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  • Writer's pictureJared

What Is The Motus Sleeve and How Can It Benefit Baseball Players And Coaches?

Do you know what time of year has the highest incidence of injury across all levels of baseball? It's the preseason. The preseason or period of time when you start to ramp up your throwing program is when the majority of injuries occur in baseball. College baseball players are now in the middle of this build up phase so this discussion will be geared toward those athletes, but the following principles can be applied to any level of baseball player. Keep reading to find out some of the reasons injury rates are highest during the preseason and how technology such as the Motus Sleeve can be beneficial in reducing injury risk and improving performance

Why are injury rates highest during the preseason?

The picture above is showing a graph of the typical workload over the course of a season. In the offseason workloads are going to be low, while workloads will be highest in season. During the build up phase of the preseason the goal is to build resiliency and prepare the body to be ready for in game action. However, progressing workloads too quickly during this period has been shown to significantly increase your risk for injury. So the question then becomes what is the appropriate rate of progression for your throwing program?

To answer this question we will introduce you to the concept of the acute to chronic (A:C) ratio, a very important measurement to assessing injury risk in throwers and how it is especially applicable during the preseason or return to throwing program.

What is the Acute to Chronic Ratio?

The acute of chronic ratio compares your acute workload to your chronic workload. Let's define what each of these mean:

  • A daily workload looks the total workload of all throws you do in a single day (includes all throws such as long toss, pregame bullpen and in game throws-traditional methods such as pitch counts or innings do not account for these throws). Did you know that bullpen throws can be 92% of the torque of in game throws? Yet these are often not taken into consideration. Workload also takes into account the intensity of the throws, not just the number of throws. In terms of stress, every throw counts and not all throws are equal.

  • Acute workload looks at the daily average of what you have done over the past week

  • Chronic workload looks at the total workload of what you have over the past month.

To calculate the acute to chronic ratio you divide your acute workload by your chronic workload. This ratio gives a good indication of your readiness, fatigue levels and determine your potential risk for injury. Don't worry you aren't required to do any of this math for this!

Why does this matter?

As mentioned above the acute to chronic ratio gives us a good insight into your level of fatigue and readiness. Did you know that throwing while fatigued has been shown to be a significant risk factor for injury? Research has even shown that you are 36x more likely to have an injury while throwing while fatigued (Olsen et al)! This is significantly higher than the risk associated with the number of pitches thrown, number of months of throwing during the year and throwing velocity (I'm not saying these aren't important considerations as well, just highlighting the importance of fatigue). Throwing while fatigued not only is going to put you an increased risk of injury, it can also affect performance and your control.

Research has shown that an pitchers with an acute to chronic ratio > 1.3 were 15x more likely to experience an injury (Mehta). This means that the player increased their workload by 30% from what they were were conditioned to do. Ideally you want to build up at a rate that stays under this ratio to decrease injury risk. You can see this visual in the graph below.

What does this mean for college baseball players and pitchers in particular?

The college baseball season schedule has always presented some unique challenges for players and coaches during the preseason phase. Players will go through fall ball, which is then followed by a relatively short shutdown period and winter break. During this time your chronic workload (what you have done over the past month) will drop significantly. This short shut down is then followed by a relatively quick ramp up phase upon return to school to prepare for the season. This scenario can often lead to spikes in the A:C ratio and put you at an increased risk of throwing while fatigued and an increased risk of injury. This season has presented even more challenges during this phase with players having an extended winter break and less direct contact with their coaches. For your reference after a shutdown for as little as 4 weeks it takes approximately 120 days (4 months) to build up the necessary chronic workload to be ready for in game action. So be aware of what these shutdowns mean and the implications it can have to being ready for your season.

How can the Motus sleeve help?

The Motus sleeve is wearable technology that now allows athletes and coaches to have access to this information at their fingertips. This wearable technology gives pitchers a more accurate picture of the workload on their arm compared to traditional pitch counts. The player wears the Motus sleeve while throwing and it will measure the torque on the arm and stress on the UCL ligament. It will also calculate your own specific acute to chronic throwing workload ratio which is a good indication of your fatigue and readiness. You can also share this information in real time with other members of your team such as the coach, trainer or physical therapist to help make the most educated decisions to get you back up to speed and stay at that level once you are competing.

This same information/concepts can also be applied to many other scenarios where players can be exposed to an acute spike in workload compared to a low chronic workload:

1. High school players going from a winter sport to a spring baseball season and trying to quickly ramp up throwing to get ready for the season

2. Fall showcases where the player has not maintained any consistent throwing program and has an acute spike in throwing intensity and volume

3. Spring training for professional players: A study by Posner in 2011 over a seven-year period for MLB players show that the large majority of injuries occur in the first month of the year.

4. Return to throwing protocols after surgery/injury: Traditional throwing programs and protocols are often one size fits and all and have standard distances or throwing intensities for each stage to determine progression. However, these protocols are incomplete and flawed in some ways. Research has shown that players have a very difficult time being perceiving what intensity they are throwing at. For example, the program/protocol may call for 50% effort at 60 feet, but research has shown that players often end up throwing at a much greater intensity than this. Using technology such as the Motus sleeve can help give a more accurate measure of the torque and workload they are throwing at and make the return to throwing protocols much more individualized.

While this information can be valuable to your return to throwing program, it is not the only piece of information that should be taken into consideration. Your strength and fitness, sleep, nutrition, recovery and individual response to throwing/training are just some of the other factors that can influence your fatigue and readiness. However, technology such as the Motus sleeve can allow us to be much more individualized with our recommendations compared to traditional measures of pitch counts and innings limits. If you have any interest in learning more about this technology or have any questions about these concepts feel free to email me at

I have also included a link to the Eric Cressey Elite Baseball Development Podcast episode with Ben Hansen which is a great listen for any of those who are interested in listening to more of these concepts:


1. Olsen, S. J., Fleisig, G. S., Dun, S., Loftice, J., & Andrews, J. R. (2006). Risk Factors for Shoulder and Elbow Injuries in Adolescent Baseball Pitchers. The American Journal of Sports Medicine,34(6), 905-912. doi:10.1177/0363546505284188

2. Mehta, S. (2019). Relationship between workload and throwing injury in varsity baseball players. Physical Therapy in Sport, 40, 66-70. doi:10.1016/j.ptsp.2019.08.001

3. Posner, M., Cameron, K. L., Wolf, J. M., Belmont, P. J., & Owens, B. D. (2011). Epidemiology of Major League Baseball Injuries. The American Journal of Sports Medicine, 39(8), 1675-1691. doi:10.1177/0363546511411700

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