title: Effects of static stretching on the hamstrings-to-quadriceps ratio and electromyographic amplitude in men.
abstract: OBJECTIVE
  The purpose of this study was to examine the effects of posterior thigh and leg stretching on leg flexion peak torque (PT), leg extension PT, the hamstrings-to-quadriceps (H:Q) ratio, and electromyographic (EMG) amplitude of the hamstrings and quadriceps in recreationally-active men.
  
  
  METHODS
  Fifteen men (mean age + or - SD = 22.0 + or - 4.4 years; body mass = 82.7 + or - 16.1 kg; height = 173.1 + or - 6.8 cm) performed three maximal voluntary concentric isokinetic leg extension and flexion muscle actions at three randomly ordered angular velocities (60, 180, and 300 degrees x s(-1)) before and after hamstring and calf static stretching. The stretching protocol consisted of 1 unassisted and 3 assisted static stretching exercises designed to stretch the posterior muscles of the thigh and leg. Four repetitions of each stretch were held for 30 s with 20-s rest between repetitions.
  
  
  RESULTS
  These findings indicated no significant (P>0.05) stretching-induced changes in leg flexion PT, leg extension PT, or EMG amplitude at 60, 180, or 300 degrees .s-1. However, the non-significant (P>0.05) 2-4% increases in leg extension PT combined with the non-significant (P>0.05) 1-2% decreases in leg flexion PT resulted in the significant (P < or = 0.05) 2-9% decreases in the H:Q ratio from pre- to post-stretching for all three velocities.
  
  
  CONCLUSIONS
  These findings suggested that static stretching of the hamstrings and calf muscles may decrease the H:Q ratio. These results may be useful for athletic trainers, physical therapists, and other allied health professionals who may use the H:Q ratio as a clinical assessment.
authors.affiliation: Biophysics Laboratory, Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA.
authors.forename: P B
authors.initials: PB
authors.lastname: Costa
authors.forename: E D
authors.initials: ED
authors.lastname: Ryan
authors.forename: T J
authors.initials: TJ
authors.lastname: Herda
authors.forename: J M
authors.initials: JM
authors.lastname: Defreitas
authors.forename: T W
authors.initials: TW
authors.lastname: Beck
authors.forename: J T
authors.initials: JT
authors.lastname: Cramer
mesh_terms: D000704:Analysis of Variance; D001265:Athletic Injuries / Q000209:etiology / Q000517:prevention & control*; D015992:Body Mass Index; D004576:Electromyography; D006801:Humans; D007866:Leg / Q000502:physiology*; D007869:Leg Injuries / Q000209:etiology / Q000517:prevention & control*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D053581:Muscle Strength Dynamometer; D052580:Muscle Stretching Exercises / Q000379:methods*; D018482:Muscle, Skeletal / Q000293:injuries / Q000502:physiology*; D052097:Quadriceps Muscle / Q000293:injuries / Q000502:physiology*; D012307:Risk Factors; D019415:Torque; D055815:Young Adult