[This article was first published in 2016]

Everyone has at least one friend who always posts their gym activity on social media. Maybe you even do it yourself.

"Ran 15 miles before work! Yeah" can be motivating to read in the morning, or incredibly annoying, depending on how much you hate that painfully overused flexed-biceps-emoji.

Researchers from Brunel University in London conducted a study in May 2015 as to why so many people share every workout on social media. The results are unflattering, to say the least.

People who are always keen on documenting their gym activities (or every time you simply go for a good, old-fashioned run) tend to be narcissists, the study found.

According to the researchers, the primary goal is to boast about how much time you invest in your looks. Apparently, these status updates also earn more Facebook likes than other kinds of posts.

"Narcissists more frequently updated about their achievements, which was motivated by their need for attention and validation from the Facebook community", the study concludes.

The high number of likes doesn't necessarily mean everyone loves seeing those bragging posts, though.

Psychology lecturer Dr Tara Marshall goes on to say that "although our results suggest that narcissists' bragging pays off because they receive more likes and comments to their status updates, it could be that their Facebook friends politely offer support while secretly disliking such egotistical displays.

"Greater awareness of how one's status updates might be perceived by friends could help people to avoid topics that annoy more than they entertain."