Biomechanical and metabolic differences between skipping and running suggest the nervous system may require an alternative motor control strategy to execute skipping. Motor control strategies can be compared across gaits by muscle modules based on which muscles are coactivated (module composition) and whether the same module compositions are used across gaits (module generalization). The purposes of this study were to identify and compare the module composition of skipping and running and determine the module generalization present across these two gaits. Six healthy young adults performed 10 s skipping and running trials on a treadmill at 2.5 m/s while electromyography (EMG) was collected from 8 muscles. A non-negative matrix factorization extracted motor modules from the EMG data. Generalization of modules, both at the group and individual level, was determined with correlations of module weights. Participants required 3.7 ± 0.5 (range: 3-4) modules to control skipping and 3.8 ± 0.4 (range: 3-4) modules to control running. Three generalized modules were found across gaits at the group level, and at the individual level each participant had at least one generalized module. The generalized modules contributed to similar biomechanical subtasks across gaits, highlighting similar gross motor task demands. The unique biomechanical demands of the skipping hop resulted in gait-specific control of the tibialis anterior and gluteus medius. Future work is needed to identify the factors that influence the amount of generalization an individual uses across locomotor tasks and whether the degree of generalization impacts the performance of each gait.

The purpose of this study was to investigate whether individuals carrying vest-borne loads of 0%, 15%, and 30% body weight can decrease peak vertical ground reaction force (vGRF) when given peak vGRF feedback and examine if the gait adaptations induced by vGRF feedback decrease peak tibiofemoral joint (TFJ) contact force and impulse. Twenty-four participants walked without and with vGRF feedback at 1.4 m·s-1 with 0%, 15%, and 30% load added. They received feedback on the average peak vGRF for each leg in two-second epochs during each of the six conditions. Participants significantly decreased the second peak vGRF and vGRF impulse with feedback, but not the first peak vGRF. Due to an adopted crouched pattern, participants increased both first and second peak TFJ contact forces. vGRF and TFJ contact forces increased directly with increased load in both feedback conditions. vGRF force feedback represents an intuitive tool for modifying walking mechanics, but when employed to decrease ground reaction forces during load carriage in this study, it did not lead to decreased TFJ contact forces. Participants adopted a crouched gait that involved increased knee flexion and subsequent quadriceps demand, ultimately elevating TFJ loading. Future strategies aimed at decreasing joint load should consider targeting primary contributors of joint load, such as knee extensor moments, quadriceps force, or joint contact forces directly.

INTRODUCTION:In efforts to optimize movement, physical therapists must have a fundamental understanding of kinesiological and biomechanical principles. REVIEW OF LITERATURE:There has not been an attempt to define educational content in biomechanics and related topics for physical therapists since 1984. The aim of this modified Delphi study was to identify core content topics related to the biomechanical aspects of human movement for physical therapists. SUBJECTS:Fourteen subject matter experts were asked to rate the importance of each biomechanical topic. METHODS:A modified Delphi approach used 3 rounds of surveys to rank the importance of 166 biomechanical topics across 11 categories. The 11 categories, gleaned from textbooks and foundational research, were units of measure; body segment variables; arthrology; kinematics; forces/kinetics; material properties; muscle mechanics; movement screen; gait; computational methods; and instrumentation. Round 1 also allowed the experts to suggest additional topics for consideration in round 2. Rounds 2 and 3 aimed for consensus for all topics. A 75% threshold as "important" or "very important" was used to determine consensus for each topic. RESULTS:One hundred and thirteen of 166 topics (68%) were identified as important or very important to teach physical therapist students. The percentage of topics that met consensus per category was as follows: units of measures (20%); body segment variables (50%); arthrology (71%); kinematics (80%); forces/kinetics (91%); material properties (79%); muscle mechanics (100%); movement screen (80%); gait (100%); computational methods (17%); and instrumentation (17%). DISCUSSION AND CONCLUSION:This study identified key topics that should serve as a guideline for curricular content related to biomechanics. Results suggest that content should focus on kinematics, forces/kinetics, material properties, muscle mechanics, movement screening, and gait. Additional topics related to units of measure, computational methods, and instrumentation could also be considered. Adoption of this core content could promote consistency in biomechanics content across physical therapist education programs.

