Altered mobility patterns in asymptomatic professional baseball pitchers may be due to factors other than capsular adaptive changes.

With the exception of muscle force production, fear of pain had a consistent influence on shoulder DOMS outcomes, even after controlling for pain intensity. This study suggests fear of pain may be a relevant psychologic factor to consider in clinical studies investigating the development and treatment of chronic shoulder pain.

We developed a questionnaire with good internal and external validity. The AFAQ is a scale that measures sport-injury-related fear avoidance in athletes and could be used to identify potential psychological barriers to rehabilitation.

The repetitive stress of long-term throwing creates altered glenohumeral rotational patterns in the throwing shoulder of the professional baseball pitcher without compromising the joint's passive restraining quality.

Objective-The experience of pain is believed to be influenced by psychologic and genetic factors. A previous study suggested pain catastrophizing and catechol-O-methyltransferase (COMT) genotype influenced clinical pain ratings for patients seeking operative treatment of shoulder pain. This study investigated whether these same psychologic and genetic factors predicted responses to induced shoulder pain.Methods-Participants (n=63) completed self-report questionnaires and had COMT genotype determined before performing a standardized fatigue protocol to induce delayed onset muscle soreness. Then, shoulder pain ratings, self-report of upper-extremity disability ratings, and muscle torque production were reassessed 24, 48, and 72 hours later.Results-This cohort consisted of 35 women and 28 men, with a mean age of 20.9 years (SD=1.7). The frequency of COMT diplotypes was 42 with "high COMT enzyme activity" (low pain sensitivity group) and 21 with "low COMT enzyme activity" (average pain sensitivity/high pain sensitivity group). A hierarchical regression model indicated that an interaction between pain catastrophizing and COMT diplotype was the strongest unique predictor of 72-hour pain ratings. The same interaction was not predictive of self-report of disability or muscle torque production at 72 hours. The pain catastrophizing × COMT diplotype interaction indicated that participants with high pain catastrophizing and low COMT enzyme activity (average pain sensitivity/high pain sensitivity group) were more likely (relative risk=3.5, P=0.025) to have elevated pain intensity ratings (40/100 or higher).Reprints: Steven Z. George, PT, PhD, Department of Physical Therapy, Brooks Center for Rehabilitation Studies, University of Florida, Health Science Center, PO Box 100154, Gainesville, FL 32610-0154 (e-mail: E-mail: szgeorge@phhp.ufl.edu). NIH Public Access Author ManuscriptClin J Pain. Author manuscript; available in PMC 2009 April 16. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptDiscussion-These findings from an experimental model converge with those from a surgical cohort and provide additional evidence that the presence of elevated pain catastrophizing and COMT diplotype indicative of low COMT enzyme activity have the potential to increase the risk of developing chronic pain syndromes.Keywords biopsychosocial model; chronic pain; catastrophizing; COMT genotype; shoulder pain; delayed onset muscle sorenessThe experience of pain varies considerably among individuals. Social, cultural, environmental, psychologic, and genetic factors are all believed to contribute to this variability. A model for the development of idiopathic pain conditions that takes into consideration these sources of variability was recently proposed. 1 In this model, it is suggested that high levels of psychologic distress and pain amplification (ie, genetic predisposition for biologic or physiologic processes) are the primary factors contributing to the development of idiopathic pain conditions. 1Few studies to da...