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Daniel E Lieberman - One of the best experts on this subject based on the ideXlab platform.
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tradeoffs between impact loading rate vertical impulse and effective mass for walkers and Heel Strike runners wearing footwear of varying stiffness
Journal of Biomechanics, 2015Co-Authors: Brian J Addison, Daniel E LiebermanAbstract:Abstract Humans experience repetitive impact forces beneath the Heel during walking and Heel Strike running that cause impact peaks characterized by high rates and magnitudes of loading. Impact peaks are caused by the exchange of momentum between the ground and a portion of the body that comes to a full stop (the effective mass) during the period of the impact peak. A number of factors can influence this exchange of momentum, including footwear stiffness. This study presents and tests an impulse–momentum model of impact mechanics which predicts that effective mass and vertical impulse is greater in walkers and Heel Strike runners wearing less stiff footwear. The model also predicts a tradeoff between impact loading rate and effective mass, and between impact loading rate and vertical impulse among individuals wearing footwear of varying stiffness. We tested this model using 19 human subjects walking and running in minimal footwear and in two experimental footpads. Subjects walked and ran on an instrumented treadmill and 3D kinematic data were collected. As predicted, both vertical impulse (walking: F (2,54)=52.0, p =2.6E−13; running: F (2,54)=25.2, p =1.8E−8) and effective mass (walking: F (2,54)=12.1, p =4.6E−5; running: F (2,54)=15.5, p =4.7E−6) increase in less stiff footwear. In addition, there is a significant inverse relationship between impact loading rate and vertical impulse (walking: r =−0.88, p r =−0.78, p r =−0.88, p r =−0.82, p
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tradeoffs between impact loading rate vertical impulse and effective mass for walkers and Heel Strike runners wearing footwear of varying stiffness
Journal of Biomechanics, 2015Co-Authors: Brian J Addison, Daniel E LiebermanAbstract:Humans experience repetitive impact forces beneath the Heel during walking and Heel Strike running that cause impact peaks characterized by high rates and magnitudes of loading. Impact peaks are caused by the exchange of momentum between the ground and a portion of the body that comes to a full stop (the effective mass) during the period of the impact peak. A number of factors can influence this exchange of momentum, including footwear stiffness. This study presents and tests an impulse-momentum model of impact mechanics which predicts that effective mass and vertical impulse is greater in walkers and Heel Strike runners wearing less stiff footwear. The model also predicts a tradeoff between impact loading rate and effective mass, and between impact loading rate and vertical impulse among individuals wearing footwear of varying stiffness. We tested this model using 19 human subjects walking and running in minimal footwear and in two experimental footpads. Subjects walked and ran on an instrumented treadmill and 3D kinematic data were collected. As predicted, both vertical impulse (walking: F(2,54)=52.0, p=2.6E-13; running: F(2,54)=25.2, p=1.8E-8) and effective mass (walking: F(2,54)=12.1, p=4.6E-5; running: F(2,54)=15.5, p=4.7E-6) increase in less stiff footwear. In addition, there is a significant inverse relationship between impact loading rate and vertical impulse (walking: r=-0.88, p<0.0001; running: r=-0.78, p<0.0001) and between impact loading rate and effective mass (walking: r=-0.88, p<0.0001; running: r=-0.82, p<0.0001). The tradeoff relationships documented here raise questions about how and in what ways the stiffness of footwear Heels influence injury risk during human walking and running.
Daniel Schmitt - One of the best experts on this subject based on the ideXlab platform.
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mechanics of Heel Strike plantigrady in african apes
Journal of Human Evolution, 2020Co-Authors: Angel Zeininger, Daniel Schmitt, Roshna E WunderlichAbstract:The initiation of a walking step with a Heel Strike is a defining characteristic of humans and great apes but is rarely found in other mammals. Despite the considerable importance of Heel Strike to an understanding of human locomotor evolution, no one has explicitly tested the fundamental mechanical question of why great apes use a Heel Strike. In this report, we test two hypotheses (1) that Heel Strike is a function of hip protraction and/or knee extension and (2) that short-legged apes with a midfoot that dorsiflexes at Heel lift and long digits for whom digitigrady is not an option use Heel-Strike plantigrady. This strategy increases hip translation while potentially moderating the cost of redirecting the center of mass ('collisional costs') during stance via rollover along the full foot from the Heel to toes. We quantified hind limb kinematics and relative hip translation in ten species of primates, including lemurs, terrestrial and arboreal monkeys, chimpanzees, and gorillas. Chimpanzees and gorillas walked with relatively extended knees but only with moderately protracted hips or hind limbs, partially rejecting the first hypothesis. Nonetheless, chimpanzees attained relative hip translations comparable with those of digitigrade primates. Heel-Strike plantigrady may be a natural result of a need for increased hip translations when forelimbs are relatively long and digitigrady is morphologically restricted. In addition, foot rollover from the Heel to toe in large, short-legged apes may reduce energetic costs of redirecting the center of mass at the step-to-step transition as it appears to do in humans. Heel Strike appears to have been an important mechanism for increasing hip translation, and possibly reducing energetic costs, in early hominins and was fundamental to the evolution of the modern human foot and human bipedalism.
