Influence of school bag loads and carrying methods on body strain among young male students

Abstract This study examined the influences of schoolbag carrying modes combined with carrying weights on the body posture alterations, muscle activations, and subjective discomfort scores of participants. Twelve male university students were recruited as participants and executed nine test combinations of three carrying methods (2-strap backpack, 1-strap side backpack, and 1-strap crossbody carrying) generally used by Taiwanese young students and three loads (5%, 10%, and 15% of their respective body weights [BWs]). The results revealed that carried load and method significantly affected body posture and trapezius activation. Side backpack carrying should be avoided because of the relatively high lateral shoulder tilt, trunk flexion, right trapezius activation, and low lumbosacral angle observed compared with other two carrying methods. The unbalanced load of side backpack carrying may cause an uneven shoulder posture, thus resulting in extra body strains. Furthermore, carrying loads at 10% of BW was recommended when carrying a 2-strap backpack. Relevance to industry The daily carriage of a schoolbag or backpack on the musculoskeletal health of young students has been a permanent concern. The findings suggest that carrying a load weighing 15% of BW and using the unbalanced side backpack carrying method should be avoided.