title: Small-sided soccer games on sand are more physically demanding but less technically specific compared to games on artificial turf.
abstract: BACKGROUND
  The use of sand has been suggested as fitness-enhancing surface in field-based team sports. However, concerns have arisen in regard whether physical responses associated to sand training are sport-specific. We compared physical and technical demands during small-sided soccer games (4 vs. 4 + goalkeeper; SSGs) played on artificial turf and on sand.
  
  
  METHODS
  Movement patterns, rating of perceived exertion (RPE) and technical parameters were obtained from eight adult male soccerers (20.1±1.0 years, 176±4 cm and 70.1±2.0 kg) using Global Positioning Systems, Visual Analogue Scale questionnaires, and notational analysis.
  
  
  RESULTS
  High-intensity actions (high intensity running, high intensity activities), low changes of speed, as well as peak and average speed were higher on artificial turf (P<0.05; effect sizes (ES) 0.41 to 0.82). In contrast, time spent by jogging as well as high and maximum changes of speed was higher on sand (P<0.05; ES: 0.59 to 0.82). Moreover, players perceived more demanding to play on sand (P<0.05; ES=0.72). Rating of successful actions was higher during turf SSGs than sand SSGs (P<0.05; ES: 0.44 to 0.73), whereas actions requiring lifting the ball were higher on sand (P<0.05; ES: 0.47 to 0.50).
  
  
  CONCLUSIONS
  The use of sand can be considered as complemental to on-turf soccer training, when the training goal is to tax lower limb muscle strength or to require high-ball situations. Nonetheless, sand training is not appropriate when the achievement of maximal speed is desired. Further research should clarify the suitability of sand training within soccer conditioning programs.
authors.affiliation: Center of Research, Education, Innovation, and Intervention in Sport, University of Porto, Porto, Portugal - vincenzo.rago@live.com.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Rago
authors.affiliation: Center of Research, Education, Innovation, and Intervention in Sport, University of Porto, Porto, Portugal.
authors.forename: António N
authors.initials: AN
authors.lastname: Rebelo
authors.affiliation: Academy Strength and Conditioning Department, Futebol Clube do Porto, Porto, Portugal.
authors.forename: Federico
authors.initials: F
authors.lastname: Pizzuto
authors.affiliation: Center of Research, Education, Innovation, and Intervention in Sport, University of Porto, Porto, Portugal.
authors.forename: Daniel
authors.initials: D
authors.lastname: Barreira
mesh_terms: D000328:Adult; D054874:Athletic Performance; D040362:Geographic Information Systems / Q000706:statistics & numerical data; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D005082:Physical Exertion / Q000502:physiology; D012420:Running / Q000502:physiology; D012916:Soccer / Q000502:physiology*; D055815:Young Adult