Women are four to eight times more likely to injure their anterior cruciate ligament (ACL) compared to men. It is most commonly injured through a non-contact mechanism during game time situations. During landings, women display valgus collapse, where a less active gluteus medius muscle (GMed) may be unable to control the internal rotation of the thigh, causing an increase in knee joint abduction angle, augmenting the risk of ACL injury. This study’s purpose was to determine the difference between 12 male and 12 female athletes in muscle activity, specifically the GMed, and the 3D kinematics and kinetics of the lower-limb during drop jump landings from three heights; maximum vertical jump height, tibial length, and a commonly used height of 40cm. Results showed that females had greater hip adduction and knee abduction angles compared to men. The GMed activity showed no significant differences between sexes at each drop jump height.

Orientador: José Corrêa de Lacerda Neto / Banca: Thiago Luiz de Salles Gomes / Banca: Claudia Acosta Duarte / Banca: Flora Helena de Freitas D'Angelis / Banca: Antonio de Queiroz Neto / Resumo: Objetivou-se avaliar o efeito da suplementação com diferentes concentrações de óleo de soja e do treinamento de resistência nas adaptações do músculo glúteo médio de 20 eqüinos da raça Puro Sangue Árabe. Os animais foram distribuídos em cinco grupos, cada grupo foi composto por quatro cavalos. O grupo controle não recebeu óleo e os demais foram suplementados com 6, 12, 18 e 24% de óleo. Os animais foram submetidos a sete semanas consecutivas de exercício em esteira rolante e trilha. Analisou-se a influência do treinamento e da suplementação com óleo sobre o peso e escore corporal, concentração de glicogênio muscular e características das fibras do músculo glúteo médio. Os resultados demonstraram que as diferentes concentrações de óleo na dieta não influenciaram as variáveis estudadas. Houve redução significativa do peso corpóreo após o treinamento, no entanto o escore corporal permaneceu constante. O músculo glúteo médio expressou três tipos de fibras puras: I, IIA, IIX. O treinamento não induziu hipertrofia das fibras do músculo glúteo médio. O treinamento ocasionou aumento na proporção e na área relativa das fibras tipo IIA em detrimento das fibras IIX, melhorando a capacidade oxidativa muscular. Tanto as dietas com óleo como o treinamento não aumentaram as concentrações de glicogênio muscular. / Abstract: The aim of this study was evaluate the effects of supplementation with different concentrations of soy oil and endurance training on gluteus medius muscle adaptations in twenty Arabian horses. The horses were randomized in five groups (four horses each group). The control group did not receive the oil and the other groups were supplemented with 6%, 12%, 18% and 24% of soy oil. The animals were submitted to seven weeks of exercise on treadmill and track. The influence of training and oil supplementation on body weight, corporal score, muscular glycogen stores and characteristics of the gluteus medius muscular fibers were analyzed. The results showed that the supplementation of soy oil in diet was not significantly effective on the studied parameters. There was a significant reduction of the body weight after the end of training; however the corporal score showed no changes. The gluteus medius muscle expressed three types of pure fibers: I, IIA and IIX. The training induced a increase in the proportion and relative area of the type IIA fibers in detriment of type IIX fibers, improving the oxidative capacity muscular. No hypertrophy of the muscular fibers was observed. There were no significant changes in the values of the total glycogen after the training period. / Doutor

Women are four to eight times more likely to injure their anterior cruciate ligament (ACL) compared to men. It is most commonly injured through a non-contact mechanism during game time situations. During landings, women display valgus collapse, where a less active gluteus medius muscle (GMed) may be unable to control the internal rotation of the thigh, causing an increase in knee joint abduction angle, augmenting the risk of ACL injury. This study’s purpose was to determine the difference between 12 male and 12 female athletes in muscle activity, specifically the GMed, and the 3D kinematics and kinetics of the lower-limb during drop jump landings from three heights; maximum vertical jump height, tibial length, and a commonly used height of 40cm. Results showed that females had greater hip adduction and knee abduction angles compared to men. The GMed activity showed no significant differences between sexes at each drop jump height.

