Springing into action: Comparing escape responses between bipedal and quadrupedal rodents.

Predation is a fundamental selective pressure on animal morphology, as morphology is directly linked with physical performance and evasion. Bipedal heteromyid rodents, which are characterized by unique morphological traits such as enlarged hindlimbs, appear to be more successful than sympatric quadrupedal rodents at escaping predators such as snakes and owls, but no studies have directly compared the escape performance of bipedal and quadrupedal rodents. We used simulated predator attacks to compare the evasive jumping ability of bipedal kangaroo rats () to that of three quadrupedal rodent groups-pocket mice (), woodrats (), and ground squirrels ().

From Behavior to Bio-Inspiration: Aerial Reorientation and Multi-Plane Stability in Kangaroo Rats, Computational Models, and Robots.

Tails play essential roles in functions related to locomotor stability and maneuverability among terrestrial and arboreal animals. In kangaroo rats, bipedal hopping rodents, tails are used as effective inertial appendages for stability in hopping, but also facilitate stability and maneuverability during predator escape leaps. The complexity of tail functionality shows great potential for bio-inspiration and robotic device design, as maneuvering is accomplished by a long and light-weight inertial appendage.

Effects of a Total Motion Release (TMR®) Protocol for the Single Leg Squat on Asymmetrical Movement Patterns.

Background: Improving single leg squat (SLS) movement symmetry may benefit rehabilitation protocols. The Total Motion Release® (TMR®) protocol has been theorized to evaluate and improve patient-perceived movement asymmetries.

Hypothesis/purpose: The purpose of this study was to evaluate whether perceived asymmetries identified by a TMR® scoring protocol were related to biomechanical asymmetries and whether improving perceived asymmetries influenced movement mechanics.

Examining movement asymmetries during three single leg tasks using interlimb and single subject approaches.

Purpose: s: To examine whether healthy individuals displayed asymmetric trunk and lower extremity kinematics in the frontal and sagittal planes using both interlimb and single subject models.

Methods: Trunk, pelvis, and lower extremity kinematic waveforms were analyzed bilaterally during the single leg squat (SLS), forward step down (FSD), and lateral step down (LSD). Participants identified task specific preferred and non-preferred legs based on perceived stability for interlimb analyses.

Differences in lower extremity joint stiffness during drop jump between healthy males and females.

The primary purpose of this study was to examine sex differences in lower extremity joint stiffness during vertical drop jump performance. A secondary purpose was to examine the potential influence of sex on the relationship between joint stiffness and jump performance. Thirty healthy and active individuals performed 15-drop jumps from 30 and 60 cm boxes.

Application of Polynomial Regression Model for Joint Stiffness.

Quasi-stiffness (joint stiffness) is often used to characterize leg properties during athletic and other activities and has been reported by a single slope of angle-moment curve. However, the joint angle-moment relationship of some relationship are not effectively represented by a simple linear regression model. Thus, the purpose of this analysis was to investigate the benefits of utilizing a 2 order polynomial regression (quadratic) model as compared to the linear model when calculating lower extremity joint stiffness incorporating subdivided eccentric phases.

Comparison between the kinematics for kangaroo rat hopping on a solid versus sand surface.

In their natural habitats, animals move on a variety of substrates, ranging from solid surfaces to those that yield and flow (e.g. sand).

Elastic energy storage across speeds during steady-state hopping of desert kangaroo rats (Dipodomys deserti).

Small bipedal hoppers, including kangaroo rats, are not thought to benefit from substantial elastic energy storage and return during hopping. However, recent species-specific material properties research suggests that, despite relative thickness, the ankle extensor tendons of these small hoppers are considerably more compliant than had been assumed. With faster locomotor speeds demanding higher forces, a lower tendon stiffness suggests greater tendon deformation and thus a greater potential for elastic energy storage and return with increasing speed.

Plantar flexor muscles of kangaroo rats (Dipodomys deserti) shorten at a velocity to produce optimal power during jumping.

