Effects of weight distribution in a handle of a cordless stick-type vacuum cleaner: Muscle activity and subjective discomfort of the upper limb

This study investigated muscle activity and discomfort of the upper limb as a function of weight distributions in a handle of a cordless stick-type vacuum cleaner. Seventeen female college students with the experience of vacuum cleaner-use were recruited for testing. Handle mock-ups with five different centers of mass (top front, top rear, bottom front, bottom rear, and center) were manufactured, and muscle activity (electromyography) and discomfort (Borg CR10) were measured during vacuuming with the mock-ups. The results showed that the %MVC of the Extensor Carpi Ulnaris (p = 0.0155) and Upper Trapezius (p = 0.0228) decreased when the center of mass moved from the bottom to top of the mock-up. However, the %MVC of the Biceps Brachii had reverse propensities under the same conditions (p = 0.0151). Meanwhile, the discomfort on the hand (p = 0.0080), upper arm (p = 0.0160), shoulder (p = 0.0112), and neck (p = 0.0226) decreased when the center of mass moved from the bottom to top of the mock-up.