Dear EA Dice,
Hi! It’s me, Austin. I’m writing to you today because I just picked up Mirror’s
Edge Catalyst. You know, the sequel you waited eight fucking years to make. You know what
I was doing in 2008? Masturbating and playing World of Warcraft, and just...this. What is
this. Look at me. What the fuck was I, even? Get that fucking thing off your chin, you
weirdo.
Where was I? Oh, right. Mirror’s Edge Catalyst. The rooftop running simulator that puts you
in minimalist shoes of Faith Connors, a superhuman parkour expert who operates in the background
of respectable society as a “runner.” She’s basically Han Solo if he were an Asian
woman who ran across rooftops and did flips and rolls instead of not shooting Greedo first.
Faith Connors runs, jumps, wall runs, tucks, rolls, and kicks her way through the game
like it’s effortless. As someone who’s largely sedentary in my life and gets winded
anymore by cycling five miles, the more I played Mirror’s Edge Catalyst, and the more
I heard Faith’s feet slam over and over on the floor as she ran and only very rarely
sounding winded, I found myself more and more aware of how much fucking exercise she’s
doing, for extended periods of time, too. So I couldn’t help but wonder: is Mirror’s
Edge completely fucking ridiculous? Is it even possible for someone to run, jump, and
perform extended periods of exertion to the level that Faith does without killing yourself
or breaking a leg? This question, while seemingly simple at face value, has consumed me for
the past week. I’ve lost sleep analyzing gameplay footage, charting graphs, and reading
sports medical journals. And the truth behind the reflection of Mirror’s Edge is deep,
complex, and surprisingly cool.
The first step is to look at Parkour. Parkour is similar to a sport called Freerunning--similar
enough, in fact, that some people use them interchangeably, but they’re fundamentally
different and have vastly divergent core philosophies. Freerunning is built around getting from Point
A to Point B as creatively as possible. People doing backflips, twirls, and little dances?
That’s Freerunning. Parkour, by contrast, is about efficiency of motion, and therefore
all the techniques utilized in it are about conserving momentum, energy, and by extension
maximising safety.
Surprisingly, the wall runs in Mirror’s Edge are not only possible, they’re not
all that challenging if you’re practiced enough. Well-trained parkour runners can climb
walls 15 feet high. It seems like they’re defying the laws of gravity and motion, but
in actuality, it’s quite the opposite. When you run up to a wall and hit it, you’re
stopping because the wall is exerting enough force back into you to reduce your speed rapidly.
This same principle is exploited in a successful vertical, and similarly horizontal, wall run.
If you can successfully match your speed approaching the wall so that your foot is exerting force
on the wall that is equivalent to the force the wall’s pushing back, both backward and
forward momentum are canceled out, allowing you to push yourself up for a limited amount
of time.
But what about those falls? Sure, fine, all the parkour moves and traversal methods Faith
does are completely and totally feasible, but alling is one of the most dangerous things
a human can do, and incidentally is one of the places our game is most likely to fall
short. The earth is pretty intense, and really, really doesn’t like it when we leave, so
it pulls us back down whenever we’re in the air at a feisty 9.8 meters-per-second.
That means for every second of freefall, you’re speeding up by 9.8 meter second, which is
pretty damned fast. For instance, if you fall from just 10 feet up, you’re hitting the
ground at a painful 17 miles per hour. What, that doesn’t sound that bad? That’s like
running nearly full speed into a wall. And if you fall from 20 feet up in the air, you’re
hitting the ground at 24 miles per hour, which is more like an olympic sprinter running at
top speed into a brick wall. So, yeah, it can mess you up. A fall from a height like
that is unlikely to kill you, but it certainly can, and it’s highly, highly likely to seriously
injure you.
That is, of course, if you don’t know what you’re doing. You see, Mirror’s Edge,
like many other games, has instituted a falling roll to reduce the force of impact. This is
bullshit, right? Hollywood flair to make falling look fucking cool. It doesn’t actually help
you, does it? Well...that’s where you’re wrong.
