Dissertations / Theses on the topic 'Hamstring muscle strength'

Thesis (M. Ed.)--Bowling Green State University, 2005.
Includes bibliographical references (leaves 38-44). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Hamstring strain injuries are endemic in running-based sports, often resulting in substantial performance decrements and costing professional sporting organisations millions of dollars each year. This program of research has contributed new knowledge relating to factors which may predispose to, and manifest as a result of hamstring injury, while also providing novel data which may be used to inform injury prevention and rehabilitation practices.

The main aim of this thesis was to examine hamstrings anatomy and its influence on knee flexor muscle function in healthy young men. A secondary aim was to better understand the implications of hamstrings anatomy and function, and their variability, in relation to the risk of strain injury. The functional and conventional H:Q ratios (examined up to high angular velocities) as well as the knee joint angle-specific isometric H:Q ratio exhibited good test-retest reliability at joint positions that closely replicated the conditions of high injury risk. Football players did not exhibit any differences in angle-specific or peak torque H:Q ratios compared to recreationally active controls. Knee extensor and flexor strength, relative to body mass, of footballers and controls was similar for all velocities, except concentric knee flexor strength at 400° s-1 (footballers +40%; P < 0.01). Muscle volume explained 30-71% and 38-58% of the differences between individuals in knee extensors and flexors torque respectively across a range of velocities. A moderate correlation was also found between the volume of these antagonistic muscle groups (R2= 0.41). The relative volume of the knee extensors and flexors explained ~20% of the variance in the isometric H:Q ratio and ~31% in the high velocity functional H:Q ratio. Biceps femoris long head exhibited a balanced myosin heavy chain isoform distribution (47.1% type I and 52.9 % total type II) in young healthy men, while BFlh muscle composition was not related to any measure of knee flexor maximal or explosive strength. Biceps femoris long head proximal aponeurosis area varied considerably between participants (>4-fold) and was not related to biceps femoris long head maximal anatomical cross-sectional area (r= 0.04, P= 0.83). Consequently, the aponeurosis:muscle area ratio exhibited 6-fold variability (range, 0.53 to 3.09; CV= 32.5%). Aponeurosis size was not related to isometric or eccentric knee flexion strength. The findings of this thesis suggest that the main anatomical factor that contributes to knee flexors function in vivo is hamstrings muscle size, while muscle composition and aponeurosis size do not seem to have a significant influence. The high inter-individual variability of the biceps femoris long head proximal aponeurosis size suggests that a disproportionately small aponeurosis may be a risk factor for strain injury. In contrast, biceps femoris long head muscle composition does not seem to explain the high incidence of strain injuries in this muscle. Quadriceps and hamstrings muscle size imbalances contribute to functional imbalances that may predispose to strain injury and correction of any size imbalance may be a useful injury prevention tool. Finally, regular exposure to football training and match-play does not seem to influence the balance of muscle strength around the knee joint.

Bakgrund: Inom forskningen studeras styrkeförhållandet i lårets muskler och anges ofta som flexor/extensor kvot (F/E-kvot). Ett sätt att mäta denna kvot är att använda isokinetiska styrketest.  Forskningen är inte överens om ett optimalt styrkeförhållande i denna muskulatur eller om för stor styrkeskillnad kan ge upphov till skada. Om en optimal kvot kan fastställas är det intressant i ett förebyggande och rehabiliterande syfte.  Syfte: Att beskriva och jämföra F/E-kvoten hos en grupp manliga fotbollsspelare med en grupp fysiskt aktiva män mellan 16 och 25 år. Metod: Mätning av maximal isokinetisk styrka i knäledens flexor och extensormuskler genomfördes med Genesis Single. Resultat: Studien fann en F/E-kvot hos fotbollsspelarna på 78,2 % på höger ben och 77 % på vänster ben. Jämförelsegruppen hade en F/E-kvot på 73,7 % på höger ben och76,4 % på vänster ben. Utifrån detta kunde man inte finna någon signifikant skillnad mellan de båda grupperna Slutsats: Studien fann ingen signifikant skillnad i F/E-kvot i höger respektive vänster ben mellan en grupp fotbollsspelare och jämförelsegrupp. Vidare forskning om reliabilitet och validitet med Genesis Single som mätinstrument bör utföras innan fler studier utförs med maskinen.
Background: The kneeflexor and kneextensor muscle strength ratio (F/E ratio) is a widely researched area where isokinetic tests are often used. There seems to be little consensus regarding the optimal ratio and also whether a low ratio increase the risk of injury. It would be interesting from a preventive and rehabilitative stand point if an optimal ratio could be decided upon.  Objectives: To compare the F/E ratio between a group of 16-25 year old soccer players and a group of physically active males. Methods: Isokinetic maximal strength in kneeflexors and kneextensors were measured with Genesis Single. Results: The ratio of the soccer players was 78,2 % in the right leg and 77 % in the left. The comparison group was found to have a ratio of 73,7 % in the right leg and 76,4 % in the left leg. There were no significant differences between the two groups. Conclusions: No significant differences could be determined between the two groups. Genesis Single needs to be further investigated with regards to its reliability and validity.

