title: Physiological and Biomechanical Responses to Prolonged Heavy Load Carriage During Level Treadmill Walking in Females.
abstract: Heavy load carriage has been identified as a main contributing factor to the high incidence of overuse injuries in soldiers. Peak vertical ground reaction force (VGRFMAX) and maximal vertical loading rates (VLRMAX) may increase during heavy prolonged load carriage with the development of muscular fatigue and reduced shock attenuation capabilities. The objectives of the current study were (1) to examine physiological and biomechanical changes that occur during a prolonged heavy load carriage task, and (2) to examine if this task induces neuromuscular fatigue and changes in muscle architecture. Eight inexperienced female participants walked on an instrumented treadmill carrying operational loads for 60 minutes at 5.4 km·h-1. Oxygen consumption ( V ˙ O 2 ), heart rate, rating of perceived exertion (RPE), trunk lean angle, and ground reaction forces were recorded continuously during task. Maximal force and in-vivo muscle architecture were assessed pre- and posttask. Significant increases were observed for VGRFMAX, VLRMAX, trunk lean angle, [Formula: see text], heart rate, and RPE during the task. Increased vastus lateralis fascicle length and decreased maximal force production were also observed posttask. Prolonged heavy load carriage, in an inexperienced population carrying operational loads, results in progressive increases in ground reaction force parameters that have been associated with overuse injury.
authors.affiliation: 1 Appalachian State University.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Lidstone
authors.affiliation: 1 Appalachian State University.
authors.forename: Justin A
authors.initials: JA
authors.lastname: Stewart
authors.affiliation: 1 Appalachian State University.
authors.forename: Reed
authors.initials: R
authors.lastname: Gurchiek
authors.affiliation: 1 Appalachian State University.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Needle
authors.affiliation: 1 Appalachian State University.
authors.forename: Herman
authors.initials: H
authors.lastname: van Werkhoven
authors.affiliation: 1 Appalachian State University.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: McBride
mesh_terms: D015502:Absorptiometry, Photon; D000886:Anthropometry / Q000379:methods; D001696:Biomechanical Phenomena / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D018763:Muscle Fatigue / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D016138:Walking / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult
keywords: cardiovascular drift; fatigue; ground reaction force; load carriage; muscle architecture