Title: Kinesiological analysis of selected techniques in greco-romain wrestling Objective: The aim of this Thesis is to measure the extent to which various muscles are involved during the practice of the wrestling technique body lock, lift and suplex. It also considers the order in which the muscles are involved. The research applies surface electromyography. Methods: The theoretical part of this Thesis is predominantly based on the method of analysis and synthesis of the specialized literature. In the practical part, the surface electromyography was used to measure which muscles are involved in the body lock, lift and suplex. Subsequently, the difference of the motion performance of the four probands was evaluated. Furthermore, the timing of muscle activation was monitored. Results: The evaluation of the result showed that musculus rectus femoris is the most involved in the movement and the least musculus obliquus externus abdominis. In addition, it was found that m. Obliquus externus abdominis is involved first, while the last one is involved with m. Biceps femoris. Key words: Wrestling, electromyography, quality of movement, muscle activation

The purposes of this investigation were to: (1) assess kinetic characteristics of overload, (2) examine eccentric and concentric muscle activations and (3) explore velocity measurement as a method of intensity prescription in inertial flywheel squat training. A series of two experiments were performed: one assessing kinetic and muscle activation characteristics of flywheel squat training using three progressive inertial loads. The second experiment assessed inertial load-velocity relationships using six progressive inertial loads. Peak force, net impulse, positive–negative impulse ratio and positive–negative impulse duration ratio were each statistically significant between all three load conditions (p < 0.05). Concentric vastus lateralis muscle activation was the only significant increase between inertial loads (p < 0.05). Although not statistically significant, concentric quadricep muscle activation was increased from the lowest to highest inertia. Conversely, eccentric quadricep muscle activation was reduced from the lowest to highest inertia. In the second experiment, statistically significant regression equations were observed for average concentric velocity (R2 = 0.66) and peak concentric velocity (R2 = 0.60). In conclusion, our results indicate (1) overload is possible kinetically, (2) phase-specific muscle activation responds differently to increased inertia and (3) velocity has the potential to be used for load prescription in the inertial flywheel squat.

The purpose of the present study was to compare total knee arthroplasty (TKA) rehabilitation with and without whole-body vibration (WBV) to 1) understand if WBV is a useful treatment during TKA rehabilitation to increase quadriceps strength and function, and 2) to investigate the effect of WBV on quadriceps voluntary muscle activation. Subject and Methods. Individuals post TKA (WBV n=8, control n=8) received physical therapy with and without WBV for four weeks. Quadriceps strength and muscle activation, function, perceived pain, and knee range of motion were measured. Results. No adverse side effects were reported in either group. There was a significant increase in strength and function for both groups (P<0.01). There was no difference pre to posttest between groups for strength, muscle activation, or pain (Hotelling’s T2=0.42, P=.80) or for function (F=0.54, P=0.66). Discussion and Conclusion. In individuals with TKA, WBV showed equal strength and function improvement to physical therapy directed progressive resistive exercise. Influence of WBV on muscle activation remains unclear, as initial muscle activation was near established normal quadriceps levels and remained so post treatment.

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The magnitude of improvements in muscular strength and size are influenced by the volume and intensity of a resistance training program. While it is clearly advantageous for resistance-trained individuals to utilize programming specific to these goals, it not clear which is more important. Therefore the purpose of the present investigation was to determine the effect of focusing on training volume versus intensity on changes in muscle size and strength. Changes in muscular strength and size were examined in 29 resistance-trained men following 8 weeks of resistance training. Participants were randomly assigned to either a high volume (VOL, n = 14, 4 x 10 – 12RM, 1min rest) or high intensity (INT, n = 15, 4 x 3 – 5RM, 3min rest) resistance training program. Lean body mass, lean arm and leg mass, were assessed by dual energy X-ray absorptiometry, while ultrasound images (VL-vastus lateralis, RF-rectus femoris, PM-pectoralis major, and TB-triceps brachii) were used to assess changes in muscle cross-sectional area (CSA) and thickness (MT). Strength was measured by one repetition-maximum (1RM) squat (SQ) and bench press (BP). Changes in muscular (RF & VL) activation in response to increases in submaximal SQ intensity (40-, 60-, 80-, & 100%-1RM) were assessed via surface electromyography. Blood samples were collected at baseline, immediately post, 30min post, and 60min post-exercise at week 3 (WK3) and week 10 (WK10), to assess plasma/serum testosterone, growth hormone (GH), insulin-like growth factor-1 (IGF1), cortisol (CORT), and insulin. Area under the curve analysis revealed a greater (p < 0.05) increase for VOL (WK3: GH & CORT; WK10: CORT) compared to INT. Compared to WK3, WK10 showed reduced responses for VOL (GH and CORT) and INT (IGF1). Significant group differences were observed for changes in lean arm mass (INT: 5.2 ± 2.9%, VOL: 2.2 5.6%) and BP 1RM (INT: 14.8 ± 9.7%, VOL: 6.9 ± 9.0%). Over the course of 8 weeks, our data indicate that trained men would benefit more when focusing on training intensity, rather than volume, for strength and size improvements.

Purpose: The upper trapezius to serratus anterior muscle activation ratio is essential for optimal shoulder function. An alteration of this ratio, specifically a decrease in upper trapezius and increase in serratus anterior activation, is a main area of focus in shoulder rehabilitation (Kibler, 1998; Paine & Voight, 1993). Electromyography (EMG) biofeedback has been shown to be an effective rehabilitation technique to address many musculoskeletal disorders but there is limited research on the retention of improvements seen with EMG biofeedback (Ma et al., 2011; Lim et al., 2014; Weon, et al., 2011). The purpose of this study was to determine if EMG biofeedback can be used to improve scapular control by decreasing the upper trapezius to serratus anterior activation ratio. A secondary purpose was to determine if these predicted improvements in the ratio can be retained beyond the timeframe in which the treatment is provided. Methods: Twenty college aged (age=21.75±1.77) subjects (10 males, 10 females) volunteered to participate in this study. Subjects were randomized to the exercise only group or EMG biofeedback group. The exercise only group performed three exercises twice a week for four weeks with supervision. The EMG biofeedback group performed the same exercises twice a week for four weeks with the addition of watching EMG biofeedback on a computer monitor with the instructions to decrease the upper trapezius activation and increase the serratus anterior activation by adjusting the corresponding lines on the monitor. The percent maximal voluntary contraction (MVC) for each muscle during each exercise was measured on visit one, visit nine (after the four weeks of practice) and visit ten (after a two-week retention period). The ratio and the individual muscle changes were analyzed using multi-factor ANOVAs against group, exercise, and group by exercise interaction. Results: There was no significant effect of any of the variables on the ratios visit one to visit nine, nor when comparing visit nine to visit ten. The was a significant effect of group on the upper trapezius when comparing visit one to visit nine (p=0.007) with no effect seen comparing visit nine to visit ten. There was also a significant effect of group on the serratus anterior activation for both visit one to visit nine (p=0.000) and visit nine to visit ten (p=0.001). Conclusion: EMG biofeedback did not decrease the upper trapezius to serratus anterior activation ratio, but the individual muscle activation changes indicate that EMG biofeedback is effective at altering muscle activation rates in individual muscles and that those changes can be retained beyond the timeframe of the intervention. Additional research is needed with more subjects and in populations with shoulder pathologies to further investigate the effectiveness of this concept.

The increased prevalence of crash avoidance technologies like autonomous emergency braking necessitates understanding of occupant responses during low-speed frontal pre-crash braking and low-severity crash events. Active human body models (HBMs) have emerged as valuable tools to evaluate occupant safety during these events, but must be validated with relevant volunteer data to accurately represent the responses of live occupants. The objective of this dissertation was to quantify the occupant responses of relaxed and braced 5th percentile female and 50th percentile male volunteers during low-speed frontal and frontal-oblique sled tests designed to simulate pre-crash braking and low-severity crash events. A study comprised of 160 low-speed sled tests was performed with 20 volunteers. The volunteers' kinematics, kinetics, and muscle responses were compared to determine how altering impact direction (frontal and frontal-oblique), impact severity (1 g and 2.5 g), demographic group (mid-size male and small female), and muscle state (relaxed and braced) affected occupant responses. The volunteers' occupant responses were significantly affected by impact direction, impact severity, demographic group, and muscle state. The frontal-oblique tests resulted in greater leftward excursions compared to the frontal tests. Increasing the pulse severity resulted in greater forward excursions, reaction forces, and muscle activation. The male volunteers exhibited greater forward excursions and reaction forces compared to the female volunteers. However, the two demographic groups exhibited similar muscle activation during the sled tests. Bracing increased the volunteers' initial joint angles, muscle activation, and reaction forces prior to the sled tests. Bracing decreased forward excursions and increased reaction forces during the sled tests. The relaxed volunteers exhibited greater relative changes in occupant responses compared to the braced volunteers. Overall, this study demonstrated that muscle activation significantly affected the volunteers' kinematics, kinetics, and muscle responses for both mid-size males and small females during low-speed events. Observed differences between demographic groups were more prominent when relaxed and more diminished when braced. These results underscore the importance of validating active HBMs with relevant volunteer data in order to be more representative of live occupants for a wider range of demographic groups in varying muscle states. Finally, this dissertation provides a large, comprehensive, and novel biomechanical dataset that can be used to develop and validate active HBMs for use in assessing occupant response during frontal pre-crash braking and low-severity crash events. These models will help improve the understanding of potential injury risk and development of effective vehicle safety systems for use during low-speed events. / Doctor of Philosophy / Computer models, known as active human body models (HBMs), have emerged as tools that can be used to assess occupant safety during low-speed vehicle crashes. In these types of events, occupants have enough time to react and potentially brace before the crash, which could in turn affect their responses during the crash. It is important to understand how occupants respond during crashes so that effective vehicle safety systems can be developed. Active HBMs are particularly valuable because they can simulate muscle activation to reflect the response of live occupants. However, data are needed from live occupants to ensure that these models are accurate. To gather this data, a study was performed where volunteers experienced low-speed frontal sled tests when they were relaxed and braced. The sled tests were designed to simulate pre-crash braking and low-severity vehicle crashes. Mid-size male and small female volunteers were recruited to participate to represent the standard adult occupant populations used in current frontal impact vehicle safety standards. A motion capture system was used to measure the volunteers' forward motion, load cells were used to measure the volunteers' exerted reaction forces on the test buck, and electrodes were used to measure the volunteers' muscle activity. The volunteers' responses were significantly different between the relaxed and braced muscle states, and between the males and females. Comparing between males and females, the males moved farther forward and exerted larger reaction forces, but both demographic groups exhibited similar muscle responses. Comparing between muscle states, bracing increased the volunteers' muscle activation and reaction forces before the sled tests. Bracing also increased the volunteers' reaction forces during the sled tests, but decreased forward movement. Overall, the volunteers exhibited greater relative changes in response when they were relaxed compared to when they were braced. Overall, this study demonstrated that muscle activation significantly affected the volunteers' responses for both mid-size males and small females during low-speed events. These results highlight the importance of developing active HBMs with relevant volunteer data in order to be more representative of live occupants. Finally, the data from this study can be used to develop active HBMs to improve their accuracy, so that the models can be used to assess occupant safety during low-speed frontal vehicle crashes. This will help improve the understanding of potential injury risk and development of effective vehicle safety systems, to reduce the number of injuries caused by vehicle crashes.

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