Impact of military type footwear and workload on heel contact dynamics during slip events

Introduction: Slips, trips and falls due to an induced loss balance have been identified as the leading cause of occupational injuries. This study aimed to analyze the impact of two military boots, standard boot (STD) and minimalist boot (MIN) on slip events, before (PRE) and after (POST) a military type load carrying task. Methods: Sixteen male participants (age: 27 +/- 3.9 years; height: 178 +/- 6.2 cm, mass: 87 +/- 12.4 kg) were tested for heel kinematics using motion capture, during unexpected (US) and expected slips (ES) both before and after the task. Slip parameters of heel slip distance (HSD) and mean heel slip velocity (MHSV) were analyzed with a 2 (STD x MIN) x 2 (PRE x POST) x 2 (US x ES) repeated measures ANOVA. Results: Significantly greater HSD (p = 0.002) and MHSV (p = 0.001) were demonstrated in STD compared to MIN, regardless of the load carrying workload and the type of slip. No significant interactions between boots, workload and slip type were found. MIN exhibited a greater percent of nonhazardous slips compared to STD. Conclusions: Greater HSD and MHSV seen in STD, suggests that MIN performed better under slippery conditions. The military type workload and the type of slip did not appear to influence slip parameters, with boot differences seen as the major influence on these slip outcomes. MIN boot's better performance could be attributed to the minimalist sole, tread and groove pattern, lighter mass and flexible shaft aiding in better maneuvering under slippery conditions. Relevance to industry: Slip outcomes in two different military boots, before and after a military type load carrying workload are addressed. The lighter minimalist tactical boot outperformed the standard tactical boot, under slippery conditions. Findings from this study will help offer suggestions for footwear design in the military, especially for maneuvering slippery environment. (C) 2018 Elsevier B.V. All rights reserved.