title: Impact forces of plyometric exercises performed on land and in water.
abstract: BACKGROUND
  Aquatic plyometric programs are becoming increasingly popular because they provide a less stressful alternative to land-based programs. Buoyancy reduces the impact forces experienced in water.
  
  
  OBJECTIVE
  To quantify the landing kinetics during a range of typical lower limb plyometric exercises performed on land and in water.
  
  
  METHODS
  Crossover design.
  
  
  METHODS
  Eighteen male participants performed ankle hops, tuck jumps, a countermovement jump, a single-leg vertical jump, and a drop jump from 30 cm in a biomechanics laboratory and in a swimming pool. Land and underwater force plates (Kistler) were used to obtain peak impact force, impulse, rate of force development, and time to reach peak force for the landing phase of each jump.
  
  
  RESULTS
  Significant reductions were observed in peak impact forces (33%-54%), impulse (19%-54%), and rate of force development (33%-62%) in water compared with land for the majority of exercises in this study (P < 0.05).
  
  
  CONCLUSIONS
  The level of force reduction varies with landing technique, water depth, and participant height and body composition.
  
  
  CONCLUSIONS
  This information can be used to reintroduce athletes to the demands of plyometric exercises after injury.
authors.affiliation: Institute of Sport, Physical Education and Health Sciences, University of Edinburgh, United Kingdom.
authors.forename: Orna A
authors.initials: OA
authors.lastname: Donoghue
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Shimojo
authors.forename: Hideki
authors.initials: H
authors.lastname: Takagi