Effect of hand-held loads on the maximum reach envelope

BACKGROUND: Reach envelope used in the design and layout of workstation is important for decreasing fatigue and injury by improving productivity, health, and safety. OBJECTIVES: The objective of this investigation was to determine differences between maximum reach envelope with and without a load in a seated position. METHODS: Measurements were conducted using a computerized potentiometric system for anthropometric measures (CPSAM). Participants performed six trials of each three load conditions of 0 Kg, 0.5 Kg and 1.0 Kg. RESULTS: Cylindrical coordinates (r, θ ,Z )were determined in panels of Z-level by θ angle in relation to each participant’s acromion. Mean and median reach values were computed for each panel to create the envelope. The reach envelope for the load conditions was smaller than the control (0 Kg). There was no significant difference between the two load conditions. CONCLUSIONS: The decrease in reach envelope when a load is added suggests that load is a factor affecting reach and should be considered when designing a workspace. Layouts requiring hand-held items such as tools or protective equipment may require considerations of a decreased reach. At what specific load level reach is affected should be further investigated.