Introduzione: Le lesioni muscolari agli ischiocrurali sono fra i più frequenti infortuni in cui incorre uno sportivo che compie gesti atletici come corsa, scatti e decelerazioni, cambi di direzione e salti. L’eziologia lesiva di questi muscoli dimostra come la stragrande maggioranza degli infortuni avvenga durante una contrazione eccentrica, dove i muscoli esercitano la loro principale funzione. Si è deciso di indagare l’efficacia del rinforzo muscolare eccentrico in prevenzione agli infortuni a tale gruppo muscolare. Obiettivo: Ricercare le evidenze in letteratura sull’efficacia del rinforzo muscolare eccentrico in prevenzione agli infortuni al gruppo muscolare degli ischiocrurali. Metodi: La ricerca è stata svolta presso le principali banche dati biomediche, includendo le Revisioni Sistematiche pubblicate negli ultimi 10 anni in lingua inglese, che indagassero l’efficacia di un intervento comprendente il rinforzo muscolare eccentrico ai muscoli ischiocrurali su una popolazione di sportivi, e i cui outcome misurassero l’incidenza degli infortuni. Risultati: Sono stati selezionati 3 studi, valutati tramite AMSTAR Checklist. I risultati raccolti dagli autori valutano positivamente, con più o meno evidenza scientifica, l’efficacia del rinforzo muscolare in prevenzione agli infortuni ai muscoli ischiocrurali, nel contesto in cui sono stati somministrati. Una revisione dimostra come la compliance all’intervento mostrata dai partecipanti influenzi significativamente i risultati ottenuti. Conclusioni: I risultati ottenuti dalle revisioni suggeriscono il proseguimento delle ricerche riguardanti l’efficacia di tale intervento in prevenzione agli infortuni ai muscoli ischiocrurali, tramite nuovi studi condotti con un rigore metodologico maggiore. I limiti mostrati dagli studi inclusi devono essere usati come orientamento per le future ricerche, nel tentativo di giungere a risultati il più significativi possibili.

