Department of Exercise, Sport and Lifestyle Medicine

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Browsing Department of Exercise, Sport and Lifestyle Medicine by browse.metadata.advisor "Bouic, Patrick J. D."

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    Endocrine response to small-sided games and match play in elite u19 South African soccer players
    (Stellenbosch : Stellenbosch University, 2017-03) De Waal, Simon Jake; Venter, Ranel; Bouic, Patrick J. D.; Stellenbosch University. Faculty of Education. Dept. of Sport Science
    ENGLISH ABSTRACT : Purpose Small-sided games (SSGs) are used worldwide with the intention of stimulating significant physiological adaptations in players that are specific to match demands. The external load of SSGs and matches in soccer is well documented, but far fewer studies are aimed at measuring the internal response to these activities. The endocrine response to SSGs and matches in soccer is less well known although the respective hormones; cortisol, testosterone and dehydroepiandrosterone (DHEA) provide a valid measure of training load and total stress in several other methods of exercise. This study aimed to measure the internal endocrine response to training and matches and identify any variations between playing position and whether SSGs were preparing the players for match demands. Methods 22 elite male soccer players (16 – 23 years old), divided into positional subcategories of goalkeeper (n = 4), defender (n = 7), midfielder (n = 5), and attacker (n = 6) provided saliva samples; at rest, in response to 11v11, 7v7, and 4v4 SSGs, friendly and competitive matches, and a yoyo level two intermittent endurance test (YoyoII). Cortisol, testosterone, T:C, and DHEA concentrations were analysed using an ultra-high-performance liquid chromatographic method with mass spectrometric detection in response to small-sided games and matches. Statistically, hormones were analysed through one and two way ANOVA’s to compare different time points and positions. Results Cortisol (ng/ml) increased significantly (0,70 ± 0,40 SD to 3,94 ± 3,26 SD) from resting values in response to competitive match-play immediately after the match amongst the squad as a whole (p < 0.01). Cortisol increased significantly during all small-sided games (p < 0.05). T:C ratio (ng/ml) significantly decreased (0,89 ± 1,93 to 0,19 ± 0,28) from resting values in response to competitive match-play (p < 0.01) while testosterone showed no significant changes in response to match-play. No significant differences were found between the endocrine response of all positional subgroups over any SSGs or matches. DHEA presented no significant changes between all time-points and T:C ratio remained constant throughout the eight month testing period. SSGs presented no significant differences in endocrine response based on the number of players on the field. Yoyo2 produced comparable endocrine response to those at rest amongst the squad as a whole. Conclusions SSGs do not prepare soccer players for matches because they do not stimulate the same stress response than matches. The stress response is likely correlated to more than just physical exertion, therefore cortisol could be used as an indicator of total stress including anxiety and emotional stress as opposed to physical stress alone. Different positions do not result in different internal responses to training and matches regardless of differing external positional requirements. SSGs as a method of training seems to present no risk of overtraining. Future studies should seek to correlate cortisol, testosterone and DHEA with other, more affordable measures of internal training load or be used in conjunction with external training load measures. Future studies should perform repeated testing on smaller study samples due to the high intra-individual variability of endocrine response betweentime-points.
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    Workloads of semi-professional cricket players, participating in three different match formats over a competitive season
    (Stellenbosch : Stellenbosch University, 2016-12) Nell, Bradley John; Venter, Ranel; Bouic, Patrick J. D.; Stellenbosch University. Faculty of Education. Dept. of Sport Science
    ENGLISH ABSTRACT : Although cricket is one of the oldest organised sports, there is a relative lack of scientific research of the sport and it’s players. There are, for example, very few studies of the physiological demands of cricket or of the specific physiological, biochemical or anthropometric attributes of top-class cricketers. International cricket is undergoing a phase of rapid changes as it competes to attract a more global audience. As a result, modern international cricketers are now exposed to greater physical and psychological demands. These expanded demands include more five- and one- day matches per season, a longer season without a real winter break, more frequent tours and less time spent at home. (Noakes & Durandt., 2000). The introduction of T20 cricket has been the latest addition to the formats. The shortened format was initially introduced to bolster crowds for the domestic game, and was not intended to be played internationally, but the first T20 International took place on 17 February 2005. Australia defeated New Zealand, and the first tournament was played two years later, with the introduction of the ICC World T20. There remain limits on how many T20 Internationals a team can play each year, in order to protect Test cricket and One Day Internationals. (Twenty20 International, 2016). The demands on players has steadily increased over the years. The introduction of T20 tournaments such as the Indian- and Caribbean- Premier League, Big Bash and Pakistan Super League, has resulted in some players having very busy schedules. Cricket today demands greater physical effort from players at vital stages during their careers. It is the duty of the players, coaches, medical support team, and administrators to put in place measures to ensure that unnecessary injuries do not prevent players from reaching their full potential (Stretch, R.A., 2003). First utilized for athlete tracking in 1997, GPS technology is now increasingly used in team sport settings to provide sports scientists, coaches and trainers with comprehensive and real-time analysis of on-field player performance during competition or training (Cummins et al., 2013). There are a limited amount of studies observing training and match loads in cricket, especially over an entire season. Most studies deal with injury prevalence and loads over a short period of time. A few studies have compared the match loads of fast bowlers and non-fast bowlers, but few studies have included the other disciplines such as batsmen, spin bowlers, all-rounders and wicket keepers. This study seeks to address unanswered questions in terms of differences between formats and player disciplines over an entire season. The TDS scores decreased steadily throughout the season. Load that players experience can be physical as well as emotional/psychological. The TDS scores in this study mirrored the results of the matches.