HIIT training or High Intensity Interval Training is dominating the mainstream media this January as a fix all to lose body fat for time poor individuals.
While training with intensity is a useful thing to do, to say it is the most effective way of training is a bit misleading- especially when you are looking to change your body composition.
HIIT in itself can fit nicely in to short bite size chunks this message of simplicity first is one that personally I like- it’s often better to do something rather than nothing. For people though who train regularly I want to investigate whether this is an efficient and effective way to train and if instagramable routines are the future.
Bring On The Science
Here’s the science bit…. When training there are three main energy systems we are challenging:
1. ATP-CP also termed Alactic System.
This systems provides immediate energy for about 10 seconds at maximal output.
2. Glycolytic also termed Anaerobic System.
This system provides a bridge between the ATP-CP system and the long term aerobic system. After 10 seconds of maximal effort this energy system kicks in. The primary fuel here is stored carbohydrates. At full tilt this system has about 2 minutes of work before lactic acid build up and other factors compromise performance.
3. Oxidative also termed Aerobic System.
This system is the default energy system of the body at rest and during recovery. It provides long term lower intensity energy. The aerobic system plays a role in all work and it’s role starts to build after 30 seconds of activity. Therefore a strong aerobic system maintains a strong power output for longer.
Why is this important?
Your training programme will challenge all of these energy systems but which ones you challenge is important for how you adapt and develop your fitness.
Training on a typical HIIT programme will work the ATP-CP system initially and then if your interval is sub 2 minutes the anaerobic system, after this the aerobic system kicks in to gear taking all the load (if you are going full tilt).
Most interval training proposes an interval of 30-60 seconds with a parallel recovery. In most routines I have watched the intensity level being worked at is no where near maximal (this is okay in certain situations and I’ll explain why in a bit). In this situation the perception is that the glycolytic system is being challenged but what is mainly taking the work load is the aerobic system.
The aerobic system will maintain work at sub-maximal workloads. This is okay if we are looking to develop a base level of fitness. This is why beginners see decent results from this type of training for about 6 weeks before their conditioning plateaus off as they adapt.
Most of these programmes tend to ignore one of the most important component of a workout… recovery.
Recover to Go Harder.
Basically, if recovery is inefficient you are not challenging the energy system you set out to train and all work becomes predominantly aerobic recovery.
Working out at high intensity is hard work- the longer you work without recovery then the lower the intensity. What we are trying to do is increase the amount of work done in a given time in order to facilitate all those cool adaptations in the body that mean your fitness is enhanced.
What Not To Do.
So how do we guarantee a result?
Unfortunately if you want to burn a lot of fat or get super fit one block of burpees for 4 minutes won’t cut it unless you are dieting yourself in to a hole. This January has seen the publication of the 1 minute workout (seriously)…. With the need for quicker fixes all the time it had to happen at some point though.
Truthfully, I can’t deny there may be good markers for health from short term interval work (the science is really patchy in truth) but the returns level out once you become adapted to this type of training.
How Do I Work Out Smart(er)?
What follows is a rough template of workouts I have used for a variety of clients from athletes to those looking to shape up. As the list goes down what you will notice is that the intensity decreases and the recovery time needed increases. As a side note we do not prioritize all energy systems at the same time. Training is about adaptation and specificity so making everything as hard as possible isn’t really working that smart You also need to do enough work at a given intensity to develop certain energy systems- this basically highlights that your one minute workout won’t cut it for energy systems development after 6 weeks. Just to also highlight one thing aerobic work can cause the same positive changes meaning HIIT is no more effective than performing aerobic work if you are a beginner.
1. Aerobic Steady
Emphasis Aerobic output- can be used as recovery from intense sessions.
Duration: 30-60minutes or more
Number of Sessions: 1-3
Description of Exercise: Steady paced cardiovascular exercise or low level weights circuits
Intensity: Steady Pace
2. Aerobic Intervals
Emphasis Improving oxygen utilization of the muscles balancing speed and endurance.
Duration: 1-2 sets of 10-20 minutes.
Recovery: 5-10 minutes
Number of Sessions: 1-2 a week
Description of Exercise: Anything that can be paced rowing, air bike, ski-erg,
Intensity: Pacing is key- this type of session is based on resistance as opposed to speed. Your heart rate should sit at around 150bpm or around 65-80% of max (individuals vary though).
3. Intervaled Recovery
Emphasis: Fast twitch power output and resistance to fatigue increase oxidative recovery.
Duration: 8-15 sets of 2minutes.
Recovery: 1 minute “active” recovery.
Number of Sessions: 1-2 a week.
Description of Exercise: Complexes and Multi-joint lifts such as kettlebell swings twinned with a core or mobility exercise.
Intensity: Again around 150bpm/ 65-80% max with recovery down to sub- 130bpm.
4. Anaerobic Endurance
Emphasis: Power endurance.
Duration: 4- 6 interval sets of 4 to 8 minutes
Recovery: 2-4 minutes of low level recovery
Number of Sessions: 1-2 a week with at least 48 hours recovery between sessions
Description of Exercise: Multi-joint compound movements/ “full body”
Intensity: 90% maximum of your heart rate
5. Max Output
Emphasis: Maximal efforts so working the ATP-PC system. Typically the most risky for injury due to explosive nature
Duration: 10-20 sets of 10-30 seconds.
Recovery: 3-5 minutes of recovery between sets.
Number of Sessions: 1-2 a week with 48-72 hours between workouts.
Description: Generally, works better for task specific drills e.g. sprints, jumps and explosive throws.
Intensity: Maximal effort “explosive” in nature, speed shouldn’t be compromised by fatigue.
You may not perform all of these style of workouts in a week. Indeed this depends on the person you are working with and what you are trying to achieve and what energy systems you are trying to develop. When you consider things like the Tabata protocol and why it has become popular (20 seconds of work followed by 10 seconds rest) is simply is that it is easier to perform that than grinding out 2-4 minutes at 90% of your maximum heart rate for 10 sets.
Does it matter for beginners? Well I guess something is better than nothing. However if you are stressed, tired and with a bad diet maximal sessions may not be beneficial for your health and steady aerobic work may be restorative and invigorating without burying you under more “stress.”
From an anecdotal point of view for a period my average client was the stressed out, time poor client averaging 2 or less hours of activity in a week. These individuals just aren’t in the position to do high intensity work.
A Note On Training For Body Composition.
Which one of these gives me a six pack though?
Well, they are all activity- that is great for creating a calorie deficit. They all will improve physicality so therefore you can work at a higher intensity to burn more calories. As a side note the maximal output has the lowest calorific yield for time spent. The other options will depend on relative intensity maintained as well as duration. Intensity does play a role in fat mobilization so stimulating adrenaline to cause fat breakdown requires intense work so the Intervaled Recovery method and the Anaerobic Endurance method are my favourite. That said the duration you can perform these well will be compromised by your anaerobic fitness (they are mentally the hardest as well).
Time should be spent also developing efficient aerobic pathways highlighting that there is a lot of value in steady state work as it can be performed more frequently for longer so for some individuals it may be more suitable for creating a calorie deficit and can be performed more regularly. This is definitely the case if you are managing fatigue, injuries or in general are a bit out of shape. Developing an efficient and effective aerobic base allows you to do more well in the future which is very important when you are looking to develop a progressive training approach.