On Base U — Separation Test
Over the next couple of weeks I will highlight the importance of (5) On Base U assessments and how/why they might show up in the swing.
Separation Test
The separation test checks the hitters ability to horizontally adduct the shoulder (move the arm across the chest).
Horizontally adducting the lead shoulder joint is important for a variety of reasons including but not limited to:
- Separation of the torso and arms
- Spacing
- Transfer of energy
- Direction
- Bat Speed (Pitch Selection etc.)
Players might fail this test due to:
- Poor shoulder joint mobility or stability
- Limited lead should horizontal adduction
- Poor lead shoulder internal rotation
- Poor thorax mobility
I personally have seen a very limited amount of athletes fail this test but wanted to share my experience with the few that did.
First it is important to understand the importance of lead shoulder adduction. Although all hitters move differently their are are few similarities in how they move. Most great hitters will lose degrees of bend in the lead arm during two phases of the swing: the forward move, and as the pelvis goes into rotation.
A hitter can be physically incable of this or need mechanical adjustments. Here are a few issues that will arise from lacking the ability to perform this movement.
Swing Depth and Path
Here is a good visual from Jerry Brewer:
What you can see is Posey is going to losing bend in the lead arm into toe touch and Weeks maintains a similar degree of bend. This is going to have huge implications on the initial direction the swing is launched and the depth of their path. Posey has created distance between the torso and the back elbow, Weeks has not. This is essential for maintaining space for the arms to swing with proper direction and the elbow the clear the back hip.
Separation/Sequence/Energy Transfer
Above is a K-Vest reading for a hitter who has failed the OBU Separation test (in addition to others) . What you see is very limited energy transfer/gain from the pelvis to the torso/arms and a huge overlap (gate swing). This could be due to a variety of reasons (inability to disassociate etc.) but her inability to adduct her lead shoulder could play a major part. Below is a video showing a similar movement pattern. (Note: She is working VERY hard to fix this!)
The hitter above has raw power and has the ability to hit the ball to all fields. It is important to remember that separation does aid in force creation but also plays a major role in our ability to be adjustable to different speeds and locations.
I also feel like lead side mechanics are often overlooked, the ability to load the lead shoulder and utilize the front last has a huge impact on force production.
I mentioned above the amount of space created between the back elbow and the trunk. Really good visual below. People often forget how important separation is for creating lanes for the arms to swing and hit different pitches.
From my experience not having this information can be extremely detrimental to your process of developing hitters. To the naked eye the hitter may be lacking spacing, pushing their hands, cutting the ball, not able to adjust (firing from the top).
It is important to remember, hitting is a domino effect, the flaw you see was likely caused by something that came before.
#HappyHitting