BACKGROUND:The etiology of plantar fasciitis remains unclear, with diagnosis relying heavily on patient history. Knowledge of foot intrinsic material properties associated with this condition may improve our understanding of the etiology and treatment efforts for plantar fasciitis. The purpose of the present study is to assess longitudinal material stiffness of the plantar fascia (PF) and relevant foot structures supporting the longitudinal arch in individuals with and without plantar fasciitis. METHODS:Individuals with no history of plantar fasciitis (controls) (n = 11), with active plantar fasciitis symptoms (n = 11), and with history of plantar fasciitis symptoms (n = 6) underwent bilateral shear wave elastography (SWE) measurements of the PF, flexor hallucis brevis, abductor hallucis muscle and tendon, and Achilles tendon. Structure thickness was assessed using B-mode imaging. Clinical foot measures including navicular drop (cm), arch stiffness (N/cm), longitudinal arch angle, arch index, and gastrocnemius and soleus flexibility were also compared between groups. FINDINGS:PF longitudinal stiffness at a proximal site was significantly lower in individuals with active plantar fasciitis than those with a history of plantar fasciitis and controls. Longitudinal stiffness varied along PF length across groups. Both plantar fasciitis groups exhibited increased thickness along the PF compared to controls. INTERPRETATION:Decreased proximal PF stiffness was observed among symptomatic participants, while increased PF thickness was observed in both plantar fasciitis groups, and no differences between groups were observed in clinical foot measures. SWE may be useful to monitor recovery and treatment effectiveness, especially in the absence of clinical foot measures and/or PF thickness changes.

It is unknown whether interlimb differences in gait mechanics affect the magnitude or distribution of tibiofemoral joint contact forces or whether load carriage increases potential effects of limb dominance. Thus, this study aimed to compare the effects of load carriage on total, medial, and lateral tibiofemoral joint contact force between the dominant and nondominant limbs. Twenty-four adults (12 women, 21 right-leg dominant) walked at 1.4 m·s-1 during 3 load carriage conditions (0%, 15%, and 30% body weight). Medial and lateral tibiofemoral joint contact forces were calculated during 5 stance phases for each limb in each condition. A 3 × 2 repeated-measures analysis of variance was used to compare the dominant and nondominant limbs across the 3 loading conditions. Peak tibiofemoral joint forces increased directly with load carriage (P < .001). The nondominant limb peak medial tibiofemoral joint contact force was greater than that of the dominant limb (P = .026), whereas dominant limb peak lateral tibiofemoral joint contact force was greater than that of the nondominant (P < .001) limb. Although the results were close to the minimal detectable difference, we concluded that the distribution of tibiofemoral joint contact force during load carriage may be influenced by limb dominance. These findings underscore the relevance of limb dominance as a consideration in research design and data interpretation.

Skipping represents a training alternative to running due to its lower knee contact forces and higher whole-body metabolic cost. The increased metabolic cost of skipping is associated with a higher vertical center-of-mass (COM) displacement during the support and flight phases of the skipping hop compared to running. However, skipping has lower muscle force impulses than running. Therefore, the study purpose was to compare the flow of mechanical power between body segments during skipping and running to determine the mechanisms enabling higher vertical displacement in skipping despite the lower vertical impulse. Running and skipping cycles were simulated in OpenSim for 5 adults (22.4 ± 2.2 y) using motion capture data collected at 2.5 m/s on an instrumented dual-belt treadmill. A segmental power analysis quantified muscle contributions to vertical body segment mechanical power, which were integrated over the stance phase of running (Run) and the hop (Skip 1) and step (Skip 2) of skipping to calculate mechanical work. Higher vertical work was done by the gluteus maximus, vasti, and soleus in Skip 1, primarily through power generation to the trunk, compared to power absorption in Run and Skip 2. Thus, despite lower muscle force impulses in Skip 1, muscles generate power through concentric contractions, leading to greater metabolic cost than in running. These muscle force impulses contribute to propelling the COM upward in Skip 1 (rather than decelerating downward COM motion in Run and Skip 2), which raises the COM and contributes to the greater COM displacement in skipping compared to running.

