Standard and Alternate Methods of Stretcher Carriage: Performance, Human Factors, and Cardiorespiratory Responses

Eleven soldiers performed two-person carries of a stretcher containing an 80-kg manikin while walking on a treadmill set at 4.8 km/hr. In separate trials, soldiers carried the stretcher using one of four methods involving (a) traditional hand carriage, (b) shoulder straps (cross-shoulder system), (c) a specially designed harness that allowed load shifting between the hips and shoulders (hip-shoulder system), and (d) a clip that fit on the pistol belt of military load-carrying equipment (LCE) and placed the stretcher mass mainly on the hips (LCE system). With each system, subjects walked until fatigued or until 30 minutes expired. While subjects walked, their expired gases and heart rates were obtained and subjects rated their perceived exertion (Borg Scale). At the conclusion of all four trials, subjects rated each system on a number of subjective measures. Average (SD) carriage times (in minutes) were 2. 7+1.4, 14.5+8.3,25.4+8.1, and 21.7+9.9 with the hand, cross-shoulder, hip- shoulder, and LCE-integrated systems, respectively. Hand carriage resulted in considerably more cardiorespiratory stress (higher heart rate and minute ventilation) than the other three systems, but there were few consistent differences among the other three systems. Perceived exertion in the upper body was less with the hip-shoulder and LCE systems than with the other two systems, and subjects preferred the hip-shoulder and LCE integrated systems overall, as well as for specific characteristics including comfort, ease of use, and stability. These data indicate that two-person stretcher carriage methods that displace the load from the hands to the shoulders and hips improve performance, reduce cardiorespiratory stress, and are preferred by subjects. Further developmental work should focus on the hip-shoulder and LCE systems.Army Research Lab Aberdeen Proving Ground is the author of 'Standard and Alternate Methods of Stretcher Carriage: Performance, Human Factors, and Cardiorespiratory Responses' with ISBN 9781423565307 and ISBN 1423565304.