The Effect of Exertion on Intra-Limb Joint Coordination Variability During Running Using a Waveform Analysis Approach

About half of all runners sustain a running-related injury in a given year. Less variable joint coordination patterns may be detrimental as stress endured by the same tissue, encountered over many running cycles, could lead to overuse running injuries. The effects of fatigue may contribute to runners\u27 risk of injury by altering joint coordination variability. Since fatigue is task-dependent, it is practical to consider a level of fatigue typically experienced by runners. The purpose of this study was to examine the influence of running in an exerted state on lower extremity joint coordination variability, using Principal Components Analysis (PCA) and traditional analysis methods. Sixteen healthy female runners were recruited. Data collection included three-dimensional motion analyses of the ankle, knee and hip before and after a run designed to mimic the subject\u27s typical training experience. Joint coordination was defined using a vector coding technique for eight pairs of joints and planes of motion (e.g. ankle-frontal/knee-transverse) considered relevant to running injury risk. The within-subject variability for these eight coordination patterns was determined from the standard deviation of the coupling angle, averaged over each 25% of stance phase. A repeated measures MANOVA was used to determine differences in joint coordination variability before and after the run. No significant differences were found for the eight coordination patterns. These results are limited by the analysis method, which requires a priori selection of time periods within stance phase as the dependent variables. PCA is an unbiased way to determine relevant differences in variability among full waveforms, and was used to determine fatigue-related changes in joint coordination variability for each of the eight coupling angle waveforms. A repeated measures MANOVA also did not reveal any differences in joint coordination variability for the eight coordination patterns before and after the run. These results suggest that healthy runners may not experience a change in joint coordination variability during their typical training run. This study established methods for using PCA to quantify changes in joint coordination variability. This can be used in injured populations to test the theory that overuse running injury is associated with low joint coordination variability

Identifying Gait Deficits in Stroke Patients Using Inertial Sensors

Falls remain a significant problem for stroke patients. Tripping, the main cause of falls, occurs when there is insufficient clearance between the foot and ground. Based on an individual’s gait deficits, different joint angles and coordination patterns are necessary to achieve adequate foot clearance during walking. However, gait deficits are typically only quantified in a research or clinical setting, and it would be helpful to use wearable devices – such as accelerometers – to quantify gait disorders in real-world situations. Therefore, the objective of this project was to understand gait characteristics that influence the risk of tripping, and to detect these characteristics using accelerometers. Thirty-five participants with a range of walking abilities performed normal walking and attempted to avoid tripping on an unexpected object while gait characteristics were quantified using motion capture techniques and accelerometers. Multiple regression was used to identify the relationship between joint coordination and foot clearance, and multiple analysis of variance was used to determine characteristics of gait that differ between demographic groups, as well as those that enable obstacle avoidance. Machine learning techniques were employed to detect joint angles and the risk of tripping from patterns in accelerometer signals. Measures of foot clearance that represent toe height throughout swing instead of at a single time point are more sensitive to changes in joint coordination, with hip-knee coordination during midswing having the greatest effect. Participants with a history of falls or stroke perform worse than older non-fallers and young adults on many factors related to falls risk, however, there are no differences in the ability to avoid an unexpected obstacle between these groups. Individuals with an inability to avoid an obstacle have lower scores on functional evaluations, exhibit limited sagittal plane joint range of motion during swing, and adopt a conservative walking strategy. Machine learning processes can be used to predict knee range of motion and classify individuals at risk for tripping based on an ankle-worn accelerometer. This work is significant because a portable device that detects gait characteristics relevant to the risk of tripping without expensive motion capture technology may reduce the risk of falls for stroke patients

Identifying Trippers and Non-Trippers Based on Knee Kinematics During Obstacle-Free Walking

