HIIT (high intensity interval training) is a great form of cardio as it can burn a ton of calories in a short time.
Some of the most common questions I get regardig cardio is “when should I do HIIT?” and “Is it better to do my HIIT session before or after my weight lifting session?” Well, this is something I’ve wondered myself, so I decided to put my nose to the grindstone to find the answer to these questions.
Here’s what I came up with:
Should I do HIIT after weight training? Yes, if you’re doing HIIT it’s recommended to place it after your weight training session. For optimal results you should do HIIT appart from your weight lifting session entirely. The best time for HIIT seems to be at least 6 hours after your weight lifting session, but preferably placed on another day completely.
I think that people get very uncertain about cardio since there’s so much noice out there. Some say do this, others say do that.
In this post I want to sort it out straight. I’ll do so by cover why it’s recommended that you place your HIIT cardio appart from your lifting, why HIIT is beneficical and how to perform HIIT.
What is HIIT?
First of all, let’s nail the definition of HIIT.
HIIT stands for High Intensity Interval Training and is a form of cardio where you’re doing quick bursts (intervals) of work accompanied with rest in between. This rest can be active or passive.
HIIT cardio raises your heart rate a lot during the intervals and then reduces it slightly during the rest. This leads to quick gains in cardiovascular fitness and some types of HIIT also has the potential to build muscle since it’s highly anaerobic.
A potential drawback of HIIT is that it requires a lot of recovery once you’re done, especially when compared to the counterpart low intenisty cardio.
The Benefits of HIIT
A lot of people looking to build an aesthetic looking lean and muscular physique skip the cardio, either because it’s hard and tough or out of the fear that it might impact gains negatively.
But, even though it’s tough, when HIIT is done right it’s very beneficial while it might actually be positive to your strength and muscle gains.
Here’s a list of the benefits:
1. HIIT can burn a lot of calories in a short time
Researchers have seen that HIIT burns 25-30% more calories than other forms of exercise for each time unit.
2. Keeps your fat burning processes on
HIIT helps keep your fat oxidation ready. This is great both if your goal is to cut down to a low body fat percentage, but also when bulking to build muscle.
By keeping your fat burning process on while bulking more of your surplus calories will go towards muscle repair and recovery instead of body fat. Furthermore, you’ll have a n easier time transition into a cutting phase if you have your fat burning processes is active and ready.
3. HIIT can lead to muscle gain
In addition to helping with fat loss, HIIT can also help increase muscle growth in certain individuals.
The individuals who can build more muscle with HIIT are mostly beginners who’ve just started lifting. For more advanced lifters it doesn’t seem that HIIT leads to increased muscle growth.
Weight training is still the “golden standard” when it comes to building muscle, but HIIT can still support small amounts of muscle growth.
4. HIIT improves cardiovascular health
It improves the flow of oxygen throughout your body, lower your blood pressure and cholesterol, and reduce your risk for heart disease, diabetes, Alzheimer’s disease, stroke, and some kinds of cancer.
5. HIIT will make you feel more energized
This is something I think is connected to the health aspect of doing cardio.
In the beginning of my fitness journey I didn’t do any cardio. All I did was watching my diet and strength trained. Even though this approach worked, as you can see in my transformation video, one thing I learned recently was that I lacked a lot of daily energy back then.
Here’s how I learned that:
When I began PT school a few months ago, I started doing cardio twice per week with my class. And this had me feel so much more energized.
I feel more productive and alert during the days, and best of all my sleep quality went up immensely. This is a very positive benefit, since sleep is one of the most important factors when it comes to maximizing muscle growth.
So, as you can see, there’s a lot of benefits of implementing HIIT training in your regimen. With that said though, if you want to see great results on your physique it’s important that you set your training up correctly:
Why You Should Ideally Spread Out Your Weight Lifting & HIIT Sessions
Doing strength training and cardio in the same session seems to be suboptimal for gains.
This was shown in a study by Robineau et al where they looked at whether sprinting after full body intense workouts with a recovery time of 0, 6, or 24 hours between strength and HIIT sequences influences the responses to a combined training program.