In order to understand this, we’re going to have to talk about the difference between
Impact and Impulse. Impulse is the amount of force you’ll experience from a fall in
total, regardless of how slowly you decelerate, while impact is an individual measurement
of peak levels of force at any given moment. A simplified way of looking at impulse is
the force of impact multiplied by time. So for example. If you jump from 10 feet up in
the air, you’re always going to experience the same amount of impulse--however, impact
is a variable of impulse. Impulse is, effectively, the force of the impact times time, so if
you can increase the amount of time it takes to change speed, you can decrease the impact,
while maintaining the same impulse, and avoiding harm. And this is where the falling roll comes
in handy.
Deceleration time is measured from the instant your feet touch the ground to the moment where
your center of mass stops moving downward. Rolling extends the deceleration time by allowing
your torso to keep moving downward, and letting you distribute the impact more evenly throughout
your body. In most cases this only adds a fraction of a second to fall time, but this
can exponentially decrease the amount of impact you experiencing, reducing the number of g-forces
you experience by up to 75%.
Because of this, elite parkour and other freefallers can actually fall from heights of up to 20
feet without injury by utilizing proper technique. So, yeah, so far, so good.
But, whatever. That’s the easy part. tl;dr, parkour is possible. Big deal. Who the fuck
cares. MatPat already proved as much in his episode of Game Lab. Well, strap yourselves
in, aspiring Near-Futuristic Dystopian Rebel Runners, because I’m just getting started.
Ultimately, what I’m more interested in isn’t Faith Connor’s techniques, other
than to prove that they’re possible--rather, I’m interested in her seemingly superhuman
endurance. I mean, this is a person who seems to be capable of endlessly running, jumping,
and climbing without stopping, which runs counterintuitively to everything most of us
know about working out. You run for a while, and your breathing gets labored, your muscles
start to ache, your feet hurt, and, eventually, you have to stop. What’s really going on
here?
Animals adapted to use oxygen in the atmosphere to, well, cheat. Breathing is second-nature
to us, so we don’t really think about it that much. We know that it’s not something
you want to stop, but it’s just as much a provider of energy to our bodies as eating.
Actually, quite a bit more so, which is why we breathe so much. Utilizing oxygen in the
atmosphere, which is a byproduct created by plants during photosynthesis, allows us to
engage in much more energy-consuming behaviors than we would be able to otherwise. Running,
blinking, having sex, and even thinking are all things that we owe to the presence of
oxygen in our atmosphere.
Our muscles turn carbs into energy by producing something called adenosine triphosphate, or
ATP. ATP is created by our bodies in three steps: Glycolysis, the Krebs Cycle, and Electron
Transport Chain. Glycolysis creates the stuff the krebs cycle needs to create stuff for
the electron transport chain, which ultimately creates ATP, the stuff our muscles and other
cells use for energy. Both glycolysis and the krebs cycle create ATP as well, but they’re
more byproducts than the main event, and the electron transport chain produces by far the
most. ATP is the fuel your body needs to run, and without enough of it, you’re grounded.
The problem is that, while the electron transport chain creates most of the ATP you’ll ever
need, it’s a relatively slow process, and you can easily burn through your stores of
ATP faster than the electron transport chain can replenish them. Luckily, your body is
fucking incredible, and it can actually utilize glycolysis as a sort of backup generator for
ATP. Unfortunately, glycolysis is part of your respiratory cycle, and requires oxygen
to run, which is why your breathing picks up when you exercise for an extended period
of time.
Of course, there’s a limit to how efficiently you can pull oxygen from your bloodstream
for glycolysis, and oxygen does serve other roles in the body, so eventually, you hit
a place where you can no longer use oxygen to give glycolysis a boost. So that’s when
your muscle stop, right? Fucking wrong. The human body is so fucking amazing that it has
a second backup contingency. You know, for those emergencies when you’re running away
from tigers and shit. If your body finds itself running low on necessary oxygen and yet still
needs to exert itself, it can start anaerobic glycolysis. Er, anaerobic is just science
speak for “without air,” in this case, oxygen.
