Browsing by Author "Walker, Claire Nancy"

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    Performance profiles and training loads of optimist sailors
    (Stellenbosch : Stellenbosch University, 2020-02-25) Walker, Claire Nancy; Welman, Karen Estelle; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Sport Science.
    ENGLISH ABSTRACT: Introduction: Despite a growth in competitive sailing, there remains a lack of research available supporting performance analysis and athlete monitoring in sailing. To understand more about the Optimist sailing class, fundamental research into competitive sailing racing and training is needed. Therefore, the overarching aims of this dissertation were to i) determine race performance indicators of high-level Optimist sailing races and ii) to quantify the training loads within different wind intensities of competitive South African Optimist sailors. A secondary aim was to develop an Optimist race performance profile from the IODA Optimist World Championships. Methods: The dissertation was structured in three parts; part 1 involves a scoping review, which identifies the gaps within the current literature, part 2 establishes race performance indicators and uses these to develop performance profiles of high-level Optimist races, while part 3 is considers the training stress imposed on Optimist sailors during training sessions in different wind intensities. Part 2 followed a retrospective descriptive study design, 28 performance indicators were identified through statistical analyses and sailing coaches input. These were used to build a performance profile of 150 Optimist races from the IODA Optimist World Championships (2014-2018). Performance profiles were developed for the qualifying series and each fleet within the final series. Part 3 was an observational study which monitored 12 high-level competitive South African Optimist sailors during 21 on-water sailing training sessions in varying wind intensities (light, medium and strong). The training loads during the training sessions were monitored using heart rate measures, to determine TRIMP (Training Impulse) and the SHRZ (Summated-Heart-Rate-Zone) score, as well as the session-rating of perceived exertion method. A relationship between these measures and energy expenditure was also determined. Results: Results in part 2 showed almost perfect relationships between positions at each mark and the final race outcome for all series (rho=0.93-0.98, p<0.01). A regression analysis coupled with input from coaches determined time difference from race leader at all marks and the finish, as well as difference in velocity made good from race winner in leg 1 for qualifications and finals as the most important performance indicator predictors. The five variables were inversely associated with less or more time leading to a higher or lower rank for final race outcome. For part 3, session-RPE was higher in strong vs. light wind intensities (p=0.02). The TRIMP scores related to energy expenditure during all wind intensities (rho=0.35-0.82). The SHRZ method showed highest total training time in zone 2 (31%; aerobic system) and zone 3 (26%; anaerobic glycolysis system). Conclusion: Coaches can use the race performance indicators and performance profiles to compare race performances and subsequently give more specific feedback to the sailors. Wind intensity applies an external stimulus to the sailor, thereby contributing to internal load on the sailor. Therefore, using the TRIMP measure for internal load is recommended. This dissertation provides a greater understanding of the race performance indicators and training loads of high-level competitive Optimist sailors. The methods identified and utilised in these investigations may prove useful to sailing coaches when analysing their Optimist sailors’ performance during competition and training.
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    Visual search strategies and executive functioning in South African sailors
    (Stellenbosch : Stellenbosch University, 2015-12) Walker, Claire Nancy; Welman, K. E.; Stellenbosch University. Faculty of Education. Dept. of Sport Science.
    ENGLISH ABSTRACT: Background: The ability to locate and identify relevant visual information is essential for skilful behaviour as well as to make performance-related decisions. Decision-making is a subcomponent of executive functioning and involves choosing between two or more possible solutions. Visual search behaviour is a dynamic self-organised perceptual skill that is based on the interaction between constraints imposed by the task, the environment, and the individual characteristics of the athlete (Williams, Ward, Smeeton, & Allen, 2004). Technologies-based feedback such as visual search behaviour may provide relevant information to enhance skill acquisition and sport performance in sailors and, as such, its usefulness to sport scientists, coaches and athletes in training is beneficial. Despite recognizing the importance of the visual search behaviour in sailing little research has been done. To the researcher‟s knowledge, no research has been done on describing South African expert sailors‟ visual search behaviour and executive functions. Aim: This investigation set out to determine the i) visual search strategies in two simulated events and ii) executive functions, as an indicator of decision-making skills, of expert South African sailors. Methods: The investigation followed an observational method descriptive design, where National level South African sailors (n = 61), with an average age of 26 years (SD = 8.88) and professional sailing years of 14 (SD = 7.54), volunteered to participate in the investigation. Visual search strategies of the sailors were determined using a mobile eye tracker during two sailing simulations (computer, n = 24; and radio controlled boats; n = 22). In order to determine the executive functioning (EF) capabilities of the sailors (n = 15), a battery of valid EF tests was compiled comprising the Montreal Cognitive Assessment (MoCA), Wisconsin Card Sorting Test (WCST), Trail Making Test (TMT part A and B), and adapted Stroop Task. Results: All the sailors fixated considerably more on their own boat than any other fixation location; however the top ranking and successful groups performed fewer fixations (d between 0.29 – 0.72) of longer duration (d between 0.05 – 0.59) compared to their counterparts in both simulation studies. The helms performed better on the TMT and Stroop task, while the crews achieved better on the WCST (d = 0.92 – 1.62). Conclusion: By describing sailors‟ visual search strategies, we know what they consider relevant information which contributes to better decision-making and subsequent skilled performance. This may help coaches to enhance sailing performance in less experienced sailors by directing their visual search behaviour to these relevant cues, specifically to look more at their own boat in order to maintain speed and improve performance. The executive functioning skills tell us that successful sailors require the skill to shift their attention and solve problems based on the constantly evolving environment.