The United States imports thousands of live vertebrate species annually as part of legal trade. Escapes and releases from captivity are major pathways of invasion, however, the risk posed by the thousands of imported vertebrate species has not been systematically assessed. We conducted a horizon scan that used a data-driven climate match to filter a list of nearly 15,000 taxa drawn from across the globe of imported fish, amphibians, reptiles, birds, and mammals for rapid assessment by taxonomic experts. Experts evaluated 840 species and identified 32 (22 reptiles and 10 fishes) as having the highest risk for establishment, spread, and negative impacts. Of those high-risk species, the majority have the capacity to disrupt ecosystem processes via their role as top predators or the unique ecological niches that they occupy, while several of the snake species pose a threat to human health. High-risk species were often scored with high confidence while in contrast, low scores were attributed to a combination of ecological redundancy, low propagule pressure, or low climate match while low confidence arose from a lack of information in the literature (i.e., data deficiency). Our study therefore highlights legally imported species likely to cause the greatest harm with the recognition that many other species could also become invasive in the United States. The ranked list of vertebrate threats can be used to prioritize watchlists and inform the development of targeted regulations for importation can be applied to regions to provide a rapid, preliminary screening for large pools of potential invaders.

. - The Mississippi Alluvial Plain (MAP) of Arkansas is a landscape where many wetlands have been altered for use as aquaculture ponds or agricultural ditches. Commercial harvest of freshwater turtles within the MAP is not restricted or limited, with reported harvest numbers for 2019 alone exceeding 4000 for spiny softshell turtles (Apalone spinifera) and 39,000 for red-eared sliders (Trachemys scripta elegans). Herein, we attempt to provide baseline estimates of freshwater turtle densities and community composition in aquaculture ponds and agricultural ditches of eastern Arkansas, the habitat types most frequently trapped by commercial harvesters. We used a capture-mark-recapture approach over 3 summers (2019-2021) to evaluate population densities and community composition of freshwater turtles in these anthropogenic aquatic habitats. We captured > 4000 individuals of 9 species of turtle. One species, the redeared slider, dominated the turtle community in both anthropogenic aquatic habitats, comprising 66% (+/- 22% SD) of all captures in agricultural ditches and 63% (+/- 32% SD) in aquaculture ponds. Diversity and richness did not differ between aquaculture ponds and agricultural ditches. We estimated densities of the 2 most commonly captured species, the red-eared slider and spiny softshell turtle. Density of red-eared sliders ranged from 0 turtles/unit area (linear kilometers in ditches or hectares in ponds) to 500 turtles/unit area, with a median of 37 turtles/unit area. The spiny softshell turtle was more frequently captured in ponds than ditches and attained average densities of 25 (+/- 19) turtles/ha and 7 (+/- 4) turtles/linear km, respectively. Our mean density estimates were lower than those in reported literature, including estimates from similar habitats, such as urban ditches and farm ponds, which resemble our study sites in structure, use, and geographical placement. We estimate the region contains 22,317 ha of aquaculture ponds and 18,350 linear km of agricultural ditches. By extrapolating our density estimates to each anthropogenic aquatic habitat type, we estimated 2 million red-eared sliders and 427,000 spiny softshell turtles occurred in aquaculture ponds and agricultural ditches across eastern Arkansas. Our results suggest that these altered wetlands provide abundant habitat for only a few generalist turtle species.

Wildlife populations at the peripheries of their distributions or on isolated islands often display divergent and poorly understood morphological or life-history characteristics compared to core populations. We used a capture-mark-recapture dataset collected over a 19-year period to characterize a northern, insular snake assemblage in coastal Maine. We captured 611 individual snakes of 4 species (Thamnophis sirtalis [Common Gartersnake; n = 221 individuals], Diadophis punctatus [Ring-necked Snake; n = 258 individuals], Storeria occipitomaculata [Red-bellied Snake; n = 81 individuals], and Opheodrys vernalis [Smooth Greensnake; n = 51 individuals]) and recorded 104 recaptures. We provide some of the first data on growth, reproduction, and movement for these species in northern New England, expanding our understanding of insular and northern snake populations. Specifically, we found that Common Gartersnakes fed primarily on earthworms and amphibians and grew rapidly, in accordance with mainland populations, but exhibited smaller size at maturity and average litter sizes. We captured an unusually large number of Ring-necked Snakes, which are uncommon elsewhere in Maine, and recorded an apparently localized nesting area for this species, as well as relatively long-distance (230-300 m) dispersal away from that location. In our population, female Ring-necked Snakes mature in their third year, and this species exhibits weak sexual size dimorphism (SSD). We found the ecology of Red-bellied Snakes at our study site to be similar to other populations, with individuals feeding on slugs, and females maturing in their second year; however, our population exhibited the strongest pattern of (female-biased) SSD. Smooth Greensnakes were restricted to the most extensive old-field habitat within our study site and fed on a variety of arthropods. We confirmed communal nesting and short incubation period for this species and provide among the first data on growth and longevity ( at least 7 years) of this relatively understudied species.