Glycolysis usually produces pyruvate as a part of its main function, and it continues
to produce this while in overdrive to make ATP. This is the chemical that is dependent
on oxygen. In the absence of oxygen, however, it doesn’t produce pyruvate--it produces
lactate, or lactic acid, which releases into the blood stream. Now, actually, glycolysis
is constantly producing both pyruvate and lactate all the time, and the body is pretty
good at mitigating lactate levels in the blood supply and keeping them at appropriate levels.
As anaerobic respiration increases, however, lactic acid can accumulate faster than the
body can clear it out. And under extreme circumstances, levels can spike dramatically.
There’s a pretty heated debate in the medical field about whether or not lactic acid itself
is responsible for muscle fatigue directly, but regardless, lactate levels in the blood
stream are directly correlated to muscle fatigue, with higher levels being associated with burning
sensations, involuntary muscle seizing, vomiting, and eventually inability to move.
The world’s best athletes train their bodies to clear lactate faster and pump blood more
quickly and in greater volumes, and it’s something that anybody who starts exercising
regularly can attest to: the more you work your body out, the less tired you get. This
is because your heart muscles actually get stronger and pump more blood, which in turn
lets your body clear lactic acid away more readily. Also, you can condition your body
to simply tolerate higher levels of lactate in the blood stream.
So what does this mean for Faith, our extraordinary parkour athlete? Well, first I had to build
an athletic profile for her. My method was complicated, but I’ll go over it really fast.
The Mirror’s Edge wiki states that Faith Connors is 5’9” and 125 pounds but this
is taken from data in Mirror’s Edge 1 and Catalyst is a reboot of the series so I needed
to run calculations of my own so I ran some calculations using pixel measurements, a cutscene,
angles, and a manequin, which I estimated at being 73 inches, the average male mannequin
height. I came within one centimeter of 5’9” so I took her measurements as accurate, making
her 125 pounds, or 56.699 kilograms. Since she’s incredibly athletic I estimated her
at having 10% body fat. Using this I calculated her basal metabolic rate at 1472 kcal/day,
61.33/hour, and 1.022 a minute, which I then applied the caloric method of hydration replenishment
to determine that her basal water loss was .86 milliliters of water per kcal.
After acquiring this information and reading several academic and medical journals, I determined
her maximal stroke volume (the amount of blood in milliliters the blood pumps at maximum
capacity per pump), her maximum heart rate in beats per minute, and her maximum arteriovenous
oxygen difference, or the efficiency her cells can grab oxygen when under maximum load. All
of these combined gives you a VO2 Max number, also known as maximal oxygen consumption,
which is a number that tells you how awesome someone’s body is at utilizing oxygen--Faith’s
VO2 number is 75.389, or the level of a highly trained athlete, but not world-record holding.
Lactate threshold, or lacate inflection point, is the point at which lactate levels start
increasing exponentially in the blood stream. Elite athletes have a lactic threshold of
80-85%, so I gave Faith a threshold of 80%, or a VO2 of 60.3184. I then built a lactate
buildup and depletion model using an exponential expression to show how lactate levels increase
exponentially as Faith reaches maximum VO2, making peak levels impossible to maintain
for too long.
I then dumped all of this data into six different escalating exertion buckets using multipliers
for calories and hydration depletion, heart rate, blood volume, and arteriovenous oxygen
difference to determine individual VO2 and therefore lactate buildup or depletion, all
by minute. I then went through the entire main quest of Mirror’s Edge, doing minimal
side quests that would help me along the way, and then poured through the footage minute-by-arduous-minute
to determine her level of exertion for the entire main story, plugged the numbers in,
graphed it out, masturbated, and now we’re here.
So. Ahem. The entire main story with a few side quests took me approximately 7 hours.
