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Mechanical and neural factors have been suggested to limit finger independence. Fingers producing involuntary movement or force production during intended actions of another finger are considered “enslaved” to that finger. The purpose of this thesis was to quantify the contribution of passive mechanical factors to this enslaving effect, in particular, the contributions of the intertendinous connections between extensor tendons. Twenty participants (10 men, 10 women) performed Master and Slave Tasks in three wrist (30° extension, neutral, 30° flexion) and two metacarpophalangeal (MCP) (straight and 90° flexion) postures. During the Master Task, the ring finger was the intended or “master” finger. Three 10 s isometric ring finger extensions were performed at 25% of maximum voluntary contraction. Finger force and surface electromyography of the 4 extensor digitorum (ED) bellies were recorded. In the Slave Tasks, the middle and little fingers (“slave” fingers during the Master Task) each performed three 10 s isometric finger extensions at their mean activation levels during the Master Task. Hypothetical mechanical contribution (HMC) was determined for the middle and little fingers. The HMC was defined as the difference between the involuntary force (from the Master Task) and the voluntary force (from the Slave Task) relative to the involuntary force. A small proportion of the HMC values (Middle: 39%; Little: 15%) were within the expected range of 0 to 100%, suggesting that the equation developed in this study provided a limited representation of the contribution of passive intertendinous structures. Index finger forces increased with MCP flexion, suggesting the importance of juncturae tendineii in finger independence. Higher ED activity during wrist extension, than neutral or flexed postures, with straight MCP supports previous evidence in the literature. The complex phenomenon of enslaving in different wrist and MCP positions warrants further research for quantifying the mechanical contribution in finger independence. / Thesis / Master of Science in Kinesiology

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This thesis is centered upon the published A Novel Method and Exoskeletons for Whole-arm Gravity Compensation (Turner, Hull 2020), and includes a novel concept for supporting the weight of a person's arm or robotic linkage. The design is capable of supporting weights held near the hand, and provides support regardless of position. This support is provided with a pantograph. The upper-arm and forearm bars are mirrored by smaller copies. Force applied to a pull point on the scaled copy of the arm is flipped and applied at a support point on the forearm or to a tool near the hand. Two exoskeletons, using different linkages make use of the pantograph design. These include the Panto-Arm Exo, which uses it's slim, reduced size to comfortably assist users in lifting their arm, and the Panto-Tool Exo which is designed for a support point that coincides with a mass representing a heavy tool. The differing topologies and purposes of these two devices resulted in different qualities regarding their ability to lift weight. The Panto-Arm Exo was specifically used in human subject testing, in which fourteen users wore electromyography electrodes and performed simple arm movements and holding tasks. While the Panto-Arm Exo did not undergo stringent design improvements or user-specific optimization, the device was shown to reduce muscle use in the measured upper-arm muscles for certain arm positions. / Master of Science / This thesis is centered upon the published A Novel Method and Exoskeletons for Whole-arm Gravity Compensation (Turner, Hull 2020), includes a new way to lift a person's arm or robotic linkage. The design can lift weights close to the hand regardless of arm placement. This support is provided with a pantograph. The pantograph design is based on a mirrored, smaller copy of the upper-arm and forearm bars, which is pulled downwards to create an upwards support force at chosen support point. This point is based underneath the forearm or at a heavy tool. The concept is similar to pushing down on a teeter-totter in order to prevent the other end from dropping. Two exoskeletons, using different linkages make use of this pantograph design. The Panto-Arm Exo is slim and light. It is made to help users in lift their arm by supporting its weight. The Panto-Tool Exo has a support point that located where a mass representing a heavy tool sits. The changes between both devices means that they display different lifting qualities. The Panto-Arm Exo was worn by 14 people, also wearing electrodes that measured muscle activation. These users held weights and moved their arms around while muscle activation was recorded. While the Panto-Arm Exo wasn't fine-tuned or adjusted for individual people, it was shown to reduce muscle activation in the measured upper-arm muscles for some of the arm placements.

Farmworkers play an integral role in the production and availability of tomato fruit for consumption. Yet the work activities of farmworkers present risk factors for musculoskeletal disorders. Tasks involving stake pounding, picking, bucket toss, and trellising entail risk factors such as repetitive motions, lifting/carrying of heavy loads, and working in flexed trunk postures. These physically demanding activities are typically associated with musculoskeletal disorders (MSDs). Presently, quantitative assessments of these jobs and health risks to the workers are rare. Access to the workers who are often migrant and seasonal can pose an impediment to such investigations. This research examines three tasks performed by tomato farmworkers using objective quantitative tools such as electromyography and physical activity monitoring. It also studies the relationship between self-reported and/or clinically diagnosed chronic health conditions among tomato farmworkers in the region, and risks for developing musculoskeletal disorders in the workplace. Finally, it provides models for studying risk factors of migrant farmworkers via cooperation with a migrant health center and the construction of a tomato test plot. The results of the test plot study show that the anterior deltoid and upper trapezius muscles are disproportionately impacted by tomato farm work activity, even though the three tasks studied are of moderate physical intensity. A high prevalence of musculoskeletal pain was found to exist among tomato farmworkers with the age of the worker influencing the presence or absence of chronic and comorbid conditions. Diabetes, obesity and hypertension were studied in relation to musculoskeletal disorders. The studies described in this dissertation lay the groundwork for future studies and may also encourage policy makers to support programs and collaborative partnerships that address the needs of migrant agricultural workers. We recommend longitudinal studies to research the interplay between comorbidities, jobs performed, and musculoskeletal conditions. We also recommend the use of test plots and full-shift evaluations to better characterize the degree of overexertion in tomato industry tasks.

The purpose of this study was to investigate and define the action potential of selected muscles in performing the three basic types of tennis serves. The muscles investigated were the triceps, anterior deltoid, middle deltoid, and posterior deltoid when executing the flat, slice, and twist serves. / Doctor of Education

The purpose of this study was to further investigate the relationship between patterns of shoulder movement and muscular response. Thirteen females were tested against maximal manual resistance in twelve different patterns, eight straight plane, and four diagonal. Five of the six subjects who met established kinematic criteria were used for electromyographic (EMG) analysis of the anterior deltoid (AD), the middle deltoid, the posteroir deltoid (PD), and the pectoralis major. No significant differences were found between number of muscles solicited or duration of muscular effort during the different movements. Maximal EMG was significantly higher for the AD in abduction and in flexion than in the other patterns, and for the PD in diagonal flexion with abduction and in transverse abduction.