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Objectives. The purpose of this study was too determine whether there were significant kinematic differences between recreational and elite hockey players and between contra-lateral lower limbs during forward hockey skating. / Methods. While skating on a hockey treadmill subjects were filmed with four synchronized digital video cameras while wearing reflective marker triads on the thighs, shanks and skates. Subjects skated within a calibrated volume at a self selected speed that they could maintain comfortably for one minute. Each subject completed three trials separated by 5 minutes of rest. Data was reduced and analyzed using programs written in MATLAB. Two-way ANOVA and Tukey Post Hoc tests were used to determine statistic significance. / Results. Elite and recreational subjects were significantly different (p≤0.05) during knee abduction and knee rotation at push off, as well as during knee abduction and knee flexion at blade contact. Contra lateral lower limbs were significantly different (p≤0.05) during ankle abduction and hip rotation at blade contact as well as during knee abduction at push off. / Conclusion. Some aspects of the skating stride are similar in elite and recreational hockey skaters but there were several kinematic differences between skill levels and contra-lateral legs. The skating kinematics of elite hockey players may serve as a model for young hockey players and recreational hockey players, helping them develop a more efficient and effective stride.

Patellofemoral pain syndrome (PFPS) is one of the most common, but least understood, knee disorders. Fulkerson (1997) believes that pathology may result from an excessive valgus force being applied to the patella. Researchers have historically examined quadriceps strength and neuromuscular activity and knee kinematics. However, results from these works have not provided conclusive answers. Powers (2003) has theorized that other structures can influence knee function, and researchers have shown that PFPS subjects can exhibit hip weakness and demonstrate altered hip kinematics during functional activities. Although they provide preliminary evidence regarding hip influences, investigations that simultaneously examine hip and knee function in PFPS subjects are needed. The primary purpose of this study was to determine functional performance, strength, neuromuscular activity (amplitudes and onset timing differences), and kinematics of the hip and knee for people diagnosed with PFPS. Eighteen females diagnosed with PFPS and 18 asymptomatic female controls participated. Subjects initially completed a 10-cm visual analog scale. Next, they completed two functional performance tests and underwent a strength assessment for the hip abductors, hip external rotators, and knee extensors. Surface electromyography (EMG) electrodes and reflective markers were donned in order to collect EMG and kinematic data during a stair-stepping task. For this purpose, subjects ascended and descended two 20-cm high steps at a standardized rate. Seven PFPS and seven control subjects were retested five to seven days later to establish measurement reliability. A repeated measures analysis of variance was used to determine group differences. Correlation coefficients were calculated to identify associations between pain and dependent measures; intraclass correlation coefficients were calculated to determine measurement reliability for both control and PFPS subjects. Results from this study showed group differences for functional performance, strength, and EMG amplitudes but none for onset timing differences or kinematics. A strong association was found between pain and hip external rotator strength and EMG amplitudes during stair-stepping. Most tests provided reliable measures with repeat testing. PFPS subjects demonstrated quadriceps dysfunction but even greater hip weakness that was correlated more with pain. Contemporary rehabilitation has focused on quadriceps strengthening; however, results from this study support the importance of the hip.

This study examined muscle activation and relative joint angles during a conventional deadlift while using either a double‐pronated or overhand/underhand (OU) grip. Ten weight‐trained individuals performed the deadlift with 60% and 80% of their 1‐repetition maximum, with three different grip variations. EMG recordings were taken of the left and right biceps brachii, brachioradialis, upper trapezius, and upper latissimus dorsi. Motion capture was used to measure angles of the wrist, elbow, knee, and hip. With an OU grip, significant bilateral asymmetry was seen in EMG activity of biceps brachii and brachioradialis. Mean wrist and elbow angle also showed significant bilateral asymmetry when using an OU grip. Training recommendations for the OU grip deadlift should emphasize the need to vary which hand is supinated/pronated to avoid muscle imbalances and possible injury. Furthermore, it may be preferential to use a double‐pronated grip to avoid asymmetric training altogether.