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ontogenetic changes in foot Strike pattern and calcaneal loading during walking in young children
Gait & Posture, 2018Co-Authors: Angel Zeininger, Daniel Schmitt, Jody L Jensen, Liza J ShapiroAbstract:The assumption that the morphology of the human calcaneus reflects high and cyclical impact forces at Heel Strike during adult human walking has never been experimentally tested. Since a walking step with a Heel Strike is an emergent behavior in children, an ontogenetic study provides a natural experiment to begin testing the relationship between the mechanics of Heel Strike and calcaneal anatomy. This study examined the ground reaction forces (GRFs) of stepping in children to determine the location of the center of pressure (COP) relative to the calcaneus and the orientation and magnitude of ground reaction forces during foot contact. Three-dimensional kinematic and kinetic data were analyzed for 18 children ranging in age from 11.5 to 43.1 months. Early steppers used a flat foot contact (FFC) and experienced relatively high vertical and resultant GRFs with COP often anterior to the calcaneus. More experienced walkers used an initial Heel contact (IHC) in which GRFs were significantly lower but the center of pressure remained under the Heel a greater proportion of time. Thus, during FFC the foot experienced higher loading, but the Heel itself was relatively wider and the load was distributed more evenly. In IHC walkers load was concentrated on the anterior calcaneus and a narrower Heel, suggesting a need for increased calcaneal robusticity during development to mitigate injury. These results provide new insight into foot loading outside of typical mature contact patterns, inform structure-function relationships during development, and illuminate potential causes of Heel injury in young walkers.
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mechanical energy and effective foot mass during impact loading of walking and running
Journal of Biomechanics, 2005Co-Authors: Daniel SchmittAbstract:Abstract The human Heel pad is considered an important structure for attenuation of the transient force caused by Heel-Strike. Although the mechanical properties of Heel pads are relatively well understood, the mechanical energy ( E tot ) absorbed by the Heel pad during the impact phase has never been documented directly because data on the effective foot mass ( M eff ) was previously unavailable during normal forward locomotion. In this study, we use the impulse–momentum method (IMM) for calculating M eff from moving subjects. Mass–spring–damper models were developed to evaluate errors and to examine the effects of pad property, upper body mass, and effective leg spring on M eff . We simultaneously collected ground reaction forces, pad deformation, and lower limb kinematics during impact phase of barefoot walking, running, and crouched walking. The latter was included to examine the effect of knee angle on M eff . The magnitude of M eff as a percentage of body mass ( M B ) varies with knee angle at impact and significantly differs among gaits: 6.3% M B in walking, 5.3% M B in running, and 3.7% M B in crouched walking. Our modeling results suggested that M eff is insensitive to Heel pad resilience and effective leg stiffness. At the instant prior to Heel Strike, E tot ranges from 0.24 to 3.99 J. The combination of video and forceplate data used in this study allows analyses of E tot and E tot as a function of Heel-Strike kinematics during normal locomotion. Relationship between M eff and knee angle provides insights into how changes in posture moderate impact transients at different gaits.
Jens Nielsen - One of the best experts on this subject based on the ideXlab platform.
