Oct 18, 2016
Here’s the Pitch
Matthew Sims, Jennifer Volberding, and Matthew O'Brien

According to the NCAA’s Injury Surveillance System (ISS), 12.1 percent of baseball programs reported 1,623 shoulder injuries from 1988 to 2004. Of the 1,623 reports, 972 injuries (59.5 percent) were associated with a throwing mechanism, with pitching accounting for 709 of the cases (73 percent). Forty-two percent of game injuries were due to a non-contact mechanism, such as pitching injuries (15.3 percent) and throwing (non-pitching) injuries (5.3 percent). Shoulder injuries alone accounted for 39.4 percent of baseball injuries and 15.8 percent of softball injuries at the collegiate level.

As these injury rates allude to, the overhead throwing motion exerts extreme forces and torque on the shoulder. These large forces generated throughout the throwing motion are counteracted during the deceleration phase. Therefore, shoulder strengthening is an important area of focus in overhead throwing athletes for performance enhancement and injury prevention.

Healthcare professionals utilize various forms of shoulder exercise protocols for athletic-related shoulder injury prevention and rehabilitation. Prior research has demonstrated that shoulder-strengthening exercises of the rotators and scapular stabilizers can be as effective as surgery in treating athletic-related shoulder injuries, especially in the throwing population.

Crossover Symmetry (CS) and Jaeger J-Bands (JJB) are two resistance-band systems utilized for shoulder strengthening, injury prevention, and rehabilitation. CS is a multi-band system with three resistance classifications that is modeled on rotator cuff and scapular strengthening. JJB is a rotator cuff strengthening program involving five dual-arm exercises (over-the-head forearm extensions, side extensions, diagonal extensions, forward flies, and reverse flies) followed by six throwing arm-specific exercises (internal rotation, external rotation, elevated internal rotation, elevated external rotation, reverse throwing and forward throwing). Contrary to CS, JJB only has one resistance level and recommends increasing repetitions rather than tension.

So do CS and JBB actually increase shoulder range of motion (ROM) and torque in internal rotation (IR) and external rotation (ER)? The results of this study suggest so. However, findings also indicate that the length of time spent on the strengthening protocol may be a bigger factor in shoulder strengthening than which system is used.

To determine this, 36 individuals (18 males, 18 females; 21.56±1.58 years) were randomly assigned to JJB, CS, or a control group. Over the course of 12 strengthening sessions, CS participants performed rows, reverse flies, and pulldowns at eye level and 90/90, as well as scaption, incline plus, and victory at knee level. The CS program consisted of eight normal repetitions (activation), 10 four-second negative repetitions (recovery; slowly resisting the release of the band’s tension), and 25 plyometric repetitions (maximal muscular contraction over a short ROM) for each exercise. In the same 12-session stretch, JBB participants performed 25 repetitions of all five dual-arm exercises and 25 repetitions of all six throwing arm-specific exercises.

Pre-participation, mid-participation, and exit dynamometer assessments of IR and ER of the dominant shoulder were each performed twice while the subject was seated with 90 degrees of shoulder abduction and elbow flexion. During active ROM measurements, participants internally and externally rotated as far as possible beginning at 90 degrees of shoulder IR. Next, they performed maximum voluntary isometric contractions in a position of 45 degrees of shoulder IR. Finally, they performed 60 degrees per second (degrees/s) and 120 degrees/s isokinetic contractions beginning at zero degrees of shoulder rotation for ER measurements and 90 degrees of shoulder IR for IR measurements.

Utilizing a two-way analysis of variance, it was determined that statistically significant differences between the three groups occurred in active IR, isometric IR and ER, at 60 degrees/s in IR and ER, and at 120 degrees/s in IR. Post-hoc contrasts identified statistically significant comparisons within time intervals, with the measures one versus three in IR occurring most often.

Overall, both CS and JJB demonstrated an impact on IR strengthening and ROM over the course of the strengthening protocol. Clinicians can use CS, JJB, and many other resistance bands in arm conditioning sessions for overhead athletes to improve IR and ER strength. Additionally, the time dedicated to a shoulder-strengthening program is a key component to the effectiveness of the program and the resultant strength increases.

Matthew Sims, LAT, ATC, is an Analytical and Institutional Research Graduate Assistant in the College of Osteopathic Medicine at Oklahoma State University. Jennifer Volberding, PhD, LAT, ATC, is an Assistant Professor of Athletic Training at OSU. Matthew O'Brien, PhD, LAT, ATC, is Associate Professor/Clinical Education Coordinator of Athletic Training at OSU. Sims can be reached at: [email protected].

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