
REHIT–The Least Amount of Exercise for Results
Video | What is REHIT? | Why It Works | How to Do REHIT | Details for Performing
If you don’t have an hour each day to do steady-state aerobic exercise. If a 20-minute High-Intensity Interval Training (HIIT) session fits your schedule but requires more effort than you are willing or able to do, I understand.
Can I interest you in 40 seconds of effort?
This is not some silly made-up thing; it is a real form of exercise called REHIT or reduced-exertion high-intensity training, and it has been shown in studies to increase aerobic capacity and metabolic health, even if you are currently sedentary. This blog post shows you why it works and how you can do it.
REHIT: At-A-Glance
- REHIT stands for reduced-exertion high-intensity (interval) training
- A REHIT exercise session lasts 10 minutes in total. It starts with a warm-up, ends with a cool-down, and includes two brief (20 sec.) periods of maximal effort in the middle.
- Your body mobilizes muscle glycogen to keep up with the energy demand of maximal exertion exercise.
- Because your body does not know the intense exercise is brief, a REHIT workout tricks your body into mobilizing more glycogen than is needed, providing a metabolic boost.
REHIT – The Least Amount of Exercise for Results [Video]
In this video, you’ll learn…
- What REHIT is and how to do it.
- The science behind why it works.
- Additional details, such as proper equipment and how to get started.
What is REHIT?
Barring any physical limitations, exercise of any type is beneficial. But, the reality is that time is not easy to come by, and intense exercise is daunting. That makes time-consuming steady-state exercises (i.e., walking, jogging, biking) and 20 to 30-minute intense workouts with minimal rest (i.e., HIIT) unrealistic for many people.
There is an alternative. It is called REHIT or reduced-exertion high-intensity interval training. It takes just 10 minutes to complete and requires just two 20-second bursts of all-out effort during the entire workout. In a study involving sedentary young adults, it was shown to improve aerobic capacity and metabolic health (1).

Why Does REHIT Work?
The purpose of exercise is to stimulate a positive physical or metabolic response. Most of that response comes after the exercise session when you are in recovery. Researchers found that with REHIT, just two 20-second intervals of maximal effort are all that is required to stimulate that response.
During these short ‘all-out’ exertions, energy demand increases exponentially. Your body cannot keep up with this intensity aerobically. To keep going, it needs to tap into its anaerobic energy system, which mobilizes stored glycogen in muscles.
This mobilization of muscle glycogen seems to be the key to why REHIT works because the muscles don’t know this is a short sprint. All they know is that there has been a dramatic and quick shift in intensity, and they must mobilize energy to meet whatever need is coming down the pike. So, the muscles are tricked into mobilizing more than is required, providing a metabolic boost.

How to Do REHIT
A REHIT exercise session lasts 10 minutes in total. It starts with a warm-up, ends with a cool-down, and includes two brief periods of maximal effort in the middle.
The study participants used stationary bikes for their workouts, which is sensible since they are stable pieces of equipment, making it a safe way to push yourself to maximal effort. You could use a different form of exercise, which I’ll touch on in a moment. But, if you’d like to follow the protocol used in the study, here is what to do:
REHIT Protocol
Start with a 3-minute warm-up at low intensity. The study defined this as 60 watts on an exercise bike. To give you an idea of what that means, according to Stages Cycling, “a beginner cyclist may average around 75-100 watts in a 1-hour workout.” So, 60 watts is pretty mild.
After the warm-up, move right into an all-out sprint for 20 seconds, giving it your maximum effort.
Return to the low-intensity level for a 3-minute and 20-second recovery period, then move right back into an all-out, 20-second sprint before returning to low-intensity for a 3-minute cool down.
And that is it. Do that three times a week for a total of 30 minutes of exercise.

Study participants repeated the 10-minute routine three times/week for six weeks.
REHIT Details (aka The Fine Print)
Let’s tie up a few loose ends and answer a few questions so you can successfully use REHIT.
Maximum Effort Required
There are only 40 total seconds of ‘all-out’ effort in a REHIT workout. But, it does have to be your maximal effort to get the benefits, and the reason why comes back to our discussion on mobilizing glycogen stores in the muscles.
The study noted earlier shared findings from traditional HIIT workout research. HIIT workouts ask participants to work at about 80% of their max effort for repeated 30-second intervals. They found that the breakdown of glycogen is only activated during the first 15 seconds of the intense interval and is notably lessened during the final 15 seconds.
The study went on to say that activation of glycogen breakdown is inhibited in subsequent repeated sprints.
In other words, this suggests that a 20-minute HIIT workout with multiple high-intensity intervals may be unnecessarily strenuous, at least when it comes to mobilizing glycogen, because that can be completed with 1 or 2 short maximum-intensity intervals.
Is HIIT A Bad Thing?
Does this mean HIIT workouts and steady-state aerobic exercises are useless? Absolutely not. The best exercise for you is the one you will do, and variety is good for overall physical and metabolic fitness.
I still do HIIT workouts, go for walks, and lift weights, and I have folded REHIT workouts into my weekly routine, especially when time is a factor, which is a top benefit of this 10-minute workout.
Equipment
Many of the studies on REHIT use stationary bikes, which, again, is a good choice because you are going all-out for 20 seconds. Trying to do that on a treadmill is not as stable, so just be sure you are comfortable sprinting on a treadmill or choose a more stable piece of equipment, like a rowing machine, where you are better supported.
When Not to Do REHIT
Also, be smart. Twenty seconds is not long, but it will tax your heart. If your heart is not healthy, don’t do this. Also, if you have been sedentary, work up to 20 seconds of max effort. The study participants did this. Their first workout included just one 10-second sprint. They then moved up to 15-second sprints for the next couple of weeks before performing the 20-second sprints.

Takeaway
Just 30 minutes of reduced-exertion high-intensity training weekly can improve your aerobic capacity and metabolic health, even if you are currently sedentary.
Thank you for reading and have a wonderful week!
Reference:
(1) Metcalfe, Richard S., et al. “Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training.” European journal of applied physiology 112.7 (2012): 2767-2775.
About the Author
Becky Gillaspy, DC, is the author of The Intermittent Fasting Guide and Cookbook and Zero Sugar / One Month. She graduated Summa Cum Laude with research honors from Palmer College of Chiropractic in 1991.