title: Salivary cortisol, heart rate, and blood lactate responses during elite downhill mountain bike racing.
abstract: OBJECTIVE
  This study aimed to quantify the intensity profile of elite downhill mountain bike races during competitions.
  
  
  METHODS
  Seventeen male downhill racers (22 ± 5 y; 185.1 ± 5.3 cm; 68.0 ± 3.9 kg; VO2peak: 59.4 ± 4.1 mL·min·kg-1) participated in the International German Downhill Championships in 2010. The racers' peak oxygen uptake and heart rate (HR) at 2 and 4 mmol·L-1 blood lactate (HR2 and HR4), were assessed during an incremental laboratory step test (100 W, increase 40 W every 5 min). During the races, the HR was recorded and pre- and postrace blood lactate concentrations as well as salivary cortisol levels were obtained.
  
  
  RESULTS
  During the race, the absolute time spent in the "easy" intensity zone was 23.3 ± 6.8 s, 24.2 ± 12.8 s (HR2-HR4) in the "moderate" zone, and 151.6 ± 18.3 s (>HR4) in the "hard" zone. Eighty percent of the entire race was accomplished at intensities >90% HRpeak. Blood lactate concentrations postrace were higher than those obtained after the qualification heat (8.0 ± 2.5 mmol·L-1 vs 6.7 ± 1.8 mmol·L-1, P < .01). Salivary levels of cortisol before the competition and the qualification heat were twice as high as at resting state (P < .01).
  
  
  CONCLUSIONS
  This study shows that mountain bike downhill races are conducted at high heart rates and levels of blood lactate as well as increased concentration of salivary cortisol as marker for psycho-physiological stress.
authors.affiliation: Department of Sport Science, University of Wuppertal, Wuppertal, Germany.
authors.forename: Billy
authors.initials: B
authors.lastname: Sperlich
authors.forename: Silvia
authors.initials: S
authors.lastname: Achtzehn
authors.forename: Mirijam
authors.initials: M
authors.lastname: Buhr
authors.forename: Christoph
authors.initials: C
authors.lastname: Zinner
authors.forename: Stefan
authors.initials: S
authors.lastname: Zelle
authors.forename: Hans-Christer
authors.initials: HC
authors.lastname: Holmberg
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D007773:Lactates / Q000097:blood*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D012463:Saliva / Q000737:chemistry*; D013312:Stress, Physiological / Q000502:physiology; D013315:Stress, Psychological / Q000097:blood; D055815:Young Adult
chemical_list: D007773:Lactates; D006854:Hydrocortisone