The effects of shoulder laxity on upper extremity blood flow in professional baseball pitchers

Background: The repetitive overhand throwing can potentially cause physiologic or pathologic changes in musculoskeletal and vascular structures. The purpose of this study was to investigate the effects of throwing on upper extremity arterial blood flow before and after a controlled pitching session. The hypothesis is that pitchers with physical signs of shoulder laxity would demonstrate differential changes in upper extremity blood flow as compared to those without laxity.

Methods: Eighteen professional male pitchers underwent a detailed shoulder physical evaluation, followed by a wrist/brachial index (WBI) vascular exam and a vascular ultrasound examination before and after a controlled throwing session.

Results: Following a 50-pitch workout, the WBI was significantly lower (0.79-0.86) in pitchers with laxity on exam versus no laxity (P < .05). For all pitchers, the average arterial volume flow increased from 234 ml/min to 482 ml/min after 50 pitches. Pitchers without physical signs of laxity had an average arterial volume flow increase of 115%, while the pitchers with laxity signs increased 35%.

Conclusion: This study demonstrated a statistically significant decrease in arterial blood flow in the laxity group compared to the nonlaxity throwers.