title: The effect of experimental groin pain on abdominal muscle thickness.
abstract: OBJECTIVE
  It is not clear whether abnormal abdominal muscle behavior in athletes with longstanding groin pain is a risk factor for groin pain or is caused by groin pain itself. Therefore, this study investigated whether anticipation of experimental groin pain influences abdominal muscle behavior.
  
  
  METHODS
  In 14 healthy athletes, abdominal muscle thickness was measured using ultrasound under conditions of anticipated groin pain and acute groin pain. Groin pain was induced using superficial electrical skin stimulation. Tasks evaluated were isometric hip adduction and active straight leg raise (ASLR) left.
  
  
  RESULTS
  The m. transversus abdominis and m. obliquus internus showed a significant decrease in thickness during "anticipation of pain" compared with "no pain" and "pain" during both hip adduction and ASLR (P values <0.04). For m. obliquus externus, a significant increase in thickness was found only during "pain" compared with "no pain" and "anticipation of pain" for ASLR (P<0.004).
  
  
  CONCLUSIONS
  If ASLR or hip adduction is associated with anticipated groin pain, abdominal muscle behavior is different from a pain-free situation and from a painful situation. These results suggest that abnormal abdominal muscle behavior found in athletes with longstanding groin pain may be caused by a pain anticipatory motor strategy. This may have implications for rehabilitation.
authors.affiliation: Department of Rehabilitation and Sports Medicine, University Medical Center Utrecht, Utrecht, the Netherlands. jjansen4@umcutrecht.nl
authors.forename: Jaap A C G
authors.initials: JA
authors.lastname: Jansen
authors.forename: Bart
authors.initials: B
authors.lastname: Poot
authors.forename: Jan M A
authors.initials: JM
authors.lastname: Mens
authors.forename: Frank J G
authors.initials: FJ
authors.lastname: Backx
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Stam
mesh_terms: D000009:Abdominal Muscles / Q000000981:diagnostic imaging*; D000293:Adolescent; D000328:Adult; D056352:Athletes; D003430:Cross-Sectional Studies; D004558:Electric Stimulation / Q000009:adverse effects; D005260:Female; D006119:Groin / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology / Q000473:pathology*; D010147:Pain Measurement; D015203:Reproducibility of Results; D013997:Time Factors; D018608:Ultrasonography, Doppler / Q000379:methods; D055815:Young Adult