The musculotendon work contributions across all joints during jumping by kangaroo rats are not well understood. Namely, measures of external joint work do not provide information on the contributions from individual muscles or in-series elastic structures. In this study, we examined the functional roles of a major ankle extensor muscle, the lateral gastrocnemius (LG), and a major knee extensor muscle, the vastus lateralis (VL), through in vivo sonomicrometry and electromyography techniques, during vertical jumping by kangaroo rats.

Comparative analysis of Dipodomys species indicates that kangaroo rat hindlimb anatomy is adapted for rapid evasive leaping.

Body size is a key factor that influences antipredator behavior. For animals that rely on jumping to escape from predators, there is a theoretical trade-off between jump distance and acceleration as body size changes at both the inter- and intraspecific levels. Assuming geometric similarity, acceleration will decrease with increasing body size due to a smaller increase in muscle cross-sectional area than body mass.

Instrument-Assisted Soft Tissue Mobilization Forces Applied by Trained Clinicians During a Simulated Treatment.

Context: Instrument-assisted Soft Tissue Mobilization (IASTM) is a therapeutic intervention used by clinicians to identify and treat myofascial dysfunction or pathology. However, little is known about the amount of force used by clinicians during an IASTM treatment and how it compares to reports of force in the current literature.

Objective: To quantify the range of force applied by trained clinicians during a simulated IASTM treatment scenario.

How to Stick the Landing: Kangaroo Rats Use Their Tails to Reorient during Evasive Jumps Away from Predators.

Tails are widespread in the animal world and play important roles in locomotor tasks, such as propulsion, maneuvering, stability, and manipulation of objects. Kangaroo rats, bipedal hopping rodents, use their tail for balancing during hopping, but the role of their tail during the vertical evasive escape jumps they perform when attacked by predators is yet to be determined. Because we observed kangaroo rats swinging their tails around their bodies while airborne following escape jumps, we hypothesized that kangaroo rats use their tails to not only stabilize their bodies while airborne, but also to perform aerial re-orientations.

Estimation of the force-velocity properties of individual muscles from measurement of the combined plantarflexor properties.

The force-velocity (-) properties of isolated muscles or muscle fibers have been well studied in humans and other animals. However, determining properties of individual muscles remains a challenge because muscles usually function within a synergistic group. Modeling has been used to estimate the properties of an individual muscle from the experimental measurement of the muscle group properties.

Functional morphology of the ankle extensor muscle-tendon units in the springhare Pedetes capensis shows convergent evolution with macropods for bipedal hopping locomotion.

This study assesses the functional morphology of the ankle extensor muscle-tendon units of the springhare Pedetes capensis, an African bipedal hopping rodent, to test for convergent evolution with the Australian bipedal hopping macropods. We dissect and measure the gastrocnemius, soleus, plantaris, and flexor digitorum longus in 10 adult springhares and compare them against similar-sized macropods using phylogenetically informed scaling analyses. We show that springhares align reasonably well with macropod predictions, being statistically indistinguishable with respect to the ankle extensor mean weighted muscle moment arm (1.

Yank: the time derivative of force is an important biomechanical variable in sensorimotor systems.

The derivative of force with respect to time does not have a standard term in physics. As a consequence, the quantity has been given a variety of names, the most closely related being 'rate of force development'. The lack of a proper name has made it difficult to understand how different structures and processes within the sensorimotor system respond to and shape the dynamics of force generation, which is critical for survival in many species.

Exploring Bipedal Hopping through Computational Evolution.

Bipedal hopping is an efficient form of locomotion, yet it remains relatively rare in the natural world. Previous research has suggested that the tail balances the angular momentum of the legs to produce steady state bipedal hopping. In this study, we employ a 3D physics simulation engine to optimize gaits for an animat whose control and morphological characteristics are subject to computational evolution, which emulates properties of natural evolution.

Tendons from kangaroo rats are exceptionally strong and tough.

