Masters of Science / BACKGROUND: Hamstring injuries remain a growing concern within a large variety of sports from the elite athlete to the weekend warrior. A copious amount of research has been performed in an attempt to reduce these injuries. The aim of this study was to understand the changes in lengthened state eccentric strength of the hamstrings following four separate protocols. METHODS: A quantitative research approach, using a true experimental design, was adopted for this study. A convenience sample of non-sedentary, 35 male participants, between the ages of 18 and 35 within the City of Cape Town was used. Participants were randomly allocated to one of four groups namely; Control group (C), resistance training alone (RT), neuromuscular electrical stimulation alone (NMES), or NMES superimposed with RT (NMES&RT). Participant’s eccentric hamstring strength was tested in a lengthened state, on the Biodex system 4 Pro™ for the pre- and post-test. The intervention spanned over four weeks. SPSS version 25 was used for data analysis. RESULTS: All groups demonstrated a mean increase in relative peak torque. However, a repeated-measures analysis of variance (ANOVA) showed no interaction effect (p = 0.411) between the four groups. Further analysis using Magnitude-based inferences (MBI), to identify the magnitude of changes, showed a small positive effect for both the NMES and NMES&RT group when compared to the C and RT groups. CONCLUSION: Although there are no statistically significant differences between the four groups employed in this study (C, RT, NMES, NMES&RT), NMES and NMES&RT did show small positive effects compared to C and RT with a very low likelihood of negative effects. Thus, using NMES either alone or superimposed with resistance training will be beneficial for trained athletes but it is not a necessity and the use of specific resistance training may be just as effective. / 2019-04-30

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.

The frequency of hamstrings injuries in football has increased in recent years. Hamstring injuries have been studied extensively. There is, of course, not just one reason for the occurrence of hamstring injuries, as several risk factors should be examined. The aim of the study was to investigate the frequency and risk factors related to hamstring injuries among academy football players aged 15-21. The survey was sent out to 15 football clubs and 32 high schools with nationally approved sports programs (NIU) in southern Sweden (Götaland). The response rate was equal to 67 survey responses, of which 17 had experienced a hamstring injury at some point, and eight had suffered a hamstring injury in the past 12 months. The injury frequency was calculated to be 0,05 injuries per 1000 training hours. The number of participants was too small to draw any definitive conclusions. However, different tendencies were observed, such as the majority of injuries being so-called “non-contact” injuries, as well as the indication that preventive training can be a crucial factor in avoiding injuries. / Frekvensen av hamstringsskador i fotboll har ökat under de senaste åren. Hamstringsskador har studerats i en stor omfattning. Det finns flera anledningar till förekomsten av hamstringsskador, därför bör ett flertal riskfaktorer examineras. Syftet med detta arbete var att undersöka skadefrekvensen och riskfaktorerna kring hamstringsskador hos akademifotbollsspelare mellan 15-21 år. Enkäten skickades ut till 15 fotbollsföreningar och 32 gymnasieskolor med nationellt godkända idrottsutbildningar (NIU), i södra Sverige (Götaland). Svarsfrekvensen blev 67 enkätsvar varav 17 hade någon gång haft en hamstringsskada och åtta hade haft en hamstringsskada de senaste 12 månaderna. Skadefrekvensen beräknades vara 0,05 skador per 1000 tränade timmar. Deltagarantalet var för litet för att kunna fastställa några slutsatser. Däremot observerades olika tendenser, till exempel att största delen av skadorna var så kallade“non-contact” skador och att förebyggande träning kan vara en avgörande faktor för att inte bli skadad.

