<<Was that actually proven? If that is true, why HGH is still popular for many professional athletes?>>
Well, there's this from the same article:
"The research, which used volunteers who had engaged in regular athletic training for at least a year, used lower doses of growth hormone than athletes are reported to use, and for a shorter time.
"We can speculate, therefore, that the drug's effects on performance might be greater than shown in this study, and its side effects might be more serious," says Ho."