Identification of the optimum gait pattern for descending stairs in a flooded condition: An electromyographic study

摘要

The objectives of this study were to investigate the lower extremity muscle activities of subjects while they descend a staircase under a flooded condition, and to identify the most effective gait in terms of both walking speed and protection against falling. By using a real-size staircase model that was equipped to generate a stream of water from the top of the stairs to the base, we simulated a flood rescue operation in an underground area. The subjects were asked to descend the stairs using different gait patterns and their surface electromyograms (EMGs) were recorded simultaneously. The EMG signals were measured for the 5 muscles of the right lower extremity. Two conditions with respect to water levels were employed: 0 cm (dry condition) and 30 cm from the top of the staircase. A total of 6 gait patterns were chosen: (a) normal descend, i.e., descending forward with each step corresponding to the landing of the descending foot, (b) descending backwards, i.e., descending in the backward direction with each step corresponding to the landing of the descending foot, (c) descending forward such that the 2 feet are placed on each step before taking the next step, (d) descending in the backward direction such that the 2 feet are placed on each step before taking the next step, (e) descending laterally towards the right side such that the 2 feet are placed on each step before taking the next step, and (f) descending laterally towards the left side such that the 2 feet are placed on each step before taking the next step. Our observations revealed that the normal descending pattern allowed the fastest gait speed; however, this pattern was related to a greater risk of falling because the activities of the rectus femoris and tibialis anterior muscles increased greatly under flooded conditions. Moreover, the activities of the 2 muscles differed only slightly between descending backwards under the 0 cm and 30 cm flooded conditions. In summary, we conclude that the backward descending gait presents the least risk of falling and can be employed during a safe and effective rescue approach, whereas the normal descending pattern is the best strategy during a hasty situation. However, the normal descending pattern may substantially increase the risk of falling and we do not recommend it, unless the rescuer is a well-trained personnel.