M.Tech. (Chiropractic)
Purpose: This study aims to compare the effects of spinal manipulation versus mobilization of the lumbar spine and sacroiliac (SI) joints on the contractile strength of the hamstring muscle group with regards to strength and flexibility. Method: This study consisted of 2 groups of 15 participants between the ages of 18 and 50 years of age. Males and females were first separated to ensure equal male to female ratios within each group. The potential participants were examined and accepted according to the inclusion and exclusion criteria. The method of treatment administered to each group was determined by group allocation. Group 1 received spinal manipulation directed towards restrictions located within the lumbar spine and/or SI joints. Group 2 received spinal mobilization directed towards restrictions located within the lumbar spine and/or SI joints. Procedure: Treatment consisted of 4 treatment sessions with an additional follow up visit over a 2 week period. Objective data was recorded on visit 1 before and after treatment, visit 3 before and after treatment and on visit 5 in which there was no treatment administered, its purpose was purely to obtain measurements. The measurements were taken in this way in order to determine immediate as well as medium term changes. Objective data consisted of hamstring muscle strength readings taken using a handheld dynamometer and hamstring muscle flexibility readings taken using a digital inclinometer. Analysis of collected data was performed by a statistician. The manipulation and mobilization techniques used were directed towards dysfunctional joints within the lumbar spine and/or SI regions, which were detected by motion palpation. Results: Regarding muscle strength, statistically significant results were noted in Group 1 at visits 1 and 3 on both the right and left sides when determining the immediate effects of the treatment. Medium term changes were seen during the time interval between visits 1 and 3, as well as between visits 1 and 5 bilaterally. When determining the immediate effects of the treatment, Group 2 did not demonstrate muscle strength changes at visit 1 on the right, however statistically significant results were found at visit 3 on the right as well as at visits 1 and 3 on the left. Medium term changes were seen during the time interval between visits 1 and 3, as well as between visits 1 and 5 bilaterally. Manipulation and mobilization were shown to have a statistically significant effect on hamstring muscle strength, although manipulation was shown to have a more beneficial effect on muscle strength both immediately and over time, though this was only found on the left. Regarding muscle flexibility, statistically significant results were noted in Group 1 on both right and left sides at visits 1 and 3 when determining the immediate effects of the treatment. Statistically significant changes only occurred on the left between visits 1 and 5 when determining the medium term effects of the treatment. Group 2 showed statistically significant changes at visit 3 on the right as well as at visits 1 and 3 on the left when determining the immediate effects of the treatment. When determining the medium term effects of the treatment no statistically significant changes were found over the duration of the study. There was no difference found between the groups in terms of the effect that the treatment had on hamstring muscle flexibility, although isolated improvements occurred over time in the manipulation group. Conclusion: The results show that both manipulation and mobilization have a statistically significant effect on hamstring muscle strength. However, manipulation was shown to have a more significant effect. Changes in hamstring muscle flexibility were found to occur immediately and over time in the manipulation group, however only immediate effects were noted in the mobilization group. Therefore, when compared to mobilization, manipulation appears to have a greater effect on hamstring muscle strength and flexibility.

M.Tech. (Chiropractic)
Purpose: According to Jonhagen, Nemeth and Erikson (1994), hamstring muscle injury as a result of weakness is prevalent. Hoskins and Pollard (2005) states that a previous or recent hamstring muscle injury is the most recognized risk factor for future injury. Given the high reoccurrence rate, hamstring injuries provide a significant challenge to the treating clinician. Knowledge surrounding the optimal treatment is critical to improve hamstring muscle strength in preventing these injuries. The aim of this study is to determine the most effective treatment method, when comparing sacroiliac joint manipulation with or without dry needling and the effect it has on hamstring strength. Design: Thirty participants between the ages of 18 and 35 years old presenting with SI joint dysfunction and hamstring trigger points, were considered for this study. The participants were randomly divided into two groups of 15 participants each (group A and B). Group A received manipulation to the sacroiliac joint and group B received manipulation to the sacroiliac joint, as well as dry needling of the active myofascial trigger points in the semimembranosus muscles. Each participant was treated six times over a period of three weeks. Measurements: All measurements were collected at the first, third and fifth consultation prior to treatment and on the seventh consultation where no treatment was performed. Subjective measurements included the McGill questionnaire and a visual analogue pain scale. Objective measurements included algometer, readings of pressure pain threshold of the hamstring muscle trigger points and hamstring muscle strength recorded using a dynamometer instrument. Results and Conclusion: Group A and group B proved to have a statistical and clinical improvement overall. Group A had a better improvement in both subjective tests and in the objective tests. In comparing the statistically significant data for hamstring muscle strength in this study, it would appear that Group A responded better to treatment than Group B. Although both groups did improve, it suggests that Group A achieved the greatest overall improvement. Therefore it can be suggested that myofascial dry needling of the hamstring muscle was found not to have an additive effect for improving vii hamstring muscle strength, it actually appears to have done worse. The reason for this might be due to the post treatment soreness after needling. This may cause muscle inhibition and decreased muscle contraction, due to the pain or tenderness, which could have affected the muscle strength. In conclusion, the results in this study show that chiropractic manipulation combined with dry needling did not have better results in improving hamstring strength.

