Comparative analysis: effects of positive and negative lateral acceleration on isometric fatigue in the forearm

The purpose of this investigation was to determine the difference, if any, produced by +/- Gy acceleration on forearm fatigue. The Dynamic Environment Simulator (DES) at the USAF Aerospace Medical Research Laboratory was used to create a lateral acceleration environment. The experiment was designed to measure the forearm strength, endurance, recovery from fatigue, and surface electrical activity of six subjects during +/- 2 Gy acceleration.

isometric performance was degraded during -2 Gy acceleration compared to + 2 Gy acceleration. The percentage drop in center frequency of the EMG signal was determined to be unreliable as a fatigue index during lateral acceleration. When head and shoulder restraints were used during lateral maneuvers, they were a factor in pilot performance, with + 2 Gy being superior to -2 Gy. This study suggested a way of analyzing the EMG signals that may permit quantification of isometric fatigue during lateral acceleration.