Inferring demographic structure with moccasin size data from the Promontory Caves,Utah

The moccasin assemblage Julian Steward recovered from the Promontory caves in 1930–31 provides a novel example in which material culture can be used to understand the structure of an AD thirteenth century population. Several studies shed light on the relationship between shoe size, foot size, and stature. We develop an anthropometric model for understanding the composition of the Promontory Cave population by using moccasin size as a proxy for foot size. We then predict the stature of the individual who would have worn a moccasin. Stature is closely related to age for children, subadults and adult males. Although there are predictable sex and age factors biasing moccasin discard practices, moccasin dimensions suggest a relatively large proportion of children and subadults occupied the Promontory caves. This bison and antelope hunting population appears to have thrived during its stay on Promontory Point. Am J Phys Anthropol 156:76–89, 2015 © 2014 Wiley Periodicals, Inc.     

Lower limb joint stiffness and muscle co-contraction adaptations to instability footwear during locomotion

Unstable shoes (US) continually perturb gait which can train the lower limb musculature, but muscle co-contraction and potential joint stiffness strategies are not well understood. A shoe with a randomly perturbing midsole (IM) may enhance these adaptations. This study compares ankle and knee joint stiffness, and ankle muscle co-contraction during walking and running in US, IM and a control shoe in 18 healthy females. Ground reaction forces, three-dimensional kinematics and electromyography of the gastrocnemius medialis and tibialis anterior were recorded. Stiffness was calculated during loading and propulsion, derived from the sagittal joint angle-moment curves. Ankle co-contraction was analysed during pre-activation and stiffness phases. Ankle stiffness reduced and knee stiffness increased during loading in IM and US whilst walking (ankle, knee: p = 0.008, 0.005) and running (p < 0.001; p = 0.002). During propulsion, the opposite joint stiffness re-organisation was found in IM whilst walking (both joints p < 0.001). Ankle co-contraction increased in IM during pre-activation (walking: p = 0.001; running: p < 0.001), and loading whilst walking (p = 0.003), not relating to ankle stiffness. Results identified relative levels of joint stiffness change in unstable shoes, providing new evidence of how stability is maintained at the joint level.     

Effects of Forefoot Shoe on Knee and Ankle Loading during Running in Male Recreational Runners

Objectives: Although overuse running injury risks for the ankle and knee are high, the effect of different shoe designs on Achilles tendon force (ATF) and Patellofemoral joint contact force (PTF) loading rates are unclear. Therefore, the primary objective of this study was to compare the ATF at the ankle and the PTF and Patellofemoral joint stress force (PP) at the knee using different running shoe designs (forefoot shoes vs. normal shoes). Methods: Fourteen healthy recreational male runners were recruited to run over a force plate under two shoe conditions (forefoot shoes vs. normal shoes). Sagittal plane ankle and knee kinematics and ground reaction forces were simultaneously recorded. Ankle joint mechanics (ankle joint angle, velocity, moment and power) and the ATF were calculated. Knee joint mechanics (knee joint angle velocity, moment and power) and the PTF and PP were also calculated. Results: No significant differences were observed in the PTF, ankle plantarflexion angle, ankle dorsiflexion power, peak vertical active force, contact time and PTF between the two shoe conditions. Compared to wearing normal shoes, wearing the forefoot shoes demonstrated that the ankle dorsiflexion angle, knee flexion velocity, ankle dorsiflexion moment extension, knee extension moment, knee extension power, knee flexion power and the peak patellofemoral contact stress were significantly reduced. However, the ankle dorsiflexion velocity, ankle plantarflexion velocity, ankle plantarflexion moment and Achilles tendons force increased significantly. Conclusions: These findings suggest that wearing forefoot shoes significantly decreases the patellofemoral joint stress by reducing the moment of knee extension, however the shoes increased the ankle plantarflexion moment and ATF force. The forefoot shoes effectively reduced the load on the patellofemoral joint during the stance phase of running. However, it is not recommended for new and novice runners and patients with Achilles tendon injuries to wear forefoot shoes.     

Explicit finite element modelling of heel pad mechanics in running: inclusion of body dynamics and application of physiological impact loads

Many heel pathologies including plantar heel pain may result from micro tears/trauma in the subcutaneous tissues, in which internal tissue deformation/stresses within the heel pad play an important role. Previously, many finite element models have been proposed to evaluate stresses inside the heel pad, but the majority of these models only focus on static loading boundary conditions. This study explored a dynamics modelling approach to the heel pad subjected to realistic impact loads during running. In this model, the inertial property and action of the body are described by a lumped parameter model, while the heel/shoe interactions are modelled using a viscoelastic heel pad model with contact properties. The impact force pattern, dynamic heel pad deformation and stress states predicted by the model were compared with published experimental data. Further parametrical studies revealed the model responses, in terms of internal stresses in the skin and fatty tissue, change nonlinearly when body dynamics changes. A reduction in foot's touchdown velocity resulted in a less severe impact landing and stress relief inside the heel pad, for example peak von-Mises stress in fatty tissue, was reduced by 11.3%. Applications of the model may be extendable to perform iterative analyses to further understand the complex relationships between body dynamics and stress distributions in the soft tissue of heel pad during running. This may open new opportunities to study the mechanical aetiology of plantar heel pain in runners.     

Assessment of pollen assemblages on footwear for evidence of pollen deriving from a mock crime scene: a contribution to forensic palynology

To provide evidence of a link between a crime scene and a suspect, pollen analysis is occasionally employed. However, experimental research linking pollen on footwear to a specific crime scene has been infrequently undertaken such that there are limited references to cite in court. In this blind study, the author had to determine, which of 12 pairs of footwear had walked on a mock scene by comparing their assemblages to those of two scene controls. An additional four control pairs of footwear that had not been worn on or near the scene were also analysed. The pollen data from the footwear was assessed and compared with the scene control samples for: number of taxa, key types, Czekanowski Coefficient and general assemblages. Results indicated that six of the pairs of footwear had walked on the scene and these were, indeed, the ones that actually had done so. The four control pairs were dissimilar in most aspects, particularly key types. This research demonstrates, with some limitations, that evidence of a match between footwear sample and location can be found, even when material from other habitats is present on an exhibit.