title: The Influence of Blood Removal on Pacing During a 4-Minute Cycling Time Trial.
abstract: OBJECTIVE
  To examine the influence of manipulating aerobic contribution after whole-blood removal on pacing patterns, performance, and energy contribution during self-paced middle-distance cycling.
  
  
  METHODS
  Seven male cyclists (33 ± 8 y) completed an incremental cycling test followed 20 min later by a 4-min self-paced cycling time trial (4MMP) on 6 separate occasions over 42 d. The initial 2 sessions acted as familiarization and baseline testing, after which 470 mL of blood was removed, with the remaining sessions performed 24 h, 7 d, 21 d, and 42 d after blood removal. During all 4MMP trials, power output, oxygen uptake, and aerobic and anaerobic contribution to power were determined.
  
  
  RESULTS
  4MMP average power output significantly decreased by 7% ± 6%, 6% ± 8%, and 4% ± 6% at 24 h, 7 d, and 21 d after blood removal, respectively. Compared with baseline, aerobic contribution during the 4MMP was significantly reduced by 5% ± 4%, 4% ± 5%, and 4% ± 10% at 24 h, 7 d, and 21 d, respectively. The rate of decline in power output on commencement of the 4MMP was significantly attenuated and was 76% ± 20%, 72% ± 24%, and 75% ± 35% lower than baseline at 24 h, 21 d, and 42 d, respectively.
  
  
  CONCLUSIONS
  Removal of 470 mL of blood reduces aerobic energy contribution, alters pacing patterns, and decreases performance during self-paced cycling. These findings indicate the importance of aerobic energy distribution during self-paced middle-distance events.
authors.forename: Nathan G
authors.initials: NG
authors.lastname: Lawler
authors.forename: Chris R
authors.initials: CR
authors.lastname: Abbiss
authors.forename: Aaron
authors.initials: A
authors.lastname: Raman
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Fairchild
authors.forename: Garth L
authors.initials: GL
authors.lastname: Maker
authors.forename: Robert D
authors.initials: RD
authors.lastname: Trengove
authors.forename: Jeremiah J
authors.initials: JJ
authors.lastname: Peiffer
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001642:Bicycling / Q000502:physiology*; D001782:Blood Donors; D004734:Energy Metabolism / Q000502:physiology; D005080:Exercise Test; D006339:Heart Rate / Q000502:physiology; D006400:Hematocrit; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D013997:Time Factors
chemical_list: D006454:Hemoglobins
keywords: aerobic power; anaerobic capacity; performance; self-paced