title: Evaluation of stress responses to interval training at low and moderate altitudes.
abstract: OBJECTIVE
  The purpose of the present field study was to explore whether extensive interval training (IT) performed with a similar behavior of blood lactate (LA) at an altitude of 1800 m (ALT) and near sea level (SL) goes along with a comparable hormonal, metabolic, and acute phase response in highly trained endurance athletes.
  
  
  METHODS
  Twelve distance runners (VO2 64.6 +/- 6.9 mL.kg(-1) ) performed IT (10 x 1000 m, 2-min rest) at SL with a running velocity (V) corresponding to 112% of the individual anaerobic threshold (IAT). After an acclimatization period of 7 d, IT was repeated with a lower V (107% IAT) at ALT. Blood samples were drawn at rest, 0, 0.3, 3, and 24 h after IT. LA during IT was similar at SL and ALT (5.4 +/- 1.3/5.3 +/- 1.2 mmol.L(-1)), whereas HR tended to be higher at SL.
  
  
  RESULTS
  Postexercise rises in plasma noradrenaline (NA), NA sulfate, adrenaline, glucose, interleukin-6 (IL-6), and neutrophils were significantly more pronounced at ALT. The increase of cortisol and human growth hormone showed an insignificant trend toward higher values at ALT. A slight but significant increase of plasma erythropoietin was only apparent after IT at ALT. No differences between either condition were observed for exercise-related changes in free fatty acids, IL-8, lympho-, or monocyte counts.
  
  
  CONCLUSIONS
  In spite of a matched accumulation pattern of LA between ALT and N, stress responses, such as sympathetic activation and hepatic glucose release, still appear to be greater at ALT. This additional impact of moderate ALT on the stress response to IT should be taken into account if repeated training sessions are performed within a short period of time.
authors.affiliation: Center of Internal Medicine, Department of Rehabilitative and Preventive Sports Medicine, University of Freiburg, Freiburg, Germany. niess@msml.ukl.uni-freiburg.de
authors.forename: Andreas Michael
authors.initials: AM
authors.lastname: Niess
authors.forename: Elvira
authors.initials: E
authors.lastname: Fehrenbach
authors.forename: Gunther
authors.initials: G
authors.lastname: Strobel
authors.forename: Kai
authors.initials: K
authors.lastname: Roecker
authors.forename: Elisabeth Marion
authors.initials: EM
authors.lastname: Schneider
authors.forename: Julia
authors.initials: J
authors.lastname: Buergler
authors.forename: Simone
authors.initials: S
authors.lastname: Fuss
authors.forename: Rainer
authors.initials: R
authors.lastname: Lehmann
authors.forename: Hinnak
authors.initials: H
authors.lastname: Northoff
authors.forename: Hans-Hermann
authors.initials: HH
authors.lastname: Dickhuth
mesh_terms: D000328:Adult; D000531:Altitude; D016207:Cytokines / Q000097:blood; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010807:Physical Endurance; D012420:Running / Q000502:physiology*; D013315:Stress, Psychological
chemical_list: D016207:Cytokines; D019344:Lactic Acid; D005947:Glucose; D006854:Hydrocortisone; D009638:Norepinephrine