Cardio - cardi-yo or cardi-no

In the New Year the gyms are full of people pounding on the treadmills, the cross trainers and the bikes. Same old story! In some gyms people are queuing up, waiting for the machines! There goal. to burn fat! But are they making the best choice? Can their choice actually be causing them to store fat in the long run?

There has been a lot of bad press about cardio, with a lot of extremist views! Never do cardio, it will make you 'skinny fat' a term meaning a smaller version of your fat self. Or the other side of the argument, cardio is the best for fat burning! The truth, it's somewhere in the middle! Let me explain.....

I have always been fit, but never been extremely muscular, and part of the reason for this was the amount of sport I played. Football 2-3 times a week kept me fit, kept the fat off but also stopped me putting on muscle. When i stopped playing football in my lat year of university, my weight and fat levels rocketed! For the first time in my life I was overweight and too fat! Considering only 3 years before this i was a very small 9 1/2 stones, it was a dramatic turn around. Cardio from the football obviously had something to do with keeping the fat off. I made a decision to get back playing and the fat dropped off.

Fast forward 6 years and i decided to run the London Marathon. At this point I was training regularly, and was very happy with how i looked. So off i embarked on the gruelling training schedule. It was all worth it in the end when i ran 3:29! I was aiming for 3:15 but had double hamstring cramp from 21 miles (about an hour of excruciating pain, it was by far the hottest day of the year and lots of runners struggled, not recommended!). BUT the training I had done over the last few months had made my muscle pretty much disappear, as well as all my fat. Not as much as some memes will have you believe (see >>>>) but i was definitely skinnier! Which threw up a huge question for me, why did the cardio from football preserve my muscle, but the cardio from running didn't?

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Not all cardio is equal!

From my experiences in football and the Marathon, I had inadvertently discovered the huge difference between continuous and interval training (you may have heard these called steady state and HIIT - High Intensity Interval Training). You see football involves periods of sprinting, jogging and resting - that is interval training in a nutshell. My marathon training on the whole involved running a one pace for miles and miles. These two types of cardio have different effects on the body, and it all comes down to our hormones!

Hormones are chemical messengers sent out by the body to control different processes. Our body likes to be in a constant state, known as homeostasis. It doesn't want to be too hot or too cold, blood sugar must be at the right level, similarly our fat levels shouldn't be too high or low either. We have two main groups of hormones that control body composition, namely anabolic (build muscle) catabolic (break down muscle, which then can lead to fat gain)

The major player in the catabolic game is cortisol! You have heard me mention this before, normally in a bad light, so let me defend cortisol a little. Cortisol is released during periods of stress and uses muscle as an immediate source of energy. This is vital as in the past, when a lion fancied a bit of human as a snack, we would need that energy to run away or be eaten. It is linked heavily to our 'fight or flight response'. Cortisol also peaks in the morning when the sun rises to wake us up! You don't want to be asleep when that lion comes calling! And finally, during periods of starvation (such as the winter famine our ancestors experienced) it uses the muscles to get the essential nutrients for us to survive!

Fast forward to now and we no longer have the famine or the lion, but we have a heap of other stresses to contend with; work, home life, lack of sleep, our diets, money and sadly exercise! Yep, exercise is a stress to our bodies, particularly when that short sprint escaping form the lion turns into a long run! Let's get geeky and look at a graph of what happens during prolonged cardio.

If we look at the graph on the left, the blue line shows cortisol. For 15 minutes there is no change, but between 15 and 30 minutes the levels of cortisol goes up by 150%. It stays elevated until approximately 90 minutes. This means that between 15 and 90 minutes, for 75 minutes, your body is using your muscle as a fuel rather than fat!

Now hands up who spends between 15 and 90 minutes in the gym doing cardio to burn fat and is struggling to achieve results! It all comes down to cortisol!

And here's the twist of the knife, it's your muscle that burns fat! Having less muscle inhibits your ability to burn fat! This explains what many people experience when doing cardio, they lose weight but after a few weeks the results stop. The weight they initially lost is a combination of some fat but 20-50% of muscle too!

The good things is though if you run past 90 minutes, you do go into rapid fat burning! This is what I experienced on the Marathon training, i lost a lot of muscle and then a lot of fat as my runs got longer.

However I know not all of you have more than 90 minutes each exercise so what can you do?

Yes! Interval training for most people is excellent at burning fat! HIIT training is characterised by a period of intense exercise followed by a period of rest or recovery at a lower intensity. There are many protocols you could follow for this, and one I will give you below!
But I want to draw your attention to the graph above again, this time on the right hand side!

The black line shows growth hormone, an extremely potent fat burner and muscle builder! This is only release in traditional cardio at around 45minutes. With HIIT training you can experience an increase in Growth Hormone of 200% and above after only 10 minutes of exercise! And not only that the increase in Cortisol is a lot lower too!

Just to repeat that, HIIT training gives you an increase in fat burning hormones, stops the release of too much fat storing hormones and saves you time! Now that sounds like a winning workout!

However, it does require a lot of effort (if only for a short time!) It isn't recommended for those with heart conditions or an absolute beginner to exercise. The words 'High Intensity' are vital for success! You'll know HIIT is working if you experience breathlessness, burning in the muscles, and you sweat!

The is another benefit to HIIT. As well as the release of Growth Hormone, the body takes longer to recover from the intense exercise, this is called the afterburn effect. And for up to 2 days after you will burn fat at a faster rate! That means that even if you can't exercise as regularly as you would like, you are STILL getting benefits in the days following a HIIT session!

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Is there a better form of cardio to help me lose fat?

This is why I experienced better results in football, notably on the maintenance of muscle levels, I was effectively doing HIIT! I burned fat but kept my muscle which meant my results were sustained

So should I never Do cardio?

No not at all! 

Being on a extremely low calorie diet can cause rapid muscle loss, but research shows that if you exercise as well, you mitigate some of the muscle loss. It must be said that neither the low calorie only approach or low calorie plus exercise approach is effective in the long run for sustained fat loss!

Cardio training is also the BEST training for one muscle imparticular! THE HEART! Often overlooked by the "cardio is bad" group, doing aerobic long duration exercise keeps your heart healthy! And let's face it, if your heart packs up you've had it! 

And there is one more huge positive for cardio! The effect on mental health! Cardio again has been proven to help keep you happy! Endorphins are released during cardio such as serotonin, making you feel happy! 

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Want to try HIIT?

If you have been exercising for at least for weeks and have no heart conditions, then you should be ok to try the following:

Choose a cardio exercise, running, cycling, swimming, rowing

Go at a steady pace for 5 minutes to warm up

Then go as fast as you can for 20 seconds, before slowing right down to fully recover.
Next go as fast as you can for 40 seconds, before slowing right down to fully recover.
Next go as fast as you can for 60 seconds, before slowing right down to fully recover.

Repeat the above sequence for 20 minutes.


The great thing about this format is you get to choose your rest time. Rest enough to allow you to complete the next interval at a high intensity.


Doing the above 3 times a week could be enough to kick start your fat burning again!