title: Lower limb flexion posture relates to energy absorption during drop landings with soldier-relevant body borne loads.
abstract: Fifteen military personnel performed 30-cm drop landings to quantify how body borne load (light, ∼6 kg, medium, ∼20 kg, and heavy, ∼40 kg) impacts lower limb kinematics and knee joint energy absorption during landing, and determine whether greater lower limb flexion increases energy absorption while landing with load. Participants decreased peak hip (P = 0.002), and knee flexion (P = 0.007) posture, but did not increase hip (P = 0.796), knee (P = 0.427) or ankle (P = 0.161) energy absorption, despite exhibiting greater peak hip (P = 0.003) and knee (P = 0.001) flexion, and ankle (P = 0.003) dorsiflexion angular impulse when landing with additional load. Yet, when landing with the light and medium loads, greater hip (R(2) = 0.500, P = 0.003 and R(2) = 0.314, P = 0.030) and knee (R(2) = 0.431, P = 0.008 and R(2) = 0.342, P = 0.022) flexion posture predicted larger knee joint energy absorption. Thus, military training that promotes hip and knee flexion, and subsequently greater energy absorption during landing, may potentially reduce risk of musculoskeletal injury and optimize soldier performance.
authors.affiliation: Oak Ridge Institute for Science and Education (ORISE), Belcamp, MD, USA; U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, MA, USA. Electronic address: tyler.n.brown4.civ@mail.mil.
authors.forename: T N
authors.initials: TN
authors.lastname: Brown
authors.affiliation: U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, MA, USA.
authors.forename: M
authors.initials: M
authors.lastname: O'Donovan
authors.affiliation: U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, MA, USA.
authors.forename: L
authors.initials: L
authors.lastname: Hasselquist
authors.affiliation: U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, MA, USA.
authors.forename: B
authors.initials: B
authors.lastname: Corner
authors.affiliation: U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, MA, USA; Liberty Mutual Research Institute for Safety, Hopkinton, MA, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Schiffman
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D007866:Leg / Q000502:physiology*; D008297:Male; D008889:Military Personnel; D009068:Movement / Q000502:physiology; D011187:Posture / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult
keywords: Energy absorption; Impact force; Kinematics; Kinetics