title: The acute effects of various types of stretching static, dynamic, ballistic, and no stretch of the iliopsoas on 40-yard sprint times in recreational runners.
abstract: OBJECTIVE
  The potential adverse effects of static stretching on athletic performance are well documented, but still appears to be controversial, especially as they relates to sprinting. The prevalence of this practice is demonstrated by the number of competitive and recreational athletes who regularly engage in stretching immediately prior to sprinting with the mindset of optimizing their performance. The purpose of this study was to examine the effects of acute static, dynamic, and ballistic stretching, and no stretching of the iliopsoas muscle on 40-yard sprint times in 18-37 year-old non-competitive, recreational runners.
  
  
  METHODS
  Twenty-five healthy recreational runners (16 male and 9 female) between the ages of 24 and 35 (Mean = 26.76 yrs., SD = 2.42 yrs.) completed this study. A repeated measures design was used, which consisted of running a 40-yard sprint trial immediately following each of 4 different stretching conditions aimed at the iliopsoas muscle and lasting 1 minute each. The 4 conditions were completed in a randomized order within a 2-week time period, allowing 48-72 hours between each condition. Prior to each 40-yard sprint trial, a 5-minute walking warm-up was performed at 3.5 mph on a treadmill. The subject then ran a baseline 40-yard sprint. After a 10-minute self-paced walk, each subject performed one of the 4 stretching conditions (ballistic, dynamic, static, and no stretch) and then immediately ran a timed 40-yard sprint.
  
  
  RESULTS
  There was a significant interaction between stretching conditions and their effects on sprint times, F(3,72) = 9.422, p<.0005. To break down this interaction, simple main effects were performed with 2 repeated measures ANOVAs and 4 paired t-tests using a Bonferroni corrected alpha (α = .0083). There were no significant differences between the 4 pre-condition times, p = 0.103 (Greenhouse-Geisser) or the post-condition times, p = 0.029. In the no stretch condition, subjects improved significantly from pre- to post- sprint times (p<0.0005). There were no statistically significant differences in pre- and post-stretch condition sprint times among the static (p = 0.804), ballistic (p = 0.217), and dynamic (p = 0.022) stretching conditions.
  
  
  CONCLUSIONS
  Sprint performance may show greatest improvement without stretching and through the use of a walking generalized warmup on a treadmill. These findings have clinically meaningful implications for runners who include iliopsoas muscle stretching as a component of the warm-up.
  
  
  METHODS
  Level 2.
authors.affiliation: Western Kentucky University, Bowling Green, Kentucky, USA.
authors.forename: Harvey W
authors.initials: HW
authors.lastname: Wallmann
authors.forename: Scott D
authors.initials: SD
authors.lastname: Christensen
authors.forename: Craig
authors.initials: C
authors.lastname: Perry
authors.forename: Donald L
authors.initials: DL
authors.lastname: Hoover
keywords: Recreational runners; sprinting; stretching; warm‐up