The purpose of this study was to examine the acute effects of the power snatch exercise at specific intensities on vertical jump performance. 10 weightlifters attended two sessions: a power snatch (PS) and control (CON) condition. Each session was separated with at least 48 hours in between. This study used a 1-group experimental design. During the PS condition, participants performed the power snatch exercise at increasing intensities (40% 1 repetition max [RM], 60% 1RM, and 80% 1RM) after a dynamic warm up. Vertical jump performance was measured prior to the warm up, and after each power snatch exercise in the PS condition. During the CON condition, vertical jump performance was measured at the same times, with the participants substituting the power snatch exercise for a seated position. The results showed no significance ( p > 0.05) in vertical jump performance during each condition, with a trend being seen during the gradual increase in intensities. These results suggest further research is needed utilizing a larger sample size to show significance.

Caffeine is the most widely consumed socially acceptable drug in the world and is commonly used for its ergogenic properties with demonstrated performance enhancing effects in endurance, power and strength based activities. Despite a wealth of evidence concluding a caffeine induced performance benefit, the direct effects of the drug on peripheral physiological processes have not been fully examined. Early works showed high dose caffeine has direct force potentiating effect on skeletal muscle, a notion that has only recently been confirmed by James et al. (2005) to also occur at a maximal human physiological concentration (70µM). The present research, using mouse muscle as a model for mammalian muscle in general, provides an in-depth assessment of the direct effect of physiological concentrations of caffeine on isolated skeletal muscle performance. This research uniquely: quantifies the dose response relationship; assesses the effects of caffeine on maximal and sub maximal muscle power output and fatigue; looks at the relationship between muscles with different fiber type compositions. As high concentrations of caffeine and taurine are a constituent of many energy drinks, the suggested interaction of these ingredients to further potentiate muscle mechanical performance was also assessed. The study further examines how mammalian muscle mechanical properties change over an age range of development to aged, and how this differs between muscles with predominantly different anatomical locations and functions. In light of this the age related direct effect of physiological concentrations of caffeine was assessed in order to examine whether the ergogenic benefit changed with age. The present results demonstrate a direct muscle performance enhancing effect of physiological concentrations of caffeine that is likely to promote greater benefit on long duration endurance based activities. Furthermore, the present study demonstrates that there is no direct effect of physiological concentrations of taurine and no further performance enhancing benefit when combined with caffeine. Finally this research uniquely highlights the muscle specific age related changes in mechanical performance and further indicates that the direct effect of caffeine changes with age.

Professional sport and its legislation I choose this topic for its currency and for in my opinion ignored need of solving problems mentioned in the thesis. In scope of this thesis I tried not only to assess legal status of individual and collective professional sportsmen or in other words of performance of their activity on professional level, but I also tried to solve chosen problematic points resulting from the confrontation of professional sport activity and strict provisions of Czech law (in particular Labour Code), by which the performance of sport activity and related legal relations are governed. Thesis is systematically divided into four chapters besides the introduction and conclusion which contains other subchapters. These subchapters specify topics contained in chapters. First chapter is the introduction to the topic devoted to reciprocal relation of sport and law. In this chapter I deal with the term "sport" and its possible definition from the law point of view and its basic organization and division in general. There is also one subchapter dedicated to act on support of sport. In second chapter I deal with the performance of sport activity by individual professional sportsman in detail and with two possible options of its inclusion into law. New Civil Code is also reflected here....

- 6 - Abstract Title: Comparison of performance tests results determined during kayak spiroergometry with achieved kayak paddling performance. Objectives: The aim of the study was to determine relationships between functional parameters values found during kayak spiroergometry and sport performance at 1000 meters distance, and how are these relationships going to change based on training period. Methods: To determine statistical dependence between sport performance at 1000 meters distance and choosen factors of sport performance, the correlation research was used - as a variable-dependent value the final result of sport performance at 1000 meters distance was used, as a variable-independent amounts functional parameters values found during kayak spiroergometry were used. To discover the statistical dependence methods of Pearson's correlation coefficient and regression analysis were used. Results: General level of kayak-athletes from testing file indicated by functional parameters values and demonstrated by kayak spiroergometry performance depends on kayak- athlete's level of sport performance at 1000 meters distance in prepared-training period only, when importance for general condition is emphasized. We did not discover the same phenomenon based on pre-racing period testing results. Sport performance at...

