Throwing "Bows"

Did you ever think that someone's hitting problems could be due to their body shape? Try this test on yourself, straighten your arms out in front of you with your palms facing up as shown in Figures 1 a) and b). Notice how in Figure 1 a) the subject's arms form a straight V shape, while in b) the subject's elbows are more inverted, coming closer together when their arms are straight.

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b)

Figure 1: Example of straight elbows a), example of inverted elbows b). Click to enlarge images.

But what does this have to do with hitting? Well, someone having inverted elbows will be more likely to slot their back elbow incorrectly. As your hips start to rotate and your elbow starts to slot, your back elbow should come in close to your body with a small gap between your elbow and torso. From a side view, you should see your hands lead your elbow as shown in Figure 2 a) through f), or the blue dots (hands) are always leading the red dots (elbow).



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b)

c)

d)


e)

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Figure 2 a) - f): Hitter 1. Frame by frame beginning of swing. Representation of properly slotted elbow, with hands leading elbow. The blue dots mark the hitter's hands and the red dots mark the hitter's elbow. The green dot marks the bat head, and the yellow line marks the height of the bat head. Click to enlarge images.

If you have inverted elbows your elbow is more likely to lead your hands as you slot them, because this position feels more natural. As shown in Figure 3 a) through f), the red dot starts to lead the blue dot as the hitter starts to bring her hands forward.


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b)

c)

d)

e)

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Figure 3 a) -f): Hitter 2. Frame by frame beginning of swing. Representation of an incorrectly slotted elbow. As the hitter starts her swing, her elbow (red dot) drops in to her side, and leads her hands (blue dot). Green dots mark the bat head and yellow line marks the height of the bat head. Click to enlarge images

There are several ill effects of letting your elbow lead your hands. First and most importantly, it causes your top hand to go away from you over the plate creating a circular swing, also known as casting (refer to older post). Notice in Figure 2 f) how straight Hitter 2's front arm is, resulting from her top hand going away from her body. Also, from what we know about casting, it doesn't allow the hitter to reach forward to the pitcher with their top hand, also known as extension. Instead, the hitter's swing is "cut off," and her top hand rolls over early as shown in Figure 4 a) and b). Notice the yellow line marking the height of the bat head, and how high it comes up upon rolling over. In fact, from one frame to the other, the bat head raised almost 14 inches! Now imagine if a hitter rolled their wrists earlier in their swing, closer to contact, how hard it would be to hit the ball!


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b)

Figure 4: Subsequent frames of Hitter 2's swing after contact. Lack of extension due to casting. The red circle in b) shows the top hand rolling over causing the bat head to raise up, marked by the yellow line. Click to enlarge images

Figure 5 a) through c) below show Hitter 1's extension. Due to properly slotting her elbow, her top hand is able to face up and reach toward the pitcher.

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b)

c)

Figure 5 a) - c): Hitter 1 frame by frame after contact extension. Notice how the hitter's top hand is facing up in all 3 frames. Click to enlarge images

Also, dropping your elbow into your side, as seen in Figures 3 c) and d), causes to bat head to drop considerably. In fact, comparing Figure 3 c) and d) (Hitter 2) to Figure 2 c) and d) (Hitter 1), the bat head drops approximately 5 inches more in Hitter 2's swing than Hitter 1's. This downward momentum thus makes it harder to hit higher pitches. Since momentum is a vector quantity (mass x velocity), Hitter 2's hands must overcome a greater downward momentum than Hitter 1 in order to adjust to the higher pitch, as shown in the schematic in Figure 6.



Figure 6: Schematic of vector addition of momentum. Properly slotting your elbow causes the bat head to have less momentum in the downward direction, therefore less momentum to overcome to hit the high pitch.

There is also another reason why one would slot their elbow incorrectly, with or without inverted elbows. If a hitter rotates their hips too slow, their upper body naturally wants to help them out in order to be in the right position to hit the ball square. The most efficient way that your arms can move your hips is by dropping down lower, aka dropping your hands and tucking your elbow into your side. The most efficient way to move an object is to apply force closest to the center of mass. By lowering your hands and bringing them closer to your waist, the centripetal force applied during swinging is therefore acting on your center of mass more efficiently. The result is that that hitter has opened her hips, but an incorrectly slotted elbow, back to square one.

So how does one fix this problem? Try taping a football on the inside of your bicep as shown in Figure 7, and swing as normal. The football prevents your elbow from getting too close to your body, and making it harder for your elbow to lead your hands. View the 3 swings in slow motion here, you should be able to see the hitter's hands leading her elbow.


Figure 7: A football taped to a hitter's inner bicep prevents her elbow leading her hands. Click to enlarge image