4x4 Intervals

4x4 intervals are also a high intensity interval program it means that you have 4 periods that each last for 4 minutes and then you have 3 minutes rest or just low intensity. And of course warm-up first and cool down in the end  a 4x4 interval training usually takes about 30-45 minutes depending on how long time you use on warm-up and cool down phase. But its well worth it, the results are good.

 Your puls in the intensity phases should be from 85-95% of you max pulse wich means its a anaerobe training and it boosts your Vo2 intake.  And that is what your goal should be.