Actually nobody knows how low of an E-2 is acceptable or "normal" for males. The E-2 trough has never been studied exclusively, although peak levels have to some extent, in females and males with congenital disease, but obviously cyclist are in a different category altogether! More specifically their high testosterone levels could "counterbalance" the effects of low E-2 in those studies, minimizing their applicability in male cohorts. Nevertheles,
I've evaluated BB and lifters with a E-2 of ZIP, ZERO, ZILTCH "never felt better DOC, I'm all male now", lol! That being said E-2 does have KNOWN effects primarily on lipids and bone metabolism, I believe (no data) it should be kept above 10pg/ml and hover between 10-20pg/ml. Afterall is not like E-2 is the cyclist best friend since it increases SHBG, diminishes LH secretion and decreases steroidogenesis. Moderation mate!