title: Traditional posterior load carriage: effects of load mass and size on torso kinematics, kinetics, muscle activity and movement stability.
abstract: Traditional posterior load carriage (PLC), done without the use of an assistive device (e.g., backpack), has been associated with low back pain (LBP) development. This study evaluated the effects of important task demands, related to load mass and size, on potential mechanisms linking traditional PLC with LBP. Nine healthy participants completed PLC tasks with three load masses (20%, 35% and 50% of individual body mass) and three load sizes (small, medium and large). Torso kinematics, kinetics, muscle activity and slip risk were evaluated during PLC on a walkway, and torso movement stability was quantified during PLC on a treadmill. Increasing load mass caused increased torso flexion, L5/S1 flexion moment, abdominal muscle activity and torso movement stability in the frontal plane. Increasing load size also caused higher torso flexion, peak torso angular velocity and acceleration, and abdominal muscle activity. Complex interactive effects of load mass and size were found on paraspinal muscle activity and slip risk. Specific task demands, related to load mass and size, may thus influence the risk of LBP during PLC.
  This study examined the effects of load mass and size on low back pain (LBP) risk using intermediary measures derived from torso kinematics, kinetics and muscle activity. Our current findings, along with earlier work, suggest that load mass and size can influence LBP risk, and that use of smaller and light loads may be beneficial during PLC.
authors.affiliation: a Industrial Engineering , Institute of Technology Bandung , Bandung , Indonesia.
authors.forename: Khoirul
authors.initials: K
authors.lastname: Muslim
authors.affiliation: b Department of Industrial and Systems Engineering , Virginia Tech , Blacksburg , USA.
authors.forename: Maury A
authors.initials: MA
authors.lastname: Nussbaum
mesh_terms: D000009:Abdominal Muscles / Q000502:physiology; D001696:Biomechanical Phenomena; D015992:Body Mass Index; D064368:Healthy Volunteers; D006801:Humans; D007700:Kinetics; D017116:Low Back Pain / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D009068:Movement / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D013647:Task Performance and Analysis; D060726:Torso / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult
keywords: kinematics; kinetics; load carriage; slip risk; spine; stability