Trips are a major cause of falls. Sagittal-plane kinematics affect clearance between the foot and obstacles, however, it is unclear which kinematic measures during obstacle-free walking are associated with avoiding a trip when encountering an obstacle. The purpose of this study was to determine kinematic factors during obstacle-free walking that are related to obstacle avoidance ability. It was expected that successful obstacle avoidance would be associated with greater peak flexion/dorsiflexion and range of motion (ROM), and differences in timing of peak flexion/dorsiflexion during swing of obstacle-free walking for the hip, knee and ankle. Three-dimensional kinematics were recorded as 35 participants (young adults age 18–45 (N = 10), older adults age 65+ without a history of falls (N = 10), older adults age 65+ who had fallen in the last six months (N = 10), and individuals who had experienced a stroke more than six months earlier (N = 5)) walked on a treadmill, under obstacle-free walking conditions with kinematic features calculated for each stride. A separate obstacle avoidance task identified trippers (multiple obstacle contact) and non-trippers. Linear discriminant analysis with sequential feature selection classified trippers and non-trippers based on kinematics during obstacle-free walking. Differences in classification performance and selected features (knee ROM and timing of peak knee flexion during swing) were evaluated between trippers and non-trippers. Non-trippers had greater knee ROM (P = .001). There was no significant difference in classification performance (P = .193). Individuals with reduced knee ROM during obstacle-free walking may have greater difficulty avoiding obstacles

Spherical Coordinate Systems for Streamlining Suited Mobility Analysis

Introduction: When describing human motion, biomechanists generally report joint angles in terms of Euler angle rotation sequences. However, there are known limitations in using this method to describe complex motions such as the shoulder joint during a baseball pitch. Euler angle notation uses a series of three rotations about an axis where each rotation is dependent upon the preceding rotation. As such, the Euler angles need to be regarded as a set to get accurate angle information. Unfortunately, it is often difficult to visualize and understand these complex motion representations. It has been shown that using a spherical coordinate system allows Anthropometry and Biomechanics Facility (ABF) personnel to increase their ability to transmit important human mobility data to engineers, in a format that is readily understandable and directly translatable to their design efforts. Objectives: The goal of this project was to use innovative analysis and visualization techniques to aid in the examination and comprehension of complex motions. Methods: This project consisted of a series of small subprojects, meant to validate and verify a new method before it was implemented in the ABF's data analysis practices. A mechanical test rig was built and tracked in 3D using an optical motion capture system. Its position and orientation were reported in both Euler and spherical reference systems. In the second phase of the project, the ABF estimated the error inherent in a spherical coordinate system, and evaluated how this error would vary within the reference frame. This stage also involved expanding a kinematic model of the shoulder to include the rest of the joints of the body. The third stage of the project involved creating visualization methods to assist in interpreting motion in a spherical frame. These visualization methods will be incorporated in a tool to evaluate a database of suited mobility data, which is currently in development. Results: Initial results demonstrated that a spherical coordinate system is helpful in describing and visualizing the motion of a space suit. The system is particularly useful in describing the motion of the shoulder, where multiple degrees of freedom can lead to very complex motion paths

EMU Suit Performance Simulation

Introduction: Designing a planetary suit is very complex and often requires difficult tradeoffs between performance, cost, mass, and system complexity. To verify that new suit designs meet requirements, full prototypes must be built and tested with human subjects. However, numerous design iterations will occur before the hardware meets those requirements. Traditional drawprototypetest paradigms for research and development are prohibitively expensive with today's shrinking Government budgets. Personnel at NASA are developing modern simulation techniques that focus on a humancentric design paradigm. These new techniques make use of virtual prototype simulations and fully adjustable physical prototypes of suit hardware. This is extremely advantageous and enables comprehensive design downselections to be made early in the design process. Objectives: The primary objective was to test modern simulation techniques for evaluating the human performance component of two EMU suit concepts, pivoted and planar style hard upper torso (HUT). Methods: This project simulated variations in EVA suit shoulder joint design and subject anthropometry and then measured the differences in shoulder mobility caused by the modifications. These estimations were compared to humanintheloop test data gathered during past suited testing using four subjects (two large males, two small females). Results: Results demonstrated that EVA suit modeling and simulation are feasible design tools for evaluating and optimizing suit design based on simulated performance. The suit simulation model was found to be advantageous in its ability to visually represent complex motions and volumetric reach zones in three dimensions, giving designers a faster and deeper comprehension of suit component performance vs. human performance. Suit models were able to discern differing movement capabilities between EMU HUT configurations, generic suit fit concerns, and specific suit fit concerns for crewmembers based on individual anthropometr

