Work Text:
I've seen a few claims that BBC Sherlock isn't very strong.
ACD's Sherlock was a practitioner of Bartitsu. Holmes credits the martial art for his defeat of Moriarty at Reichenbach Falls. He was also an expert at singlestick, fought with his cane, fenced, and was a bare knuckle fighter.
He was described by ACD: "In height he was rather over six feet, and so excessively lean that he seemed to be considerably taller."
and yet:
In several stories, Holmes is described or demonstrated as having above average physical strength. As an example, in "The Adventure of the Speckled Band", Dr. Roylott, 6 feet tall and wide as a doorframe, demonstrates his strength by bending a fire poker in half. After the Doctor leaves, Holmes said, "laughing, 'I am not quite so bulky, but if he had remained I might have shown him that my grip was not much more feeble than his own.' As he spoke he picked up the steel poker and, with a sudden effort, straightened it out again." In "The Yellow Face" Watson comments of Holmes, that "Few men were capable of greater muscular effort." - Wikipedia
BBC's Sherlock has a framed 1st dan (shodan) judo black belt certificate above his bed. 1st dan isn't as high as you can go in judo, but it's nothing to sniff at either. From what I've read it takes competitor's 3-4 years to reach shodan and 5-7 years for non-competitors. Either way it hints that Sherlock knows a martial art and is possibly extremely good at it. He is also able to climb into windows that are above his head, leap from roof top to roof top, swing agilely over high fences, wrestle guns out of assailants hands, withstand John punching him straight in the face (yes he falls down but he gets right back up.), run forever without stopping, etc etc.
There is a difference between being thin and being "physically weak".