PURPOSE: To examine gluteus medius strength and endurance in relation to lower limb stability, targeting and agility. METHODS: 57 participants performed isometric and dynamic gluteus medius strength and endurance tests of both lower limbs. Lower limb dominance was determined using the Waterloo Footedness Questionnaire-Revised (WFQ-R). Strength and endurance of gluteus medius were compared to single-leg performance of a stork stand, a lateral foot targeting task and a hopping test of agility. RESULTS: Body mass normalized isometric gluteus medius strength was found to be weakly and inversely correlated to agility score for both dominant limbs (r=-0.262, p=0.026) and non-dominant limbs (r=-0.335, p=0.006) with a lower agility score indicating better agility performance. For non-dominant limbs only, body mass normalized isometric gluteus medius strength correlated negatively to targeting speed (r=-0.229, p=0.045) and isometric gluteus medius endurance measured as percentage drop in strength over time correlated weakly and positively to the amount of body sway demonstrated during a single-leg stork stand task (r=0.253, p=0.030). CONCLUSION: Gluteus medius strength may be weakly related to improved agility performance while gluteus medius endurance may weakly relate to improved single-leg static balance performance. It is likely that other factors such as neuromuscular training have a much larger influence on stability, targeting ability and agility than the strength and endurance of the hip abductors alone.

M.Tech. / The term „myofascial‟ is derived from the word „myo‟ meaning muscle and „fascia‟ meaning connective tissue. Myofascial pain syndrome is a regional pain syndrome characterized by the presence of myofascial trigger points (Mense and Simons, 2001). The most crucial component of myofascial pain is muscle shortening from contracture (or „spasm‟). In fact, myofascial pain does not exist without muscle shortening. Prolonged shortening not only causes pain in the muscle but also physically pulls on tendons, thereby straining them and distressing the bone and joints they insert into and act upon (Gunn, 2002). Trigger points are most often discussed in the setting of myofascial pain syndromes, in which widespread or regional muscular pain is associated with hyperalgesia, psychological disturbance and significant restriction of daily activities (Huguenin, 2004).

Women are four to eight times more likely to injure their anterior cruciate ligament (ACL) compared to men. It is most commonly injured through a non-contact mechanism during game time situations. During landings, women display valgus collapse, where a less active gluteus medius muscle (GMed) may be unable to control the internal rotation of the thigh, causing an increase in knee joint abduction angle, augmenting the risk of ACL injury. This study’s purpose was to determine the difference between 12 male and 12 female athletes in muscle activity, specifically the GMed, and the 3D kinematics and kinetics of the lower-limb during drop jump landings from three heights; maximum vertical jump height, tibial length, and a commonly used height of 40cm. Results showed that females had greater hip adduction and knee abduction angles compared to men. The GMed activity showed no significant differences between sexes at each drop jump height.

