The first thing you need to know is what you are trying to accomplish with the workout. You have to have a purpose and specific intentions when designing a HIIT workout.
CLARITY is the key.
If you don’t have CLARITY, then you are like a ship without a skipper: you don’t know where you are going. Without clarity your workouts will be arbitrary and probably not safe for your clients. Therefore, the workouts will lose their effectiveness and enjoyment. When you have CLARITY, then it will be easy for you to design a workout with the right training variables.
When you have clarity and you know what you want to accomplish, you can then start testing different HIIT training variables.
When you design a high intensity interval training program there are five training variables that you should consider:
1. Work duration, both time under tension and repetitions – This training variable will affect how you select other training variables. This selection depends on your intentions or what you are trying to accomplish with the workout.
2. Rest period duration – This selection depends on the work duration and the workout intentions. What is the purpose of the workout—is it to improve your client’s ability to perform maximal efforts repeatedly or to sustain exercise at high intensity?
3. Work intensity – After you select the work-to-rest ratio, you select the intensity level (the two are intricately connected). Another option is to determine work intensity first, and then it will dictate your selection of the other training variables.
4. Intensity during recovery – Are you going to have passive or active recovery?
5. Training volume – Less is more. Volume progression or control is extremely important. If you are in doubt, start with a low training volume and progress slowly.
Alright let’s continue and move on to step 3 – which is the final step. This is not to make it too complicated but to show the reasoning behind the exercise selection.
Why HIIT and HIRT (and HIPT)
We started seeing the trend of people using an intermingling combination of endurance exercises (cycling, running, and battling ropes, for example) and strength training exercises (push-ups, squats, lunges, and TRX rows, for example) in their HIIT workouts.
Is it wrong or less than ideal to combine and intermingle these endurance and resistance exercises in a single HIIT workout?
It depends on your intentions—
Do you want to enhance oxidative capacity and aerobic endurance, or do you want to increases muscle hypertrophy (growth)?
Enhancing oxidative capacity
If increasing endurance capabilities is one of our workout goals, then activating the AMPK pathway is key to achieving it.
Endurance exercises activate AMPK pathway (and also through calorie restriction). AMPK is an energy sensor that is very important for overall health.
AMPK pathway is key to jumpstarting the activation of autophagy, fat burning, and endurance capabilities.
AMKP is a master controller of PGC-1alpha (I apologize for the fancy words).
The activation of PGC-1alpha has been shown to be very important in mitochondria biogenesis.
When the process for producing new mitochondria gets pushed into action, it enhances our endurance capabilities.
If increasing muscle mass is one of our workout goals, then activating the mTOR pathway is key to achieving it.
The mTOR pathway is activated by mechanical stimuli as well as by other means, like growth factors (IGF-1) and nutrients (amino acids for example leucine).
Resistance exercise is great way to create mechanical overload or muscle activation. Research over the last two decades has shown that resistance exercise will increase hypertrophy and muscle strength.
So, to activate the mTOR pathway, which in turn should result in muscle hypertrophy or increases in muscle mass and strength, we should perform resistance exercises exclusively.
Here is why….
the AMPK pathway has an inhibitory effect on mTOR pathway.
Does this mean that we can’t use resistance exercises during HIIT protocols, either exclusively or in combo with endurance exercises?
Of course, we can use resistance exercises during HIIT protocols, but we shouldn’t call it HIIT. Instead, we should call it HIRT or high intensity resistance training.
This will distinguish or make clear what we are trying to accomplish with our workouts and what adaptations we are trying to create.
With HIIT we’re targeting the AMPK pathway to increase endurance and mitochondria biogenesis.
With HIRT we’re targeting the mTOR pathway to increase protein synthesis and hypertrophic response, which translates to increasing participants’ muscle mass and strength.
Now enough with the boring stuff! Check out this amazing workout!
Best regards from Iceland.
By Helgi Gudfinnsson