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- ItemAn exploratory study into select technical key performance Indicators and estimated transfer fees in the 2nd division of the German Bundesliga(Stellenbosch : Stellenbosch University, 2023-03) Horn, Carsten; Jacobs, Shaundre; Lamberts, Robert; Meyer, Tim; Stellenbosch University. Faculty of Medical and Health Sciences. Dept. of Exercise, Sport and Lifestyle Medication.ENGLISH ABSTRACT: In light of the escalating transfer fees in professional football, an inflated market and clubs having to adjust their budgets due to the ongoing restrictions resulting from the COVID-19 pandemic, accurate financial management of sporting organisations is required. This especially applies to football clubs playing outside Europe’s big five leagues, as well as those in the lower divisions of professional football. The overall aim of this MSc project was to shed light on a second division league which has previously received less attention than first divisions. More specifically, the current study assessed how a player’s performance in the season immediately before his transfer influenced his transfer fee. This was done through the lens of the Moneyball approach, which states that specific characteristics and/or skills are being undervalued by the labour market. As transfer fees can rise to millions of euros paired with clubs being under financial pressure, quantitative rather than intuitive decision-making is required. This study assessed the relationship between select technical key performance indicators (KPIs) and their relationship to estimated transfer fees in the 2nd division of the German Bundesliga, using publicly available data. The selected KPIs for defenders, midfielders and strikers were tackles and interceptions, tackles and assists, and goals and assists, respectively. A statistician was consulted for a sample size calculation and revealed a minimum of 12 participants per position (defender, midfielder, striker) were required. Statistical analysis was performed with the use of GraphPad Prism (Version 9.3.1, GraphPad Software, LLC, USA). Prior to statistical analyses, normality tests were conducted using the Kolmogorov-Smirnoff and Shapiro-Wilk tests. A Kruskal Wallis test was employed to assess the differences between the various player positions. Where significant differences were found, a Dunn’s post hoc test was performed. Associations between variables were tested for by means of Spearman correlations. All data are presented as median, and significance was set at p < 0.05. Analyses revealed that interceptions have no association with the transfer fees of defenders (rs=0.06, p=0.76). Tackles were found to be negatively associated with the transfer fees of defenders (rs=-0.41, p=0.03), while no association was found between tackles and the transfer fees of midfielders (rs= 0.17, p=0.24). Midfielders’ transfer fees displayed a positive association with assists (rs=0.44, p=0.00), while no association was found between the transfer fees of strikers and assists (rs=0.15, p=0.34). In addition, strikers’ transfer fees also did not display any association with goals (rs=0.22, p=0.16). As interceptions were found to be negatively associated with the transfer fees of defenders, it is possible that interceptions are being undervalued. However, as more successful teams tend to dominate ball possession, it is likely that players from less successful teams have more opportunity to intercept a ball, and, as less success reduces transfer fees, this would explain this association. Tackles, on the other hand, may display a negative association with transfer fees of defenders as tackles may be a sign of an error prone and/or tactically inapt player, as tackles may be used to recover from tactical and/or technical errors. Assists’ positive association with the transfer fees of midfielders is explained by the increased chances of success with an increased number of assists. Consequently, one would also expect such an association for strikers. However, previous studies have found that the transfer fees of strikers in higher divisions are associated with a publicity premium. Consequently, it is hypothesised, that due to the reduced media attention in the lower leagues, this publicity premium only exists to a much smaller degree and thereby reduces the extend to which assists influence strikers’ transfer fees. The same reasoning applies to how goals influence a strikers transfer fees, as goals also did not show an association with the transfer fees of strikers. As the current study did not control for players moving up or down a division, results need to be interpreted with caution. The findings support previous research with tackles displaying a negative association with the transfer fees of defenders and assists displaying a positive association with the transfer fees of midfielders. However, as opposed to most other leagues, goals are not the determining factor for the transfer fees of strikers transferring to or within the 2nd division of the Bundesliga. This implies that other characteristics and/or KPIs may be at play that impact the transfer fees of strikers significantly more than the selected ones, and future research is tasked with identifying these.
