title: Effect of plyometric training on sand versus grass on muscle soreness and jumping and sprinting ability in soccer players.
abstract: OBJECTIVE
  The lower impact on the musculoskeletal system induced by plyometric exercise on sand compared to a firm surface might be useful to reduce the stress of intensified training periods or during rehabilitation from injury. The aim of this study was to compare the effects of plyometric training on sand versus a grass surface on muscle soreness, vertical jump height and sprinting ability.
  
  
  METHODS
  Parallel two-group, randomised, longitudinal (pretest-post-test) study.
  
  
  METHODS
  After random allocation, 18 soccer players completed 4 weeks of plyometric training on grass (grass group) and 19 players on sand (sand group). Before and after plyometric training, 10 m and 20 m sprint time, squat jump (SJ), countermovement jump (CMJ), and eccentric utilization ratio (CMJ/SJ) were determined. Muscle soreness was measured using a Likert scale.
  
  
  RESULTS
  No training surface x time interactions were found for sprint time (p>0.87), whereas a trend was found for SJ (p = 0.08), with both groups showing similar improvements (p<0.001). On the other hand, the grass group improved their CMJ (p = 0.033) and CMJ/SJ (p = 0.005) significantly (p<0.001) more than players in the sand group. In contrast, players in the sand group experienced less muscle soreness than those in the grass group (p<0.001).
  
  
  CONCLUSIONS
  Plyometric training on sand improved both jumping and sprinting ability and induced less muscle soreness. A grass surface seems to be superior in enhancing CMJ performance while the sand surface showed a greater improvement in SJ. Therefore, plyometric training on different surfaces may be associated with different training-induced effects on some neuromuscular factors related to the efficiency of the stretch-shortening cycle.
authors.affiliation: Franco M Impellizzeri, Neuromuscular Research Laboratory, Schulthess Clinic, Lengghalde 2, 8008 Zurich, Switzerland. franco.impellizzeri@kws.ch
authors.forename: F M
authors.initials: FM
authors.lastname: Impellizzeri
authors.forename: E
authors.initials: E
authors.lastname: Rampinini
authors.forename: C
authors.initials: C
authors.lastname: Castagna
authors.forename: F
authors.initials: F
authors.lastname: Martino
authors.forename: S
authors.initials: S
authors.lastname: Fiorini
authors.forename: U
authors.initials: U
authors.lastname: Wisloff
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D006801:Humans; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010146:Pain / Q000503:physiopathology; D010806:Physical Education and Training / Q000379:methods*; D006109:Poaceae; D012420:Running / Q000502:physiology*; D012822:Silicon Dioxide; D012916:Soccer / Q000502:physiology*
chemical_list: D012822:Silicon Dioxide