The Influence of Occupational Footwear on Slip Responses

Abstract

Falls in the workplace most often occur due to slips and unsuitable footwear. While industry standardized occupational footwear (OF) is required for the safety of occupational activities, little is known about how OF influences how individuals respond to an unexpected slip. Therefore, the purpose of this study was to investigate how OF affects balance recovery strategies and slip outcome in response to an unexpected slip during walking. Twenty-five individuals (13 males, 12 females) completed a total of 12 walking trials at a self-selected pace in either barefoot (BF) or while wearing OF. The first five trials consisted of the no-slip condition, where individuals walked over a sheet of high friction aluminum foil. On the sixth trial and without the participant’s knowledge, the aluminum foil was replaced with a low friction hard plastic surface to induce an unexpected slip. The remaining six trials were conducted over the low friction surface while participants were aware of the low friction surface. For each walking trial, ground reaction forces, lower limb electromyography and kinematics were recorded. It was found that when individuals in both groups first experienced the unexpected slip, both groups responded with a macro-slip. However, the slip was less severe in the OF group, with a 13 cm shorter heel slip distance and a 0.6 m/s slower heel slip velocity, compared to the BF group. A less severe slip may have been due to differences found in normal walking, since the OF group applied 23% less shear force and had a 16% smaller co-efficient of friction utilized. Differences in slip severity may have also contributed to the ensuing slip response. The OF group, who experienced a less severe slip, demonstrated 35-49% less muscle activity in the left (slip limb) medial hamstrings and left tibialis anterior as well as 2˚ less plantar-flexion after encountering the slip. The OF group also activated their right (non-slip) tibialis anterior, medial gastrocnemius, and vastus lateralis to a lesser extent, by 66-78%, after the slip onset. Although walking in OF appears to lead to a decreased slip risk and a less severe slip outcome, more research is required to evaluate the effectiveness of these slip recovery responses in reducing workplace falls.