Keiser Rotational Power and Pitch Velocity

Ricky Norton (Sports Performance Expert)

Tyler Standifird PhD (Assistant Professor in Biomechanics)


It is well understood that rotational athletes need power and strength in order to perform at a high level. Unfortunately most of the measurements of power and strength in rotational athletes are measured in linear or sagittal movements such as squats, deadlifts, bench presses and other similar type exercises. It would make sense that rotational power measurements would be more closely related to the performance of rotational athletes, but more studies are needed to investigate if this relationship does exist. Keiser machines allow for the measurement of peak rotational power and provide great information to trainers and coaches about movements that may be more closely tied to their rotational athletes. The purpose of this study was to investigate the relationship between rotational power as measured by a keiser machine to throwing velocity in High School and College Pitchers. It was thought that rotational power would be related and important to the maximum velocity in these baseball pitchers. 


Fifteen high school level baseball players participated in the study. First, the athletes went through our standard dynamic warm-up. Then they performed 1 set of 10 reps of each exercise of the Jaeger Band Series. Following that, they each performed 2 sets of 10 reps of a Reverse Throw and a Pivot Pick-Off throw using a 32 Oz Plyocare ball. The pitchers were then given as many throws with a 5 Oz baseball as needed until they felt their arms were warm and ready for testing. Once warm, testing consisted of 10 Pull- Down throws (Crow Hops) for max velocity into a net. Of these ten throws, the last three throws were used for analysis. These last few throws led to the most consistent throwing velocities for analysis. 

Peak power was then assessed using a Keiser Performance Trainer (rotational machine) and was completed on a task that was familiar to many of the players due to training experience (Rotational Chop at chest height). Peak power was assessed after a warm up that consisted of 5 reps at 30 PSI, followed by 5 reps at 35 PSI, followed by 5 reps at 40 PSI. They then tested with 5 reps at 50 PSI. The Peak Power of the 5 reps at 50 PSI was recorded.


A simple linear regression analysis was completed in order to understand the relationship between keiser peak rotational power and pitch velocity. The peak power measured on the keiser appears to be highly related to pitch velocities for the athletes in this study. The R^2 value of 0.467, which suggests that the rotational power of these athletes accounted for nearly 50% of the variability in throwing velocity. This value suggests a moderate to large relationship for these two variables. The data suggests that for every increase of 40 watts of power on the keiser rotation test, the athletes would have a one mph increase in throwing velocity. 


As hypothesized, the findings of this study suggest that rotational power and maximum throwing velocity in baseball players, are related. For the athletes tested in this study, the R^2 value of nearly 0.50 shows a moderate to strong relationship for the two variables under consideration. The findings of this study show evidence to support the importance of training for the improvement of rotational power. Strength and conditioning coaches of baseball players should focus heavily on rotational movements and specifically how they can improve power as measured on a keiser rotational test. Rotational range of motion in the core (Hips & Thoracic Spine), strength of the hips and trunk in rotational movements and improvement on technique, are just some of the areas that can lead to increased performance on the keiser rotational test. Also, improving core stability seems to help increase rotational power, anecdotally. Coaches and trainers should understand these important relationships and should ensure that athletes spend a bulk of their time on movements in the transverse plane, and training exercises that will lead to improvements in rotational power, and not just linear (Sagittal plane) strength. Future studies should continue to investigate these relationships and if more groups of baseball players would have similar results. Also, adding a mound for the pitcher population to see if there is more or less of a relationship to the keiser test. If these relationships continue to be strengthened, it will be important to learn and understand what specific training can improve rotational power and also throwing/pitch velocity.

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