Squishing Bugs?

We've all heard this one before, "Squish that bug!" referring to pivoting your back foot when swinging. I'm not really sure where it came from, but it seems silly to me making all those unsightly holes in the field. Squishing the bug is an inefficient movement because of the following. First, it moves the center of gravity of the hitter lower and too far back, making it difficult to reach out in front of the plate for extension. Second, it's slow due to the the friction between cleats and ground providing resistance, and not allowing the hips to move as fast as they could. Three, and most importantly, it breaks the kinematic sequence. By squishing the bug, it is impossible to separate the rotation of the hips and shoulders. They instead rotate at the same time, making the hitter use their arms a lot more, resulting in slower batspeed. See what happens when you squish the bug versus kicking <here>. Squishing the bug causes the centre of gravity of the hitter to move backwards over the back foot. Kicking keeps the hitter's centre of gravity in one place, therefore being able to rotate about the hitter's spine. And since the bat head is supposed to move forward towards the pitcher, it is counter productive to have the centre of gravity to be going in the opposite direction towards the catcher. See how much farther the hitter can reach, relative to the tee in Figure 1 below, when the centre of gravity stays still (aka extension).

a)

b)

Figure 1: Differences in position of centre of gravity in squishing a), and kicking b). In a) the hitter's center of gravity is much farther back than in b), and her bat is therefore not able to reach forward as far relative to the tee. Click to enlarge images.

To overcome friction between cleats and ground, we can avoid it all together by having our back foot in the air! No contact, means no friction, means quicker movement. By "kicking" your back foot forward, it keeps the rotation of your hips tighter aka quicker. Also, by kicking forward, you are driving against your front leg for more power, much like throwing a ball, or pitching.

As mentioned before, it's impossible to separate the rotation of your shoulders and hips when you squish the bug. But why? From the kinematic sequence we know that it starts from the feet, moves to the hips, then shoulders then hands. Squishing the bug is a movement initiated by the hips, in the middle of the sequence. Try wringing a towel out by holding the top still and wringing out the bottom. See how the towels twists gradually starting from the bottom moving up, like a nice kinematic sequence. Now hold the top and bottom still and have someone grab the middle of the towel and start twisting. See how the towel twists above and below the initial rotation at the same time, just like squishing the bug.

Note #1: Even though we're using our hips for power, we're not actually "using" them in the sense that we are using those muscles. We must make sure the kicking action initiates the hip rotation, not the hip rotation causing the kicking. Since the hip muscles are bigger, they cannot move as fast as the foot and knee. By using the hip muscles to kick the foot creates a slower, more sweeping movement with the hips.

Note #2: There is an intermediate movement to kicking the foot and hip rotation called "the elvis." It's when the hips shift forward towards the pitcher before starting to rotate, creating a tilt with the upper body, it's also the start of loading the hands. As the hips shift forward, it makes it easier and almost automatic for the back foot to kick forward. Figure 2 below shows first a hitter's load and then elvis.

a)

b)

Figure 2: Hitter first loads hands a), then shifts her hips forward b). This shift is called the elvis, and creates a good angle from the front hip to the head. Click to enlarge images