Effects of using exposure footwear for firemen and fitness training shoes on lower limb biomechanics during walking

Exposure footwear for firemen (EFF) is a crucial component of firefighters' personal protective equipment, designed to protect against hazards, such as heat, punctures, impact, and electrocution. However, its effect on gait biomechanics remains unclear. This study was aimed to investigate the influence of EFF on firefighters' lower limb biomechanical performance and the underlying mechanisms. Twenty healthy male firefighters (mean height: 175.41 ± 4.39 cm, mean weight: 65.74 ± 5.81 kg, mean BMI: 21.37 ± 2.17 kg/m²) were randomly assigned to wear EFF and fitness training shoes for comparison during walking tasks. Lower limb biomechanics were analyzed, focusing on joint range of motion (ROM), moments, work and muscle activity. The results indicated that wearing EFF led to increased hip and knee joint ROM in the sagittal plane, reduced ankle and metatarsophalangeal (MTP) joint ROM in the sagittal plane, increased peak hip flexion/extension and ankle dorsiflexion moments, and decreased MTP joint dorsiflexion peak moments. EFF use also resulted in increased positive work done by the hips, increased negative work done by the ankles, reduced positive work done by the ankle joints, and increased negative work by the MTP joint, The activation levels of the rectus femoris and tibialis anterior muscles were higher when wearing EFF compared to fitness training shoes. In conclusion, EFF significantly alters the biomechanical characteristics of firefighters' lower limbs during walking, leading to elevated muscle activation in the rectus femoris and tibialis anterior. This increased demand on the lower limb muscle groups for mechanical energy generation heightens the risk of fatigue, musculoskeletal injuries, and osteoarthritis. Therefore, it is recommended that EFF boots be designed using lightweight and flexible materials. Additionally, training programs should prioritize strengthening the hip flexor/extensor, ankle dorsiflexor muscle groups, and especially the rectus femoris and tibialis anterior muscles.