title: Metastability in plyometric training on unstable surfaces: a pilot study.
abstract: BACKGROUND
  In the past, plyometric training (PT) has been predominantly performed on stable surfaces. The purpose of this pilot study was to examine effects of a 7-week lower body PT on stable vs. unstable surfaces. This type of exercise condition may be denoted as metastable equilibrium.
  
  
  METHODS
  Thirty-three physically active male sport science students (age: 24.1 ± 3.8 years) were randomly assigned to a PT group (n = 13) exercising on stable (STAB) and a PT group (n = 20) on unstable surfaces (INST). Both groups trained countermovement jumps, drop jumps, and practiced a hurdle jump course. In addition, high bar squats were performed. Physical fitness tests on stable surfaces (hexagonal obstacle test, countermovement jump, hurdle drop jump, left-right hop, dynamic and static balance tests, and leg extension strength) were used to examine the training effects.
  
  
  RESULTS
  Significant main effects of time (ANOVA) were found for the countermovement jump, hurdle drop jump, hexagonal test, dynamic balance, and leg extension strength. A significant interaction of time and training mode was detected for the countermovement jump in favor of the INST group. No significant improvements were evident for either group in the left-right hop and in the static balance test.
  
  
  CONCLUSIONS
  These results show that lower body PT on unstable surfaces is a safe and efficient way to improve physical performance on stable surfaces.
authors.affiliation: Institute for Sports and Sport Science, University of Kassel, Damaschkestr. 25, Kassel 34121, Germany.
authors.forename: Armin
authors.initials: A
authors.lastname: Kibele
authors.affiliation: Institute for Sports and Sport Science, University of Kassel, Damaschkestr. 25, Kassel 34121, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Classen
authors.affiliation: Division of Training and Movement Science, University of Potsdam, Potsdam, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Muehlbauer
authors.affiliation: Division of Training and Movement Science, University of Potsdam, Potsdam, Germany.
authors.forename: Urs
authors.initials: U
authors.lastname: Granacher
authors.affiliation: School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
authors.forename: David G
authors.initials: DG
authors.lastname: Behm
keywords: Balance training; Instability resistance training; Physical fitness test; Stretch-shortening cycle
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