title: Heart rate and autonomic balance during stand tests before and after fighter combat missions.
abstract: BACKGROUND
  High workload during combat missions is a critical factor in the use of modern aircraft. Our objective was to evaluate the impact of piloting in war zones on the kinetics of the sympathovagal balance during recovery.
  
  
  METHODS
  There were 40 military pilots who were monitored during operational flights in Afghanistan. Electrocardiographic activity was recorded during stand tests performed 1 h before takeoff (T-1), immediately after landing (L+0), 2 h after (L+2), and 4 h after (L+4) the flight. Missions were divided in two groups according to flight duration.
  
  
  RESULTS
  The mean length of long flights was 4:31 +/- 0:53 h and of short flights 1:27 +/- 0:09 h. For long flights, at L+0, all indices related to parasympathetic modulation rose significantly in comparison to T-1, L+2, and L+4 (total power L+0: 2083 +/- 414 ms2 x Hz(-1),T-1: 1269 +/- 158 ms2 x Hz(-1), L+2: 1095 +/- 148 ms2 x Hz(-1), and L+4: 1238 +/- 124 ms2 x Hz(-1); high-frequency normalized units (HFnu) L+0: 16 +/- 2%, T-1: 11 +/- 1%, L+2: 10 +/- 1%, and L+4: 11 +/- 1%). At the same time the sympathetic frequency components significantly decreased (low-frequency normalized units (LFnu) L+0: 83 +/- 2%, T-1: 88 +/- 1%, L+2: 90 +/- 1%, and L+4: 89 +/- 1%; LF/HF L+0: 7 +/- 1, T-1: 11 +/- 1, L+2: 13 +/- 2, and L+4: 16 +/- 3). For short flights, the sympathetic components were higher at L+0 (LFnu: 77 +/- 2%; LF/HF: 14 +/- 3) than at T-1 (LFnu: 66 +/- 5%; LF/HF: 6 +/- 1). A concomitant reduction of vagal components was observed.
  
  
  CONCLUSIONS
  Modulations of autonomic balance differed with the type of mission. A postflight sympathetic increase represents an autonomic adaptation due to stress and flight. A raise of parasympathetic modulation after flight may be related to the decrease of alertness.
authors.affiliation: Institut de Médecine Aérospatiale du Service de Santé des Armées, Département de physiologie, Brétigny-sur-Orge Cedex, France. carodus@hotmail.com
authors.forename: Caroline
authors.initials: C
authors.lastname: Dussault
authors.forename: Laurent
authors.initials: L
authors.lastname: Lely
authors.forename: Christophe
authors.initials: C
authors.lastname: Langrume
authors.forename: Fabien
authors.initials: F
authors.lastname: Sauvet
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Jouanin
mesh_terms: D000328:Adult; D000337:Aerospace Medicine; D001341:Autonomic Nervous System / Q000502:physiology*; D015716:Electrocardiography, Ambulatory; D005221:Fatigue / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008889:Military Personnel; D013315:Stress, Psychological / Q000503:physiopathology; D013997:Time Factors; D016526:Workload