The group doing their sprint intervals directly after strength training gained less strength than the other three groups, but there were no differences in strength gains between the strength-only group and the two groups resting at least six hours between their strength training and their sprint intervals.
So, resting at least 6 hours between sessions seems to be optimal for strength adaptations if doing combined resistance and HIIT training on the same day.
Also, a recent meta-analysis from 2017 by Murlasits et al showed that, if you need to do cardio on the same day, then doing it after lifting is better for strength improvements compared to doing it before.
Use Low Impact Cardio Types
The type of endurance training that are being used seems to significantly affect the magnitude of gains in strength and muscle mass.
A meta-analysis of 21 studies done by Wilson et al showed that resistance training concurrently with running, but not cycling, resulted in significant decrements in both hypertrophy and strength.
This seems to be because running is much more disruptive of the muscular system with a movement that is also very nonspecific to strength training.
During running there’s such a large eccentric portion, where every step causes eccentric shocks that are known to cause a lot of muscle damage. With running the stress on the legs would simply be too large, making recovery harder, which would ultimately result in decreased strength training performance and muscle mass.
While contrarily, cycling has nearly no eccentric portion at all, meaning less total stress, while it is also more similar to a squat or leg press movement.
This means that cycling done in combination with resistance training adds just enough training volume so that the body can still recover, while also doing so through a longer range of motion that is very specific to squatting or leg pressing.
What’s also worth mentioning is that, if for some reason you are not seeking to add a lot of muscle mass to your legs, but seeking to really build your upper body, then running might still be a viable option, since it mainly stresses your legs.
However, this would only be viable as long as the total amount of volume from doing running in combination with upper body training don’t get too high so that you can’t recover on a full body systemic level.
So, in summary. To get the best results possible spread out your strength and HIIT sessions by at least 6 hours. And focus your energy on low impact cardio modalities such as cycling, rowing and swimming. Try to avoid running since it’s very taxing to your legs, unless you don’t care about leg size, then it doesn’t matter that much.
How to Perform HIIT
What you can see below is my HIIT cardio recommendations that I first discussed in this post.
Instead of doing HIIT routines like the one above, you could play sports 1-2 times per week on rest days for 20-30 minutes. Sports usually involve short periods of high intensity efforts with periods of walking or resting, so it’s very similar to HIIT.
A great benefit of playing sports is that they’re typically more enjoyable than normal “cardio” because you do something that’s not as repetitive, and you can have fun playing with your friends or a team in the meanwhile.
Is it OK to do HIIT every day? This depends a lot on your goals, training experience and recovery capacity. If your goal is to build the most amount of muscle that you can, then doing HIIT every day will be negative to your strength training recovery, which will then reduce your gains a bit. But if you’ve been training for a long time and can recover well, then you might be able to train HIIT every day.
If you’re in your beginner to intermediate stages I recommend that you stick to 2-3 HIIT sessions per week tops, placed separately from your lifting, as this will lead to the best gains in strength and muscle mass. From there you can slowly increase your HIIT sessions if you want to do more of them.
Does HIIT burn belly fat? Burning body fat is all about being in a calorie deficit. With that said though, HIIT can still help you burn more calories and hence that help you burn of your belly fat.
But you still need to control that you’re actually in a calorie deficit over time. Otherwise you might start to compensate for the calories burned when doing cardio by eating more, which is very common.
Now, one interesting benefit of HIIT is that once you’ve become fairly lean, around 10-12% body fat where your abs are starting to show, HIIT can help you burn off the last stubborn fat, usually placed over lower abs and hips.
HIIT effectively ramps up fat burning hormones such as adrenaline, noradrenaline, cortisol and growth hormone that activate an enzyme named Lipase.
Simply speaking, this enzyme enters your fat cells and effectively “pull out” your stored body fat and turn it into free fatty acids now circulating in your blood stream. These FFA are ready to be used as energy by the body throughout the day.