It's 8am. I'm shirtless in an alleyway. 2 angry dogs are chasing me.

Sounds weird. but living in Thailand this happens on a daily basis. 5km run before morning training.

There are (or were) a lot of strays in certain parts of Thailand, who'd sit there waiting for a chase to happen every morning. Too bad, you still had to run. No ifs,' no buts, no questions.

I've not been shy about badmouthing running before (look out for the article on that one).

But the underlying idea is right here

For the past 20 or so years, there has been an obsession with high intensity training. There are entire gyms dedicated to high intensity cardio (they generally don't do it properly, but we'll save that for yet another article).

Fighting is a very intense sport, So naturally, we think high intensity sport = high intensity cardio. There's truth to that, but it's not the only thing you need. And more and more often it's over emphasised to the detriment of having well rounded conditioning.

For optimal conditioning we need more than just high intensity work. We need a strong low-intensity aerobic system too.

Here's 3 reasons why:

Your Aerobic System Is Your Backup (And More)

Your body uses different energy systems for different levels of intensity. The explosive, impressive, cool relies primarily on the high intensity systems. But the problem is they burn out fast. And they use a huge amount of energy while doing it.

Your low intensity (aerobic) system can't produce the same level of power, but it can run waay longer. The longer your fight goes, the more important it becomes.

This isn't just the system you fall back on either, it's the system responsible for refuelling the high intensity ones. When our high intensity systems inevitably burn out, they depend on our aerobic system to give them the space and resources the recharge and go again.

Fighting Isn't Just High Intensity

In studies like this one, a series of amateur MMA fights were time-motion analysed to find the amount of time spent in high vs low-intensity effort. They found that the ratio of high intensity to low intesity work was generally between 1:2 and 1:4. So for every 10 seconds of high intensity work in a fight, you can expect 20 to 40 seconds of low intensity work.

This should ring true if you've seen a lot of MMA fights. generally it's only panicky first time fighters who come out relentlessly swinging only to inevitably burn out. High level fights are generally characterised by short blasts of high intensity exchanges, with longer periods of footwork, movement and distance control in between.

The principle of specificity dictates that our training should match the demands of the sport. So if 65-80% of our time competing is spent at low intensity, it makes sense to optimise for that.

o by doing long, mid to low intensity steady state cardio, we build up that reserve. There's multiple ways to improve it - you can build up its power (so it can handle some more intense work) or its capacity (so it lasts longer).

Low & High Intensity Cardio Do Different Things

A standard question here is

"but can't I just train at a higher intensity and improve my cardio all round?"

It would save us a lot of time if we could. HIIT gyms will tell you you can. But unfortunately, it doesn't work that way.

Low intensity training causes the left ventricle in your heart to pump a large volume of blood. Doing this repeatedly with regular training causes the ventricle walls to stretch and get larger, like a balloon filling with water. Over time this results in a larger left ventricle, capable of pumping more blood with each heartbeat.

High intensity training causes its own different adaptation - it makes the ventricle walls thicker and stronger. But past a heart rate of around 150 BPM, the heart is pumping too fast for the left ventricle to ever be completely full. Because of this, high intensity work can never give you the same adaptation low intensity can.

Using Low Intensity

The general message here is that your conditioning should involve both high and low intensity work if you want the be the most complete, capable fighter you can be.

There is some wisdom in traditional road work for this very reason. Is it the best way to do it? No. But we'll save that for another article.