- ItemThe change in postural control in highly trained trail runners following a short, competitive, off-road time trial(Stellenbosch : Stellenbosch University, 2023-03 ) Price, Nicholas; De Waal, Simon; Arnold, Sarah; Stellenbosch University. Faculty of Medical and Health Sciences. Dept. of Exercise, Sport and Lifestyle Medication.ENGLISH ABSTRACT: Research on acute effects of trail running (TR) induced fatigue and postural control (PC) in highly trained trail runners is scarce. Therefore, the aim of this study was to measure the change in select postural control variables following a short, real-world, trail run time trail (26km; +900m) in a sample of highly trained trail runners. Thirteen (N=13) male, highly trained trail runners (age: 30.00 5.58 years old; weekly running: 65.00 6.45 kilometres) participated in this study. Participants completed five postural control system (PCS) tests before and after a short, real-world, TR time trial (26km +900m ascent). Balance tests included a Modified Clinical Test of Sensory Interaction of Balance (MCTSIB), Single Leg Modified Clinical Test of Sensory Interaction of Balance (SLMCTSIB) and a Star Excursion Balance Test (SEBT). Postural sway and sway frequencies were measured via a Gyko Inertial Measurement Unit (Microgate, Italy) during four different stance conditions; firm surface with eyes open (FO), firm surface with eyes closed (FC), compliant surface with eyes open (CO), and compliant surface with eyes closed (CC). Jump tests included a Countermovement Jump Test (CMJ) and Single-Leg Countermovement Jump test (SLCMJ). Jump height and flight time were measured using OptoJump (Microgate, Italy) and two Logitech web cameras (30 fps). Tests for normality were performed using the Shapiro-Wilk test. A combination of paired samples t-tests and Wilcoxon signed-rank tests were used to identify differences in mean scoresbefore and after the time trial (significance flagged as p<0.05). Statistically significant increases (p<0.05) in mediolateral sway were observed in stance conditions FO, FC and CC while anteroposterior sway showed significant increases (p<0.05) for stance conditions FO, and CO during the MCTSIB. A statistically significant increase (p<0.05) in mediolateral sway was observed in the SLMCTSIB for the FO stance condition. A significant decrease in reach length was observed during the SEBT in the anterior movement only (p<0.05) and only on the right foot. No statistically significant changes (p>0.05) were observed for maximal and mean jump height and time for CMJ. However, statistically significant decrements (p<0.05) were found for all variables during the SLCMJ test. This study's key finding was that significant changes in select PC variables were observed following a short TR time trial. In conclusion, it appears general TR-induced fatigue negatively impacts PC regulation following a 26km (+900m) trail run time trial. However, a combination of training status, task experience and compensatory strategies appear to limit the magnitude that general neuromuscular fatigue can have on PC regulation. A greater contribution from cognitive resources such as increased awareness and attentional demand could improve sensory detection capabilities needed to identify optimal balance demands via proprioceptive sensory sources. Future studies should measure trail runners of varying training statuses to better understand this phenomenon.
- ItemComparison of kinematic, and gait-spatio-temporal factors in ultra-trail runners with zero-drop versus regular-drop shoes(2023-03 ) Henning, Robert; De Waal, Simon Jake; Lamberts, Robert P.; Venter, Ranel; Stellenbosch University. Faculty of Medical Health Sciences. Dept. of Exercise, Sport and Lifestyle Medication.ENGLISH ABSTRACT: Few studies have explored zero-drop (ZD) shoes, with no studies investigating these shoes in trail- and ultra-trail running. The aim of this study was to investigate the difference in relative oxygen uptake related and gait-spatiotemporal variables in a homogenous group of ultra-trail runners wearing ZD shoes versus those wearing regular-drop (RD) shoes. Twenty-nine recreational ultra-trail runners participated in this study: 15 habitually RD runners (age 36 ± 8.9 years; mass 70.48 ± 11.85 kg; height 174.14 ± 7.85 cm), and 14 habitually ZD runners (age 32 ± 9.31 years; mass 75.53 ± 32.99 kg; height 174.5 ± 8.23 cm). Participants ran a VO2 max protocol to determine maximal fitness, as well as to determine treadmill speed at VO2 max (vVO2 max). Thereafter, participants ran a protocol at 70% and 85% of their vVO2 max to determine relative oxygen uptake, gait spatio-temporal variables, ankle kinematics at ground contact and foot strike pattern. All physiological measures were determined by breath-by-breath analysis (COSMED, Rome, Italy), and gait-spatiotemporal measurements were done via the Optogait system (Microgate, Bolzano, Italy) and video interpretation (Kinovea, Belgium). ZD runners displayed a significantly greater VO2 max and VO2 at anaerobic threshold (AT) (p < 0.05). There was no significant difference between ZD and RD runners for all the gait-spatiotemporal variables at both 70% and 85% vVO2 max. However, a large effect size for ankle angle was observed for both 70% (d=1.24) and 85% (d=1.11) speeds, indicating that ZD runners (86.54 ± 3.12o) were more dorsiflexed than RD runners (85.81 ± 4.15o) at ground contact. Furthermore, RD runners