Tendons must be able to withstand the forces generated by muscles and not fail. Accordingly, a previous comparative analysis across species has shown that tendon strength (i.e.

The Contributions of Individual Muscle-Tendon Units to the Plantarflexor Group Force-Length Properties.

The combined force-length (F-L) properties of a muscle group acting synergistically at a joint are determined by several aspects of the F-L properties of the individual musculotendon units. Namely, misalignment of the optimal lengths of the individual muscles will affect the group F-L properties. This misalignment, which we named [Formula: see text], arises from the properties of the muscles (i.

Jumping mechanics of desert kangaroo rats.

Kangaroo rats are small bipedal desert rodents that use erratic vertical jumps to escape predator strikes. In this study we examined how individual hind limb joints of desert kangaroo rats () power vertical jumps across a range of heights. We hypothesized that increases in net work would be equally divided across hind limb joints with increases in jump height.

Functional capacity of kangaroo rat hindlimbs: adaptations for locomotor performance.

Many cursorial and large hopping species are extremely efficient locomotors with various morphological adaptations believed to reduce mechanical demand and improve movement efficiency, including elongated distal limb segments. However, despite having elongated limbs, small hoppers such as desert kangaroo rats () are less efficient locomotors than their larger counterparts, which may be in part due to avoiding predators through explosive jumping movements. Despite potentially conflicting mechanical demands between the two movements, kangaroo rats are both excellent jumpers and attain high hopping speeds, likely due to a specialized hindlimb musculoskeletal morphology.

Why do mammals hop? Understanding the ecology, biomechanics and evolution of bipedal hopping.

Bipedal hopping is a specialized mode of locomotion that has arisen independently in at least five groups of mammals. We review the evolutionary origins of these groups, examine three of the most prominent hypotheses for why bipedal hopping may have arisen, and discuss how this unique mode of locomotion influences the behavior and ecology of modern species. While all bipedal hoppers share generally similar body plans, differences in underlying musculoskeletal anatomy influence what performance benefits each group may derive from this mode of locomotion.

Grizzly bear () locomotion: forelimb joint mechanics across speed in the sagittal and frontal planes.

The majority of terrestrial locomotion studies have focused on parasagittal motion and paid less attention to forces or movement in the frontal plane. Our previous research has shown that grizzly bears produce higher medial ground reaction forces (lateral pushing from the animal) than would be expected for an upright mammal, suggesting frontal plane movement may be an important aspect of their locomotion. To examine this, we conducted an inverse dynamics analysis in the sagittal and frontal planes, using ground reaction forces and position data from three high-speed cameras of four adult female grizzly bears.

Muscle contributions to frontal plane angular momentum during walking.

The regulation of whole-body angular momentum is important for maintaining dynamic balance during human walking, which is particularly challenging in the frontal plane. Whole-body angular momentum is actively regulated by individual muscle forces. Thus, understanding which muscles contribute to frontal plane angular momentum will further our understanding of mediolateral balance control and has the potential to help diagnose and treat balance disorders.

Grizzly bear (Ursus arctos horribilis) locomotion: gaits and ground reaction forces.

Locomotion of plantigrade generalists has been relatively little studied compared with more specialised postures even though plantigrady is ancestral among quadrupeds. Bears (Ursidae) are a representative family for plantigrade carnivorans, they have the majority of the morphological characteristics identified for plantigrade species, and they have the full range of generalist behaviours. This study compared the locomotion of adult grizzly bears (Ursus arctos horribilis Linnaeus 1758), including stride parameters, gaits and analysis of three-dimensional ground reaction forces, with that of previously studied quadrupeds.

Scaling of the spring in the leg during bouncing gaits of mammals.

Trotting, bipedal running, and especially hopping have long been considered the principal bouncing gaits of legged animals. We use the radial-leg spring constant [Formula: see text] to quantify the stiffness of the physical leg during bouncing gaits. The radial-leg is modeled as an extensible strut between the hip and the ground and [Formula: see text] is determined from the force and deflection of this strut in each instance of stance.