Master of Science (Exercise and Sport Studies)

Lower limb injuries are serious cause for concern in military forces, which have been attributed to the shock absorption properties of combat boots – an essential protective gear for military personnel. Recent footwear studies have proposed using perceived comfort to select comfortable footwear that allows one to remain in their preferred movement path, potentially reduces injury risk. However, the use of comfort perception to determine combat boots is still unclear. Also, the proper fit of combat boots for the Asian population is lacking. This study aims to evaluate four different Singapore Armed Forces (SAF) combat boots, namely Wellco Peruana (Boot 1), Altama (Boot 2), Magnum XTB Black (Boot 3) and Magnum Spartan XTB Green Jump (Boot 4). Specifically, this study intends (1) to compare the ground reaction force (GRF) variables of four different combat boots during unloaded and loaded walking, (2) to measure the comfort ratings of four different combat boots, and (3) to examine the relationship between comfort and biomechanical loading of each boot. Sixty-five male participants were recruited. In each combat boot, they completed a 10-m walk in unloaded and 20-kg loaded conditions. The order of the boots and walking conditions were randomized. GRF variables – average peak force, average loading rate, and impulse were assessed using a wireless in-shoe sensor, the loadsol® system. Boot comfort was assessed using a 7-point Likert scale. Statistical analyses included 2 × 4 (walking condition × boot model) repeated measures ANOVA, Friedman, and Spearman’s rank correlation tests (p <0.05). Results showed that participants preferred Boots 3 and 4 as they were rated more comfortable and lighter than Boots 1 and 2. Participants also walked faster in Boots 3 and 4 which may be an advantage for increased work efficiency. Boots 1 and 2 displayed attenuation of GRF due to the likelihood of thicker heel cushioning material. However, a higher impulse was shown and attributed to increased weight, harder cushioning, and slower walking speed. No significant correlation was shown between perceived comfort and biomechanical loading. Thus, comfort perception cannot be used exclusively to determine loading forces and vice versa. A combination of other factors such as boot mechanics and foot structure are required to assess combat footwear and injury risk. Findings of this study suggest that lighter boots are more comfortable resulting in faster walking speed and therefore improve work performance. But at the same time, a higher loading rate due to walking faster may pose potential injury risks. A thicker heel cushioning may be more effective in reducing impact.