title: Endurance and performance during multiple intense high +Gz exposures with effective anti-G protection.
abstract: BACKGROUND
  In many high-intensity wartime scenarios, pilots may be required to fly multiple, strenuous missions during the same day.
  
  
  OBJECTIVE
  New anti-G protection allows fighter pilots to endure multiple high +G, exposures during several sorties in a limited time interval.
  
  
  METHODS
  Nine well-trained centrifuge subjects were exposed to tactical aerial combat maneuvers using balanced pressure breathing during G (PBG) and an extended coverage anti-G suit. The centrifuge exposures consisted of five simulated sorties during a 4-h period, each consisting of four engagements with rapid onset cycles (6 G x s(-1)) varying between +4 G, and -9 GC. The subjects executed a tracking task before, during, and after each engagement and verbally indicated their effort level. Neck muscle strength was measured before and after the test.
  
  
  RESULTS
  Seven of the nine subjects could endure all five sorties during the 4-h period. On a scale from 0 (no effort) to 11 (maximum possible effort), highest effort level during runs varied from 5.5 to 11 units (mean 8.7). Maximal heart rate varied from 140-173 bpm (mean 159) and minimum finger oxygen saturation from 75-93% (mean 88). Maximal peripheral and central light-loss varied from 0 to 100% (mean 71 and 40, respeclively). Three G-LOCs (two in the same subject) and four cases of near loss of consciousness occurred. The general fatigue recovery time varied from 9 to 48 h (mean 21). The tracking tests showed that performance deteriorated significantly during all G exposures; the neck muscle contraction was impaired by 12% (p = 0.035) after the C exposures.
  
  
  CONCLUSIONS
  It is possible to train subjects to withstand five simulated flight sorties during a 4-h period with a total of up to 80 peaks to +9 Gz and 80 peaks to +8 Gz using PBCG and an extended coverage anti-G suit.
authors.affiliation: Biodynamics and Protection Division, Air Force Research Laboratory, Brooks AFB, TX 78235-5105, USA. ulf.balldin@brooks.af.mil
authors.forename: U I
authors.initials: UI
authors.lastname: Balldin
authors.forename: P M
authors.initials: PM
authors.lastname: Werchan
authors.forename: J
authors.initials: J
authors.lastname: French
authors.forename: B
authors.initials: B
authors.lastname: Self
mesh_terms: D000337:Aerospace Medicine; D004576:Electromyography; D005676:Gravity Suits; D006801:Humans; D018471:Hypergravity; D008297:Male; D009119:Muscle Contraction; D009334:Neck Muscles; D013647:Task Performance and Analysis; D014474:Unconsciousness