Although traditional prevention and management strategies for hamstring injuries have focussed on optimising muscle strength, flexibility and endurance, incidence and/or recurrence rates of these injuries remains high. A theoretical framework was developed considering additional factors that increase the stabilising demand of the hamstrings. These factors included loss of related stability at the knee and lumbopelvic regions and extrinsic factors during functional and sporting activities. The aims of this research were to determine whether electromyographic (EMG) derived hamstrings, quadriceps and gluteal muscle activation patterns as well as isokinetic torque generation patterns could differentiate athletes who had incurred a hamstring injury from uninjured control athletes. It was hypothesised that the EMG activity of the injured participants would be decreased compared to uninjured control participants during maximal activities, but increased during weight bearing activities. The research included the identification of laboratory-based tasks relevant to the function of the hamstring muscles; test-retest reliability of EMG variables recorded during these tasks; and a comparative cross-sectional study of hamstring-injured (hamstring group, HG) and control athletes (control group, CG). Electromyographic activation patterns were determined during assessment of concentric and eccentric isokinetic strength of the thigh muscles, during transition from double- to single-leg stance, and forward lunging. Isokinetic and EMG onset and amplitude variables were compared both within- and between-groups. Despite no significant differences for peak torque, the HG injured limb generated lower average eccentric flexor torque towards the outer range of motion in comparison to the HG uninjured limb (P = 0.034) and the CG bilateral average (P = 0.025). Furthermore, the EMG root mean square (RMS) decrease from the start to the end range of the eccentric flexor contraction was greater for the HG injured limb hamstrings than the CG bilateral average. During the transition from double- to single-leg stance, the EMG onsets of the HG injured limb (biceps femoris [BF] P < 0.001, medial hamstrings [MH] P = 0.001), and the HG uninjured limb (BF P = 0.023, MH P = 0.011) were earlier in comparison to the CG bilateral average. The transition normalised EMG RMS was significantly higher for the HG injured side BF (P = 0.032), MH (P = 0.039) and vastus lateralis (VL, P = 0.037) in comparison to the CG bilateral average. During the forward lunge, no significant differences were observed within- and between-groups for the normalised EMG amplitude prior to and following initial foot contact. These results suggest that during maximal isokinetic eccentric flexor contractions, the average torque and EMG activity is decreased towards the lengthened position of the hamstring-injured limb. This may be due to structural changes or neurophysiological inhibitory mechanisms. During the static weight bearing task an earlier onset of the HG hamstring muscles was evident in comparison to controls. The hamstrings and the VL of the injured limbs were activated at greater normalised amplitude. The increased muscle activation in the hamstring-injured limbs during the support phase may indicate a greater demand towards stability of the kinetic chain or changes in proprioceptive function. Future research should consider the mechanisms and clinical implications underlying a loss of eccentric flexor torque towards the outer range of contraction, and investigate why increased activation of thigh muscles occurs during the static weight bearing task in hamstring-injured athletes.

M.Tech. / The aim of this research study was to determine the most effective way of treating sacroiliac joint dysfunction with associated gluteus medius trigger points, using adjusting of the sacroiliac joint or needling of the gluteus medius muscle or both. The participants were recruited randomly and placed in 3 different groups. Participants in group 1 were treated with an adjustment of the sacroiliac joint, as well as needling of the most prominent gluteus medius trigger point. Participants in group 2 were adjusted only and participants in group 3 were needled only. The treatment of the participants took place at the University of Johannesburg’s chiropractic day clinic. The objective data was acquired using a Digital Inclinometer to measure the ranges of motion at the spinal levels of the 5th lumbar vertebra and the first sacral vertebra (L5/ S1). An Algometer was used to measure the amount of pressure required to evoke pain, within the most prominent trigger point being treated. The subjective data was acquired using the Oswestry Pain and Disability Questionnaire, as well as the Numerical Pain Rating Scale. The results of the trial were of no statistical significance, but clinical improvement in both objective and subjective data was found. Group 2’s mean value percentage improvement was the greatest, when looking at range of motion. Group 1’s mean value percentage improvement was the greatest, with the Algometer and the subjective readings. The outcome of this study was that overall all three treatment protocols had a positive effect on the participants. Group 1 and group 2 had a slightly greater overall improvement. Thus it is suggested that when treating sacroiliac joint dysfunction with associated gluteus medius trigger points, the doctor can use an adjustment or adjusting with needling, both are effective. It is important to take the patients preference into account in order to make them feel at ease with the treatment they are receiving.