Master of Science / Department of Animal Sciences and Industry / Terry Houser / A total of 45 top sirloin butts (IMPS 184) were procured from three commercial beef processing facilities to determine the effects of post-mortem aging time and blade tenderization on the quality of beef gluteus medius (GM) steaks. Top sirloin butts were randomly assigned to five post-mortem aging periods (5, 19, 33, 47, and 61 days). One-half of each beef GM was randomly assigned to either a blade tenderized treatment or a non-blade tenderized treatment that was not blade tenderized. Steaks were then evaluated for thiobarbituric acid reactive substances (TBARS), metmyoglobin reducing activity (MRA), oxygen consumption rate (OCR), visual color panel, instrumental color, Warner-Bratzler shear force (WBSF), Lactic Acid Bacteria (LAB) enumeration, pH, and sensory properties. Aging × blade tenderization interactions (P < 0.05) were found for display color panel, discoloration panel, WBSF, overall tenderness, myofibrillar tenderness, bloody/serumy, metallic, overall sweet, and bitter (P < 0.05). As steaks were aged longer and blade tenderized they became more discolored during display and more tender. In addition, there were aging × display time interactions (P < 0.05) observed for L*, a*, b*, display color panel, and discoloration panel. As steaks were aged longer, they had increased L*, a*, b*, and hue angle values and display color panel scores when initially put into a retail case, but L*, a* and b* decreased and discoloration scores increased as display time increased. Furthermore, there were blade tenderization × display time interactions (P < 0.05) found for display and discoloration panels. Blade tenderized steaks discolored faster in retail display than non-blade tenderized steaks. With increased aging time, there was an increase (P < 0.05) in TBARS, OCR, initial color panel, LAB enumeration, and warmed-over flavor, as well as a decrease in MRA. Also, as aging increased there was a decrease (P < 0.05) in MRA, initial color panel scores, and WBSF values. Blade tenderization significantly increased (P < 0.05) initial color panel scores, rancid flavor, and spoiled flavor. Increasing the aging time of the GM, produced steaks with decreased color stability, altered the flavor profile, and increased tenderness. Blade tenderization significantly increased tenderness, increased discoloration in a retail case, and produced more undesirable flavors.

Running is becoming an increasingly popular sport; however, runners have a high rate of injury and are therefore often treated in the orthopedic or sports medicine setting. One current focus of these patients' treatment is gluteus medius muscle (GM) strengthening and gait retraining, with the goal of decreasing frontal plane pelvic drop. Unfortunately, there is a research void assessing the role of GM function on pelvic drop, and the effect of an increased pelvic drop on running performance. The specific aims of this research were to investigate a link between frontal plane pelvic drop and (1) isometric GM torque, (2) GM surface electromyography (sEMG) peak amplitude and onset timing, and (3) GM fatigue; and (4) to study the relationship between frontal plane pelvic drop and increased metabolic energy demands. Subjects were recreational runners who ran an average of five or more miles per week. Data from an initial ten subjects were collected, followed by an additional eleven subjects tested for Specific Aims #1, 2, and 3. GM maximal isometric torque was obtained prior to the run. Subjects ran on a treadmill for thirty minutes while three-dimensional pelvic kinematics, GM sEMG, and metabolic data were collected. Pearson's Correlations and scatter plots of the variables showed no relationship between GM maximal isometric strength, GM peak amplitude and onset timing, or GM fatigue rate and frontal plane pelvic drop. The change in pelvic drop also had no effect on the change in running economy (RE) from the start to end of the run. Clinicians should not employ a GM centered treatment approach when treating frontal plane pelvic instability in runners. Future research into additional core stabilizing muscles and their interactions could provide insight into which muscles should be the focus of treatment in runners with proximal instability. These studies should also include kinetic as well as lower extremity (LE) kinematic analysis of running gait to investigate the link between these variables, their relationship to muscle performance, as well as to running performance.