Exercising the leg in a manner similar to running is theorized to have the potential effect of increasing performance and reducing occurrence of injuries in running athletes. Development of an exercise device that can help facilitate this method of specificity training could be beneficial to the sports community and should be investigated. Understanding the trajectory of the foot during the running gait is primary to further pursue this concept. 26 running athletes of varying characteristics participated in this study. Each subjects sex, age, weight, height, leg length, activity level and participation amount in their respective sport was recorded. Retro-reflective cameras captured the three-dimensional trajectory of each subjects right leg while running at speeds of 2, 3.8, 4.52 and 5.36 m/s for 10-15 seconds on a treadmill, respectively. The range of foot movement in each cardinal plane was determined for each speed. An ANCOVA revealed that leg length was the most determinate factor in trajectory range differences among subjects. Subjects were subsequently divided into quartiles based on leg length where further analysis revealed that foot displacement increased vertically and horizontally in the sagittal plane with increases in speed while trajectory in the third plane remained constant and substantially less in magnitude.

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Motion planning for redundant manipulators poses special challenges because the required inverse kinematics are difficult and not complete. This thesis investigates and proposes methods for motion planning for these systems that do not require inverse kinematics and are potentially complete. These methods are also compared in performance to standard inverse kinematics based methods.

Purpose of study: Examine ASO (soft) and Malleoloc semi-rigid stirrup (SRS) ankle orthosis designs on ankle kinematics during field-sport movements: sprint, one-legged jump, and 45-degree cut. Participants: 13 competitive Ultimate players who regularly wore an ankle orthosis during physical activity. Methods: ASO or Malleoloc orthosis was randomly assigned to each person. Kinematic data were captured while the participants performed several trials for each movement in a motion analysis laboratory. Participants repeated the protocol with the other orthosis. Results: ASO allowed significantly more plantar-flexion during weight acceptance of the planting foot in cutting (p=0.038). In jumping, the Malleoloc allowed significantly more eversion-inversion range during stance (p=0.048) and eversion-inversion angular velocity from midstance to toe-off (p=0.026). Qualitative data also showed a significant preference for ASO. Conclusion: Hypotheses that ankle inversion and eversion would be greater with the ASO; and plantar-flexion and dorsiflexion would be greater with the Malleoloc were refuted.

Parallel robotic manipulators are a specific type of robot that has multiple limbs which are ultimately connected to a moving body. Within this regime, there are several sub-classes of robots characterized by certain inherent traits. Common to all sub-classes is the ability to articulate the moving platform by actuating each of the limbs. In general, it has been shown that these types of robotic manipulators possess several types of advantageous properties. Some of these properties are: good dynamic character, high stiffness, high precision, large payload to weight ratio, and high speed. Flexible and reconfigurable manufacturing regimes are new manufacturing system paradigms that aim at achieving cost-effective and rapid system changes. Essentially, a system classified as flexible or reconfigurable would be one that is adaptive to change in the market without the need to re-design or re-develop its components. The advantage of such a system is in theory very large. To date, there has been some enhancements made in the area, however there are still many open aims and possible improvements to be investigated. Much of which aims at furthering the concepts from theory to practical applications. The main objective of this dissertation is to enhance the knowledge base in flexible and reconfigurable systems through parallel robotics. Specifically, by utilizing new ideas in parallel robotics tailored to these manufacturing regimes, significant improvements in the knowledge base are attained. These can be classified under one specific regime of parallel robotics and further categorized as passive, semi-active, and active (adaptive). This thesis first focuses on a new design methodology related to flexible and reconfigurable manufacturing. Essentially, the method proposes a systematic approach to recon figure the dynamic properties of robotic devices for various functional requirements that would be part of a flexible manufacturing situation. The method is tested on an example structure and results indicate that the proposed reconfiguration method outperforms existing devices. Next, this dissertation focuses on the design of new robotic architectures that are more adaptive. Specifically, the goal is to achieve structures that can be adaptive in real-time. Existing structures are only reconfigurable passively and need to stop operation in order to reconfigure manually. To this end, a hybrid structure that is semi-active reconfigurable is first investigated. It is dubbed the ReSl-Bot. A complete engineering analysis and design is conducted illustrating its properties. To take this one step further, a novel class of hybrid adaptive parallel robots is then proposed. A 6-DOF robot belonging to this class called the HAPM mk.1 is studied in detail. It is effectively shown that this novel design has the ability to adapt properties actively. This type of adaption could be used for the performance enhancement in many applications, particularly for flexible manufacturing. Properties such as DOF, stiffness, dexterity, precision, kinetics, energy consumption, backlash, etc. could potentially be altered for varying applications and requirements. Notably, a complete theoretical analysis is conducted, ending with analytical dynamics and control.