Throwing mechanics and RPE

Biomechanics picture joe marsh

Every throw anybody ever makes, from warm up tosses to max effort 0-2 fastballs, has some kind of rate of perceived exertion (RPE) associated with it. This RPE is essentially what percentage of “max effort” the throw feels like to the thrower, and ranges from 0-100%. This is an extremely important concept in baseball, as pitchers can’t just throw at 100% RPE every time they pick up a ball (without eventually getting injured), and so understanding how to incorporate RPE into a training program is critical. A good program not only needs to manage RPE on a day-to-day basis, it also has to consider weekly, monthly, and even yearly timescales and adjust accordingly to make sure an athlete isn’t building up too much fatigue in a given time period. The problem then is developing an athlete’s optimal throwing program within these constraints of RPE management. I won’t even go into how strength, mobility, injury history, etc. play into this equation, but it’s safe to say that this is extremely complicated!

There are many ways of solving this problem, and due to all of the variables involved the solution for each athlete is going to be highly individualized. However, there is one important consideration in solving this problem that I believe is often overlooked by a lot of players and coaches (myself included until recently!), and that is how an athlete’s mechanics change at varying RPE’s. A lot of people in baseball assume (incorrectly) that an athlete’s mechanics at max effort or game intensity are going to be the same as they are at lower intensities, when in reality a lot of critical movments can change. As I’ll discuss more below, I recently had a conversation with my Driveline online trainer Dean Jackson about this exact topic, and he referred me to this series of tweets by Joe Marsh. Joe did a biomechanical analysis of a given thrower and noticed that at low intensities, certain aspects of the throwers mechanics were very different compared to higher intensities.  Here’s a GIF of the athlete below (green is an 86 mph throw, and red is a 71 mph throw by the same athlete). As we can see, the 86 mph throw has significantly more torso counter rotation at stride foot contact than the 71 mph throw, as well as lower kinematics velocities overall (which is what one would expect…note how the green arm “catches up” to the red arm):

Biomechanics gif Joe Marsh 2

So, what are the implications of this? Joe’s analysis only looked at one particular athlete, and it is possible that different biomechanical variables change for different athletes at lower vs. higher intensities, but it is fair to say that we shouldn’t expect an athlete’s 60% and 100% RPE mechanics to be identical. Joe’s athlete had less torso counter-rotation and scap loading (shoulder horizontal abduction) at lower intensities, which makes sense given that these variables are correlated with velocity, and I wouldn’t be surprised if this is a common trend among throwers. Either way, one needs to consider how mechanics change at varying intensities when designing a program, and that it might be better to work on certain mechanical changes at higher intensities as compared to lower ones. Obviously, it is pretty tough to work on your mechanics at max effort, and it is possible that certain changes can be made even at 50-60% intensity, but for movements like torso counter rotation or scap loading, it might be better to work at higher intensities (e.g., 80%+). This adds a new layer of complexity to the problem of designing a program, as athletes that have a specific mechanical inefficiency to work on might be better off doing this at a higher RPE (or not), so a good program must be designed with this in mind while still maintaining reasonable RPE loads over longer timescales. Due to the fact that every thrower’s mechanics are different, a certain degree of trial and error is necessary in order to figure out what RPE’s are best for each individual athlete (and for each mechanical inefficiency).

Another important consideration of this is command training and pitch design work implications. For command training, it is clear that the goal is to command the ball well at game intensity, so it makes sense to use higher intensities (70%+) when doing command work, as Bill Hezel points out in this blog post. This isn’t to say that command work at lower intensities is useless, but the issue with it is that command is such a precise skill that any small variations in mechanics can lead to major changes in where the ball ends up going (with one important caveat that I will discuss below), so by training command at lower RPE’s (and therefore different mechanics), it is more difficult to transfer this to game intensity. There is a similar issue in doing pitch design work at lower intensities, although the way it manifests itself is a little bit different. As Michael O’Connell discusses in this blog post, the spin efficiency (essentially, the component of the angular velocity of the pitch in the plane perpendicular to the direction of travel, which is critical in determining how the pitch actually moves) of different pitches can actually change with RPE. Therefore, if you want to work on developing a curveball, throwing a lot of curveballs at 70% RPE might not be the best way to do it, because your mechanics at 95% RPE might be a bit different and could influence the spin axis of the pitch. Therefore, in general it is better to do command and pitch design work at higher intensities in order to maximize the carryover to actual games, while managing RPE well on a day-to-day, week-to-week, etc. basis in order to avoid fatigue buildup as much as possible.

long toss

With all of this in mind, there is an important caveat that I want to discuss when it comes to variability in pitching mechanics. Not all variability is bad, and we actually need some kind of variability in order to have stable mechanics over the long run. As Randy Sullivan from the Florida Baseball Ranch discusses in this blog post, by adding variability to your mechanics through training modalities like long toss, your arm gains the ability to adjust when small fluctuations inevitably happen over the course of a game or season. Randy goes on to discuss a dynamic systems theory approach to pitching mechanics, which could honestly be a topic for another post, but essentially his point is that certain movements in the pitching delivery (the attractors) should be trained to be stable, whereas other movements (the fluctuations) should be allowed to…fluctuate. Thus, if certain core movements/attractors of the delivery are changing at different RPE’s (e.g., torso counter-rotation), then it wouldn’t be wise to try and specifically train these movements at lower intensities. However, if other movements (fluctuations) will indeed fluctuate during a game, then they should be allowed to vary in training, and long toss does exactly this. Therefore, while some game-specific work is necessary, making every throw off a mound 60 feet, 6 inches away from home plate is misguided, and will prevent your mechanics from actually being adjustable in a real game.


My week of training

This past week was the first week of offseason training for me, and I’m taking a few weeks of deloading on the throwing side, meaning that I’m not going to be throwing at over 70-80% intensity (on the lifting side, though, I’m ramping back up from in-season to offseason loads). As I mentioned earlier, I noticed this exact movement pattern of not counter-rotating my torso at lower intensities in my own mechanics last Friday (see video above). Initially I was a bit worried, especially because the stresses on these throws were a bit high given that they were only at 50-60%, but after talking with Dean and looking up the tweet from Joe that I mentioned earlier I realized this sort of makes sense. I still think my torso counter-rotation could use some work (and it’s sort of been an ongoing issue this past season, even at higher intensities), but now I know not to necessarily expect it to be perfect at lower intensities.

The plan moving forward is to stay on this deload block for the next few weeks, and then work into bullpens after that, eventually getting into live at bats after I get back home from school. I mentioned this in my last post, but the goal for this offseason is to develop more mechanical and mental consistency through live AB work, but also have the ability to train full time, as opposed to playing in a summer league and limiting my development window a bit. I also am strongly considering spending another month or so at Driveline at the end of the summer, and getting live AB work in there as well as an assessment to build a better plan of attack moving forward. I’m excited for the summer and for these next few weeks of training leading up to it, and I think it’s a big opportunity for me to really turn a corner.

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