title: Effects of stretching and warm-up routines on stability and balance during weight-lifting: a pilot investigation.
abstract: BACKGROUND
  The efficacy of warm-up and stretching in weight-lifting remains unknown, especially for the weight-lifter's stability and balance during lifting.
  
  
  METHODS
  13 subjects were randomly assigned a 10-minute stretching routine (SR) or a 10-minute warm-up routine (WR) and compared against 5 controls (no stretching or warm-up). Before and after the individually assigned routine, the participants' centre of pressure (CoP) was assessed using plantar-pressure sensors. The subjects were measured during 10 repetitions of air squat (no load, "AS"), front squat (FS; 20 kg/15 kg bar), overhead squat (OHS; m: 20 kg / f: 15 kg bar), and a deadlift lifting exercise ("DL"; 20 kg/15 kg bar). The impact on CoP dynamics of the warm-up and stretching routines were examined with repeated two-factor analysis of variances (ANOVA) of the mean and the coefficient of variance (CV, shown in %), as proxies for stability and balance.
  
  
  RESULTS
  After stretching, the SR athletes shifted the mean CoP towards the toes (≈1 cm; p < 0.01) while the WR athletes shifted the CoP towards the heels (≈1 cm; p < 0.01) during AS. For the remaining exercises, the SR athletes shifted the CoP towards the heels (between 0.8 cm and 5.7 cm) compared to WR (≈1.9 cm towards the heels in FS, no significant change in OHS (≈1 mm) and DL (≈3 mm)). The controls did not show any change between pre- and post-datasets. After stretching, the CV decreased for the AS and OHS exercises (AS: 10.2% to 7.0%, OHS 9.8% to 7.8%), but increased after WR (AS: 7.1% to 10.1%) or did not change significantly (OHS). Both WR and SR resulted in increased CV values for FS and DL. No change of CV was observed in the controls.
  
  
  CONCLUSIONS
  SR had a stronger impact on CoP during the assessed exercises than either WR or controls. A reduction in CV after SR exercises (AS, OHS) suggests a clear improvement in stability and balance during weight-lifting. The lack of a significant effect for complex movements (OHS) suggests only a limited effect of a 10-minute warm-up routine on CoP features. 10 minutes stretching might therefore be more efficient for improving stability than a general 10 minute warm-up.
authors.affiliation: Federal Institute of Technology (ETH), Zurich, Gloriastrasse 35, Zurich 8092, Switzerland. rolf.adelsberger@ife.ee.ethz.ch.
authors.forename: Rolf
authors.initials: R
authors.lastname: Adelsberger
authors.forename: Gerhard
authors.initials: G
authors.lastname: Tröster
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D056352:Athletes; D054874:Athletic Performance / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D017770:Lifting; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D010865:Pilot Projects; D016059:Range of Motion, Articular / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult