Orientador: Vania Celia Vieira de Siqueira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-04T00:44:28Z (GMT). No. of bitstreams: 1 Sousa_MeireAlvesde_M.pdf: 711072 bytes, checksum: 46ae7204f05c9e14c19bfd81de9b1add (MD5) Previous issue date: 2004 / Mestrado / Ortodontia / Mestre em Ortodontia

A computer model of the human single motor unit potential has been created for the purpose of developing methods of automated analysis in clinical electromyography. This approach was taken in order to examine the effects of pathological changes on the electromyographic potentials. A comprehensive review of the previous methods of automatic analysis of clinical EMG signals described in the literature has been presented and discussed, together with the relevant work on the production and detection of electrical activity with intramuscular electrodes. A methodology has been devised for the collection and preprocessing of the electromyographic signals and an . EMG data base established at U.B.C. An interactive graphics routine was developed to display the EMG waveform and allow the extraction of single motor unit potentials for further analysis. A computer model has been proposed for the generation of single motor unit potentials observed during clinical EMG examinations of the normal biceps brachii muscle. This model was based on physiological findings. In the model the single fiber activity was represented by a dipole current source and the motor unit was constructed from a uniform random array of fibers. Motor unit potentials generated from this array were examined at various points both inside and outside the array and the effects of single fiber axial dispersion, were investigated. The simulated motor unit potentials generated by the model have been compared with existing data from multielectrode studies in biceps brachii. The hypothesis that there is a variation in motor unit potential shape at successive discharges was investigated and the model employed for this purpose. It has been shown that for the normal motor unit potential, one major contributor to the shape variance is electromyographic jitter. The predictions from the model were compared with human experimental data. These results reveal that the variance may be a useful diagnostic indicator, although further research is warranted. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

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The purpose of this investigation was to compare performance and neuromuscular adaptations following ballistic and heavy resistance training. Twenty male university students were divided into a training (n=10) or control group (n=10). Each subject in the training group, by random assignment, trained the elbow extensors of one arm with heavy resistance (HR.) [(5 sets of the maximal weight that could be lifted for 5-7 repetitions (reps.)]; the other with ballistic (BL) actions (5 sets of 6 reps. at 10% of their isometric MVC). Training was done 3 times per week for 17 weeks. Following training, both training HR. and BL regimens produced significant (p≤0.05), but not significantly different increases in ballistic performance peak torque (2.5 vs. 2.7 N·m, peak velocity (1.0 vs. 1.3 rad·s⁻¹), and peak power (32.8 vs. 48.4 W). Similarly, elbow extension movement time decreased to the same extent (-12.5 vs. -6.3 ms; p≤0.05). In contrast, HR training produced significantly greater increases in maximal weight lifting (I RM) (15.8 vs. -0.1 N·m; p≤0.001) and isometric (MVC) strength (8.1 vs. 0.8 N·m; p≤0.01). Electromyography (EMG) recordings of the agonist (AG) triceps brachii indicated significant (p≤0.05) increases in average EMG (AEMG) during I RM, MVC, and ballistic tests (collapsed across training conditions). The only difference between training regimens was the greater 1 RM AEMG after HR. training. Ballistic training resulted in significantly (p≤0.05) greater antagonist ballistic/MVC, and antagonist coactivation (ballistic/MVC) EMG ratios compared to HR. training. Evoked isometric twitch torque and torque-time integral increased only after HR training. Fiber (needle biopsies of triceps) area increases were also significantly (p≤0.001) larger in the HR than the BL arm after training in type I (28.0% vs. -4.7%), type IIa (43.0% vs. 8.3%), and type IIb (41.4% vs. 3.0%) fibers. Dual photon x-ray absorptiometry regional arm analysis revealed that only the HR. arm significantly (p≤0.05) increased in lean mass following training. Heavy resistance training resulted in a significant (p≤0.05) decrease in the percentage of type IIb fibers with a corresponding increase in IIa; whereas ballistic training did not result in any fiber type conversion. These data suggest that although neuromuscular adaptations may differ, either form of training can increase ballistic performance, but only HR. training is effective in increasing muscle size and maximal force during I RM and MVC single joint actions. Heavy Resistance, Ballistic, Torque, Velocity, Power, Electromyography, Evoked Contractile Properties, Fiber Type, and Fiber Area / Thesis / Master of Science (MSc)

Low back pain is the number one cause of disability in the world. It is a well established problem in industry often caused by excessive repetition, awkward postures, and heavy lifting. Back support exoskeletons have increasingly been studied as a solution to this problem. In addition to evaluating exoskeletons, giving some focus to the various lifting styles themselves can also provide some insight into ameliorating this problem. Research evaluating warehouse workplace postures has found that workers switch between a variety of tasks and many different lifting styles, beyond the standard squat and stoop postures, on a daily basis. This dissertation is primarily a compilation of three papers. The first focuses on the VTLowe's exoskeleton and the kinematic differences found during Stoop, Squat, and Freestyle lifting. These lift styles were evaluated while the study participants lifted boxes weighing 0% or 20% of their body weight both With and Without the exoskeleton. Evaluating the kinematic results showed that wearing the exoskeleton resulted in a 1.5 degree increase in ankle dorsiflexion, a 2.6 degree decrease in knee flexion, and a 2.3 degree decrease in SHK angle. Subjects' shoulder, elbow, and wrist heights were slightly higher while wearing the exoskeleton, and they lifted slightly more slowly while wearing the exoskeleton. Subjects moved more quickly while bending down as compared to standing up, and with the 0% bodyweight box as compared to the 20% bodyweight box. The values for Freestyle lifts generally fell in between Squat and Stoop lift styles or were not significantly different from Squat. EMG data (analyzed in a different study) from the leg muscles had relationships with torso torque while the back and stomach muscles showed no significant relationships. Exoskeleton efficacy research has a strong focus on Stoop, Squat, and Freestyle lifting. However, asymmetric styles such as One Legged lifting and Kneeling were found to be frequently used lifting styles in a warehouse setting. The second paper in this dissertation focuses on variations of asymmetric lifts while lifting light objects including Split Legged, Heel Up, One Legged, Kneeling, Asymmetric Squat, Bent Over (a freestyle task) and Bend Walk (picking up bean bags from the ground while walking forward and maintaining a bent over posture). These lift styles can be found not only in industry, but in any individual's daily life such as when it comes to picking up a dropped pen or sorting toys in a bin on the floor. Evaluating Split Legged, Heel Up, and One Legged found that many of the significant differences in muscle activity are dependent on the lifting stance (whether the front foot is on the same side or opposite side as the hand used to pick up objects). Combining the results that same side lifts have greater muscle imbalance in the iliocostalis and overall back muscle activity is greater in Split Legged than in Heel Up or One Legged suggests that One Legged or Heel Up in an Opposite side stance are the best options in regards to minimizing back muscle activity. Although there is a trade-off with the biceps femoris for these lift styles, back injuries are far more prevalent and supporting the back takes priority over minimizing muscle activity in the legs. The analysis for Asymmetric Squat, Bend Walk, Bent Over, and Kneeling was divided into three portions: bending down, picking bags, and rising up. Relevant differences between the lift styles for these portions were seen in the biceps femoris, longissimus, and rectus abdominis, with Bend Walk generally being the most taxing activity. Overall, there were minimal differences while rising up from any of these postures with most changes seen in the biceps femoris. Rising Up also generally had a higher peak muscle activity compared to bending down or picking bags. The final paper in this dissertation evaluates the effect of a different back exoskeleton with the variety of lift styles studied in the second paper. It is important to see how exoskeleton use aids or harms many of the lift styles commonly used by industry workers. Lift side was once again a factor in the Split Legged, Heel Up, and One Legged tasks. Participants benefited more from the exoskeleton in same side lifts as opposed to opposite side. For Asymmetric Squat, Bend Walk, Bent Over, and Kneeling greater benefits were seen in the back and leg muscles while rising up as opposed to bending down. Focusing on the peak of the lift (taken at the peak of bending down for the more static postures) found that the exoskeleton had more significant differences for Split Legged, Heel Up, and One Legged compared to Asymmetric Squat, Bend Walk, Bent Over, and Kneeling. One highly important aspect in evaluating exoskeletons is determining the subject population that would most benefit from its use. Focusing on body mass, the longissimus saw decreased benefits as the body mass increased, with subjects under 75 kg benefiting the most from the exoskeleton, while the iliocostalis and biceps femoris typically saw the opposite effect when results were significant (i.e., heavier subjects benefited the most). / Doctor of Philosophy / Low back pain is the number one cause of disability in the world. It is a well established