I have a number of FB friends who comment on their various physical activities - super-long (to me) bike rides, climbing, running, all sorts of things. They're great, I love seeing the pics they post, and it's kind of inspiring because as far as I can tell, there's absolutely nothing competitive about the posts at all.
The one who gets on my nerves is the one who posts her run time/distance and then comments about how sloooooooow she was today. Her tortoise-like pace is what I can barely manage on a good day. That's just obnoxious, but she only does it rarely so I just ignore.
I have a couple of SuperMom FB friends too, I find I just skip over their posts because otherwise it would drive me up the wall, since they mainly consist of "I should have my head examined! I just spent all day doing A, B, C, D, E, F, and G for my kids, isn't that crazy???"