O objetivo da presente dissertação foi verificar o efeito da participação de jovens jogadores de futebol em competições com calendário congestionado (CC) nas medidas de desempenho físico, e comparar as acelerações (ACC), as desacelerações (DEC), a potência metabólica média (PM), distância total percorrida (DT) e distância percorrida em alta velocidade (DAV) em 24 jogadores de futebol juvenil (sub-15, n = 11 e sub-17, n = 13) expostos a campeonatos de CC e períodos regulares de calendário não congestionados (calendário regular; CR); como critério de retenção dos dados dos jogadores, adotou-se, a participação mínima de 75% do tempo total de jogo em cada partida. Adicionalmente as medidas de desempenho físico foram normalizadas pelo tempo de participação em minutos na partida. Foram analisados 10 jogos internacionais no formato de CC (5 para cada categoria), realizados durante 3 dias sucessivos, incluindo 2 dias com 2 jogos consecutivos jogados com intervalo de 4-5 horas; para estabelecer uma condição \"controle\", 10 jogos de CR, de cada categoria, foram analisados; os jogos de CR foram realizados com um intevalo de pelo menos 7 dias. Os jogadores usavam uma unidade GPS de 15 Hz com um acelerômetro triaxial de 100 Hz alocada em uma veste especial. Uma diferença classificada como digna de consideração (tamanho do efeito; TE> 0,20) entre CC e CR, foi observada para os parâmetros de desempenho físico ACC, DEC e PM, para sub-15 e sub-17, com valores mais elevados no CC. Enquanto que DT e DAV apresentaram valores superiores para CR, apenas para o sub-15. Contrariamente à hipótese levantada, os parâmetros de desempenho físico mostram que os jogadores juvenis de elite avaliados elevaram a intensidade do jogo quando participaram de torneio CC. Uma diminuição em ACC e DEC, do 1° tempo para o 2° tempo foi observada (sub-15 e sub-17) nos diferentes formatos de campeonato. No entanto, observou-se um aumento da PM do 1° tempo para o 2° tempo; com um aumento muito grande para ambas as categorias durante a CR; para o CC, a PM aumentou (1ª para a 2ª metade) para o sub-17, mas diminuiu para o sub-15. Os resultados do presente estudo, sugerem que os perfis de taxa de trabalho dos jogadores não são prejudicados no CC e que o desempenho físico aumentado nesse tipo de competição pode estar associado a uma estratégia de auto-regulação ou \"pacing\" da intensidade de realização das ações. Apesar das semelhanças para os dados de desempenho físico (sub-15 e sub-17), a PM para o sub-17 foi amplamente aumentada no CC (vs CR) em comparação com os valores de PM do sub-15; sugerindo assim, uma maior capacidade dos atletas, com um suposto nível mais elevado de treinamento (sub-17) em otimizar o desempenho físico neste tipo de competição. Estas informações podem servir como um meio alternativo e eficiente de representação do desempenho físico e auxiliar na organização de uma preparação específica de equipes participantes destes formatos de competições (CC); adicionalmente, os resultados indicam a importância de de considerar as medidas de ACC, DEC e PM na análise do desempenho físico de jovens jogadores, ao invés da utilização isolada de medidas relacionadas a DT e DAV / The aim of this study was to compare the physical performances in youth players during congested (CM) versus regular match (RM) schedules. The accelerations (ACC), decelerations (DEC), average metabolic power (MP), total distance covered (TD) and distance covered at high speed (HSD) were compared across congested match (CM; 10 international matches played over 3 successive days, including 2 days with 2 consecutive matches played with a 4-5 hr interval) and 10 regular non-congested match periods (RM), played with a 7-day interval between matches, in elite youth soccer players (U15, n=11; U17, n=13).; as criterion for retention of the players\' data, it was adopted, the minimum participation of 75% of the total match time of each game. In addition, all variables were normalized per min of on-field playing time. Each player wore a 15-Hz GPS unit coupled with a 100 Hz tri-axial accelerometer (SPI Elite, GPSports, Canberra, Australia A difference classified as worthy of consideration (effect size; ES > 0.20), between CM and RM, was observed for ACC, DEC and MP, for U15 and U17, with higher values in CM. While TD and HSD showed lower values for CM for u15. Contrary to the hypothesis, the relative values of the physical performance parameters were higher for CM. A decrease in ACC and DEC, from the 1st half to the 2nd half of the match was observed (U15 and U17) for both CM and RM. However, an increase in MP from the 1st half to the 2nd half of the match was observed; with a very large increase for both categories during the RM; during the CM, MP increased (1st half to the 2nd half) in the U7, but decreased in U15. The present findings suggest that the players work rate profiles are not impaired in CM and that the intensity of the match-play is increased in this type of competition, and might be associated to self-regulation or pacing strategy; despite the similarities for physical performance in U15 and U17), MP was largely increased in U17 during CM (vs CR) compared to U15; this result suggests that the higher the level of the conditioning, the greater the ability of the athlete in optimizing physical performance in this type of match schedule. This information can serve as an alternative and efficient means of representing physical performance and may help coaches to organize and monitor specific preparations of teams participating in these type of competitions (CM); additionally, the results indicate the importance of considering the ACC, DEC and MP measurements in the analysis of physical performance of young players, instead of using only measures related to total distance covered and distances covered at different speeds

