Researchers from The University of Sydney followed the sexual habits of over 1,700 men ages 70 and up who were part of the Concord Health and Ageing In Men Study. The men were asked to report the frequency of their erections and intercourse, as well as how their sex drive compared to when they were 50. They also looked at the mens' levels of testosterone, the male sex hormone that helps create strong bones and muscles, healthy sperm, and is also thought to help maintain a healthy sex drive, according to the NIH.
They followed up two years later and found that low baseline levels of testosterone didn't really predict lowered desire or sexual activity in the future. However, a decline in testosterone was strongly related to having less sex and less desire for sex.
"In older men, decreased sexual activity and desire may be a cause -- not an effect -- of low circulating testosterone level," lead author Benjamin Hsu said in a statement.
While low testosterone often is associated with lowered sex drive, there are many other factors that can play a part in desire. Environmental factors like stress, lack of sleep and even depression have been known to lower a man's libido.
So does the study simply mean that when it comes to sexuality, you either use it or lose it? It's not quite that simple. Researchers say it's still unclear whether there are other age-related factors at play here which may be to blame for lower testosterone.