title: Moderate exercise increases endotoxin concentration in hypoxia but not in normoxia: A controlled clinical trial.
abstract: BACKGROUND
  Hypoxia and high altitudes affect various organs, which impairs important physiological functions, such as a disruption of the intestinal barrier mediated by increased translocation of bacteria and increased circulating endotoxin levels. Physical exercise can alter endotoxin concentration in normoxia. The aim of this study is to evaluate the effects of moderate exercise on endotoxin concentration in normobaric hypoxia.
  
  
  METHODS
  Nine healthy male volunteers exercised on a treadmill for 60 minutes at an intensity of 50% VO2peak in normoxic or hypoxic conditions (4200 m). Blood was collected at rest, immediately after exercise and 1 hour after exercise to evaluate serum endotoxin levels.
  
  
  RESULTS
  Under hypoxic exercise conditions, SaO2% saturation was lower after exercise compared with resting levels (P < 0.05) and returned to the resting level during recovery in normoxia (P < 0.05). Endotoxin concentration increased after exercise in hypoxia (P < 0.05); it remained high 1 hour after exercise in hypoxia compared with normoxia (P < 0.05) and was higher after exercise and recovery compared with resting levels (P < 0.05). HR was higher during exercise in relation basal in both conditions (P < 0.05) and RPR increase after 60 minutes in comparison to 20 minutes in hypoxia (P < 0.05).
  
  
  CONCLUSIONS
  Moderate exercise performed in hypoxia equivalent to 4200 m increased endotoxin plasma concentration after exercise. One hour of rest in normoxic conditions was insufficient for the recovery of circulating endotoxins.
authors.affiliation: Department of Bioscience Department of Physiology Department of Psychobiology, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Paola
authors.initials: P
authors.lastname: Machado
authors.forename: Aline
authors.initials: A
authors.lastname: Caris
authors.forename: Samile
authors.initials: S
authors.lastname: Santos
authors.forename: Edgar
authors.initials: E
authors.lastname: Silva
authors.forename: Lila
authors.initials: L
authors.lastname: Oyama
authors.forename: Sergio
authors.initials: S
authors.lastname: Tufik
authors.forename: Ronaldo
authors.initials: R
authors.lastname: Santos
mesh_terms: D000328:Adult; D004731:Endotoxins / Q000097:blood*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D064368:Healthy Volunteers; D006801:Humans; D000860:Hypoxia / Q000097:blood*; D008297:Male; D012146:Rest / Q000502:physiology; D013997:Time Factors; D055815:Young Adult
chemical_list: D004731:Endotoxins