Hi, I’m new as well.. Thanks for the great explanation, I find it very helpful. Especially when I try the exercises, I wasn’t sure whether I should contract as hard as possible or not. My question is, when you hold a contraction for several seconds, after a good amount of contractions, should your muscle start to tire? Sometimes I feel when I’m holding it, my BC muscle starts to shake, almost like I’m struggling with a repetition in the gym, to hold it. Any thoughts? Thanks!