Effect of Boot Weight and Sole Flexibility on Gait and Physiological Responses of Firefighters in Stepping Over Obstacles

Abstract

Objective:The authors investigated the effect of boot weight and sole flexibility on spatiotemporal gait characteristics and physiological responses of firefighters in negotiating obstacles.Background: Falls and overexertion are the leading causes of fire ground injuries and fatalities among firefighters. There have been few in-depth studies conducted to evaluate the risk factors of falls and overexertion associated with firefighter boots.Method: For the study, 13 female and 14 male firefighters, while wearing full turnout clothing and randomly assigned boots, walked for 5 min while stepping over obstacles. The independent variables included boot weight, sole flexibility, gender, and task duration. Spatiotemporal measures of foot trajectories and toe clearance were determined. Minute ventilation, oxygen consumption, carbon dioxide production, and heart rate were measured.Results: Increased boot weight was found to significantly reduce trailing toe clearance when crossing the 30-cm obstacle. Significant increases in lateral displacement of the foot were found near the end of the 5-min walk compared with the beginning of the task. Increased boot weight significantly increased oxygen consumption. There were significant decreases in oxygen consumption for more flexible soles.Conclusion: Firefighters were more likely to trip over obstacles when wearing heavier boots and after walking for a period of time. Boot weight affected metabolic variables (5% to 11% increases per 1-kg increase in boot weight), which were mitigated by sole flexibility (5% to 7% decrease for more flexible soles).Application: This study provides useful information for firefighters and boot manufacturers in boot selection and design for reducing falls and overexertion.

Effects of wearing gumboots and leather lace-up boots on lower limb muscle activity when walking on simulated underground coal mine surfaces

“…As a knee flexor, the role of biceps femoris during pre-swing is to inhibit knee extension and assist the knee in a flexed position ready for swing (Perry, 1992). Immediately after pre-swing, if the limb is not adequately flexed the boot will contact the supporting surface, causing a trip (Austin et al, 1999;Chiou et al, 2012). As heavier boots tend to decrease trailing limb toe clearance (Chiou et al, 2012), the additional biceps femoris muscle activity required in the present study when the participants were wearing the leather lace-up boot compared to the gumboot could be considered a strategy to compensate for the additional boot mass in order to prevent a trip.…”

“…Immediately after pre-swing, if the limb is not adequately flexed the boot will contact the supporting surface, causing a trip (Austin et al, 1999;Chiou et al, 2012). As heavier boots tend to decrease trailing limb toe clearance (Chiou et al, 2012), the additional biceps femoris muscle activity required in the present study when the participants were wearing the leather lace-up boot compared to the gumboot could be considered a strategy to compensate for the additional boot mass in order to prevent a trip. As there were no significant differences between the knee joint or hip joint angles at pre-swing, it is postulated that the increased muscle activity was successful in maintaining the required limb position when wearing the heavier leather lace-up boots compared to the gumboots.…”

“…The authors concluded that muscle activity decreased when sufficient support was provided by an individual's footwear (No e et al, 2009). We speculate that the between-study difference could be attributed to the influence of boot mass on lower limb motion, irrespective of the changes in boot support (Chiou et al, 2012). It is also possible that regardless of stability, a stiffer boot shaft has more impact when walking on surfaces that already require additional muscular activity and joint motion, such as an incline and decline, compared to static postural sway tasks and level walking.…”

“…Increased heel contact velocities have also been documented when wearing heavier boots (Chiou et al, 2012), indicating an additional braking force is required to stabilise the leading limb at initial contact compared to when wearing lighter boots (Lockhart and Kim, 2006). During initial contact vastus lateralis decelerates and controls the leading limb as it contacts the ground (Perry, 1992), particularly when walking down a decline where a larger knee extensor moment is required to control the amount of knee flexion and allow the leading limb to support the body's mass without buckling (Lay et al, 2007).…”

The Effect of Shoe Weight on Sprint Performance: A Biomechanical Perspective

“…In addition to practical applications in sports, the effects of reduced shoe weight on sprinting performance should also be considered for the design of shoes in professional environments, e.g., fire-fighter boots. In fact, reduced weight of fire-fighter boots have been shown to lead to improved fire-fighter performance, i.e., decreased metabolic cost and reduced likelihood of tripping during an obstacle course [29,30]. Enhanced sprinting performance may be an additional benefit of reduced shoe weight that encourages light-weight boot concepts for fire-fighters.…”