Got What It Takes to Compete in Speed Climbing?

Speed climbing is a real sport. In fact, it will be one of three new climbing events in next year’s Olympic Games in Tokyo. The goal is to scale a 15-meter wall and slap a timer button at the top before your opponent in an adjacent lane does. The wall has outcroppings to grab and push off of, and they’re always the same, so competitors have every move memorized.

Still, the speeds they reach are insane—the race looks like a 100-meter dash up a vertical wall. Spider-Man would be jealous! The world record is currently held by an Iranian man named Reza Alipour, aka the Persian Cheetah, with a time of 5.48 seconds. Seriously, check out this video of Alipour at the IFSC World Championships last year.

So you’re thinking, “Hey, it’s early days in this sport. This might be my big chance to make an Olympic team before everyone gets in.” The question you need to answer is this: If you practiced enough—if you mastered the technical skills—do you have what it takes physically to get somewhere close to that speed?

To find out, we want to look at the idea of an athlete’s power output. What is power? In physics, it’s the time rate of energy use. No? OK, let’s refresh.

What Is Power?

Remember how light bulbs used to be rated in watts? Watts are a unit of power. A 100-watt bulb drew energy at a higher rate than a 60-watt bulb, so it was brighter. If you ran them both for an hour, the 100-watt bulb would use up more energy. (In fact, they’d use 100 watt-hours and 60 watt-hours of energy, respectively.)

It’s the same if you hoist a barbell off the floor. There is a decrease in the energy stored in your body, while the barbell increases in kinetic energy (because it speeds up) and gravitational potential energy (because it moves up). To execute the lift fast, you need a high power output. If you take a long time, you’ll have the same transfer of energy but a much lower power level.

You get the idea: In speed climbing, you’re competing on time, so the limiting factor on your performance is your power output—the time rate of energy use. Only here you’re both the motor and the object being moved: You’re using your muscles to hoist your body mass up a wall, in defiance of gravity, which would like you to stay on the ground.

Power Output of a Speed Climber

So what kind of power levels are we talking about? We can estimate it from the video above of Alipour’s climb. All we need to know is the time to the top of the wall and the amount of energy used over that interval. Here’s our basic equation. Power (P ) equals the change in energy (𝚫E) divided by the change in time (𝚫t):

Illustration: Rhett Allain

How do we estimate the change in energy? Let’s think about it: A climber has to do two things. He has to increase his speed (accelerating from rest) and also increase his height.

The increase in height corresponds to an increase in gravitational potential energy (U). We can easily calculate that as:

Illustration: Rhett Allain

Here g is the local gravitational field with a value of 9.8 newtons per kilogram, and 𝚫y is the change in height (in meters). It also depends on the mass, m, of the climber, which I’ll guess is around 70 kilograms.

The increase in speed means there will be a change in kinetic energy (𝚫K), which can be calculated as:

Illustration: Rhett Allain

To get that, I just need to know the change in speed (v) as Alipour goes up the wall. Oh sure, I could just use the distance traveled (about 15 meters) to get it—but what fun is that? Instead, I’m going to get position-time data from each frame of the video using the Tracker video analysis tool. Here’s my plot of height as a function of time.

Check it out: The slope of the curve at any point is his speed at that moment (since it’s distance/time). Fitting an overall slope to this curve, I get 2.22 meters per second as an average velocity. I’m actually surprised to see that he moves upward with a fairly consistent velocity—it’s almost a straight line. He just slows down a little bit in the last 2 meters to about 1.8 m/s.

I can also use Tracker to get the change in height (Δy) of his center of mass as he moves up the wall. This is actually less than 15 meters, since only his hand needs to reach the buzzer at the top. (My estimate here may be slightly off because of the way the camera pans up during the motion.)

Maybe Keep Your Day Job …

Great, now we have all the number inputs, and we can run the calculations. I put them in Python in case you want to try this with your own data. (Click the pencil icon to see the code. You can enter your own weight and time.) Here are the results.

So Alipour’s power output is 1,482 watts. How does that compare to what an average person can do? It depends on how long you have to sustain it. Humans are capable of large bursts of power over short time intervals.

Try this: Get out of your chair and jump, as explosively as you can, into the air. If you move maybe 20 centimeters in a fraction of a second, say 0.2 second, you could have a power output as high as 680 watts. Now jump over and over … yeah, your power level is plummeting. If you got on a bike and pedaled for an hour, you’d probably be down to about 100 watts.

But what about elite athletes? Tour de France cyclists can sustain levels of around 500 watts for hours. (They eat a lot of sandwiches.) In a 15-second sprint for the finish line, they’ll hit levels of around 1,200 to 1,400 watts. (In his book Bicycling Science, Dave Wilson has a data point with a power output of 2,378 watts for three seconds, which seems almost impossible.)

That’ll give you some frame of reference. Needless to say, Alipour’s 1,482 watts of power is going to be hard to beat in Tokyo.

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