The age of the treadmill is over, long live HIIT

Aerobic exercise sucks, it's a fact masquerading as an opinion. On the other hand, being able to burn off your rivals in sport and generally having a great level of aerobic fitness is a very attractive proposition. If only there was a way in which you could get the aerobic fitness without doing the long and slow aerobic exercise? Well, there is and I promise you you'll never look back. It's called High Intensity Interval Training (HIIT). 

First a quick biochemistry lesson:

As the crudely drawn out diagram shows, aerobic metabolism (exercise performed where there is enough oxygen) is a very simple process. Glucose (sugar) enters the cell and get's converted into a product called pyruvate. Each conversion only produces a small amount of energy and requires no oxygen. However, its turnover speed is unregulated and so it can potentially produce lots of energy very quickly if the turnover demand is high. 

Afterwards the new pyruvate molecules go into the mitochondria and then through a slower process get broken down releasing lots of energy, but oxygen is necessary. 

The difference between these two processes is why you can sprint very fast for a short period of time (anaerobic) or run more slowly for a long period of time (aerobic). 

Aerobic exercise works by performing exercise at a low enough intensity so the aerobic section doesn't get overwhelmed by the anaerobic section. 

With me so far? Time to mix things up and introduce some high intensity stuff. 

The crude diagram above is what your cell looks like when you are performing exercise as hard as you can. The cell is screaming for energy and so glucose conversion gets sped up hugely. The anaerobic process produces a massive amount of energy in a very short period of time. Unfortunately, as anyone who has performed HIIT will report, there are consequences. 

The anaerobic system is producing pyruvate faster than the aerobic system can break it down, as the aerobic system is running at maximum capacity. Thankfully there is a way out,  when the aerobic system runs maximally it stimulates the pyruvate to be converted into lactate, soon to be called lactic acid; and this is why HIIT is so great. 

The lactic acid which accumulates in your muscles is dangerous, potentially damaging the functioning of the muscle and so needs to be eliminated as quickly as possible. So in an effort to clear it the liver takes on the role of lactic acid clearance. 

When multiple sets of HIIT are performed a backlog of lactate in the liver develops. This is because the muscles are cleared and ready to go again before the liver has finished the conversion. Every set you perform creates more lactate for the liver to deal with. 

This is exactly what you want because once it's in the liver it can't hurt you any more. Finally the best news of all is that converting lactate back into useful glucose requires a great deal of energy most of which comes from fat. 

Here's a quick run down of the benefits, HIIT:

1. shouldn't take much more than 5 minutes total
2. Is comparable (or better) to a much longer time on a treadmill
3. Creates an afterburn of energy long after you have finished
4. improves aerobic fitness by maximally stimulating the mitochodria
5. Improves anaerobic threshold
6. Improves insulin resistance, which can help lose fat

There is however one condition to all these great benefits, it has to be performed at 100% intensity. If it is not done in this manner then it will not have the same effects as there will not be a significant enough difference in the energy system activity. All that is happening is you are performing a small amount of sub-maximal exercise, which means you should have stuck to the treadmill. 

A great way to perform HIIT is with battle ropes. 

The way to know that you're giving enough should be apparent, after a few seconds you should be at peak power output, from then on the amount of noise you can make should decrease in a linear fashion (As you can see on crudely drawn diagram number three). 



If by the end of the set you are still producing the same amount of noise as you were 15 seconds ago, you know that you weren't going hard enough to begin with. By the end of your 30 seconds you should be struggling, but that's fine because all that matters is that you are at the limit of your capability for 30 seconds. It takes time to really appreciate how far you can push yourself, but when it comes, you'll reap the rewards. 

So if you are a client of mine and I'm shouting at you to 'Give 100%', you'll know that it's not just sadistic pleasure, I'm also looking out for you and your results.