Today we are going to find out what scientists have established as the very limits of human
abilities.
How fast can we run?
How many Gs can we withstand?
What’s the ultimate limit of human endurance?
I’m Stu this is debunked and we’re here to sort the truths from the myths and the
facts from the misconceptions.
This episode is sponsored by Skillshare!
How Fast Can We Run?
Now this one seems really straightforward on paper.
I say the name Usain Bolt and we move on to the next topic.
After all, he holds the record for the fastest time over 100m at 9.58 seconds, meaning he
ran with a speed of 23.4 miles or 37.6 kilometres per hour.
But that’s just his average, Bolt reached his top speed around the 60 to 80 meters mark,
where he hit 27.79 miles or 44.72 km per hour.
Over 19% faster.
However, there’s a twist in the tale.
Heading back to the 1964 Olympics, Bob Hayes ran the distance in just 8.6 seconds - almost
a second faster than Bolt’s current world record.
But Hayes set the time as the last runner during the 100m relay, meaning he didn’t
have a standing start like the 100m sprint.
But, luckily Bolt has also run this leg of the 100m relay...
and his fastest time, is 0.05 seconds slower than Bob Hayes.
Now we know Hayes officially has the quickest time ever recorded over 100m.
But in 1964 the technology wasn’t there to record his top speed,
but we can work out his average, and
what we do know is Hayes is 0.58% quicker than Bolt’s fastest ever time,
so we could calculate that Hayes top speed is 0.58% faster than Bolt’s too.
Adding the fact that the cinder track Hayes ran on is judged to be 2-3% slower than modern
rubber tracks we could estimate
that the fastest speed ever run by a human is 46.09km or 28.64 miles per hour
But could the humans of tomorrow run even faster?
Well, without wanting to sound like a communist pig, it could be a case of ’Four legs good,
two legs bad’.
A 2010 study found that humans aren’t that effective at running
because when we’re sprinting we’re actually airborne for a surprisingly large amount of
time -
meaning there’s no force propelling us along.
“A human who’s really fast… ...is on the ground roughly 42 or 43 percent
of the total stride time.
But for a fast-running quadruped it’s two-thirds of the stride time.”
The fastest running quadruped can clock up speeds of over 30 meters per second - about
three times quicker than the fastest humans in history.
Four legs means these animals have increased contact with the ground while running, so
they can propel themselves along quicker.
Humans are already blessed with four limbs, we just don’t use two of them for running
- usually.
But some people are already running on all fours.
A 2016 study looked at the fastest 100m times
for humans running on all fours, and found that since records of the feat began in 2008
to the setting of the 2015 world record, that the time fell rapidly from 18.58 to 15.71
seconds.
If this progress could be maintained, the study suggested that humans running on all
fours could break the two-legged record by 2048.
How Hard Can We Punch?
When it comes to hitting stuff really hard, a 2005 study conducted by Cynthia Bir, Professor
of Biomedical Engineering at Wayne State University has given us a pretty good idea of how hard
we can hit.
During the experiment, seven Olympic boxers were tasked with hitting a dummy, which measured
the force of each punch it received.
On average, these Olympic-level punches landed with a force of 3,427 newtons.
To put that into perspective the average human exerts a force of only 600N on the Earth.
The hardest punch thrown during this study was a staggering 4,471!
This time equivalent to a half-ton polar bear.
A similar study from 1985, involving heavyweight boxer Frank Bruno, found that the future world
champion could land a punch of 4096N on a suspended pendulum in test conditions.
From that the scientists involved estimated that, in practice, a similar blow on a human
head would land with 6320N of force.
The study equated such a punch to being hit with a 6kg padded wooden mallet being swung
at 20 mph (32 KMH).
Such a punch (or presumably the mallet) would accelerate a head with a g-force of 53gs.
Which leads us nicely on to…
How Many Gs Can We Withstand?
As ever, different humans have different tolerances for g-forces.
Plus the effect on the human body is not just dependent on the level of g-force, but also
the orientation of the body and how long said g-force is acting on our body.
Vertical acceleration can be a problem for our bodies, as this can send your blood down
towards your feet and away from your brain, depriving it of oxygen.
Your brain can only handle about 4 seconds without O2 before you lose consciousness and
most of us would be out of it at 5g in under 10 seconds.
Coming at it from another angle, humans have a much higher tolerance for forwards and backwards
acceleration.
In the 1940s and 1950s, US military experiments used a rocket-propelled sled to find out how
many Gs a person could handle at a time when 18gs was considered the limit.
The poster boy for those experiments was a Colonel named John Stapp, a U.S. Air Force
aviation doctor who put himself through extreme physical punishment to prove the human body
was capable of handling more than conventional scientific opinion thought possible.
A lot more.
“His face reflecting the strain, Col. Stapp is subjected to gravitational pressure 35
times his own body weight”
His final, and most famous, test in 1954 saw Stapp ride a sled that had nine rockets on
the back, capable of producing 40,000 pounds of thrust.
When blast off took place, those rockets fired Stapp to 632mph (1,017 km/h) in just 5 seconds.
From that top speed, the sled came to a complete standstill in just 1.4 seconds.
