I've been doing HIIT (freeletics.com) for over a year now and I can confirm that the effects on my body of only a few minutes a day of exercise are far beyond w

I've been doing HIIT (freeletics.com) for over a year now and I can confirm that the effects on my body of only a few minutes a day of exercise are far beyond what I expected. I started as a weak person and in 8 weeks I could do pullups easily. Now I do 50 in less than 3 minutes. It is the most extenuating exercise that I can imagine in just about 8-10 minutes a day, 4 times per week.