Abstract Background: The Gluteus Medius (GM) muscle has an important role in stabilizing the pelvis and controlling the knees during athletic activities. Weakness in the GM can affect performance negatively and increase the risk of lower extremity (LE) injuries. During functional activities different parts of the muscle becomes activated depending on the degree of hip flexion. However, many GM strength exercises only train the GM in one fixed degree of hip flexion. Purpose: The purpose of the present study was to develop and validate a new training device designed to increase the muscle activation of the GM during progressive hip flexion in squats. Methods: The new device was developed to offer resistance training against hip abduction during squats. To be able to validate the new device in activating the GM, 32 female athletes (mean age 20 ± 3) with various athletic backgrounds was included in the study. All subjects performed squats on and off the device while surface electromyographical (SEMG) activity was recorded from GM on both sides of the body. Results: All test subjects were able to perform the squat and to activate the GM. When the squats were performed on the new device the muscle activation in GM was significantly higher compared to bodyweight squats (Z=-4.9, p &lt; 0.001). Correlation tests between a complete sequence of five squats and one selected repetition revealed that activation was consistent throughout the exercise, (right GM: rs = 0.93, p &lt; 0.001, left GM: rp = 0.92, p &lt; 0.001) . No differences in activation were found between the right and left GM when squatting on the device. Conclusion: This study showed that the newly developed training device increased the muscle activity in GM during squats. Moreover, the results showed that squatting on the device activates the left and right side of the body equally and that the GM was activated during the whole exercise, under ongoing hip flexion. This information could be used to develop new training methods with the aim to improve stabilization of the pelvis and lower extremities during functional activities. / Sammanfattning Bakgrund: Gluteus medius (GM) fyller en viktig funktion vid idrottsliga aktiviteter genom att den stabiliserar bäckenet och kontrollerar knäna. Svaghet i GM kan påverka prestationen negativt samt öka risken för skador i de lägre extremiteterna (LE). Vid funktionella aktiviteter aktiveras olika delar av GM beroende på graden av höftflexion. Många styrkeövningar för GM tränar emellertid muskeln i endast en fixerad grad av höft flexion. Syfte: Syftet med den här studien har varit att utveckla samt validera ett nytt träningsredskap, designat för att optimera muskelaktiveringen av GM under höftflexion. Metod: Träningsredskapet utvecklades för att erbjuda motstånd mot abduktion vid knäböj. För att validera redskapets förmåga att aktivera GM inkluderades 32 kvinnliga idrottare (medelålder, 20 ± 3 år) med varierande idrottslig bakgrund. Alla försökspersoner utförde knäböjningar med och utan träningsredskapet samtidigt som elektromyografisk aktivitet mättes i höger och vänster GM. Resultat: Alla försökspersoner kunde utföra knäböjningar och lyckades aktivera GM. Knäböjningar som utfördes på träningsredskapet resulterade i signifikant högre aktivering av GM jämfört med knäböjningar utan redskapet (Z=-4.9, p &lt; 0.001). Korrelations test mellan kompletta sekvenser om fem repetitioner och enstaka repetitioner visade att aktiveringen var konstant under hela övningen, (höger GM: rs = 0.93, p &lt; 0.001, vänster GM: rp = 0.92, p &lt; 0.001). Inga skillnader i aktivering hittades mellan höger och vänster GM vid knäböjningar på redskapet. Slutsats: Studien visade att det utvecklade träningsredskapet ökade aktiveringen av GM vid knäböjningar. Resultaten visade också att denna aktivitet var jämnt fördelad mellan höger och vänster GM samt att aktiveringen var konstant under hela övningen. Resultaten i denna studien kan användas för att utveckla nya träningsmetoder med syfte att förbättra stabiliseringen av bäckenet och de lägre extremiteterna vid funktionella aktiviteter.

The Gluteus Medius and the Tensor Fascia Lata are two of the main muscles involved in the action of hip abduction. This action is important for both dynamic movements in athletic pursuits and in every day ambulation. Weakness in these muscles has been connected to multiple injuries in the lower limb, but the question of the casual relationship between gait change, hip abductor weakness, and lower limb injury is still up for debate. As presented by the current research, younger populations tend to have overuse injuries with females having a greater susceptibility for injuries connected to hip abductor weakness, and older populations tend to have injures related to atrophy and degeneration of either the hip abductor muscles or the joint surrounding the hip. Research in this field has increasingly focused on sub-sets of the populations, such as just females or just males, trying to pinpoint the role that hip abductor weakness plays in these injuries. By trying to minimize or even eliminate the confounding variables that have previously made it difficult to determine the role hip abductor weakness plays in these gait changes and injuries, these studies have been able to make more clear conclusions at the expense of making a broader generalization. Similarities and differences between how the sub-groups present with hip abductor weakness are discussed, as well as discrepancies observed within the research done on similar cohorts. Future directions for research in this field are discussed, as well as implications for clinical implementation of targeted rehabilitation programs to ensure the best possible outcomes.