title: Acute painless shoulder weakness during high-intensity athletic training.
abstract: BACKGROUND
  High-intensity repetitive athletic activities may predispose the brachial plexus to repetitive stretch, compression, and subsequent injury, although painless shoulder weakness is a rare event.
  
  
  OBJECTIVE
  The physical examination and electrodiagnostic findings in a series of United States Navy special warfare trainees who presented with acute painless shoulder weakness are presented, along with subsequent treatment and return-to-duty timeline.
  
  
  METHODS
  Case series; Level of evidence, 4.
  
  
  METHODS
  From August 2005 to August 2006, a total of 11 of 212 (5%) Navy Basic Underwater Demolition School trainees were identified with acute onset (<3 weeks) painless shoulder weakness without any prior shoulder injury. In all shoulders, symptoms began during a telephone pole lift-carry drill. All trainees underwent serial examinations, electrodiagnostic testing, and a comprehensive rehabilitation program.
  
  
  RESULTS
  Physical examination revealed universal weakness in flexion and abduction and electrodiagnostic studies confirmed injury to the C5-6 area of the brachial plexus (axillary, suprascapular, and musculocutaneous). All 11 patients were removed from training and started on a physical therapy program until functional recovery at a mean of 21 weeks after onset of symptoms (range, 12-24). All 11 resumed military activities; however, only 6 completed the Navy Basic Underwater Demolition School program.
  
  
  CONCLUSIONS
  In physically intense training or athletic environments, injuries to the upper brachial plexus may present with various forms of upper extremity dysfunction, including painless shoulder weakness. This information provides insight into a potentially debilitating shoulder problem and offers guidance on future training principles.
authors.affiliation: Naval Medical Center San Diego, Department of Orthopaedic Surgery, San Diego, CA 92134-1112, USA.
authors.forename: Tyler
authors.initials: T
authors.lastname: Vachon
authors.forename: Michael
authors.initials: M
authors.lastname: Rosenthal
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Dewing
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Solomon
authors.forename: Alexander Y
authors.initials: AY
authors.lastname: Shin
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Provencher
mesh_terms: D000328:Adult; D001917:Brachial Plexus / Q000293:injuries; D012090:Cumulative Trauma Disorders / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008889:Military Personnel; D018908:Muscle Weakness / Q000209:etiology*; D005082:Physical Exertion / Q000502:physiology*; D012782:Shoulder / Q000294:innervation / Q000503:physiopathology*; D013177:Sports; D055815:Young Adult