Premature osteoarthritis after anterior cruciate ligament reconstruction (ACLR) is common among athletes. Reduced knee contact forces after ACLR likely contribute to the multifactorial etiology of the disease. Whether this reduction is accompanied by compensatory increases in joint contact forces (JCF) at adjacent or contralateral joints is unclear. It is also unclear if compensatory effects depend on the task demands. Thus, we compared hip, knee, and ankle JCF symmetry between individuals with reconstruction and a matched control group during walking and running. Thirty participants (19 females), 2-7 years post-unilateral ACLR (mean = 47.8 months), and 30 controls matched on sex, mass, and activity level were recruited. Limb symmetry indices of peak contact forces and force impulses were calculated for each joint during walking and running, and analyzed using two-factor (group, activity) analysis of variances. Lower ACLR group peak knee JCF (p = 0.009) and knee JCF impulse (p = 0.034) during walking and running were observed. An interaction of group and activity was observed for peak hip JCF, with ACLR participants demonstrating greater involved limb peak hip JCF during running (p = 0.012). Ankle JCF and ground reaction force symmetry indices were not different between groups or across tasks. Decreased knee and increased ipsilateral peak hip JCF during running suggests that proximal adaptations exist at 2-7 years after ACLR, particularly during activities with increased task demand. Clinical significance: Knee and hip JCF asymmetry at 2-7 years after ACLR may underscore a need for clinical strategies and follow-up assessments to identify and target such outcomes.

Context Translocation is a common management strategy for wildlife populations, yet hard-release of reptiles, including box turtles (Terrapene spp.), has often proven ineffective due to homing attempts and wandering. Soft-release translocation has been presented as a possible method for mitigation of the negative effects of hard-release translocation, but studies incorporating standard soft-release strategies have produced mixed results and often see persistent homing attempts by soft-released study animals. Aims The aim of this study was to examine long-term holding (>1 year) of box turtles at an off-site location prior to translocation as a means to reduce homing attempts and wandering commonly observed in immediate-release box turtles. Methods We radiotracked translocated Terrapene carolina triunguis to compare movements of nine immediate-release box turtles and nine box turtles that had been maintained for >1 year at a nearby off-site holding facility (long-term holding) prior to a 750–1000 m translocation. Key results Box turtles held long-term before a short-distance translocation moved significantly shorter distances each day post-release than immediate-release turtles. Turtles held long-term moved in non-directional, random orientations, whereas immediate-release turtles exhibited consistent directionality in movements back towards their initial capture (home) locations. Conclusions Our results demonstrated that turtles held off-site remained within the translocation site more reliably than the immediate-release turtles, which had a higher tendency to home. Implications Long-term holding of turtles prior to translocation could significantly reduce homing responses and wandering, thus increasing translocation efficacy while reducing intensity of post-translocation management.

Chronic exposure to high tibiofemoral joint (TFJ) contact forces can be detrimental to knee joint health. Load carriage increases TFJ contact forces, but it is unclear whether medial and lateral tibiofemoral compartments respond similarly to incremental load carriage. The purpose of our study was to compare TFJ contact forces when walking with 15% and 30% added body weight. Young healthy adults (n = 24) walked for 5 minutes with no load, 15% load, and 30% load on an instrumented treadmill. Total, medial, and lateral TFJ contact peak forces and impulses were calculated via an inverse dynamics informed musculoskeletal model. Results of 1-way repeated measures analyses of variance (α = .05) demonstrated total, medial, and lateral TFJ first peak contact forces and impulses increased significantly with increasing load. Orthogonal polynomial trends demonstrated that the 30% loading condition led to a curvilinear increase in total and lateral TFJ impulses, whereas medial first peak TFJ contact forces and impulses responded linearly to increasing load. The total and lateral compartment impulse increased disproportionally with load carriage, while the medial did not. The medial and lateral compartments responded differently to increasing load during walking, warranting further investigation because it may relate to risk of osteoarthritis.

