Scientific evidence refutes the claim that frequent masturbation decreases testosterone levels in men. Studies measuring hormone levels before and after masturbation show either an increase or no association at all with serum testosterone.
The retrieved literature contains direct evidence regarding masturbation and testosterone levels. Paper [1] is an empirical study directly measuring hormone levels before and after masturbation, finding that testosterone and other steroid levels actually increased rather than decreased. Paper [2] evaluated ejaculation frequency and masturbatory habits in a large cohort and concluded there was no association with serum testosterone levels. None of the provided papers support the claim that masturbation decreases testosterone, making the verdict clearly Refuted.