I would think absorption rate of an intramuscular injeciton could also be influenced by how much that muscle is worked as well. Just is just theory, but all gear should be injected into muscle (not fat), if you are hittting fat only, then pin your quad. I happen to think if you hit your quad, then work you quads hard, the injection will become dispersed quicker into your body. I only pin my quads because it is easier for me to aspirate properly. If I do not work legs, I might be sore for a day or two sometimes. If I work legs, then I get no soreness at all because I am sure the fluid is getting dispersed better. Plus, the obvious notion that working a muscle increases blood flow and circulation to that area. Anyway, just a thought. I would make an assumption that pinning a seldom worked muscle group might inadvertantly lengthen the job of the esther. Good luck finding one. Calves? lol