I recently took some video of me doing pull ups to study to natural of the movement. Specifically, I’m interested in the velocity and acceleration (and forces) of a typical pull up. Results follow. *Warning: This may bore you, I’m not offended if you don’t read it*
Here’s the experiment set up. Basically just measuring distance traveled at each frame in the video.
Set-up: So I did some pull ups and recorded the displacement at each from. From this I fond velocity (change in distance/time), and acceleration (change in velocity/ time). It is noted that the calculations have some error, and this error is multiplied in each sucessive derivative (acceleration is not as accurate as velocity). This is expected, and can be accounted for if I wasn’t lazy.
Figure 1: Velocity of Pull Ups
As expected, velocity increases, reaches a maximum, and then declines or levels out. The polynominal fit of V1 is of particular interest. It shows a near zero velocity at the top of the pull up. This zero velocity time is exactly when the climber wants to contact the next hold. Practicing lock-offs and stopping at different points in the pull up may help the climber’s muscle memory to attain this “floating” point in different scenarios.
Figure 2: Acceleration of a Pull Up
This was my real objective of the experiment. I wanted to see how much additional force is exerted on the fingers when doing a pull up. It is shown that acceleration rates may typically be 3-4m/s^2, and possibly higher. For a 160 lbs. climber, this is equivalent to a dead hang with 56 additional pounds of resistance (albeit very briefly). Additionally, pull ups are working more muscles than dead hangs.
It is noted that the point where the acceleration crosses the x axis is the point of constant velocity of the climber.
Think of that time you pulled too hard and popped off, or of how you stalled out because you moved too slowly. Controlling your acceleration, and subsequent forces is vitally important, and yet isn’t typically a conscious concern.