Addressing Deficiencies in Blast’s Rotational Acceleration Score

By Nunzio Signore (BA, CSCS, CPT, NASM, FMS)

When an athlete comes into RPP, they receive a physical assessment, as well as a full hitting analysis. This analysis along with the strength/mobility assessment makes up the critical pieces for creating the best “game-plan” for our hitters. The 4 pieces of tech that we use to assess our hitters are as follows:

The first two, Video and Blast Motion will be the pieces of tech we will be discussing today.  I’m going to specifically focus on the Rotational Acceleration from Blast Motion.  I am also going to talk about several mechanical issues we see during the video analysis as well as movement issues even further down the chain that can also affect these numbers. Basically, it involves combining tech with our “hands-on” assessment.

While technology provides answers that are calculated and stored, it is neither creative nor does it have the capacity to ask questions. These qualities are human.

  – Bill Hartman (co-owner IFAST)

Rotational Acceleration measures how quickly the bat accelerates through the zone from first move to getting on plane. Essentially, it tells how quickly the hitter gets on plane with the pitch once they begin their swing. According to Blast Motion, the average MLB player has a Rotational Acceleration of 17g.

A high Rotational Acceleration helps players create power at contact and gives the maximum amount of time to react to a pitch. While there are many variables that contribute to better acceleration, today we’ll look at what I feel are the big 3 we see a lot with young athletes in our facility, they are:

    1. Lower body stability / mobility
    2. Maintain scapular strength / mobility
    3. Anterior core strength / lateral stability

A. Lower Body Stability / Mobility

The swing, much like pitching, is generated from the “ground up”. So, as a result, just about all speed/power issues that shake free in upper body metrics are usually related to a disconnect in the lower half, especially in younger athletes who usually haven’t developed an adequate base of strength.

Mechanics: This lack of lower body strength can show up on video with an unstable base at foot plant or poor lead leg blocking due to a loss of posture during the linear move. This will make it hard for these athletes to not only load the back hip/glute, but keep it loaded all the way through the linear move and into the beginning of rotation. This lower half leak compromises posture as well as weight distribution at heel plant preventing a good stable base to transfer force up through the upper half and into the bat to achieve maximum acceleration.

(Lateral KB Lunge)

B. Maintain Scapular Strength / Mobility

The more the upper half lags behind the lower half, the more force or kinetic energy can be created by increasing the elastic load on the trunk. Creating a good scap load plays a big part in helping to create this tension (torque) with the upper half in the opposite direction of the force being created with the lower half, much like wringing out a wash rag.

Mechanics: it’s important not to confuse torso rotation with a scap load. Remember the scap is bringing the arm back NOT the trunk. When analyzing video, wrapping the bat can be a dead giveaway that the torso may be counter-rotating too much. That’s why strengthening ext. rotation as well as scap stability can be a game changer.

(Band Pull Apart)

(Dowel Trap Raise)

It’s important to note that we not only need to be able to load the scap but maintain that load in order to keep slack out of the body as the lower body power is transferred through the core. This brings us to point number 3.

C. Anterior Core Strength / Lateral Stability

Good anterior as well as lateral core strength/stability will allow for greater hip shoulder separation as well as the ability to hold that separation for later in the swing.

Mechanics: A strong core can help prevent the arm/shoulder from going early and losing energy transfer into the arm and ultimately into the bat, reducing rotational acceleration and bat speed. When analyzing video, inadequate space with the hands at foot plant is a dead giveaway that the abdominal sling is not being stretched tight enough thus creating too much slack thus less than optimal hip/shoulder separation.    Working the anterior core as well as the obliques can go a long way in not only creating rotation but holding it there until needed as well.

(Plank w/ Reach)

(Side Bridge)


By connecting a strong and stable lower half to a great upper half, scap load via a strong core helps us keep slack out of the body. This can help create a tighter turn while maximizing acceleration. The more efficient the hitter becomes at generating maximum acceleration, the quicker he can deliver bat speed and increase overall power production at contact.

See ya’ in the gym…

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