Adaptation of the Aesop’s Fable paradigm for use with raccoons (\u3ci\u3eProcyon lotor\u3c/i\u3e): considerations for future application in non‑avian and non‑primate species

To gain a better understanding of the evolution of animal cognition, it is necessary to test and compare the cognitive abilities of a broad array of taxa. Meaningful interspecies comparisons are best achieved by employing universal paradigms that standardize testing among species. Many cognitive paradigms, however, have been tested in only a few taxa, mostly birds and primates. One such example, known as the Aesop’s Fable paradigm, is designed to assess causal understanding in animals using water displacement. To evaluate the universal effectiveness of the Aesop’s Fable paradigm, we applied this paradigm to a previously untested taxon, the raccoon (Procyon lotor). We first trained captive raccoons to drop stones into a tube of water to retrieve a floating food reward. Next, we presented successful raccoons with objects that differed in the amount of water they displaced to determine whether raccoons could select the most functional option. Raccoons performed differently than corvids and human children did in previous studies of Aesop’s Fable, and we found raccoons to be innovative in many aspects of this task. We suggest that raccoon performance in this paradigm reflected differences in tangential factors, such as behavior, morphology, and testing procedures, rather than cognitive deficiencies. We also present insight into previously undocumented challenges that should better inform future Aesop’s Fable studies incorporating more diverse taxa

Evaluating Suit Fit Using Performance Degradation

The Mark III suit has multiple sizes of suit components (arm, leg, and gloves) as well as sizing inserts to tailor the fit of the suit to an individual. This study sought to determine a way to identify the point an ideal suit fit transforms into a bad fit and how to quantify this breakdown using mobility-based physical performance data. This study examined the changes in human physical performance via degradation of the elbow and wrist range of motion of the planetary suit prototype (Mark III) with respect to changes in sizing and as well as how to apply that knowledge to suit sizing options and improvements in suit fit. The methods implemented in this study focused on changes in elbow and wrist mobility due to incremental suit sizing modifications. This incremental sizing was within a range that included both optimum and poor fit. Suited range of motion data was collected using a motion analysis system for nine isolated and functional tasks encompassing the elbow and wrist joints. A total of four subjects were tested with motions involving both arms simultaneously as well as the right arm only. The results were then compared across sizing configurations. The results of this study indicate that range of motion may be used as a viable parameter to quantify at what stage suit sizing causes a detriment in performance; however the human performance decrement appeared to be based on the interaction of multiple joints along a limb, not a single joint angle. The study was able to identify a preliminary method to quantify the impact of size on performance and to develop a means to gauge tolerances around optimal size. More work is needed to improve the assessment of optimal fit and to compensate for multiple joint interactions

A training programme to build cancer research capacity in low- and middle-income countries: Findings from Guatemala

PROBLEM: Guatemala is experiencing an increasing burden of cancer but lacks capacity for cancer prevention, control and research. APPROACH: In partnership with a medical school in the United States of America, a multidisciplinary Cancer Control Research Training Institute was developed at the Instituto de Cancerología (INCAN) in Guatemala City. This institute provided a year-long training programme for clinicians that focused on research methods in population health and sociocultural anthropology. The programme included didactic experiences in Guatemala and the United States as well as applied training in which participants developed research protocols responsive to Guatemala\u27s cancer needs. LOCAL SETTING: Although INCAN is the point of referral and service for Guatemala\u27s cancer patients, the institute\u27s administration is also interested in increasing cancer research - with a focus on population health. INCAN is thus a resource for capacity building within the context of cancer prevention and control. RELEVANT CHANGES: Trainees increased their self-efficacy for the design and conduct of research. Value-added benefits included establishment of an annual cancer seminar and workshops in cancer pathology and qualitative analysis. INCAN has recently incorporated some of the programme\u27s components into its residency training and established a research department. LESSONS LEARNT: A training programme for clinicians can build cancer research capacity in low- and middle-income countries. Training in population-based research methods will enable countries such as Guatemala to gather country-specific data. Once collected, such data can be used to assess the burden of cancer-related disease, guide policy for reducing it and identify priority areas for cancer prevention and treatment