碩士
臺北市立大學
運動健康科學系碩士班
103
Background: It is well known that stretching exercises could enhance body flexibility. Some researches indicate that stretching and strength training could improve joint mobility, flexibility, and muscle strength. Objective: To investigate two ways of dynamic stretching, active straight leg raise (ASLR) and modified toe-touch (MTT), and to compare how they influence the results of flexibility test, muscle function, and muscle strength differently. Methods: A group of 16 healthy male college students, pre-test and post-test their muscle stiffness, pain measurement, flexibility measurements of passive straight leg raise (PSLR) and active straight leg raise (ASLR ), and muscle strength (concentric and eccentric strength) with one dynamic stretching in between. Seven days later, another pre-test and post-test with the other dynamic stretching in between. Results: The result of ASLR group is significant in muscle stiffness, flexibility, and concentric strength (p < .05). The result of MTT group is significant in pain threshold, muscle stiffness, flexibility, and concentric and eccentric muscle strength (p < .05) Conclusion: The results showed that MTT stretching exercises could increase flexibility and decrease muscle stiffness. However, the performance on muscle strength declined and decrease the threshold of muscle soreness. The reason might be excessive stretching that reduces the bonding range of muscle cross bridge and decreases power performance. Adjustments on the intensity and the duration on stretching are recommended.

M.Tech.
Purpose: In soccer the re-injury rate of Hamstring muscle strains is between 12 and 14 percent. A previous or recent Hamstring injury is the most recognised risk factor for future injury. On recurrence of the injury, it tends to be more severe and disabling than the initial injury. Given the high recurrence rates, Hamstring injuries provide a significant challenge to the treating clinician. Knowledge surrounding optimal treatment and preventative measures is therefore critical (Hoskins and Pollard 2005). The aim of this study is to assess the effectiveness of lower lumbar spine segment adjustment, namely the L4/5 spinal level, in the contractile strength of the Hamstring muscle group in professional soccer players that have a history of a Hamstring strain. Design: Forty professional soccer players between the ages of 15 and 34 years with a history of a grade one or grade two Hamstring strain were considered for this study. Participants in this research were obtained from the University of Johannesburg inter-residence players and from the University of Johannesburg first soccer team. Two groups of twenty players were randomly assigned to one of two groups. Group A received spinal adjustive therapy (SAT) to the L4/5 spinal segment with an ultrasound treatment to their Hamstring muscle group and Group B will receive only the ultrasound treatment to the hamstring muscle group. Each participant was treated five times over a period of three weeks. Measurements: Before any intervention was given to either of the groups, Hamstring muscle contractile strength was first recorded using a Cybex system 2000. Hamstring contractile muscle strength measurements were taken again after the fifth treatment for both groups and compared to ascertain if there had been any change in the contractile strength of the Hamstring muscles. Results and Conclusion: Even though the two groups did not start at the same contractile strength for the Hamstring muscle in knee flexion, as measured a CCybex system 2000 possibly due to the selection criteria used in the study in terms of age and body weight of the participants, results showed that spinal adjustive therapy was more effective in improving the muscle contractile strength of the Hamstring muscle in knee flexion since there was a favourable difference in both Group A and Group B following intervention, but more so in Group A (in the once injured leg) which received spinal adjustive therapy due to a greater increase in the overall muscle contraction in the Hamstring muscle group. For the Chiropractic profession this opens huge potential with regards to the Chiropractic benefits and improving the functioning of professional soccer players.

