An ergonomics evaluation of the vibration backpack harness system in walking

• We construct a vibration backpack harness system.
• There are four vibrators sewn in the four different positions of harness system.
• Objective and subjective observations state the effect of the harness system.
• There is a positive effect on reducing muscle activity with low frequency vibration.
• There is a positive effect on improving overall comfort with low frequency vibration.

Many studies in backpack design have been focused on reducing trunk muscle activity and improving overall comfort while the wearers (college students and outdoor enthusiasts) were walking. However, little work has done on combining the vibration with harness system design. The purpose of the present study was to evaluate the effect of the vibration backpack harness system on trunk muscle activity and overall comfort in walking. There were four vibrators sewn in the four different positions of our harness system. Subjects were asked to support a load (20% body weight) on their backpack while performing 5-min walking trials on the treadmill (speed = 1.6 m/s) with different frequencies of vibration (0 Hz, 28 Hz, 35 Hz, 42 Hz). The objective measures of trunk muscle activity (electromyography) were obtained during the walking task. Subjects also were asked to complete subjective ratings of comfort. The results of the objective measures in this study had shown that the vibration function had a positive effect on reducing muscle activity for upper trapezius (UT), but not for erector spinae (ES). From the data of the two subjective surveys in our study, the comfort level of no-vibration state (0 Hz) was worse than vibration state (28 Hz, 35 Hz, 42 Hz) for both muscles, and when the frequency was 35 Hz, the comfort of the harness system was higher than the other three frequencies. The findings of the present study support that backpack with low frequency vibration has a positive effect on reducing trunk muscle activity and improving overall comfort level for wearers in walking.Relevance to industryObservations of present study is beneficial in assisting wearers to reduce muscle activity and improve overall comfort in walking according to the vibration backpack harness system. New backpack design criteria for harness systems are discussed to optimize production strategies. The wearers could be students, outdoor enthusiasts and old people.