Doctoral Degrees (Exercise, Sport and Lifestyle Medicine)


Recent Submissions

Now showing 1 - 5 of 49
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    Transitioning out of the professional player pathway: A grounded theory on the process in South African Men’s tennis
    (Stellenbosch : Stellenbosch University, 2022-04) Skinstad, Deborah Anne; Stellenbosch University. Faculty of Medical and Health Sciences. Dept. of Sport Science.; Grobbelaar, Heinrich W.; Babchuck, Wayne A.
    ENGLISH ABSTRACT: To understand and describe the athlete and their environment(s), researchers, historically, have confined their description of retrospective events, such as sport participation, development, career transitions, etc., to the sport context. This approach has been limiting to researchers’ scope of interpretation (qualitative designs) and / or projection (quantitative designs) of past, present and future (athletic) selves along with transitioning and non-transitioning sporting careers. In other words, the person and athlete are portrayed as mutually exclusive. Considering this, the motivation for the current research project was to understand, reimagine and amplify the human experience of South African men’s tennis players, i.e., the people within their development pathways. To do this, a rigorous constructivist grounded theory (GT) methodology was employed both as the research process and as a strategy to generate theory. This GT study explored South African men’s tennis player transitions within and out of the professional player pathway in the Western Cape Province, South Africa. Four research questions guided the study: 1) what is happening in the development process of a promising competitive junior tennis player in the Western Cape, South Africa?; 2) what is happening [on and off the court] in the development of these players?; 3) what are the transitional processes throughout the junior career pathway and how are these transitions understood?; and 4) how do men’s tennis players [with a promising national junior ranking] transition out of the professional player pathway? To best answer these research questions, a range of tennis participants (n = 34) were selected using purposeful sampling (theoretical sampling) along with maximum variation sampling. Data collection entailed semi-structured interviews augmented with observational work. Theory generation adhered to the procedures for constructivist GT analysis (initial codes, focused codes, categories and categories underpinning theory). As a result, a GT model that explains South African men’s tennis player development and transition processes was developed. This model is underpinned by eight core categories: 1) pursuing a rich man’s sport; 2) transitioning steps; 3) playing inside the lines [small world]; 4) SA Coaching world; 5) life orbiting tennis; 6) college: driving the tennis vehicle; 7) manhood eclipsing childhood; and 8) being a pro at life, not tennis. The practical implications of this model are recognised firstly in its approach to tennis development, i.e., placing greater emphasis on the person and their individual life transitions and how these influence their tennis trajectories. Secondly, this model provides a unique context to the South African tennis player journey. A journey that Tennis South Africa’s (TSA) current long-term player development model (LTPD) generically and collectively attempts to accommodate in a long-term development plan. However, without context and individual experiences of junior to senior transitions, i.e., sport within life domains, the South African tennis player remains (figuratively) confined to a linear, reductionist and prescriptive approach to development and the complexity of their path is grossly misunderstood and misrepresented. A practical recommendation for TSA is to accommodate the doubles format as a mechanism for tennis development and utilize it as a viable professional tennis pathway.
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    The effect of active brain-breaks on in-school physical activity, fundamental movement skills and executive functioning in grade one children
    (2021-03) Van Stryp, Odelia; Africa, Eileen Katherine; Duncan, Michael J.; Faculty of Medicine and Health Sciences. Dept. of Sport Science.
    Thesis (PhD)--Stellenbosch University, 2021.
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    Eye tracking as a diagnostic and monitoring tool for sports-related concussion
    (Stellenbosch : Stellenbosch University, 2020-03) Snegireva, Nadja; Welman, Karen; Derman, Wayne; Patricios, Jon; Stellenbosch University. Faculty of Medicine and Health Sciences. Sport Science.
