Eva Voortman - Insideout softball science, May 2020
Throwing, smijten or pitching? Pitching from top till toe to the top - Separation time
What do you need to throw hard? Well actually, everything. From the big toe of the push-off foot, to the hand in your glove, and from the toe of your landing foot to the fingertips of your pitching hand. To accelerate the ball in an optimal way, you need the fingers of your pitching hand to go as fast as they can, and this acceleration literally comes from your big toe. The reasoning behind this, and how you can accelerate your body from that toe to your fingers is what I will explain the coming weeks along findings from scientific articles combined with my experience as a pitcher(trainer). This week: Separation time
Most research finds that both length and weight are important factors for ball velocity. But, with relatively small pitchers who still are able to pitch high velocities, it is easy to conclude that there are more factors which influence ball velocity. The timing of the pitching motion is quite difficult to measure and has not been researched as often, but seems to be an important factor. Both the timing and speed of the body, in other words the speed and timing of the kinetic chain.
The kinetic chain, rotational velocities, degrees of freedom, it is getting clearer how difficult it actually is to throw as hard and accurate as pitchers want to. In the previous articles the underlying mechanisms of human movement are explained, now it is time to explain a specific link in the chain: The link between the pelvis and the thorax (upper body). The link has, on both sides, a rotational velocity, namely the rotational velocity of the pelvis and the rotational velocity of the thorax. To measure the timing of the pitching motion, the time between the peaks of those rotational velocities is measured. The time between the peak rotational velocity of the pelvis and the peak rotational velocity of the thorax is the so-called separation time of the torso.
Another term, the separation time. The separation time of the torso was the subject of my master’s research. Both my thesis and bachelor’s research before, were already focused on soft- and baseball throwing. My interest for the separation time came because of my curiosity towards the timing of the pitching motion, and because not much research has been done in this area.
An important link, that was already mentioned above, is the one between the pelvis and the thorax. Here, the energy is transferred from the powerful bottom of the chain to the whipping top of the chain. How long this transfer takes, or maybe a better question, what this time is supposed to be, is still an unanswered question.
In order to get to know more about the separation time in softball pitching both the peak rotational velocity of the pelvis and peak rotational velocity of the thorax are measured with sensors. By calculating the time between the measured peaks from the signals, the separation of each pitch is measured.
From the measurements in the research, it stands out that quite some negative separation times were measured. A negative separation time means that the chain was not initiated in the right order, the thorax rotated before the pelvis did.
Because it is more interesting to see what the timing is supposed to be, when the kinetic chain is initiated in the right order, it is valuable to look at the measurements resulting in a positive separation time. If so, it appears that peak rotational velocity of the pelvis, peak rotational velocity of the thorax and the separation time are significantly associated with ball velocity.
So, let’s twist that pelvis? No, it is not that simple. The three factors are and will be part of a chain. The order, speed and peak determine how much energy is transferred upwards. The links before the trunk determine how much energy goes into the chain, the links after the trunk link, determine how much will get out of it.
This is where the title of the articles refers to, from top to toe to the top. The principles are discussed, the link with the separation time of the trunk is explained. Time to put the link in the chain, in the phases of pitching. From set-up to follow-through.
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Until the next one!