Did my friend fluke out?

[Yarg!]

I have friend who decided to start working out just recently. I recommended 5x5 for his biceps and he agreed. So he did 5x5 barbell curls with a weight thats heavy for him and no other bicep excersise. I just recommended it to him because he claims he knows what 5x5 is. Am I wrong or arent you suppose to add pounds to 5x5 every set? And arent you suppose to have 2 other excersise accompanying 5x5 for the target muscle? Well miraculously he added quite a peak to his biceps after just 3 sessions. What gives?

 

[Legion Kreinak2]

You're supposed to add weight every workout session, increasing by five pounds.

The increase he has could simple be a pump.

Three sessions, you say? How frequently does he workout?