Does fin affect athletic performance negatively, positively, or at all?

The World Health Organization’s Adverse Drug Reaction Database contained 508 reports of serious muscle-related side effects suspected of being linked to the use of finasteride, mostly atrophy, weakness, myalgia and sudden, strong muscle tightening (spasms).

Results newly reported in JAMA show that the muscle mass of men is not affected by inhibition of 5 alpha-reductase, the enzyme that produces the androgen 5 alpha-dihydrotestosterone (DHT) from testosterone