Elbow Joint Active Replication in College Pitchers Following Simulated Game Throwing: An Exploratory Study

Elbow joint injuries are common among college baseball players because of the tremendous stress placed on the elbow during throwing or pitching. Joint proprioception is the ability to detect movement, or kinesthesia, and perceive joint position.19 Correct joint position sense may be important for injury prevention. Signals for joint position sense are thought to arise from receptors in the skin, muscles, and joint capsule.19 Some also believe that intra-articular capsular receptors provide major contributions to joint position sense,7,13 whereas others suspect that extra-articular receptors play a more important role.6,9,14 Proprioception and kinesthesia can be clinically assessed through reproduction of active joint position. Reproduction is thought to involve the stimulation of joint and muscle receptors, and it provides a more functional assessment of the afferent pathways.20 Although knee and shoulder joint proprioception have been studied extensively, only 2 studies have examined proprioception in the elbow.19,22 Khabie et al examined the application of an elastic bandage to the elbow and the injection of an intra-articular anesthestic.19 Based on an isokinetic device for determining range of motion tested, mean elbow joint position sense reproduction without a bandage was within 3.3° ± 1.3°; when an elastic bandage was applied, sense reproduction was diminished to 2.2° ± 1.2°. According to Khabie et al, the application of an elastic bandage improved position sense, which suggests that tactile cues from cutaneous or other extra-articular receptors may play a role in elbow proprioception.19 Intra-articular anesthesia, however, had little effect, suggesting that intracapsular receptors play a lesser role in elbow proprioception. Using standard goniometry, Macrina et al assessed elbow joint proprioceptive characteristics in professional baseball players22—specifically, their ability to actively reproduce a passive joint position from a common starting point. Significant proprioceptive deficits existed for the dominant (4.23°) and nondominant (4.03°) elbows at 50% range of motion. A proprioceptive deficit (4.06°) occurred in the nondominant elbow at 90% range of motion. If muscle coordination is impaired as a result of altered joint proprioception, the elbow may be at risk for injury. Muscle fatigue adversely alters upper and lower extremity joint proprioception and neuromuscular control.2,21,23,27,32,33,39 Throwing a baseball at high velocities is considered a fatiguing activity. Following eccentric and concentric exercises, Brockett and colleagues found that elbow fatigue altered joint position sense; a gradual recovery of position sense to normal occurred by 3 days postexercise.4 No studies have assessed active elbow joint replication following pitching. It is possible that significant injury occurs to the ulnar collateral ligament if proprioceptive deficits exist or if proprioception is diminished in midranges, wherein this ligament provides the greatest resistance to a valgus stress at the elbow. The objectives of this study were to examine the effect of 3 simulated innings of throwing on active elbow joint replication testing. The null hypothesis was that there would be no significant difference in elbow joint active reproduction between the dominant and nondominant extremities following a simulated 3-inning pitching bout.