Abstract on the Examination of The Kinetic Arm Throwing Sleeve and its Effects on Throwing Mechanics

 "The Perfect Arm data shows a significant statistical decrease in elbow torque," -Brittany Dowling, MS, Director of Research and Validation for Motus Global


Zareminski et al. (2018). Orthop J Sports Med.
Saltzman et al. (2018). J Shoulder Elbow Surg
Boddy et al. (2019) PeerJ,
Abstract Conducted with Motus Sensor/2019


In the overhead throwing athlete, elbow injuries commonly occur, especially in baseball players. Various methods have attempted to manage throwing volume and load via manipulation of training or performance factors, such as pitch counts, inning limits, or pitch type restrictions. However, even with these methods in place elbow injuries continue to rise. In high school, collegiate, and professional baseball pitchers there has been no link to pitch and inning counts and reduced injury risk [1,2]. Recently, a throwing device, The Perfect Arm worn on the throwing arm has been developed in attempts to alleviate the stress seen at the elbow.  The purpose of this study is to investigate the effects of The Perfect Arm device on the athlete’s throwing biomechanics, specifically elbow valgus torque, arm rotational velocity, arm rotation, and arm slot.


A total of 8 high school and collegiate baseball players (age 18.8±2.9 yrs; height 71.8±1.9 in; weight 183.9±32.2 lbs) were used in this study. Players reported to Elite Edge (Chamblee, GA) facility and were fitted with a motus baseball biomechanics sensor and sleeve (Motus Global, Rockville Centre, NY, USA). Each player was given unlimited time to warm-up for maximum effort throwing. When ready, players were asked to throw 5-8 throws without wearing the PA device and then 5-8 throws while wearing the PA device. Throws were made into a target on a net at a distance of 20 ft away with maximum effort. Players were allowed to crow-hop and were instructed to take their time between throws. Ball velocity was recorded with a radar gun (Pocket Radar, Santa Rosa, CA) for each throw. The sensor recorded four metrics - elbow valgus torque, arm rotational velocity, arm rotation, and arm slot - for each throw. Previous research has shown the biomechanics sleeve to be a valid tool for these measurements [3]. For each player, measurements were averaged for both conditions. Paired t-tests were used to compare without PA throws and with PA throws. The level of significance was set at p < 0.05.


Means and standard deviations were calculated for both conditions (Table 1). Elbow valgus torque was lower in the PA condition (p=0.01). There were no differences in arm rotation, arm speed, or arm slot between conditions. The Perfect Arm sleeve is a unique intervention that directly manages biomechanics on the throwing upper extremity for the throwing athlete. The Perfect Arm sleeve could be applied to the broad spectrum of the care of the throwing athlete. Specifically, the PA could be utilized for all aspects of the athlete’s throwing arm preseason, in-season, and post-season management. For rehabilitation of the throwing athlete, the PA could serve as a rehabilitative assistive device for the return-to-sport phase for throwing, similar to how post-operative ACL patients may utilize aquatic therapy to facilitate return to running.


Wearing The Perfect Arm device allows for the same throwing mechanics in baseball players while decreasing elbow valgus torque. This device can be used in the rehabilitation of players as they progress in their return to throw programs preseason, in season, or post injury as a workload management tool to reduce stress at the elbow.
Table 1: Arm biomechanics when throwing with and without the Perfect Arm (aka Kinetic Arm).


Without PA

With PA


Torque (Nm)*

42 ±13



Arm rotation (°)




Arm speed (RPM)




Arm slot (°)




Ball velocity (MPH)




* Significant difference (p<0.05).