Hamstring strain injuries (HSI) are extremely common in football and are the primary cause of re-injury in football players. Although the isokinetic strength ratios have often been used to predict hamstring injuries in football players, the rate of torque development hamstring to quadriceps ratio (RTD H/Q) has rarely been considered in previous reports. Furthermore, little consideration has been given to selective hamstring lengths and their influence on torque production and knee muscle balance, especially under muscle fatigue condition in previously injured hamstrings. Thus, the present dissertation contemplated two approaches. The first, presented in Chapter 3, which aimed to determine the RTD H/Q at long hamstring lengths and the conventional (concentric/concentric) and functional (eccentric/concentric) hamstrings/quadriceps (H/Q) ratios. The second approach, presented in Chapter 4, aimed to determine the effect of muscle fatigue, induced by a specific protocol seeking to mimic the loads and characteristics of team sports, on the knee muscle balance, given by the RTD, conventional and functional hamstrings/quadriceps (H/Q) ratio. Twenty-four professional men's football players, divided into two experimental groups, with (PI) and without (UG) previous HSI, competing in the 1st and 2nd national leagues, participated voluntarily in the studies (approved by the local ethical council – CEFMH: 13/2018). Players performed both quadriceps and hamstring maximal voluntary isometric contractions at 30º of knee flexion (long hamstring lengths) and maximal concentric isokinetic contractions at 180°.s-1 and 60°.s-1. Isokinetic eccentric contractions at 180°.s- 1 and 60°.s-1 of hamstring muscles were also performed. Conventional and functional H/Q ratios based on peak torque throughout the entire isokinetic range of motion and at 30° of knee flexion were calculated. Long hamstring lengths RTD H/Q ratios were extracted at incrementing time periods of 50 milliseconds (ms) from the onset of contraction (50-250 ms). The main findings showed that players with a previous HSI (PI) have a small effect towards lower eccentric torque and RTD H/Q at the initial period of contraction (50 ms, p> 0.05, d=0.4). The PI also showed small to moderate (0.4>d<0.6) higher rate of torque development ratios in late time intervals (>100 ms) as well. Following fatigue, significant differences were found between groups (PI and UG) in the RTD H50/Q50 ratio (p<0.05; d=1.0). Previous hamstring strain injury group showed small to moderate (p> 0.05; 0.3>d<0.6) lower RTD H/Q ratios in early time intervals (<150 ms) as well (<150 ms). In conclusion, to the best of our knowledge, these were the first studies to investigate the rapid H/Q ratio at long hamstring lengths in professional football players with previous HSI. The findings presented in this dissertation may have important implications for future injury prevention and rehabilitation programs and for the explosive strength improvement of the hamstrings. Future studies should also investigate whether lower RTD H/Q ratios are an adaptation to injury, or if it’s a risk factor to future HSI. Also, future studies should seek to investigate whether training in a fatigue state reduces the injury incidence, and, if successful redirect new injury prevention guidelines, to help reduce the large (re-)injury rates of HSI in professional football.
As roturas dos isquiotibiais (RISQ) são extremamente comuns no futebol e representam a primeira causa de recidiva de lesão em jogadores de futebol. Apesar dos rácios isocinéticos entre isquiotibiais e quadricípites (rácios ISQ:QUAD) serem amplamente divulgados na literatura como preditores de RISQ, o rácio para a taxa de produção de força (TPF ISQ:QUAD) tem sido muito raramente referenciado em investigações anteriores. Além disso, pouca relevância tem sido dada à influência do estado de alongamento dos ISQ na capacidade de produção de força e no equilíbrio funcional do joelho, sobretudo num contexto de fadiga muscular em isquiotibiais previamente lesionados. Deste modo, a presente dissertação contemplou duas abordagens. Uma primeira, (Capítulo 3), procurou determinar o TPF ISQ:QUAD em condição de alongamento dos ISQ, assim como os tradicionais rácios ISQ:QUAD convencional (ISQconc/QUADconc) e funcional (ISQexc/QUADconc). A segunda abordagem (Capítulo 4), procurou determinar o efeito da fadiga muscular, induzida por um protocolo específico envolvendo ações caraterísticas da modalidade, no equilíbrio muscular e funcional da articulação (rácios ISQ:QUAD convencional, funcional e da TPF). Vinte e quatro jogadores profissionais de futebol, divididos em dois grupos experimentais, com (PI) e sem (UG) historial prévio de RISQ, com prática competitiva atual nos campeonatos das 1ª e 2ª ligas nacionais, participaram voluntariamente nos estudos. Foram realizadas contrações isocinéticas concêntricas (QUAD e ISQ) e excêntricas (ISQ) a 180°.s-1 e 60°.s-1 e contrações isométricas máximas (QUAD e ISQ) a 30º de flexão do joelho. Os rácios convencional e funcional foram calculados com base no momento de força máximo obtido em toda a janela isocinética e a 30º de flexão do joelho. O TPF ISQ:QUAD foi calculado em intervalos incrementais de 50 milissegundos (ms) a partir do instante inicial de contração (50-250ms). Os principais resultados revelaram que jogadores com historial de RISQ (PI) apresentam ligeiro efeito para um reduzido momento de força excêntrico e do TPF ISQ:QUAD no período inicial de contração (50ms; p>0,05; d=0,4). O PI revelou ainda um pequeno a moderado efeito (p>0,05; 0,4>d<0,6) para rácios TPF ISQ:QUAD superiores em períodos mais tardios da contração muscular (>100ms). Em condição de fadiga, foram observadas diferenças significativas entre grupos no rácio TPF ISQ:QUAD aos 50ms (p<0,05; d=1,0). Foram ainda encontradas pequenos a moderados efeitos (p>0,05; 0,3>d<0,6) para rácios TPF ISQ:QUAD inferiores nos períodos prematuros da contração (<150ms). Em conclusão, este foi o primeiro estudo a investigar o rácio para a TPF ISQ:QUAD em condição de alongamento dos ISQ em jogadores profissionais de futebol com historial de RISQ. Os resultados encontrados podem ter implicações futuras nos programas de prevenção e reabilitação de lesão e no desenvolvimento da força explosiva dos ISQ. Estudos futuros devem investigar a verdadeira origem dos desequilíbrios evidenciados neste estudo, analisando se decorrem de uma adaptação à própria lesão, ou se poderão decorrer da prática desportiva e do processo de treino. A influência da fadiga na incidência de lesão também deve ser investigada. Se bem-sucedidos, estes estudos poderão fornecer novas diretrizes sobre a prevenção de rotura dos ISQ.

