Action heroes get punched. A lot. They fall down flights of stairs, get drowned, choked, jump out of collapsing buildings, and get thrown through walls. And through it all, traditionally in movies, they come out of it with barely a scratch. Lately, though, there's been a movement towards making fight scenes and their brutal aftermath at least a smidge more realistic, to give audiences a taste of the stakes involved. (Even Sterling Archer, a cartoon spy, is shown developing tinnitus from the many times a flash bang or gun goes off near his ears, even if getting shot and beaten has no lasting effect on him.) But despite the increasing realism, action heroes are still routinely shown getting up from knockout punches, recovering from being beaten to a pulp without a scar, and moving on with their lives, concussions and lifelong brain injuries be damned.

To learn a little about what these fights would be like IRL, I talked to Michael Kelly, a sports medicine physician and author of Fight Medicine, about the consequences of brawling like a spymaster. We zeroed in on Atomic Blonde, out on July 28, for which Charlize Theron is already getting rave reviews for her fight scenes as Lorraine, a Cold War–era spy. In one particular fight, shown in the film's trailer, Lorraine takes on two opponents in a stairwell in brutal fashion. The scene is getting a lot of attention in the press for being badass. Kelly takes us through what it would cost a real person.

First, a little age discrimination for Hollywood. When it comes to action movies, one thing no one seems to take into account is that most of our action stars are no longer spring chickens. After age 35, brain volume shrinks a little, which puts older individuals at higher risk of developing a subdural hematoma, which is when blood vessels around the brain burst, from heavy blows to the head or a fall, Kelly says. Daniel Craig's last outing as James Bond, for example, came out in 2015, when the actor was 47 years old—not a great age to survive repeated blows to the head (there's a reason professional boxers tend to retire by their thirties).

Age aside, the cumulative effects of being hit that many times in the noggin are no picnic either. Assuming James Bond has been a spy since his late twenties and the action scenes in the Daniel Craig movies are indicative of the fights he typically endures during missions, he would be suffering from something called chronic traumatic encephalopathy (CTE), says Kelly, known in layman's terms as "punch drunk syndrome." CTE is a brutal enough diagnosis that some doctors and scientists have called for football and boxing to be banned because of it. People with CTE exhibit changes in mood, like explosive anger or paranoia, along with dementia, dizzy spells and Parkinson's symptoms.

It's not just how many times you get hit, but also where. In boxing, points out Kelly, it is illegal to punch someone in the back of the head. That's because while a person can take a pretty hard hit to the cheek bone, which is where most movie punches tend to land, a hard punch to the back of the head can cause a pretty severe subdural hematoma, which if not treated right away will result in death. So all of those whacks to the back of the head with a bottle in movie bar fight scenes? Well, yeah.

At 41 years old, Charlize Theron is also past prime getting-punched-in-the-head age. Kelly praises the fight scene, which he says is more realistic than most movie fights. Just like in a real street fight, Lorraine is hit repeatedly by the first assailant in quick succession. In most real fights, a person hits multiple times quickly with their dominant hand, which is why most facial injuries from fights are on the left side of the face, explains Kelly. Lorraine's technique is also very professional, "if you notice they made her turn with the punch, boxers do that, if you move away from the punch as you are hit it provides a minor protective effect," Kelly points out.

Things go south in the realism department pretty quickly, though, as Lorraine seems unaffected by the repeat punches and hits to the head, getting up quickly and continuing the fight. Kelly's main concern is the blow to the head from the heavy satchel that is hard enough to knock Lorraine to the ground. While the impact from a fist might be limited by damage to the bones of the hand, when it comes to hitting with an inanimate object, all bets are off. A full-force hit with the satchel to the head would likely cause a concussion.

While adrenaline would allow her to finish the fight, she would be wobbly and clumsy when she got up, and her coordination would be off. "It is completely unrealistic that she would bounce back from that," Kelly says. The effect is seen in MMA fights or boxing, he explains, when a skilled fighter experiences a few heavy blows to the head, and suddenly seems clumsy. That's usually the time when a doctor steps in to stop the fight. Between all the hits to the head, as the fight progressed, Lorraine would be less and less able to defend herself, points out Kelly, a scary scenario for a real-life street fight.

Bottom line, says Kelly, while Lorraine sustains a pretty hard whack to the head, a concussion can occur even with a relatively light blow. People who seem to be able to "take a punch" are actually at greater risk than those who lose consciousness easily from a hit. "From studying fighters for the last 50 years, we know that people who can take a punch and not get knocked out tend to get more concussive injuries, dazed, confused and have memory problems," Kelly explains. In the real world, the hard-headed and tough guys and gals like Bond and Lorraine would be in for a very early retirement.