuous efforts.

    HIIT Session Design

    HIIT session design is an important factor that determines if the session will be effective at creating the desired adaptations. High intensity interval training can be done in an infinite amount of ways, hence why sports like CrossFit have become so popular. This makes HIIT a little complicated, especially because it was preceded by circuit training, which was more focused on muscular endurance than cardiovascular adaptations. Let’s walk through three different session and assess how long the sessions are and how effective they are at cardiovascular adaptations.

    Sample 1:

    Bike Intervals (Mono-structural)

    4 x 3’ @90+%

    Rest 2’

    This is a perfect example of a by the book HIIT session. We can be certain that this kind of workload will be effective at increasing VO2 max. With a total time of 18 minutes and work time of 12 minutes, we will be able to reach high levels of intensity, pushing the cardiovascular system to its max.

    Sample 2:

    CrossFit HIIT (Mixed Model)

    3 x 5’

    400m Run

    20 KBS

    AMRAP Bike Cals

    Rest 2’

    In this example we see an extremely effective CrossFit style HIIT workout, that will be very effective at improving the VO2 max of individuals who perform it. The run and KBS will act a pre-fatigue for the bike whilst also stressing the cardiovascular system and some muscle groups through the KBS. The KBS will not be so difficult to block the cardiovascular intensity.

    Session 3:

    CrossFit Long


    1 Mile Run

    100 Pull Ups

    200 Press Ups

    300 Air Squats

    1 Mile Run

    This is an example of a Crossfit session that isn’t HIIT. It is too long to start with, secondly it will mainly stress the muscular endurance physical characteristics rather than physical cardiovascular characteristics. This is a great workout for an experienced Crossfitter, we just need to be careful what we label HIIT.

    Integrating HIIT into Strength Workouts

    Adding HIIT workouts to the end of strength workouts can be an extremely effective way to save time in the gym and get multiple adaptations within one session. Let’s look at a session you could perform in 60’ to get strength and cardiovascular adaptations.

    A) Back Squat

    5 x 3

    B1) Rear Foot Elevated Squat in Lunge

    4 x 8/8

    B2) Press Up on Low Barbell

    4 x 5

    B3) Hollow Hold

    4 x 40”

    C) Bike Intervals (Mono-structural)

    4 x 3’ @90+%

    This is a session I recently did with a client, she is aiming for a bodyweight back squat and a press up, whilst also maintaining cardiovascular health. The session makes sense in context with her weekly plan, this is just an example of how HIIT can be mixed with strength workouts. There are thousands of ways to skin this cat, so do not take this session as the only way to do it.

    If you enjoyed this resource you can find more below or try Programme, a fitness app that plans every workout for you – based on your progress, equipment and lifestyle.

    This resource was written by Sean Klein. Sean Richard Klein has thousands of hours of coaching experience and a BSc in Sports Science with Management from Loughborough University. He owns a gym in Bayonne France, CrossFit Essor, which runs group classes and a Personal training studio.

    Sean Klein


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