The Student Body: The Effect of Backpack Wear on Center of Mass Displacement in College Student During Walking and Static Standing

Abstract

<b>Objective:</b> To investigate center of mass (COM) displacement during static standing and walking as well as forward flexion of the trunk during walking in college students in loaded and unloaded conditions. <b>Design and Setting:</b> All data were collected in Jowers Biomechanics Laboratory, Texas State University-San Marcos. <b>Subjects:</b> Subjects included 20 college students (ages = 22.85 + 5.58 years, mass = 72.11 + 11.28 kg, height = 169.89 + 10.01 cm) with no reports of injuries to lower extremities in the last two years. <b>Measurements:</b> Participants stood on the Biodex Balance System static platform and performed postural stability tests. Subjects were then recorded walking for 5 meters, to measure movement of the hip. In both portions of the study, 3 trials were conducted in unloaded conditions, followed by 3 trials while carrying a backpack loaded to roughly 10% of subjects’ weight. <b>Results:</b> One tailed and two tailed T tests were performed. A significant difference was found in the angle of trunk flexion (t < .01). Average angle of inclination at the trunk in unloaded walking was 165.56 degrees + 6.75 and 158.29 degrees + 6.87 during loaded walking. No significant difference was found in vertical COM displacement during walking or static standing between loaded and unloaded trials. <b>Conclusions:</b> Based on these findings, this data indicates that trunk forward flexion while wearing a loaded backpack occurs in consistent correlation regardless of weight, height, weekly exercise frequency or velocity during ambulation in college students. It is also indicated, based on these results that a backpack loaded at 10% of an individuals’ body weight does not affect the COM location compared to unloaded trials during static standing, or vertical COM displacement during ambulation.