Burmese pythons ( Python molurus bivittatus ) are native to southeastern Asia, however, there is an established invasive population inhabiting much of southern Florida throughout the Greater Everglades Ecosystem. Pythons have severely impacted native species and ecosystems in Florida and represent one of the most intractable invasive-species management issues across the globe. The difficulty stems from a unique combination of inaccessible habitat and the cryptic and resilient nature of pythons that thrive in the subtropical environment of southern Florida, rendering them extremely challenging to detect. Here we provide a comprehensive review and synthesis of the science relevant to managing invasive Burmese pythons. We describe existing control tools and review challenges to productive research, identifying key knowledge gaps that would improve future research and decision making for python control.

The purpose of this study was to quantify characteristics of bimanual movement intensity during 30 h of hand–arm bimanual intensive therapy (HABIT) and bimanual performance (activities and participation) in real-world settings using accelerometers in children with unilateral cerebral palsy (UCP). Twenty-five children with UCP participated in a 30 h HABIT program. Data were collected from bilateral wrist-worn accelerometers during 30 h of HABIT to quantify the movement intensity and three days pre- and post-HABIT to assess real-world performance gains. Movement intensity and performance gains were measured using six standard accelerometer-derived variables. Bimanual capacity (body function and activities) was assessed using standardized hand function tests. We found that accelerometer variables increased significantly during HABIT, indicating increased bimanual symmetry and intensity. Post-HABIT, children demonstrated significant improvements in all accelerometer metrics, reflecting real-world performance gains. Children also achieved significant and clinically relevant changes in hand capacity following HABIT. Therefore, our findings suggest that accelerometers can objectively quantify bimanual movement intensity during HABIT. Moreover, HABIT enhances hand function as well as activities and participation in real-world situations in children with UCP.

Sampling biases resulting from capture methodology or animal behavioral responses can significantly skew our understanding of population size and structure. Behavioral responses to passive sampling with traps, such as trap-happy or trap-shy responses, can be accounted for in analyses using individual covariates but they require detailed understanding of the underlying behavioral mechanisms. We used a field experiment to investigate the impact of trap escape on capture rates and determine what traits influence trap escape rates between and within two species of semiaquatic snakes, Liodytes pygaea and Nerodia fasciata. We found that L. pygaea escaped significantly more often than did N. fasciata, smaller L. pygaea escaped at significantly higher rates than did larger conspecifics, and individual capture history significantly influenced escape rates in N. fasciata. Our findings highlight understudied sources of inter- and intraspecific capture heterogeneity in a common sampling technique, and we urge researchers to consider method-specific sampling biases when attempting to produce population parameter estimates for species that are difficult to detect.

Prairie habitat loss in the United States has led to population declines in many prairie-associated species, including Ornate Box Turtles (Terrapene ornata). Northwest Arkansas is an intergrade zone between the prairie-dwelling T. ornata and the more forest-associated Three-Toed Box Turtle (Terrapene carolina). As such, limited information exists on the potential differences in physiology and thermal ecology between the two box turtle species and how those differences might influence their habitat use. We addressed gaps in our knowledge of the thermal and spatial ecology of T. ornata and T. carolina with a three-part study. First, we compared the thermal profiles of refugia, open, and vegetated microhabitats across degraded prairie, restored prairie, and adjacent forest macrohabitats using operative temperature models and a linear mixed effect model. Second, we measured total evaporative water loss of both species across a range of body sizes. Finally, we fitted a subset of turtles with iButton data loggers and monitored them in the field to examine carapace temperatures and habitat use. Operative temperature models recorded high, largely homogeneous temperatures across microhabitats in degraded prairie and heterogeneous temperatures across restored prairie microhabitats, while forest habitat maintained stable, cool temperatures. Both species exhibited similar evaporative water loss rates; however, T. ornata experienced a broader range of temperatures in the field. Terrapene ornata were exclusively found in prairie habitat, whereas T. carolina was often found in forested habitats and subsurface refugia. Our results demonstrate key differences in box turtle thermal biology and highlight suboptimal thermal characteristics in degraded prairie and forest habitat that should be considered in prairie restoration and management for T. ornata conservation.

