I would like some explanations about the HIIT training....
It's not familiar to me....
If u can help me by explaining what it is....
I would be grateful...

HIIT. High Intensity Interval Training. You'll find a ton of stuff about it if you do a search eith on this site or on Google.

Here's just one article that I found: http://www.youronlinefitness.com/Fitness_Articles/articles/January_2003_articles/hiit_and_other_interval_training.htm

It basically sucks royally for pure lipolysis and fat loss only with lean mass preservation. Far too intense.....

~SC~