Spacesuit and Space Vehicle Comparative Ergonomic Evaluation

With the advent of the latest manned spaceflight objectives, a series of prototype launch and reentry spacesuit architectures were evaluated for eventual down selection by NASA based on the performance of a set of designated tasks. A consolidated approach was taken to testing, concurrently collecting suit mobility data, seat-suit-vehicle interface clearances and movement strategies within the volume of a Multi-Purpose Crew Vehicle mockup. To achieve the objectives of the test, a requirement was set forth to maintain high mockup fidelity while using advanced motion capture technologies. These seemingly mutually exclusive goals were accommodated with the construction of an optically transparent and fully adjustable frame mockup. The mockup was constructed such that it could be dimensionally validated rapidly with the motion capture system. This paper will describe the method used to create a motion capture compatible space vehicle mockup, the consolidated approach for evaluating spacesuits in action, as well as the various methods for generating hardware requirements for an entire population from the resulting complex data set using a limited number of test subjects. Kinematics, hardware clearance, suited anthropometry, and subjective feedback data were recorded on fifteen unsuited and five suited subjects. Unsuited subjects were selected chiefly by anthropometry, in an attempt to find subjects who fell within predefined criteria for medium male, large male and small female subjects. The suited subjects were selected as a subset of the unsuited subjects and tested in both unpressurized and pressurized conditions. Since the prototype spacesuits were fabricated in a single size to accommodate an approximately average sized male, the findings from the suit testing were systematically extrapolated to the extremes of the population to anticipate likely problem areas. This extrapolation was achieved by first performing population analysis through a comparison of suited subjects performance to their unsuited performance and then applying the results to the entire range of population. The use of a transparent space vehicle mockup enabled the collection of large amounts of data during human-in-the-loop testing. Mobility data revealed that most of the tested spacesuits had sufficient ranges of motion for tasks to be performed successfully. A failed tasked by a suited subject most often stemmed from a combination of poor field of view while seated and poor dexterity of the gloves when pressurized or from suit/vehicle interface issues. Seat ingress/egress testing showed that problems with anthropometric accommodation does not exclusively occur with the largest or smallest subjects, but rather specific combinations of measurements that lead to narrower seat ingress/egress clearance

Variation in reversal learning by three generalist mesocarnivores

Urbanization imposes novel challenges for wildlife, but also provides new opportunities for exploitation. Generalist species are commonly found in urban habitats, but the cognitive mechanisms facilitating their successful behavioral adaptations and exploitations are largely under-investigated. Cognitive flexibility is thought to enable generalists to be more plastic in their behavior, thereby increasing their adaptability to a variety of environments, including urban habitats. Yet direct measures of cognitive flexibility across urban wildlife are lacking. We used a classic reversal-learning paradigm to investigate the cognitive flexibility of three generalist mesocarnivores commonly found in urban habitats: striped skunks (Mephitis mephitis), raccoons (Procyon lotor), and coyotes (Canis latrans). We developed an automated device and testing protocol that allowed us to administer tests of reversal learning in captivity without extensive training or experimenter involvement. Although most subjects were able to rapidly form and reverse learned associations, we found moderate variation in performance and behavior during trials. Most notably, we observed heightened neophobia and a lack of habituation expressed by coyotes. We discuss the implications of such differences among generalists with regard to urban adaptation and we identify goals for future research. This study is an important step in investigating the relationships between cognition, generalism, and urban adaptation