When you look at at a treadmill in the gym you probably see machinery. And it is just that a machine.
Machines need to have commands to control them and then they will respond. As you enter these commands into the machine so does your brain equally anticipate the responding output required to meet the stresses placed upon the body and makes hundreds of thousands of calculations in anticipation of the forthcoming stress.
For instance increasing the speed will make your heart beat faster as opposed to just say walking. Now increase speed the and increase the incline. Your heart rate will increase even more and your brain will engage the calculation of what output it is going through and by second nature you will increase to a small jog.
As that speed increases your brain is constantly reading the panel in terms of a safe speed which you now you can hold for a set distance. Run too fast and you will slow down eventually as you know you not maintain that speed consistently. Especially if you don’t know the distance you have to complete.
But if you know the distance you will running its very hard for you to engage the correct demands and what stresses and calculations the brain will need to complete the distance before fatigue and VO2 limitation prevent you from taking another step.
Being able to read the calculation correctly in your head will enable you too perform better.
That is why WGC believe in running no more than 400 m at 10% incline (Intermediate) and 600 m 10 % Incline Advanced.
This is no different then 2000 m set distance for say rowing. Or the 400 m running track
10 % incline running set at 400 m and 600 m is a set distance that to perform to maximum output will take years of training to perfect.
That is not to say they are the only distance to run on a treadmill, but they are the most common targets to achieve in Gym Based Circuits.
The set distances can be trained for at any level and will give you more focus and determination
All you have to do is increase your speed to a level that you can complete either 400 m or 600 m at 10 % incline during a set circuit, its not running - its heart rate control.