That deceleration equated to 46.2g.
Remarkably Stapp was alive but not without injury - he’d cracked a few ribs, broken
both his wrists and was rendered temporarily blind.
Yet, despite his sacrifice, Stapp doesn’t hold the record.
That honour goes to the Captain Eli L. Beeding, also of the US Air Force, who in 1958 rode
a rocket sled on a shorter track while facing backwards and experienced a deceleration of
83g for 0.04 of a second.
“Beeding went into a state of shock and for a time was considered to be in a critical
condition.
5 days later however he was back at work”
Beeding holds the record of highest voluntary g-force experienced by a human.
For the non-voluntary record we need to take a trip…
...to the Texas Motor Speedway in 2003.
We’re on lap 188 of the Chevy 500 and Swedish IndyCar racer Kenny Bräck is involved in
a crash at 220 mph (354‑km/h) that sends his car flying through the air and into a
steel post.
The deceleration, which lasted for a split second, was 214g.
Giving Bräck the record for the highest g-force ever survived by a human.
HOW MUCH CAN WE LIFT?
When it comes to weights it seems like humans are already close to the limit of what they
can lift, bro.
The progression of weight lifting world records hasn’t stopped but there are signs that
progress is slowing down.
“Today’s weightlifters, including those that use steroids, are near the limit of human
potential.”
You see, the body tries to inhibit the amount a human can lift in order to prevent us from
hurting ourselves when we’re trying to show off at the gym.
Essentially, the brain limits the number of muscle fibres that are activated at a given
moment making this limit as much of a mental problem as a physical one.
Top level weightlifters are able to lift about 1,000 pounds (454kg) in a deadlift scenario
and just over half that in an overhead lift.
But if we want to go beyond that, Schroeder argues that we’ll need to improve our mental
capacity and learn to limit the signals from the brain that prevent us activating our muscle
fibres to the max.
If we can do this, Schroeder argues that we could see weightlifters improve their performance
by around 20%.
And, given that the deadlift world record has improved from 457.5 kg to 501kg in the
last 10 years, an increase of just over 9%, it seems like we’re fast approaching the
limit predicted by Schroeder.
However, if we want to try and pinpoint the heaviest weight ever lifted by a human, we
need to take a fresh approach.
That’s right folks, we’re talking the back lift.
This technique is slightly different, in that it involves lifting a weight on a platform
up on your back from a hunched position or on all fours.
This method was used in 1993 by Canadian strongman, Gregg Ernst, to lift 2422 kg - that’s about
the same as adult male white Rhino or 29 average sized Americans (13 men and 16 women).
To give you an idea of how much difference this technique makes, the 501kg record for
deadlifts equates to just 1 female Alaskan moose or only 6 Americans (3 men and 3 women)!
Stay tuned to find the ultimate limit of human endurance.
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Now let’s find out...
WHAT’S THE LIMIT OF HUMAN ENDURANCE?
For most of us the idea of running a marathon is great, providing it stays just that; an
idea.
The reality, of course, is far more daunting and challenging.
Yet as a species we are capable of accomplishing feats of endurance way more demanding than
running 26.2 miles (42KM).
Take the Self-Transcendence 3100 Mile Race, which you might have guessed, is 3100 miles
long nearly 5000 km and is the longest footrace in the world.
Competitors have 52 days to complete the distance, meaning they have to average 59.6 miles or
95.9 km per day.
Yet 60 miles a day is nothing for some, with Camille Herron running 167.8 miles / 270 km
in 24 hours to set the female record for ultra distance running in 24 hours, while the male
record holder, Yiannis Kouros, hit 188.6 miles.
And, I probably should mention Dean Karnazes, who has run 350 miles (over 560 km) in 80
hours and 44 minutes without stopping.
But what are the limits to human endurance?
Well, according to a 2019 study it boils down to a relatively simple formula - the body
is capped at burning through calories at 2.5 times the body’s resting metabolic rate.
The RMR relates to the calories the body burns through when it is, well, resting.
For most of us, burning through 2.5 times the RMR, would amount to 4,000 calories per
day.
Now, I should point out that the body is capable of consuming calories at more than 2.5 times
the RMR.
For example, running a single marathon can push that to 15.6 times and Tour de France
cyclists manage 4.9 times their RMR during the 23 days of the race.
The point, is not that we can’t burn more calories when we need them, but that over
time, our bodies can’t maintain a level higher than 2.5 times the RMR.
The study found that the metabolisms of ultramarathon runners’ taking part in a 3,080 mile race
actually slowed down to bring them within the RMR limit.
Exceeding that limit on a regular basis means you’ll gradually waste away, as you dip
into your own reserves of fat to make up the short fall.
"You can do really intense stuff for a couple of days, but if you want to last longer then
you have to dial it back.
Every data point, for every event, is all mapped onto this beautifully crisp barrier
of human endurance.
Nobody we know of has ever pushed through it."
The researchers also found that the body cannot process enough calories over longer periods
to go beyond the 2.5 times RMR cap - so simply upping your calorie count won’t be a viable
alternative.
Ultimately, it seems the body has to find a balance for its energy intake and usage
when pushed to its limits, and this is it.