Is Rock Lee's stance in this image a reference to some stance from martial arts, or was it created just for Naruto?
There is a martial artist champion who makes the same stand as Rock Lee, but he's a fan of Rock Lee, it wasnt the anime which copied his stand, but the other way around– PabloFeb 21, 2022 at 9:58
Rock Lee is evidently inspired in Bruce Lee, because of his name and hairstyle, but I couldnt find any photo of Bruce Lee making that stand. Though I could find a character from a movie from 2001 "Shaolin soccer", the goalkeeper who is a parody of Bruce Lee, who makes a similar stand to Rock Lee. Naruto started in 1999 so who knows– PabloFeb 21, 2022 at 10:20
encrypted-tbn0.gstatic.com/…– PabloFeb 21, 2022 at 10:24
pm1.narvii.com/6082/…– PabloFeb 21, 2022 at 10:24
Yes, the stance is definitely inspired from movies and is not made just for Naruto. I found this Reddit post where various commenters mentioned the use of this stance in movies released way before Naruto:
Both of these find their origins in Traditional Chinese martial arts, and are commonly known as Crane stances. (Which I would assume rock lee's stance is based on as well)– Dimitri mx ♦Apr 19 at 8:02
This stance definitely is very similar to Jet Li's Stance from the 1991 movie "Once Upon a Time in China" and Jackie Chan's stance in the 1994 movie "Drunken Master II." (See @Fumikage_Tokoyami 's answer) Additionally, in "The Matrix" (which was released earlier in the year the manga was started) the "Neo vs Morpheus" fight scene features both sides using the stance.
Though there is no concrete evidence, this stance (called the "beckoning stance" in other films) is likely a reference to these movies, additionally because Rock Lee is supposedly a master of the "Drunken Fist" taijutsu, supposedly a reference to "Drunken Master II". Because "The Matrix" was released just a tiny bit earlier than the manga, it could also be the fight scene that inspired the stance.
All notable "Bushy Brows" seem to use this stance, so the first Bushy Brow, Might Guy probably created it (in their universe), or perhaps Might Duy. The official Naruto Wiki does not seem to have information on the stance. The wiki does say that Rock Lee made a transition to look more like Might Guy. Lee may have also copied the stance.
1No, this stance is not original but is inspired from movies. See my answer. Apr 19 at 4:08
Fixed (+ Neo vs. Morpheus fight scene in "The Matrix")– thing10Apr 21 at 15:08