Maybe by training with a higher rep range it gets stimulated more?Just a thought, i don't anything about this.Actually my biceps vains and calf vains have popped out over the last six months. I got a bit leaner, but not spectacular, and size of arms and calfs didn't budge. But i was doing too many reps per set 12-15. So now i will lower the reps to 5-8 and hope that will give me more growth.