That’s impossible, right? 7 continuous hours of extreme, demanding exercise? Well, yes,
but it turns out things aren’t that simple.
The course of the main game takes place over four separate days, broken up by exposition
dumps and followed by Faith actually saying “hey, um, fuck y’all, I’m going to bed.”
She does this three separate times. This is actually huge, because this spreads the 7
hours of exercise into four major chunks that we can look at separately, and gives her time
to recover, eat, and drink. And somewhat depressingly rendered my measurements of calories and water
lost irrelevant. Oh well. Anyway. None of the graphs are that interesting, other than
they show that Faith undergoes peaks and troughs of activity. The most interesting graphs,
though, are easily the ones that show lactic acid. For one, the illustrate how short bursts
of near-peak exertion can take a long time to disperse, and they also paint an relatively
interesting picture for the entire game. In the first chunk of the game, lactic acid levels
stay relatively low--peaking near the end, and then dissipating as exertion ramps down.
Day 4, however, they start high, and stay high, and reach incredible concentrations.
But more on that in a bit.
7 hours over four days radically changes our story. Instead of being an impossibly long
marathon of self-destruction, it’s in four surprisingly manageable, albeit intense workouts.
Day one is 1 hour, 12 minutes, day two is 2 hours and 13 minutes, day three is another
2 hours and 13 minutes, and the intense day four is a breezy hour and 20 minutes.
Now, the amount of lactate that’s in your blood even at peaks is almost nothing you’d
notice if I placed it in front of you. The amounts are measured in millimoles-per-liter,
and the most highly-trained athlete in the world will never have more than a few drops
of lactate in their bloodstream at a time. That being said, it doesn’t take that much
to render you completely and totally incapacitated. Most people can’t handle much more than
15 millimoles-per-liter of lactate without doubling over. Olympic sprinters are known
for abusing their glycolysis process, and they register as high as 25 millimoles-per-liter
of lactate after a race, but they typically don’t run for more than 10 or so seconds.
Why am I telling you this? Well, because for 15 solid minutes during the last section of
the game, Faith’s estimated blood-lactate levels were at-or-near 20 millimoles, a patently
unsustainable level of exertion. It’s fucking impossible. After about a minute of this level
of lactic acid in your bloodstream, your body would just stop working, forcing you to the
ground until you’ve had time to recover and clear out the excess lactate. Not exactly
something you want to happen in the middle of a fight for your life.
So, what? This is it, right? Even under generous circumstances, Faith is complete bullshit?
Well, yes and no. Yes, the level of endurance she displayed in my game is a bit absurd.
But well-trained athletes are able to clear lactic acid levels more quickly than the average
person, and more importantly can recover from muscle fatigue with rest more quickly. Faith
in my game hit unsustainable levels of muscle fatigue because she ran nonstop into the final
mission with a hefty 12 millimoles of lactic acid per liter of blood. At her fitness level,
though, if she’d just taken ten minutes to sit, eat a snickers and drink a gatorade?
She would’ve never hit the wall at all.
So there you have it. Sure, Faith is a fucking badass, and if you play the game nonstop for
several hours, she’s going to display the endurance of fucking superman. But in most
realistic circumstances, she’s actually well within the realm of realistic human fitness,
which means that most of you, if you wanted, could spend every day training your body to
be just as awesome as hers. Just, you know, remember to rest every once in a while, or
you’ll find yourself having a really, really bad time.
Sincerely, Austin
P.S.
THAT BEING SAID, there’s a couple of ridiculous zipline and falling physics, and at least
one absurd stunt that’s near the end of the game that I won’t get into now. But
you’re not off the hook just yet, EA DICE. Some day, some day soon, I’m going to take
a closer look at that windmill.
Oh, and, uh, also, today’s Monday, right? Head on over to our Twitch channel, twitch.tv/shoddycast.
At 10 AM Central Standard Time I’m gonna be restarting my game of Mirror’s Edge Catalyst
and streaming it. See ya there! I’m probably there now.