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treadmill training with an incline reduces ankle joint stiffness and improves active range of movement during gait in adults with cerebral palsy
Disability and Rehabilitation, 2017Co-Authors: Jakob Lorentzen, Henrik Kirk, Rasmus Frisk, Nanna Scharff Nielsen, Martin Jorsal, Helena Fernandezlago, Jens NielsenAbstract:AbstractPurpose: We investigated if 30 min of daily treadmill training with an incline for 6 weeks would reduce ankle joint stiffness and improve active range of movement in adults with cerebral palsy (CP).Methods: The study was designed as a randomized controlled clinical trial including 32 adults with CP (GMFCS 1–3) aged 38.1 SD 12 years. The training group (n = 16) performed uphill treadmill training at home daily for 30 min for 6 weeks in addition to their usual activities. Passive and reflex mediated stiffness and range of motion (ROM) of the ankle joint, kinematic and functional measures of gait were obtained before and after the intervention/control period. Intervention subjects trained 31.4 SD 10.1 days for 29.0 SD 2.3 min (total) 15.2 h.Results: Passive ankle joint stiffness was reduced (F = 5.1; p = 0.031), maximal gait speed increased (F = 42.8, p < 0.001), amplitude of toe lift prior to Heel Strike increased (F = 5.3, p < 0.03) and ankle angle at Heel Strike was decreased (F = 12.5; p < 0.001)...
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gait training reduces ankle joint stiffness and facilitates Heel Strike in children with cerebral palsy
NeuroRehabilitation, 2014Co-Authors: Maria Willerslevolsen, Jakob Lorentzen, Jens NielsenAbstract:Background Foot drop and toe walking are frequent concerns in children with cerebral palsy (CP). Increased stiffness of the ankle joint muscles may contribute to these problems. Objective Does four weeks of daily home based treadmill training with incline reduce ankle joint stiffness and facilitate Heel Strike in children with CP? Methods Seventeen children with CP (4-14 years) were recruited. Muscle stiffness and gait ability were measured twice before and twice after training with an interval of one month. Passive and reflex-mediated stiffness were measured by a dynamometer which applied stretches below and above reflex threshold. Gait kinematics were recorded by 3-D video-analysis during treadmill walking. Foot pressure was measured by force-sensitive foot soles during treadmill and over-ground walking. Results Children with increased passive stiffness showed a significant reduction in stiffness following training (P = 0.01). Toe lift in the swing phase (P = 0.014) and Heel impact (P = 0.003) increased significantly following the training during both treadmill and over-ground walking. Conclusions Daily intensive gait training may influence the elastic properties of ankle joint muscles and facilitate toe lift and Heel Strike in children with CP. Intensive gait training may be beneficial in preventing contractures and maintain gait ability in children with CP.
Thomas P Andriacchi - One of the best experts on this subject based on the ideXlab platform.
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age related differences in sagittal plane knee function at Heel Strike of walking are increased in osteoarthritic patients
Osteoarthritis and Cartilage, 2014Co-Authors: J Favre, Jennifer C Erharthledik, Thomas P AndriacchiAbstract:Summary Objective To compare age-related patterns of gait with patterns associated with knee osteoarthritis (OA), the following hypotheses were tested: (H1) The sagittal-plane knee function during walking is different between younger and older asymptomatic subjects; (H2) The age-related differences in H1 are increased in patients with knee OA. Design Walking trials were collected for 110 participants (1.70 ± 0.09 m, 80 ± 14 kg). There were 29 younger asymptomatic subjects (29 ± 4 years) and 81 older participants (59 ± 9 years), that included 27 asymptomatic subjects and 28 and 26 patients with moderate and severe medial knee OA. Discrete variables characterizing sagittal-plane knee function were compared among the four groups using ANOVAs. Results During the Heel-Strike portion of the gait cycle at preferred walking speed, the knee was less extended and the shank less inclined in the three older groups compared to the younger asymptomatic group. There were similar differences between the severe OA group and the older asymptomatic and moderate OA groups. Both OA groups also had the femur less posterior relative to the tibia and smaller extension moment than the younger group. During terminal stance, the severe OA group had the knee less extended and smaller knee extension moment than the younger asymptomatic and older moderate OA groups. Conclusions The differences in knee function, particularly those during Heel-Strike which were associated with both age and disease severity, could form a basis for looking at mechanical risk factors for initiation and progression of knee OA on a prospective basis.
