title: Static stretching alters neuromuscular function and pacing strategy, but not performance during a 3-km running time-trial.
abstract: OBJECTIVE
  Previous studies report that static stretching (SS) impairs running economy. Assuming that pacing strategy relies on rate of energy use, this study aimed to determine whether SS would modify pacing strategy and performance in a 3-km running time-trial.
  
  
  METHODS
  Eleven recreational distance runners performed a) a constant-speed running test without previous SS and a maximal incremental treadmill test; b) an anthropometric assessment and a constant-speed running test with previous SS; c) a 3-km time-trial familiarization on an outdoor 400-m track; d and e) two 3-km time-trials, one with SS (experimental situation) and another without (control situation) previous static stretching. The order of the sessions d and e were randomized in a counterbalanced fashion. Sit-and-reach and drop jump tests were performed before the 3-km running time-trial in the control situation and before and after stretching exercises in the SS. Running economy, stride parameters, and electromyographic activity (EMG) of vastus medialis (VM), biceps femoris (BF) and gastrocnemius medialis (GA) were measured during the constant-speed tests.
  
  
  RESULTS
  The overall running time did not change with condition (SS 11:35±00:31 s; control 11:28±00:41 s, p = 0.304), but the first 100 m was completed at a significantly lower velocity after SS. Surprisingly, SS did not modify the running economy, but the iEMG for the BF (+22.6%, p = 0.031), stride duration (+2.1%, p = 0.053) and range of motion (+11.1%, p = 0.0001) were significantly modified. Drop jump height decreased following SS (-9.2%, p = 0.001).
  
  
  CONCLUSIONS
  Static stretch impaired neuromuscular function, resulting in a slow start during a 3-km running time-trial, thus demonstrating the fundamental role of the neuromuscular system in the self-selected speed during the initial phase of the race.
authors.affiliation: Endurance Performance Research Group, School of Physical Education and Sport, University of São Paulo, São Paulo, São Paulo, Brazil.
authors.forename: Mayara V
authors.initials: MV
authors.lastname: Damasceno
authors.affiliation: Biomedical Engineering, Federal University of ABC, Santo André, São Paulo, Brazil.
authors.forename: Marcos
authors.initials: M
authors.lastname: Duarte
authors.affiliation: Endurance Performance Research Group, School of Physical Education and Sport, University of São Paulo, São Paulo, São Paulo, Brazil.
authors.forename: Leonardo A
authors.initials: LA
authors.lastname: Pasqua
authors.affiliation: Sports Science Research Group, Department of Physical Education and Sports Science, Federal University of Pernambuco, Vitoria de Santo Antão, Pernambuco, Brazil.
authors.forename: Adriano E
authors.initials: AE
authors.lastname: Lima-Silva
authors.affiliation: Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Brian R
authors.initials: BR
authors.lastname: MacIntosh
authors.affiliation: Endurance Performance Research Group, School of Physical Education and Sport, University of São Paulo, São Paulo, São Paulo, Brazil.
authors.forename: Rômulo
authors.initials: R
authors.lastname: Bertuzzi
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D052580:Muscle Stretching Exercises; D018482:Muscle, Skeletal / Q000502:physiology*; D012420:Running / Q000502:physiology*; D013997:Time Factors