Sunday, 17 June 2012

Cardio that works

I see a lot of people running about, well more jogging really, especially since the weather is starting to get warmer, and summer is getting closer.
But what are the effects of the slow paced running, with low intensity, and does it really help, if you want to lose weight ?

First off. Long Slow Distance running (LSD), with an intensity around low to moderate, is good if you want to build up stamina, so you can continue to run for a long time. I'd say that's pretty important if you are training for Marathons or other long races.

But what is low to moderate intensity ?
Low intensity is said to be around 50-80% of your Heart-Rate (HR) Max, or average around 65% of HRmax.
Moderate is between 70-90%, or average around 80%, of your HRmax.
To find your HRmax there are 3 ways of finding it.
  1. You can do a full-out MAX test, where you push yourself to the limit (hardest one to do). Also requires an HR monitor.
  2. Make an estimate using your age. 208 - 0.7 x age
  3. The easiest way to make an estimate, also by using your age: 220 - age
Now that's all sorted, let me tell you about the effects of LSD cardio. Because it's actually not that effective again, compared to what this post is really about :)

There are 2 types of effects, the Central effects, which refers to the heart and lungs, and the Peripheral effects, which is everything else.
Doing low to moderate intensity cardio, like LSD, primarily effects the peripheral system, with minimal effects on the central system.
The list is long, but I'll try and make it short and to the point.
  • The size and number of mitochondria is increased, as well as the amount of mitochondria near the edge of the muscles.
  • The number of capillaries pr. muscle fibre is increased.
  • This makes the diffusion distance (transport distance) shorter for the oxygen in the bloodstream to the muscles.
  • Your insulin sensitivity increases.
  • The blood flow is increased to the working muscles.
  • The fat absorption from the blood is increased.
  • Consumption of fat is increased and consumption of glycogen is decreased while working for a long period of time
  • Production of lactic acids are decreased at sub-maximal work.
So, from what we can see here, doing low to moderate intens cardio does actually burn fat, and there are some effects we can use.

But, if you really want to lose some weight and burn some fat, I wouldn't recommend doing this kind of cardio.

I would recommend doing HIIT, or High Intensity Interval Training.
So HIIT is interval training with high intensity, hence the name.
High intensity is between 80-100% of your HRmax, or average around 90%.

Doing HIIT doesn't require as much time as low/moderate intensity training, since you don't need to spend 45 minutes to burn as many calories, as you would by doing 45 minutes of low/moderate intensity.
By just doing 15-20 minutes of HIIT you can burn just as many calories, if not more, due to the Afterburn-effect.

As mentioned above, low to moderate intensity cardio primarily effects the peripheral system, where as high intensity interval training effects the central system.
I'll try and sum up the long list of central effects just as I did with the peripheral effects.
  • Respiration:
    • Oxygen transport from lungs to blood-stream at maximal work is increased.
    • Respiration-muscles endurance and strength is increased.
    • Ventilation is unchanged, perhaps decreased, at sub-maximal work.
    • Ventilation increased at maximal work.
  • Amount of blood per beat is increased during rest, sub-maximal work, and maximal work.
  • Heart-rate:
    • Decreased during rest and at sub-maximal work.
    • Unchanged, perhaps decreased, at maximal work.
  • Oxygen uptake:
    • Unchanged during rest.
    • Unchanged, perhaps decreased, during sub-maximal work.
    • Increased during maximal work.
Those were just a few of them, but the most important ones, I'd say.

So, how do you do HIIT, well here's an example of what I do:
  • I started with a 2400m run, to see how fast I was able to run it (about 9:30-10min). Then I looked at the time it took me to run 400 meters (about 1:31-1:36 min (base pace)).
  • You would then make a program looking, starting out with 4 intervals of 400m running, with a pace about 4 seconds faster than your base pace.
  • The recovery period should be about 2-2.5 times your work period, meaning I would need 3-4 minutes rest, between each High Intensity Interval.
  • As you get more used to the HIIT, build up the intervals until you reach 10 intervals. When you've reached 10 intervals, you can start working on your pace some more, running a bit faster.
So, in my opinion you get better results doing HIIT than low to moderate intensity cardio.
  • It's less time consuming.
  • It burns more calories / fat.
  • It increases your overall physical condition.

You can of course do this using a bicycle / stationary bike, or something else where you use big muscle-groups.

Hope you enjoyed the read, and please comment below what you thought of it,

Bangsbo J. Michalsik L. Aerob og Anaerob træning, Danmarks Idræts-Forbund; 2002