Scarlett Johansson Perfected Her Martial Arts Moves for The Role 

Getting the billion-dollar opportunity to work with MCU, Scarlett Johansson threw herself into grueling training to achieve the physical transformation required for the role. Spending five or more hours a day in her workout sessions, learning the techniques of onscreen combat and practicing wirework stunts, Johansson dedicated herself to the role.

Scarlett Johansson went through grueling training for her MCU role
Being constantly under the supervision of a nutritionist, Scarlett Johansson mentioned why she needed to undergo so much training. According to MCU: The Reign of Marvel Studios, the actress admitted how she was out of her element when it came to the physical part of acting. And as she wanted audiences to see her, rather than her stunt double, Johansson had to engage in extreme training.
“I was totally out of my element when it came to the physical part of this work.”
Johansson perfected Black Widow’s trademark move in Iron Man 2
Eventually, the actress perfected her martial arts moves and savored the physical thrills of manhandling giant bodyguards. She became so comfortable with action sequences that in one scene with Black Widow’s trademark move of taking out an opponent by leaping up and scissoring her legs around his neck, Johansson even did a middle-of-combat hair flip.
Black Widow trademark scissoring move
Unfortunately, although Scarlett Johansson performed the move with utmost ease, fans ended up trolling her for that trademark move. The actress therefore blamed it on the s*xualization of the character that made people question her capabilities, and troll her for taking out bodyguards and flipping her hair in between.