Muscle strength has been identified as an important contributor to athletic performance. Little attention however, has been paid to the specific relationship between peak isokinetic muscle strength and sprint starting performance. The aim of this study was to determine the influence of an adapted front knee angle, as determined by isokinetic assessment (the angle of peak torque production), on starting performance. Sixteen track sprinters, of elite-national or competitive-regional standard, were asked to perform eight sprints over 50m using four separate starting techniques. Technique 1 featured the athlete’s usual starting preferences while Techniques 2, 3 and 4 featured a standardised set of starting preferences with experimental modifications of the front knee angle in the “set” position. Isokinetic muscle strength was measured at slow (60°/s) and fast (240°/s) test speeds in order to determine the angle of peak torque production for concentric knee extension of each subject’s lead leg. Using one-way analysis of variance (ANOVA) and Post Hoc analysis (LSD), no significant differences (p>0.05) were observed between the experimental techniques for: block time, force-time measures during block time, sprint times, sprint velocity and acceleratio n measures at intervals up to 50m. Significant differences (p<0.05) were however observed between reaction times for the experimental techniques. Slower reaction times are most likely due to increased upper body pretension, resulting from the increased hip elevation seen for these techniques. The results indicate that increased hip elevation may have delayed the initiation of the relevant motor response required to affect an optimal sprint start. Technique 1 resulted in the shortest reaction times, shortest block times, fastest sprint times and greatest sprint velocities for all four techniques. This result was possibly due to the athlete’s experience with, and repeated use of, this technique. The experimental techniques therefore provided no added advantage over the subject’s preferred starting technique and did not significantly optimise sprint starting performance. The results show that modification of the front knee angle had no significant influence on sprint starting performance and sprint running ve locity or acceleration patterns up to 50m. Using Pearson’s Correlation Coefficient to determine the strongest correlations between isokinetic knee strength and sprint starting performance, analysis revealed that the strongest relationships were found between sprint starting performance expressed as acceleration and isokinetic knee strength expressed as relative peak torque and absolute peak torque. For Technique 1 the strongest correlation was found between acceleration (30m - 40m) and relative peak torque as measured at a test speed of 240°/s (r = 0.62). For the remaining experimental techniques, the strongest correlation was found between acceleration (10m - 20m) and relative peak torque as measured at a test speed of 60°/s (r = 0.53) for Technique 2, between acceleration (40m - 50m) and peak torque measured at a test speed of 60°/s (r = 0.72) for Technique 3, and between acceleration (0m - 5m) and peak torque as measured at a test speed of 240°/s (r = 0.71) for Technique 4. These results suggest that isokinetic muscle strength does not correlate strongly with sprint starting performance and that additional factors, such as neuromuscular organisation and muscle fibre typing, possibly make a greater contribution to optimal sprint starting performance.

A survey research design was employed to explore the relationship between negative addiction to running and running commitment, through the construct of running enjoyment, amongst black, Zulu-speaking runners. Translated versions of the Biographical Information Questionnaire (Leask, 1997), Negative Addiction Scale (Hailey & Bailey, 1982), and Running Enjoyment Questionnaire (Basson & Macpherson, 1998) were administered to an opportunity sample of 79 Zulu-speaking runners, drawn from athletic clubs in the Durban and Pietermaritzburg regions of KwaZulu-Natal. On the basis of their negative addiction scale scores, runners were assigned to either a high (n = 23), moderate (n= 35), or low addiction group (n= 21). Multiple correlation analyses, parametric and nonparametric analysis of variance procedures, factor . analyses, and multiple regression procedures were used to examine the relationship between running dependence, the four sources of running enjoyment, and demographic variables. Significant relationships were found between running dependence and all four sources of running enjoyment. Further, the length of running history , the importance given to running by the participant, perceived fitness levels, and the number of Comrades marathons run were shown to play a role in both running dependence and commitment processes. For Zulu-speaking runners, both intrinsic and achievement running enjoyment sources were found to be more motivating than either extrinsic or nonachievement factors. Extrinsic and achievement factors were found to be more motivating for Zulu-speaking runners compared to Macpherson's (1998) sample of white runners. These results were discussed with reference to the literature on running dependence, running commitment, and cultural influences on motivation. / Thesis (M.Soc.Sc.)-University of Natal, Pietermaritzburg, 2000.

Text in English / Regular exercise has significant physical and psychological health benefits yet, paradoxically, may also have harmful effects. The purpose of this study was to investigate the physical and psychological health risks of distance running, a popular participation sport in South Africa. Structural equation modelling was employed to examine the personality and motivational antecedents of running addiction and its influence, in turn, on self-reported overuse injuries and upper respiratory tract infections in 220 athletic club members. The predictors and physical health effects of customary training load were also assessed. It was found that perfectionistic concerns, Type A behaviour pattern, and task goal orientation had a direct, positive impact on running addiction, which predicted higher running injury scores. In contrast, training workload (Volume × Intensity) was inversely related to injury risk. Neither running addiction nor any training load variables influenced infectious illness susceptibility. The findings of this study indicate that maladaptive perfectionism, Type A behaviour, and achievement goal orientation may be risk factors for running addiction, which may, in turn, contribute to increased injury incidence in South African distance runners. Conversely, heavier training loads may be protective against injury occurrences in this population. The results of this research may help to enhance current understanding of the possible health hazards of distance running. This knowledge may have practical implications for the health and well-being of runners of diverse levels of ability and experience. / Psychology / D.Litt. et Phil. (Psychology)