    ENGLISH SUMMARY : Background: Eye movements have become an easy-to-quantify biomarker for a range of disorders; however, the potential for concussion assessment still needs to be validated. The aim of this prospective cohort study was to establish whether eye tracking technology (ETT) would be a clinically useful, reliable, and valid method to diagnose and monitor youth and adult athletes who have sustained a sports-related concussion (SRC). Methods: To investigate the clinical utility of ETT, an online survey amongst sports medicine clinicians (n = 171) was conducted. For determination of reliability and validity, a testing battery with selected eye tracking metrics (n = 47) was implemented three times (3.0 ± 1.4, 26.1 ± 47.2 and 45.8 ± 19.3 days post-injury) on concussed adult and youth athletes (n = 70) and twice on non-concussed age-and-sex matched athletes (n = 92) with 7.0 ± 3.9 days between sessions. Results: There was insufficient awareness among surveyed clinicians that concussion could lead to abnormal eye movements. Thus, with the exception of abnormal pupil light reflex (examined by 68%), eye movement deficits were inspected by less than half of the respondents (46.3 ± 12%). Only 11% clinicians had actually worked with ETT. Self-paced saccade (SPS) count in the adult group, and the blink duration in the memory-guided saccade (MGS) task, proportion of antisaccade errors, and gain of diagonal smooth pursuit (SP) in the youth group indicated good reliability (ICC > 0.75). Concussed youth athletes had a higher blink duration in the fast MGS task (p = 0.001, η2 = 0.17) and a tendency for higher blink duration in the sinusoidal SP task (p = 0.016, η2 = 0.06) compared to non-concussed youths, as well as to their own subsequent post-concussion values (blink duration decreased over time by 24%, p = 0.35, and 18%, p = 0.48, accordingly). Conclusion. Overall, this study was not able to confirm the findings of previous research on eye tracking metrics for SRC assessment, due to insufficient reliability of described protocols when applied to athletes participating in contact sports. Clinicians can make use of the SPS count as indicator of a concussion among adult athletes, while longer blink durations in MGS or sinusoidal SP tasks might indicate a concussion in youth athletes. Increasing educational opportunities and practical experience of clinicians regarding the use of ETT for SRC assessment to encourage its broader use is advocated, since most deficits in saccades or smooth pursuit are missed during un-instrumented examination. Finally, serial comparison within the same individuals over time is more likely to detect the effect of a SRC than comparison to healthy controls.
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    Behavioural lifestyle factors, physical health-related fitness and cardiometabolic disease risk in women from a low socio-economic urban community in Stellenbosch (Western Cape)
    (Stellenbosch : Stellenbosch University, 2020-03) Dickie, Kasha Elizabeth; Terblanche, Elmarie; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Sport Science.
    ENGLISH ABSTRACT: Non-communicable diseases (NCDs), such as cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM), represent an ever-rising threat to the effective management of national health in South Africa. This especially among low versus high socio-economic urban communities as evidenced almost a decade ago. The results of which are likely to lead to an even higher demand for chronic public health care provision, and thus put immediate economic strain on the imminent South African (SA) National Health Insurance fund soon to be launched in 2026. However, one could argue that the evidence needed to reformulate the existing SA health policies, especially those directed at NCD-risk management and inclusive of modifiable behavioural/lifestyle factors, is either: i) not implemented and no action is taken; or ii) implemented, yet ineffective; or iii) limited and thus unable to detect a clinically significant effect to date. Thus, the primary aim of this study was to characterise behavioural/lifestyle factors namely physical activity (PA) and sedentary behaviour, as well as physical health-related fitness and cardiometabolic disease risk profiles for CVD and T2DM in a group of urban women from an under-resourced Western Cape community. In addition, to determine whether physical inactivity, sedentarism and poor health-related fitness levels are important predictors of obesity and other cardiometabolic disease risk outcomes associated with CVD and T2DM. Fifty-one (N=51) apparently healthy women (42 ± 13 yrs) underwent the following measurements: physical activity (PA) and sedentary time (ST), anthropometric, cardiovascular and physical-health related fitness (cardiorespiratory fitness [CRF] and muscular strength). Results from the study showed that less than a third of the women met the World Health Organisation (WHO) Global Health Recommendations for moderate to vigorous-intensity PA (MVPA) using accelerometry. Although