Need help with 4x4

[frysebox]

There isn't any cardio subforum here, so I guess this is the best place to post.

My primary goal is boosting up my cardiovascular system for a physical test in school. I've never really done any cardio so far in my life, but it's not that bad considering that.

I need some clarification on the 4x4 system. As far as I understand, you're supposed to run/sprint for 1 min, then lightly jog for 3, then run again for 1 min etc. repeating 4 times. Is this correct?

From what I've read you're supposed to hit 80-90% of your pulse during that 1 minute. Isn't that awfully lot for one whole minute? Is a pulse counter needed, or can you just run on the "feel" and use a regular stopwatch?

[osoeraa]

4x4

Warmup 6-8 minutes
4 minutes run between 85% and 95% of max pulse.
3 minutes jog, not under 70% of max pulse.

repeat four times, but offcourse skip the warmup the next three times.

To get the most out of the session you need a pulse counter, because most tend to run to hard, and therefore ruin the whole point of 4x4.

And it aint no problem, i do this three times a week(with a pulse counter) with no problem.

PS: Sorry for bad english...