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 (p < 0.001). The maximum strength for adduction maneuvers with both central and side sticks was also strongest at a 90° backrest angle (p < 0.001). On the other hand, the highest strength was observed at a 108° backrest angle when pulling the stick backward (p < 0.001). The abduction strength was significantly stronger than the adduction strength with a central stick (p < 0.001), but the adduction strength was significantly stronger than the abduction strength with a side stick (p < 0.001-p = 0.017). The forward and abduction strength were significantly different in different locations (p < 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.

Normative Hand Strength of Healthcare Industry Workers in Central Taiwan.

Objectives: The purpose of this study is to establish the norms of hand grip strength in the healthcare industry in Taiwan and propose models to predict the strength of hand movement by regression with demographic and anthropometric factors. Methods: This is a cross-sectional study with a stratified convenience sample of workers in healthcare service industries in central Taiwan. Three hundred twenty-nine healthy subjects were recruited. Strength of different hand movement were tested three times in both hands and rests were given between tests. Results: Female strength of these hand movement was 59.1% to 73.0% that in males (p < 0.001). In general, the hand strength of male workers in the healthcare industry was less than that of male workers in the manufacturing industry (p < 0.001). In the prediction model, sex and weight played important roles in predicting hand strength. Conclusions: The norms of different types of hand strength was investigated the first time in workers in the healthcare industry in Taiwan. The tasks performed by healthcare personnel vary widely, and this variable should be considered in a future prediction model.