But does heat affect testosterone levels. One study on boars shows that initially heat may not affect testosterone levels  However, eventually baseline T levels are actually decreased. In other words, it appears there may be a time lag from the application of the heat to the time that testosterone actually decreases. This was verified in the study on rams that showed that testosterone decreased significantly after a two week period.  One study on monkeys verified the same thing: a time lag loss of testosterone after 6 days of 30 minutes heat treatment of the testicle area.