Relationship between the value of the Wenckebach point and +Gz tolerance

The +Gz acceleration tolerance in a homogeneous group of 21 male clinically healthy pilots or candidates to airservice was evaluated. The +Gz acceleration tolerance was compared with the Wenckebach point, i.e., the lowest rate of atrial stimulation needed to produce constant Wenckebach or Mobitz II atrio-ventricular (AV) block. The Wenckebach point was used as an autonomic nervous system activity index. It was demonstrated that the degree of +Gz acceleration tolerance depends greatly upon autonomic nervous system activity, and is lower in people with enhanced parasympathetic tone. The possibility of pharmacological correction of +Gz acceleration tolerance was discussed.