Hamstring injuries have a high prevalence in rugby union players. Delayed transverse abdominus activation as well as lordosis is associated with hamstring injuries. No literature regarding this relationship in rugby players could have been found. The main purpose of this study was therefore to determine the relationship between pelvic biomechanics (transverse abdominus activation and pelvis tilt) and gluteus maximus, hamstring and erector spinae activation patterns in semi–professional rugby union players as well as the relationship of the above mentioned variables and hamstring injuries. A total of 65 players voluntarily participated in this study. Pelvis tilt (left and right) was assessed by Dartfish version 4.06.0 (Dartfish, Switzerland). Transverse abdominus activation (TrA) was assessed by pressure biofeedback and the mean onset times of the left and right gluteus maximus (GM), biceps femoris (BF), semitendinosus (ST) and lumbar erector spinae (LES) was measured with electromyography (EMG). In order to determine the role of the pelvic biomechanics and activation patterns on hamstring injuries, players were retrospectively grouped in injured and uninjured groups. Differences between the groups were determined with regards to the variables determined. Activation patterns were determined by means of descriptive statistics. The between–group pelvic biomechanic (pelvic tilt and TrA) differences in the muscle (GM, LES and hamstrings) onset times were analysed by determining practical significance by means of effect sizes. An anterior pelvic tilt on the left side was observed in 64.6% of the participants and on the right side in 83.1% of the participants. TrA testing indicated that 68.4% of participants were classified with bad activation and 31.6% with good activation. No practical significant difference was found in the mean onset times of each muscle relative to the other in the normal and anterior tilted pelvis groups as well as in the bad and good TrA groups. A total of 24.6% of the rugby players previously suffered from hamstring injuries, 37.5% of those injured participants were suffering from re–injury. No practical significant between group differences were found when the injured and uninjured groups were compared with regards to anterior pelvis tilt values (d=0.061) and TrA values (d=0.189). EMG results on the right and left side of the injured and uninjured participants present a pattern of the following activation order: LES, GM, BF and lastly ST. No practical significant between groups differences were found in the onset times of the muscles relative to each other in the injured compared to uninjured groups. The conclusions that can be drawn from this study is that semi–professional rugby union players (injured and uninjured) are prone to postural defects such as anterior tilt of the pelvis and bad TrA. Anterior pelvic tilt and bad TrA may be the reason for the earlier activation of the LES and hamstrings muscles relative to the GM in the prone hip extension to stabilize the lumbar spine. These activation patterns were however not influenced by previous hamstring injuries. / Thesis (M.A. (Biokinetics))--North-West University, Potchefstroom Campus, 2011.

Hamstring injuries have a high prevalence in rugby union players. Delayed transverse abdominus activation as well as lordosis is associated with hamstring injuries. No literature regarding this relationship in rugby players could have been found. The main purpose of this study was therefore to determine the relationship between pelvic biomechanics (transverse abdominus activation and pelvis tilt) and gluteus maximus, hamstring and erector spinae activation patterns in semi–professional rugby union players as well as the relationship of the above mentioned variables and hamstring injuries. A total of 65 players voluntarily participated in this study. Pelvis tilt (left and right) was assessed by Dartfish version 4.06.0 (Dartfish, Switzerland). Transverse abdominus activation (TrA) was assessed by pressure biofeedback and the mean onset times of the left and right gluteus maximus (GM), biceps femoris (BF), semitendinosus (ST) and lumbar erector spinae (LES) was measured with electromyography (EMG). In order to determine the role of the pelvic biomechanics and activation patterns on hamstring injuries, players were retrospectively grouped in injured and uninjured groups. Differences between the groups were determined with regards to the variables determined. Activation patterns were determined by means of descriptive statistics. The between–group pelvic biomechanic (pelvic tilt and TrA) differences in the muscle (GM, LES and hamstrings) onset times were analysed by determining practical significance by means of effect sizes. An anterior pelvic tilt on the left side was observed in 64.6% of the participants and on the right side in 83.1% of the participants. TrA testing indicated that 68.4% of participants were classified with bad activation and 31.6% with good activation. No practical significant difference was found in the mean onset times of each muscle relative to the other in the normal and anterior tilted pelvis groups as well as in the bad and good TrA groups. A total of 24.6% of the rugby players previously suffered from hamstring injuries, 37.5% of those injured participants were suffering from re–injury. No practical significant between group differences were found when the injured and uninjured groups were compared with regards to anterior pelvis tilt values (d=0.061) and TrA values (d=0.189). EMG results on the right and left side of the injured and uninjured participants present a pattern of the following activation order: LES, GM, BF and lastly ST. No practical significant between groups differences were found in the onset times of the muscles relative to each other in the injured compared to uninjured groups. The conclusions that can be drawn from this study is that semi–professional rugby union players (injured and uninjured) are prone to postural defects such as anterior tilt of the pelvis and bad TrA. Anterior pelvic tilt and bad TrA may be the reason for the earlier activation of the LES and hamstrings muscles relative to the GM in the prone hip extension to stabilize the lumbar spine. These activation patterns were however not influenced by previous hamstring injuries. / Thesis (M.A. (Biokinetics))--North-West University, Potchefstroom Campus, 2011.