Investigation into the Effects of Backrest Angle and Stick Location on Female Strength.

Objectives: The purpose of this study was to investigate the effects of backrest angle and hand maneuver direction on maximum hand strength and to recommend a strength value for the hand-controlled stick of an aircraft.

Methods: Forty-eight female subjects were recruited to perform simulated forward-backward and adduction-abduction maneuvers using control sticks. Each subject was free from musculoskeletal disorders and pain. The independent variables included four control maneuvers (forward, backward, adduction, abduction), two right-hand control stick locations (central, side), and three backrest angles (90°, 103°, 108°). The dependent variable was maximum hand strength.

Results: The maximum strength for forward maneuvers with both central and side sticks was strongest at a 90° backrest angle ( < 0.001). The maximum strength for adduction maneuvers with both central and side sticks was also strongest at a 90° backrest angle ( 0.001). On the other hand, the highest strength was observed at a 108° backrest angle when pulling the stick backward ( 0.001). The abduction strength was significantly stronger than the adduction strength with a central stick ( 0.001), but the adduction strength was significantly stronger than the abduction strength with a side stick ( 0.001- = 0.017). The forward and abduction strength were significantly different in different locations ( 0.001). The recommended strength in the Code of Federal Regulations (CFR) by the US FAA is higher than the strength values observed in this study.

Conclusions: The backrest angle, directions, and location affected the muscular strength. The recommended values should be reevaluated and adjusted for Taiwanese pilots.