overweight, women who accumulated ≥ 30-min of MVPA per day presented with more favourable body composition and regional body fat measures, compared to those who did not. In addition, women who were sufficiently active presented with reduced cardiometabolic disease risk. Although the associations between PA (intensities and volume) and CRF were not statistically significant, all were positive and showed clinically important associations. Independent of steps/day, higher CRF was associated with women who were younger and with reduced measures of total and central adiposity (p < 0.001). Whereas higher physical health-related fitness as opposed to ST and MVPA, was independently associated with reduced cardiometabolic risk but potentially mediated by adiposity. In an attempt to combat cardiometabolic disease risk for CVD and T2DM among low socio-economic community urban-dwelling women, public health interventions should target domains in which time is already spent physically active. Such as walking briskly for travel- and/or occupational-related activities, while also aiming to increase public awareness of the health-enhancing benefits associated with meeting MVPA recommendations. Furthermore, intervention strategies also aimed at reducing cardiometabolic risk should target physical health-related fitness while also reducing ST especially among women who are already sarcopenic. Although the success of which will only be met once we understand the community’s specific barriers to PA and healthy dietary habits.
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    Coordination of place kicking in Rugby Union
    (Stellenbosch : Stellenbosch University, 2020-03) Mathewson, Elizabeth; Venter, Ranel; Cockcroft, John; Preatoni, Ezio; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Sport Science.
    ENGLISH ABSTRACT: Place kicking is a crucial skill in rugby as more than 40 per cent of the points scored in professional rugby matches are achieved by means of place kicks. Research in rugby kicking has mainly focussed on isolated segment position or movement, with limited literature on segments moving relative to each other. The aim of this study was to identify characteristics of place kicking technique from a coordination and coordination variability perspective. Ten male kickers performed five trials from three different distances (40 m, 32 m, and 22 m) in a range that proficient kickers should convert successfully 80 per cent of the time. An optoelectronic motion capture system consisting of ten cameras were used for capturing total body kinematic data. Data collection took place outdoor, on a rugby field. Data reductions included normalisation of kicking phases, extracting discrete kinematic variables, joint angles, joint and segment coordination patterns (hip-knee, knee-ankle, and pelvis-torso), and coordination variability measures. ANOVA comparisons were made on discrete data, while statistical parametric mapping repeated measures ANOVA analysis was used for continuous variables to determine differences groups differences. Coordination patterns were determined by means of vector coding technique. A bivariate method of calculating the area of the ellipse at each time point was used to determine the coordination variability. A hierarchal cluster analysis was performed on sagittal plane angles at kicking events to determine different technique profiles. Parameters such as greater hip extension and external rotation during the backswing (p=0.001, p=0.015) as well as increased pelvic external rotation (p=0.015) in the 40 m kicks compared to the 22 m and 32 m kicks are related to the formation of the tension arc in attempt to increase foot speed by means of the stretch-shortening cycle. The 40 m kicks had increase knee flexion (p<0.001), increasing the pre-stretch in the thigh muscles. Both factors allow greater force to be applied to kicking foot over greater distance during forward swing. During the forward swing a period of in-phase is reported as both the hip and the knee were flexing, creating a whip-like action. During the backswing the pelvis and thorax worked together to create a tension arc, while during the forward swing, the anti-phase with pelvis dominancy was seen. The pelvis was main mover for tension arc release, while the thorax stays more stable. Even though absolute changes in joint angles were seen, no changes were reported for the coordination patterns when kicking at different distances (22 m, 32 m, 40 m). An investigation into coordination variability found no differences between groups, indicating no change in movement strategy when kicking at different intensities. The cluster analysis revealed three clusters of sagittal plane kinematics describing a knee-dominant, hip-dominant as well as a combination technique. Stemming from the above, place kick training can benefit by coaching cues and drills focussing attention on tension arc formation, and the rhythm of movements. These results impart the knowledge that different distances require similar movement coordination strategies.