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the relationship between peak knee extension at Heel Strike of walking and the location of thickest femoral cartilage in acl reconstructed and healthy contralateral knees
Journal of Biomechanics, 2013Co-Authors: Sean F Scanlan, Julien Favre, Thomas P AndriacchiAbstract:Reports that knee cartilage health is sensitive to kinematic changes, combined with reports of extension loss following ACL reconstruction, underscores the importance of restoring ambulatory knee extension in the context of preventing premature osteoarthritis. The purpose of this study was to test the relationship between individual variations in peak knee extension at Heel-Strike of walking and the anterior-posterior location of thickest cartilage in the medial and lateral femoral condyles of healthy contralateral and ACL reconstructed knees. In vivo gait analysis and knee MR images were collected from 29 subjects approximately 2 years after unilateral ACL reconstruction. Knee extension was measured at Heel-Strike of walking and 3-D femoral cartilage thickness models were reconstructed from MR images. The ACL reconstructed knees had significantly reduced knee extension (-1.5±4.2°) relative to the contralateral knees (-4.6±3.4°) at Heel-Strike of walking but did not have side-to-side differences in the anterior-posterior location or magnitude of thickest medial and lateral femoral cartilage. The anterior-posterior location of the thickest medial femoral cartilage was correlated with knee extension at Heel-Strike in both the healthy contralateral (R(2)=0.356, p<0.001) and reconstructed (R(2)=0.234, p=0.008) knees. These results suggest that ACL reconstruction can impair terminal extension at periods of ambulatory loading known to be related to cartilage morphology in healthy joints. The fact that the femoral cartilage thickness distribution had not changed at 2 years post-op, even in the subset of subjects with extension loss, suggests that loads may be shifted to thinner cartilage regions, which could have important implications on long-term joint health.
Brian J Addison - One of the best experts on this subject based on the ideXlab platform.
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tradeoffs between impact loading rate vertical impulse and effective mass for walkers and Heel Strike runners wearing footwear of varying stiffness
Journal of Biomechanics, 2015Co-Authors: Brian J Addison, Daniel E LiebermanAbstract:Abstract Humans experience repetitive impact forces beneath the Heel during walking and Heel Strike running that cause impact peaks characterized by high rates and magnitudes of loading. Impact peaks are caused by the exchange of momentum between the ground and a portion of the body that comes to a full stop (the effective mass) during the period of the impact peak. A number of factors can influence this exchange of momentum, including footwear stiffness. This study presents and tests an impulse–momentum model of impact mechanics which predicts that effective mass and vertical impulse is greater in walkers and Heel Strike runners wearing less stiff footwear. The model also predicts a tradeoff between impact loading rate and effective mass, and between impact loading rate and vertical impulse among individuals wearing footwear of varying stiffness. We tested this model using 19 human subjects walking and running in minimal footwear and in two experimental footpads. Subjects walked and ran on an instrumented treadmill and 3D kinematic data were collected. As predicted, both vertical impulse (walking: F (2,54)=52.0, p =2.6E−13; running: F (2,54)=25.2, p =1.8E−8) and effective mass (walking: F (2,54)=12.1, p =4.6E−5; running: F (2,54)=15.5, p =4.7E−6) increase in less stiff footwear. In addition, there is a significant inverse relationship between impact loading rate and vertical impulse (walking: r =−0.88, p r =−0.78, p r =−0.88, p r =−0.82, p
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tradeoffs between impact loading rate vertical impulse and effective mass for walkers and Heel Strike runners wearing footwear of varying stiffness
Journal of Biomechanics, 2015Co-Authors: Brian J Addison, Daniel E LiebermanAbstract:Humans experience repetitive impact forces beneath the Heel during walking and Heel Strike running that cause impact peaks characterized by high rates and magnitudes of loading. Impact peaks are caused by the exchange of momentum between the ground and a portion of the body that comes to a full stop (the effective mass) during the period of the impact peak. A number of factors can influence this exchange of momentum, including footwear stiffness. This study presents and tests an impulse-momentum model of impact mechanics which predicts that effective mass and vertical impulse is greater in walkers and Heel Strike runners wearing less stiff footwear. The model also predicts a tradeoff between impact loading rate and effective mass, and between impact loading rate and vertical impulse among individuals wearing footwear of varying stiffness. We tested this model using 19 human subjects walking and running in minimal footwear and in two experimental footpads. Subjects walked and ran on an instrumented treadmill and 3D kinematic data were collected. As predicted, both vertical impulse (walking: F(2,54)=52.0, p=2.6E-13; running: F(2,54)=25.2, p=1.8E-8) and effective mass (walking: F(2,54)=12.1, p=4.6E-5; running: F(2,54)=15.5, p=4.7E-6) increase in less stiff footwear. In addition, there is a significant inverse relationship between impact loading rate and vertical impulse (walking: r=-0.88, p<0.0001; running: r=-0.78, p<0.0001) and between impact loading rate and effective mass (walking: r=-0.88, p<0.0001; running: r=-0.82, p<0.0001). The tradeoff relationships documented here raise questions about how and in what ways the stiffness of footwear Heels influence injury risk during human walking and running.