title: Type of acute hamstring strain affects flexibility, strength, and time to return to pre-injury level.
abstract: OBJECTIVE
  To investigate possible links between aetiology of acute, first time hamstring strains in sprinters and dancers and recovery of flexibility, strength, and function as well as time to return to pre-injury level. [figure: see text].
  
  
  METHODS
  Eighteen elite sprinters and 15 professional dancers with a clinically diagnosed hamstring strain were included. They were clinically examined and tested two, 10, 21, and 42 days after the acute injury. Range of motion in hip flexion and isometric strength in knee flexion were measured. Self estimated and actual time to return to pre-injury level were recorded. Hamstring reinjuries were recorded during a two year follow up period.
  
  
  RESULTS
  All the sprinters sustained their injuries during high speed sprinting, whereas all the dancers were injured while performing slow stretching type exercises. The initial loss of flexibility and strength was greater in sprinters than in dancers (p<0.05). At 42 days after injury, both groups could perform more than 90% of the test values of the uninjured leg. However, the actual times to return to pre-injury level of performance were significantly longer (median 16 weeks (range 6-50) for the sprinters and 50 weeks (range 30-76) for the dancers). Three reinjuries were noted, all in sprinters.
  
  
  CONCLUSIONS
  There appears to be a link between the aetiologies of the two types of acute hamstring strain in sprinters and dancers and the time to return to pre-injury level. Initially, sprinters have more severe functional deficits but recover more quickly.
authors.affiliation: Karolinska Institutet, Stockholm, Sweden. carl.askling@ihs.se
authors.forename: C
authors.initials: C
authors.lastname: Askling
authors.forename: T
authors.initials: T
authors.lastname: Saartok
authors.forename: A
authors.initials: A
authors.lastname: Thorstensson
mesh_terms: D000293:Adolescent; D000328:Adult; D003615:Dancing / Q000293:injuries*; D005260:Female; D005500:Follow-Up Studies; D025981:Hip Injuries / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D007718:Knee Injuries / Q000209:etiology / Q000503:physiopathology; D008297:Male; D018482:Muscle, Skeletal / Q000293:injuries* / Q000503:physiopathology; D018583:Pliability; D016059:Range of Motion, Articular / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology; D012008:Recurrence; D012420:Running / Q000293:injuries*; D013180:Sprains and Strains / Q000209:etiology* / Q000503:physiopathology