This is a pretty well talked about topic,and I believe it was even brought up here about a month ago ,,so I did a little digging and ,,,(do site injects induce muscle growth ) and I would say no ,,they dont,, I believe you get a tempory swell from the oil reservior ,sat in the muscle facia whenn pinning ceases,but then the oil will disappates. And if you think about this logically most of us at least with our long esters we pin glutes and vertros and if the case was muscle growth ,,we would need a wagon or someone ,behind us just carrying our fat asses really bottom line is aas (hormones ) work on long range neuro transmitters I believe case closed ,,,what's your take