increased stride length significantly between 70% (202.46 ± 35.14 cm) and 85% (213.36 ± 41.83cm) vVO2 max, while ZD increased cadence significantly (96.83 ± 12.59 to 106.65 ± 20.88 steps.min). The first null hypothesis was rejected, as the VO2 max in the ZD group was significantly higher than the RD group. The second null hypothesis was accepted, as there were no significant differences between the ZD and RD groups for physiological fitness variables at both 70% and 85% vVO2 max. The third null hypothesis was partially rejected, as no significant difference in any of the gait-spatiotemporal variables between ZD and RD ultra-trail runners were observed, barring the distribution in foot strike pattern at 70% vVO2 max, where the ZD (n = 9) runners displayed a significantly higher distribution of MF/FF striking pattern compared to the RD (n = 1) runners. No studies have shown differences in physiological fitness and gait-spatiotemporal variables between ZD and RD ultra-trail runners. These results help runners understand how shoe drop-height affects relative oxygen uptake related variables to make informed choices in shoe selection, namely that runners wearing ZD shoes tend to strike the ground with a MF/FF pattern, as well as to expand the current body of literature regarding trail running. Further studies could investigate the effects of ZD shoes on physiological and gait-spatiotemporal variables in a much larger sample, which should provide a more accurate description of these effects.
- ItemExploring the transition of track and field athletes from Grade 12 to first year university(Stellenbosch : Stellenbosch University, 2023-03 ) Grobbelaar, Heinrich Wilhelm; Stellenbosch University. Faculty of Medical and Health Sciences. Dept. of Exercise, Sport and Lifestyle Medication.ENGLISH ABSTRACT: Many talented high school sport performers continue their studies at tertiary institutions; therefore, it is important to create awareness of the challenges faced by these athletes during the transition from school to university. The current study explored the transitional experiences, including the barriers and facilitators experienced by student track and field athletes during their transition from Grade 12 to first year university at Stellenbosch University. Semi-structured interviews were conducted with eight first-year student-athletes (three men/ five women), respectively participating in track, field, and combined events, who made the transition from high school (Grade 12 in 2019) directly into their first year at Stellenbosch University the following year (2020). This allowed for retrospective accounts of their high school experiences, as well as concurrent feedback about their experiences during the first few months of their first year at university. The interview script guided the participants to discuss their transition, covering multiple domains of their lives (i.e., athletic, psychological, psychosocial, academic/vocational, financial, and legal). Student-athletes are simultaneously transitioning from junior-to-senior level competition and from high school to tertiary education, negotiating the change into adulthood, building new and mature relationships, and becoming emotionally independent. They are reliant on financial support from family, universities, or the sport’s governing body. The study was exploratory and utilized a descriptive phenomenological qualitative research design. The Developmental Model on Transitions faced by athletes, as well as the Holistic Athletics Career Model became the lens through which the research questions were framed, and the findings and discussions were presented. The Covid-19 pandemic broke out just before these interviews were conducted. The pandemic caused unforeseen disruptions on a global scale and led to drastic changes to the 2020 academic and sporting year. The student-athletes underwent concurrent transitional experiences across multiple domains. The qualitative findings revealed seven overarching themes, namely facilitators, transitional experiences, and barriers within the academic, athletic, psychosocial, psychological, financial, and legal domains. The Covid-19 pandemic as the second transition, and support mechanisms available to student-athletes were also discussed. Each of the themes consisted of numerous subthemes and categories of codes. The domains cannot be viewed as separate entities. They must be considered as cross-domain transitional experiences and how their interaction influences the life of student-athletes. The labels of experiences either being barriers and/or facilitators depend on the individual perceptions held by the student-athletes and how they were able to negotiate the situation at hand. The student-athlete’s perceived identity depended on their motivation towards their academic and athletic pursuits. Their identities fluctuated throughout the academic year depending on the priority of the task at the specific timepoint. The Covid-19 pandemic caused a shift toward a stronger student identity because of the cancellation of sport events, the inability to train outside during the national lockdown and a subsequent increase in time to focus on studies. The support structures and systems provided by Maties Sport, if used optimally, would facilitate the student-athlete’s athletic performance, and enhance their personal growth and development and success across multiple life domains.