IntroductionChildren with unilateral cerebral palsy (UCP) have difficulty in bimanual coordination that restricts the child’s independence in daily activities. Although several efficacious interventions to improve bimanual coordination exist, these interventions often require higher training doses and have modest effect sizes. Thus, there is a critical need to find an effective priming agent that, when paired with task-specific training, will facilitate neurobiological processes to enhance the magnitude of training effects and subsequently improve functional capabilities of children with UCP. The aim of this study is to determine the effects of a novel priming agent, remote ischaemic conditioning (RIC), combined with bimanual training on bimanual skill learning and corticospinal excitability in children with UCP.Methods and analyses46 children, aged 8–16 years, will be randomly assigned to receive RIC or sham conditioning combined with 5 days of bimanual skill (cup stacking) training (15 trials per session). RIC or sham conditioning will be performed with a standard conditioning protocol of five cycles of alternative inflation and deflation of a pressure cuff on the affected arm with the pressure of at least 20 mm Hg above systolic blood pressure for RIC and 25 mm Hg for sham conditioning. Primary outcomes will be movement time and corticospinal excitability measures determined with a single-pulse transcranial magnetic stimulation (TMS). Secondary outcomes include Assisting Hand Assessment, spatio-temporal kinematic variables and paired pulse TMS measures. All measures will be conducted before and immediately after the intervention. A mixed model analysis of variance will test the group×time interaction for all outcomes with group (RIC and sham) as between-subject and time (preintervention, postintervention) as within-subject factors.Ethics and disseminationThe study has been approved by the University Medical Centre Institutional Review Board (UMCIRB #21-001913). We will disseminate the study findings via peer-reviewed publications and presentations at professional conferences.Trial registration numberNCT05777070

To understand mechanisms behind enigmatic declines of tropical reptiles, knowledge of species interactions and how they vary over space and time is important. Some tropical lizard population dynamics can be highly influenced by egg survival. Yet relatively few studies have examined relationships between lizard reproductive success and egg predators across forest and microhabitat types. In this study, we examined variation in probability of egg depredation, predatory ant abundance, prey availability, and the number of lizards and eggs encountered across four different forest types (abandoned agroforestry, abandoned plantation, secondary forest, and old-growth forest) and three microhabitats (buttress, fallen log, and leaf-litter) at La Selva Biological Station, Costa Rica. Based on previous studies, we made three hypotheses about how lizard egg abundance, egg survival, and predatory ant numbers would be related across microhabitat and forest type. Of these hypotheses, only one was supported: we found more lizard eggs in buttress and fallen log microhabitats than leaf-litter. We did not observe any differences in lizard reproduction or numbers of invertebrates by forest type alone. Based on patterns observed in this study, we suggest that future studies investigating tropical leaf-litter lizard declines focus on environmental variation at the microhabitat scale.

An understanding of interactions between anthropogenic stressors and intrinsic population drivers is needed to fully understand wildlife population declines. Density dependence is a key aspect of population regulation for many species, especially for species that have high reproductive potential, such as amphibians. However, patterns of density dependence have been characterized for only a few species and little work has evaluated how density-dependent interactions may be altered by anthropogenic stressors. We combined the results of a mesocosm experiment with demographic population modeling to investigate how the conversion of native prairie to agricultural grasslands dominated by Tall Fescue grass (Lolium arundinacea) affected larval density dependence and adult population size of an imperiled amphibian, Lithobates areolatus (Crawfish Frog). Overall, density dependence was overcompensatory, suggesting that L. areolatus exhibits scramble competition as larvae. Both vegetation treatments had low survival at high densities, but more individuals survived to metamorphosis at moderate densities in Fescue treatments compared to Prairie treatments. We evaluated the implications of our experimental results using a stochastic density-dependent matrix population model to project long-term population dynamics. Simulated populations breeding in Fescue-dominated wetlands had a more variable population size and up to 400% higher probability of quasi-extinction within 200 years, compared to populations breeding in ponds with prairie vegetation. Without varying density in experimental treatments and using mathematical models to project emergent population dynamics, our mesocosm experiment results would have suggested a slightly positive effect of Fescue grass on amphibian development and survival. Vegetation changes surrounding breeding wetlands might play an important role in the decline of amphibian populations persisting in low-intensity agricultural areas.