title: The acute effects of graded physiological strain on soccer kicking performance: a randomized, controlled cross-over study.
abstract: OBJECTIVE
  The aim of the present study was to examine the acute effects of graded physiological strain on soccer kicking performance.
  
  
  METHODS
  Twenty-eight semi-professional soccer players completed both experimental and control procedure. The experimental protocol incorporated repeated shooting trials combined with a progressive discontinuous maximal shuttle-run intervention. The initial running velocity was 8 km/h and increasing for 1 km/h every 3 min until exhaustion. The control protocol comprised only eight subsequent shooting trials. The soccer-specific kicking accuracy (KA; average distance from the ball-entry point to the goal center), kicking velocity (KV), and kicking quality (KQ; kicking accuracy divided by the time elapsed from hitting the ball to the point of entry) were evaluated via reproducible and valid test over five individually determined exercise intensity zones.
  
  
  RESULTS
  Compared with baseline or exercise at intensities below the second lactate threshold (LT2), physiological exertion above the LT2 (blood lactate > 4 mmol/L) resulted in meaningful decrease in KA (11-13%; p < 0.05), KV (3-4%; p < 0.05), and overall KQ (13-15%; p < 0.01). The light and moderate-intensity exercise below the LT2 had no significant effect on soccer kicking performance.
  
  
  CONCLUSIONS
  The results suggest that high-intensity physiological exertion above the player's LT2 impairs soccer kicking performance. In contrast, light to moderate physiological stress appears to be neither harmful nor beneficial for kicking performance.
authors.affiliation: Institute of Sport Science, University of Vienna, Auf der Schmelz 6, 1150, Vienna, Austria.
authors.forename: Ivan
authors.initials: I
authors.lastname: Radman
authors.affiliation: Institute of Sport Science, University of Vienna, Auf der Schmelz 6, 1150, Vienna, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Wessner
authors.affiliation: Institute of Sport Science, University of Vienna, Auf der Schmelz 6, 1150, Vienna, Austria.|Austrian Institute of Sports Medicine, Auf der Schmelz 6, 1150, Vienna, Austria.
authors.forename: Norbert
authors.initials: N
authors.lastname: Bachl
authors.affiliation: Motor Control and Human Performance Laboratory, School of Kinesiology, University of Zagreb, Horvacanski zavoj 15, 10000, Zagreb, Croatia.
authors.forename: Lana
authors.initials: L
authors.lastname: Ruzic
authors.affiliation: Austrian Institute of Sports Medicine, Auf der Schmelz 6, 1150, Vienna, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Hackl
authors.affiliation: University Hospital for Orthopaedic Surgery Lovran, Marsala Tita 1, 51415, Lovran, Croatia.
authors.forename: Tomislav
authors.initials: T
authors.lastname: Prpic
authors.affiliation: Motor Control and Human Performance Laboratory, School of Kinesiology, University of Zagreb, Horvacanski zavoj 15, 10000, Zagreb, Croatia. gmarkov@kif.hr.
authors.forename: Goran
authors.initials: G
authors.lastname: Markovic
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold; D054874:Athletic Performance; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D009068:Movement; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000502:physiology; D005082:Physical Exertion; D055070:Resistance Training / Q000009:adverse effects*; D012916:Soccer / Q000502:physiology*
keywords: Fatigue; Kicking performance; Lactate threshold; Precision; Soccer