碩士
高雄醫學大學
行為科學研究所博士班
96
Background: Normal anterior cruciate ligament（ACL）is an essential indicator of integral knee function. In addition to the loss of the knee function, ACL injury can also impair balance, limit functional activities, and even restrict the participation in vigorous sports activities. The reconstruction of the ACL utilizes arthroscope to transfer selection of autografts, often hamstring tendon（HT）or patella tendon（PT）, to substitute the injured ligament. The choice of the autografts may affect the recovery of knee muscle strength. Methods: ACL injured patients planned for reconstruction（12 with HT and 11 with PT aurograft）and a group of healthy, aged matched controls were recruited for this study. They were tested bilaterally for isometric knee muscle strength at knee flexion of 90°-10° with an isokinetic dynamometer, before, three and six months after reconstruction to investigate the recovery of knee muscle strength with different autografts. Results: The quadriceps of the affected side of the ACL injured clients was found to be weaker than their sound sides and the controls. Muscle strength recovery of the affected knee was found associated with the autograft selection. For both HT and PT groups, the quadriceps of the affected knees was much weaker at all testing knee positions at the third month post reconstruction. In addition, the HT group also showed significant weakness of the hamstrings at the affected side, which might be due to the damage to the donor site. At the sixth month post reconstruction, the affected quadriceps of both HT and PT groups have much recovered, though the quadriceps was till weaker than the controls at some of the testing angles. Further analysis showed that, at the sixth month post reconstruction, the PT group still exhibited more deficits in quadriceps strength, though the HT group had largely recovered to normal. Conclusion: ACL plays a very important role in knee control. The impact to knee muscle strength should not be ignored in those who have had an ACL injury and those with a reconstruction. Since a major goal of rehabilitation after ACL reconstruction is to regain normal muscle strength of knee joint, physical therapists should plan the ACL rehabilitation programs with emphasis to clients with different autografts.

碩士
國立體育學院
運動傷害防護研究所
94
Abstract Purpose: The purpose of this study was to analyze the effects on balance, power, and isokinetic strength after three commonly prescribed closed kinetic chain training: the lunge, the squat, and the leg press. Method: Thirty-five healthy male adults were randomly divided three groups into a lunge group, a squat, a leg-press, and a control. The former performed progressive weight training twice a week for eight weeks. All subjects were tested before and after the eight-week training program. A knee isokinetic strength test, a continuous jump test, and a balance test were used to determine the training effects. Result: The lunge group were significantly higher than the control group in the quadriceps concentric peak torque at 60°/sec. The lunge group and the squat group were significantly higher than the control group in the quadriceps eccentric peak torque at 60°/sec. No significant differences were found in hamstrings concentric and eccentric peak torque at 60°/sec among the lunge group, the squat group and the leg press group. The leg-press group is significantly better than the control group in the power performance. The lunge group, squat group, and leg-press group were all significantly longer than the control group in the average flight time. There were no significant differences in the balance performance. Conclusions: The lunge exercise was more useful than the squat and leg press in quadriceps concentric and eccentric strength training. The lunge, squat, and leg press exercises were all increasing quadriceps strength. The leg press exercise was more efficient than the lunge and squat exercise in the mechanical power performance. The lunge, squat, and leg press exercises were all to increasing average flight time and power performance.