Flight helmet weight, +Gz forces, and neck muscle strain.

The aim of this study was to investigate the effect of flight helmet weight on cervical erector spinae muscle strain under high +Gz forces. Two helmets of different weight were compared by recording inflight neck muscle activities with a portable surface-integrated EMG (IEMG) device. The obtained IEMG activities were normalized by comparing them with activities representing maximal voluntary contraction (MVC) of the muscles. Two test pilots carried out a total of 16 flights consisting of a series of different maneuvers. The results indicate that a lighter flight helmet may--at least in some pilots--cause less strain on neck structures than a heavier one. The effect of helmet weight was readily apparent only under high +Gz forces; changing from a heavier to a lighter helmet reduced the mean muscular strain from 9.5 to 8.8% and from 20.2 to 17.1% of the MVC under +4.0 and +7.0 Gz, respectively. Thus, some, but not all, acute inflight neck pain and related problems might be avoided by using lighter flight helmets.