- ItemThe recovery-stress states of netball players over congested university-level tournaments played in Covid-19 bubbles(Stellenbosch : Stellenbosch University, 2023-03) Heynes, Michaela Lee; Venter, Ranel; Jakowski, Sarah; Stellenbosch University. Faculty of Medical and Health Sciences. Dept. of Exercise, Sport and Lifestyle Medication.ENGLISH ABSTRACT: Due to the global pandemic, the acute recovery-stress states of athletes in Covid-19 bubbles are becoming a well-researched topic. The aim of this study was therefore to monitor the acute recovery-stress states of university-level netball players in two tournaments (10-days and five-days) played in a Covid-19 bubble using the Acute Recovery and Stress Scale (ARSS) and the Recovery-Stress Questionnaire for Athletes (RESTQ-76 Sport). All participants were university-level netball players between the ages of 18 and 25, who are in command of English, Afrikaans or IsiXhosa. The Varsity Netball Tournament (T1) and University Sport of South Africa (USSA) Netball tournament (T2) were held over 10 days and five days, respectively. Throughout both tournaments both the ARSS and RESTQ-76 Sport questionnaires were completed. The ARSS was completed twice daily before and after each match played in the tournament. The RESTQ-76 Sport was completed twice throughout the duration of the tournament with the first being completed one day before the tournament and the second being completed within three hours of the last match played on the final match day. The number of athletes who completed the ARSS in T1 was 18 participants. Overall, 58% of the athletes were included in the study with complete datasets. The results for the ARSS for all of the Recovery subscales, including Physical Performance Capability (PPC), Mental Performance Capability (MPC, Emotional Balance (EB) and overall Recovery (OR) showed statistically significant differences (p < 0.01) between the beginning and the end of the tournament with recovery being higher at the start of the tournament compared to after the tournament. Additionally, the stress subscales including Muscular Stress (MS), Lack of Activation (LA), Negative Emotional State (NES) and Overall Stress (OS) indicated statistically significant differences (p < 0.01) with higher values being seen after the tournament than before the tournament. The number of athletes included in the study for T1 with regards to the RESTQ-76 Sport and once the inclusion criteria was considered was 18 participants between the ages 19 and 24 years old. The performance level within this tournament was distributed across university (17.9%), provincial (60.7%) and international (21.4%) levels. Overall, 36 out of 66 (55%) were eligible to be included in the study. The only statistically significant difference for the duration of T1 was Social Recovery (p < 0.01) whereby scores increased pre to post tournament. The number of athletes who completed the ARSS in T2 was 23 participants. Overall, 23 out of 35 (66%) of the athletes presented complete datasets to be included in the study. All values for the recovery and stress dimensions showed statistically significant differences (p < 0.01) with the recovery scores decreasing over the duration of the tournament and the stress scores increasing pre to post tournament. The number of athletes included in the study for T2 regarding the RESTQ-76 Sport and once the inclusion criteria was considered was 41 participants between the ages of 18 and 25 years old. This tournament consisted of players who were distributed across university (29.8%), provincial (27.7%) and national (31.9%) levels. Overall, 87% of the players who responded and completed the required number of datasets to be included in the study. The subscales showing statistically significant differences over the duration of the T1 were General Well- Being (p < 0.01), Success (p < 0.01), Conflict/ Pressure (p < 0.01) and General Stress (p < 0.04) with General Well-Being and Success showing an increase in recovery over the duration of the tournament and Conflict/ Pressure and General Stress showing a decline in score over the duration of the tournament. Future studies could explore the differences in the recovery-stress states of full-time and substitute netball players under congested tournament or environmental conditions. More should pertain to the differences in recovery-stress states of the varying experience levels of athletes. Furthermore, future studies can include the addition of a stress assessment to the recovery-stress assessments used for this study for the duration of the tournament. Lastly, research can focus on the validation of recovery-stress assessments within a South African context.