Improving Speed and Power from the Stretch

The back leg is the initial power source in pitching and when pitching from the stretch, the ability to load and the unload the back leg gives a pitcher the greater advantage with runners on.

Faster more elastic athletes can stretch their tendons quickly and better harness energy while loading without requiring high levels of strength. But for more “strength-based” athletes who like to load slower in order to maximize power mostly from their muscles contracting, the stretch can be a nemesis, especially you have runners on base. So, training to get more elastic can go a long way in putting another essential tool such as getting quicker in the stretch into their toolbox, which brings us to the concept of Reactive Strength and how you test it.

Reactive Strength: Reactive strength shows an athlete’s ability to change quickly from an eccentric to a concentric contraction and their ability to develop maximal forces in minimal time via the stretch shortening cycle (SSC).  In baseball, particularly pitching, it’s like getting in-and-out of your glute load as quickly as possible.

How do we test for Reactive Strength? The reactive strength index (RSI) was originally developed as part of the Strength Qualities Assessment Test (SQAT) developed by the Australian Institute of Sport to measure the reactive jump capacity of athletes and to determine how they cope with the stress imposed on their body from plyometric exercises. It’s directly related to acceleration speed, change of direction speed, and even agility.

Creating a “Lateral RSI”

Although there are many valid and reliable tests used to measure the Reactive Strength Index in the sagittal plane, power in the frontal plane has shown to provide the greatest carry over to sport in baseball players, especially pitchers. So, for this reason we have devised a test we call the “Lateral RSI”.

Using a 12” box (to test deceleration abilities as well), the athletes drops into and out of a load (much like pitching from the stretch). Contact Time and the lateral distance jumped are both measured, and a formula is used to calculate what we call the “Lateral RSI”.

This test tells us how elastic (how well) a pitcher utilizes his SSC in the frontal plane and/or how quickly he can get down the mound.

(Lateral RSI)


We recently tested 80 Division 1 pitchers for my upcoming presentation at Pitch-a-Palooza and used the results to devise a grading system that we use to decide whether this is a weak link in the pitcher’s athleticism / delivery.  Here is the scale:

> 5.0 – Good

4.5 – 5.0 – Average (should be improved)

< 4.5 – Below Average (needs work)

Basically, any score under 5.0 tells us that a pitcher can improve his speed and more than likely his power in the stretch through additional plyometric training and/or Ecc. / Isometric lifting.

Training the Results

A Lateral RSI below 5.0 with:

A good contact time (<.350 ms) and less than optimal jump distance (less than 75”) – This athlete more than likely needs to get strong eccentrically. Enter eccentric lifting with a hold in the low position.

(Ecc. Split Squat Holds)

A slow contact time (>.350 ms) but a good jump distance (greater than 75”) – This athlete needs to work more plyometrics into his program preferably on movement days, to help reduce ground reaction time and make better use of his stretch shortening cycle. For this we use Reactive Heidens and adjust jump height to allow > .350 ms) As the athlete gets faster, the distance can be moved.

(Reactive Heidens)

Either way, testing and giving the athlete what they need is the key.

See ya’ in the gym…

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