title: Pacing Strategies and Metabolic Responses During 4-Minute Running Time Trials.
abstract: OBJECTIVE
  The aim of the current study was to investigate pacing strategies and the distribution of physiological resources in best vs worst performances during a series of 4-min self-paced running time trials (RunTTs).
  
  
  METHODS
  Five male and 5 female recreational runners (age 32 ± 7 y) completed a submaximal ramp test and 5 RunTTs on a motor-driven treadmill fitted with a speed-controlling laser system. The supramaximal oxygen-uptake (V̇O2) demand was estimated by linear extrapolation from the submaximal relationship between V̇O2and speed, enabling computation of the accumulated oxygen deficit.
  
  
  RESULTS
  There were no significant differences between the 5 RunTTs for any of the performance, physiological, or subjective responses (P > .05). The trial-to-trial variability in pacing (ie, separate quarters) was typically low, with an average within-athlete coefficient of variation of 3.3%, being highest at the start and end of the 4 min. Total distance covered and distance covered over the first and last 2 min for best and worst performances were 1137 ± 94 and 1090 ± 89 (P < .001), 565 ± 53 and 526 ± 40 m (P = .002), and 572 ± 47 and 565 ± 54 m (P = .346), respectively.
  
  
  CONCLUSIONS
  Negative pacing strategies were evident during both the best and the worst performances of the RunTT. Best performances were characterized by more aggressive pacing over the first 2 min compared with worst performances. In addition, the relatively low trial-to-trial variability in running speed suggests that pacing strategies are similar during a series of 4-min self-paced running time trials.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Watkins
authors.forename: Simon
authors.initials: S
authors.lastname: Platt
authors.forename: Erik
authors.initials: E
authors.lastname: Andersson
authors.forename: Kerry
authors.initials: K
authors.lastname: McGawley
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D004734:Energy Metabolism; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010101:Oxygen Consumption; D012420:Running / Q000502:physiology*; D013997:Time Factors
chemical_list: D019344:Lactic Acid
keywords: accumulated oxygen deficit; negative pacing; oxygen uptake; self-pacing