Hijab is the principle of "modesty" and includes behaviour and dress for both males and females. Female hijab is the covering of the head, male hijab is the covering of legs down to at least the knees.... you never see devout Muslim men wearing shorts in public.*
I have very devout Muslim friends who wear shorts all the time, and not only when engaging in sports, but just walking around.
ETA: This shouldn't be interpreted as an attempt to suggest that such rules don't exist, and I don't live in a Muslim country. But it does suggest to me that, among devout Muslims, the stigma attached to men wearing shorts is less than that attached to women going without their head covered.
ETA2: This reminds me of a conversation I had with a very good friend of mine. He is from Turkey, and he was telling me about having lunch at his cousin's home. His cousin's wife was preparing lunch while they sat in conversation. His cousin was telling him about his business trips to Russia, and at the same time exchanging text messages with his mistress in Russia. Meanwhile every few minutes the cousin's wife would say something from the kitchen and the cousin would exchange some words with her. So my friend started to have an odd reaction: he felt vaguely disgusted at his cousin's behaviour, but he noted that he wasn't really motived to do anything other than make a joke about how he was an ass. He then thought about how he would feel if the same situation happened with his sister. He told me, "If it were my sister, I would kill her." He started to tell me about how she would be dirtying the name of their family, etc. but at the same time expressing a strange cognitive dissonance saying "It's the
same situation with my cousin, so why don't I do something about
him?" He had this sort of eye opening experience about the unbalanced view he had toward male and female indiscretions within his family, and yet, as he said, his emotional reaction hadn't changed, though he did at least think there was a discrepancy that he couldn't defend.
I basically listened to the story, and we laughed about it. I made a few jokes about how, yes, it
doesn't make sense, hopefully with the implication that he might think about changing his views, but that was about the end of it.
I might perhaps add that he's one of my best friends and a person that I find to be kind, intelligent, trustworthy, well intentioned and motived to try to be a good person. He's also very willing to have conversations and listen to people that he doesn't agree with. And yet he said upfront that he would literally murder his sister if she had an affair.