problem in industry often caused by excessive repetition, awkward postures, and heavy lifting. Back support exoskeletons have increasingly been studied as a solution to this problem. In addition to evaluating exoskeletons, giving some focus to the various lifting styles themselves can also provide some insight into ameliorating this problem. Research evaluating warehouse workplace postures has found that workers switch between a variety of tasks and many different lifting styles, beyond the standard squat and stoop postures, on a daily basis. This dissertation is primarily a compilation of three papers. The first focuses on the VTLowe's exoskeleton and the differences in how people move while wearing the exoskeleton during Stoop, Squat, and Freestyle lifting. These lift styles were evaluated while the study participants lifted boxes weighing 0% or 20% of their body weight both With and Without the exoskeleton. This resulted in small changes in the ankle, knee, and hip angles. Subjects' shoulder, elbow, and wrist heights were slightly higher while wearing the exoskeleton, and they lifted slightly more slowly while wearing the exoskeleton. Subjects moved more quickly while bending down as compared to standing up, and with the 0% bodyweight box as compared to the 20% bodyweight box. The values for Freestyle lifts generally fell in between Squat and Stoop lift styles or were not significantly different from Squat. Electromyography (muscle activity) data, analyzed in a different study, from the leg muscles had relationships with torso torque while the back and stomach muscles showed no significant relationships. Exoskeleton efficacy research has a strong focus on Stoop, Squat, and Freestyle lifting. However, asymmetric styles (i.e., where one side of the body is doing something different from the other side) such as One Legged lifting and Kneeling were found to be frequently used in a warehouse setting. The second paper in this dissertation focuses on variations of asymmetric lifts while lifting light objects including Split Legged, Heel Up, One Legged, Kneeling, Asymmetric Squat, Bent Over (a freestyle task) and Bend Walk (picking up bean bags from the ground while walking forward and maintaining a bent over posture). These lift styles can be found not only in industry, but in any individual's daily life such as when it comes to picking up a dropped pen or sorting toys in a bin on the floor. Evaluating Split Legged, Heel Up, and One Legged found many of the significant differences in muscle activity are dependent on the lifting stance (whether the front foot is on the same side or opposite side as the hand used to pick up objects). The results found that there were different imbalances between the sides of the body depending on the specific lift style examined. Overall, the muscle activity results suggest that One Legged or Heel Up in an Opposite side stance are the best options in regards to minimizing back muscle activity. While leg muscle activity does increase for these lift styles, back injuries are far more prevalent and supporting the back takes priority over minimizing muscle activity in the legs. The analysis for Asymmetric Squat, Bend Walk, Bent Over, and Kneeling was divided into three portions: bending down, picking bags, and rising up. Overall, Bend Walk was the most taxing of those activities. The final paper in this dissertation evaluates the effect of a second back exoskeleton with the variety of lift styles studied in the second paper. It is important to see how exoskeleton use aids or harms many of the lift styles commonly used by industry workers. Participants benefited more from the exoskeleton in same side lifts as opposed to opposite side. For Asymmetric Squat, Bend Walk, Bent Over, and Kneeling greater benefits were seen in the back and leg muscles while rising up as opposed to bending down. The exoskeleton helped Split Legged, Heel Up, and One Legged more than Asymmetric Squat, Bend Walk, Bent Over, and Kneeling. One highly important aspect in evaluating exoskeletons is determining the subject population that would most benefit from its use. One of the back muscles saw decreased benefits as the body mass increased, with subjects under 75 kg benefiting the most from the exoskeleton, while another back muscle and the legs typically saw the opposite effect.

The problem with which this investigation is concerned is that of facial muscle activity in forming and maintaining the soprano clarinet embouchure. The purposes of the study are to collect and analyze data in the following areas: 1. Activity of the following muscles during performance on the clarinet: (1) upper orbicularis oris, (2) lower orbicularis oris, (3) upper half of the buccinator, and (4) lower half of the buccinator. Muscular activity is read as electronic potential and is presented on recordings through the use of electromyography. 2. Possible effects which the electromyographic apparatus might impose upon performance. Tape recordings weremade of the subjects' performing prescribed tasks both before and during electromyographic analysis. The possible effects of the electromyographic analysis upon performance were then tested by comparing these two recordings.

Thesis (M.S.)--University of Michigan, 1973.