Heart rate and cardiac arrhythmia during high-Gz flight

Twenty-four pilots (age 20-32 years) were monitored with a Holter monitor during 26 hours including a high-Gz flight in order to evaluate heart rate (HR) and cardiac rhythm. Flight experience did not predict the mean in-flight HR (range 69-121 beats/minute), which decreased with increasing age and correlated to the maximum HR during sleep. We recorded maximally 27 ventricular and 97 supraventricular ectopic beats, 10 junctional rhythms, 5 gray-out, 1 vestibular symptom, and 1 instance of numbness of the feet during the flight. No causal relationship between HR, cardiac arrhythmia, or symptoms was found. Adaptation to in-flight +Gz stress takes place without significant arrhythmia and at a submaximal age-related HR.