they are not going to shrink your muscle or strength as long as you use them responsibly. about which one and the dosage it depends. common that's arimidex 0.5 mg twice a week or aromasin 12.5 mg twice a week. However, this dosage can be too much or not enough. it depends on your E2 levels after you use them and the way you feel. \and in case your estrogen levels are high and your nipples feel/look differently then yeah, you may need some.