Is Your Throwing Program Putting You At Higher Risk Of Injury?


10 throws at 50%…

Most throwing programs look something like the above. What is 50% though? Is it 50% of your max velocity? Is it 50% of a range of velocities? 

The debate around this has been the focus of Twitter arguments and conference presentations. Everyone seems to feel they have an answer for the best way to utilize RPE. 

Let’s take a step back though and consider what RPE actually is. In this post we will investigate RPE and talk in depth about if we should even be using RPE in our throwing programs. 

RPE by definition is “Rate of Perceived Exertion”. It is a self identified exertion level by the athlete in an activity. In this case we are talking about throwing and identifying the effort of a throw on a 1 to 10 scale. 

Typically coaches or practitioners will tell an athlete a certain RPE that they should throw at for a specified volume of throws. This for years has been how throwing programs are constructed and it has been widely accepted as the way to manage the throwing process for athletes across the game of baseball. 

Our staff wanted to objectively understand an individual athlete’s ability to maintain or “achieve” a certain RPE range. We know many athletes struggle to maintain or “feel” a certain RPE range when asked to. What we really wanted to know though was how many athletes were able to achieve the actual range of a requested RPE. So we set up a study at KP. Here is how we did it…

To start we took a group of 18 athletes ranging in ages 14 to 19yrs. 

We pulled max fastball velocity from each athlete using our Trackman data from these athletes.

We then scaled their velocity from their maximum fastball velocity and broke out expected velocity ranges by percentage.

To conduct the study we did 2 throws at 50%, 70% and 100% while tracking the velocity with a radar gun.

We gave the athletes no other context for what to do except “throw the ball at (insert the intended RPE)”.

Below is our dataset showcasing our measures on each athlete…


Lets review some of our findings… 


Across our population of athletes for this study the average fastball velocity was 85.7. When asked to throw 100% what we saw was that our athletes on average missed their peak velocity by -3.8mph. Meaning they threw 3.8mph slower in our study than their prior peak velocity. So if our dataset held true for all athletes this would mean that when asking an athlete to throw 100% RPE we would routinely see them not reach our intended goal velocity for them and they would miss that goal velocity by almost 4mph. 


Next we went to 70% RPE and thought that our athletes might hit this number more consistently than other requested RPE. On average the 70% RPE for our athletes was 64.3 MPH. What we found was that our athletes actually were off on this number by +8 mph on average. This is concerning because it means that in situations like a return to throw athletes can be up nearly 10mph higher than we intend them to be when planning their throwing program. The amount of stress on the arm when looking at throws with 10mph variance is substantially different. We learned here that 70% and 100% throws for many athletes are quite similar when measuring total stress on the arm and this is in large part due to the lack of separation in velocity from these throws in many cases.  


Lastly we looked at 50% RPE. This one we expected a large difference from the objectively calculated 50% and the athletes ability to produce a 50% RPE throw. The average calculated throw velocity for our population was 42.8mph. Athletes were asked to throw 2 balls at 50% RPE and what we found was that on average athletes were +23mph high of the calculated 50% ball velocity. Again this is substantial in projecting stress accumulated by the athlete during a throwing progression and indicates that RPE isn’t trust worthy across a population when designing individualized throwing progressions. 

So you might be looking at our results and considering that maybe these numbers are off due to the population averages. In this study we also looked at individual variance in throws at each RPE. We wanted to determine if the RPE would be different throw to throw when an athlete expects they are in a certain range. 

So this means even if an athlete didn’t fall within the range of 50% the question is were the throws made consistently at the same velocity outside of the 50% range? Many coaches and practitioners would like to think if the velocity is consistent they can teach an athlete to get to a certain percentage of RPE and the athlete can repeat that RPE accurately. Here is what we found…


When an athlete was at 100% the variance in velocity was .9mph throw to throw. The confidence at the highest effort that an athlete could throw routinely the same velocity is high. However as we went to 70% and 50% we began to see substantial variance in velocity throw to throw. By 50% athletes have a velocity variance of 3.7mph on average. This means the lower the velocity goes for the athlete the more they struggle to maintain consistency of their velocity throw to throw. This means projected stress on an athlete can become substantially varied if using RPE in progressing a throwing program even when the individual athlete RPE is well know. 

To conclude on this study we found that using RPE can lead to substantially over or under training an athlete due to the substantial variance in projected exertion. RPE should not be utilized as a trusted measure to progress training load in throwing programs. For years we have needed a better measure of throwing exertion and a more objective way to individual throw exertions. Workload management is only as good as the individual throw measures we can collect.

Wearable technology such as our KP Sleeve brings forth a new way to more accurately govern the progression of a throwing program. When determining an athletes throwing progression it is critical we not over or under train an athlete. Wearable tech such as our KP Sleeve provides a solution to assure training load is progressed appropriately. With wearable tech such as our KP Sleeve athletes do not have to rely on subjective measures such as RPE to progress their throwing any longer. 


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