Esta investigação teórica procura identificar pontos de aproximação entre o conceito de potência orgástica, formulado pelo psiquiatra e psicanalista austríaco Wilhelm Reich (1897-1957), e o desempenho esportivo. Para isso procuramos focalizar o processo de evolução do conceito tendo como base os textos em que o apresenta e o define, partindo então para a exploração a respeito do conjunto de matizes e nuances que constituem a visão particular que Reich atribui ao termo potência. Em seguida, buscamos realizar essa aproximação com o desempenho esportivo nos sustentando em pesquisadores do tema, de modo a estabelecer pontos comuns de diálogo e similitudes que permitem um olhar sobre o desempenho esportivo à luz da obra reichiana, com especial ênfase à sua visão de potência. Por fim, fazemos uso da contribuição original de Albertini (1997) a respeito dos encontros potentes como forma de adicionar elementos à nossa reflexão e oferecer contribuições à compreensão do desempenho esportivo sob a ótica da psicologia profunda. Entendido primeiramente como a capacidade do indivíduo de se entregar ao fluxo de suas excitações sexuais no ato amoroso, de modo a atingir o orgasmo e assim descarregar sua libido represada, a evolução da obra de Reich aponta para a utilização do conceito de potência em outras dimensões da vida, nos levando a compreender que a visão de potência em Reich se refere à capacidade de ser humano estar presente e entregar-se em tudo aquilo que realiza. Essa visão se aproxima de conceitos utilizados na psicologia do esporte a respeito de estados ótimos de prontidão para o desempenho esportivo, apontados por alguns autores como ideais para a obtenção de resultados superiores. Essa aproximação, quando colocada sob o prisma da ideia de encontros potentes, nos permite reavaliar os aspectos estruturais que o conceito de potência possui no pensamento reichiano, assim como considerar a interferência dos processos transferenciais no desempenho esportivo, apontando para a ideia de que o desempenho esportivo não é afetado apenas por condições psíquicas individuais e isoladas do meio, mas especialmente pelo campo transferencial que se compõe no momento em que o desempenho ocorre / This theoretical investigation aim at the identification of approach points between the concept of orgastic potency, formulated by the Austrian psychiatrist and psychoanalyst Wilhelm Reich (1897-1957), and sport performance. To achieve this intent we first try to focus on the concept´s development process, based on the writings in which Reich presents it and defines it. Then, we continue to search and exploit the set of shades and nuances that make up the particular vision that Reich gives to the term potency. Following, we seek to achieve this approach to sports performance with the support of researchers in this area, in order to establish a common ground of dialogue and point out similarities that allow a glimpse into sports performance through the light of Reich\'s work, with special emphasis on his vision of potency. Finally, we use the original contribution of Albertini (1997) about the \"potent encounters\" as a way to add elements to our reflection and offer contributions to the understanding of sports performance from the perspective of depth psychology. Understood primarily as the ability of an individual to surrender to the free flow of his sexual excitations in lovemaking, in order to achieve orgasm and so discharge their repressed libido, the evolution of this concept points to the use of the term potency in other dimensions of life. Thus, leading us to the understanding that potency, in Reich´s view, refers to the ability of human beings to surrender and be present in everything they do in life. This view is similar to some sport psychology´s concepts about optimal states and readiness for performance, pointed out by some authors as ideal for achieving superior results. This approach, when placed under the light of the potent encounter´s notion, allows us to re-evaluate the structural aspects that the potency concept has on Reich\'s thinking, as well as to consider the interference of transference processes in sports performance. With this we were able to point at the idea that sport performance are not influenced only by individual and isolated psychological conditions, but specially by the transference field composed at/in the moment the performance occurs

Motivation: The prevalence of non-communicable diseases such as diabetes mellitus (DM) and cardiovascular disease (CVD) is rapidly increasing in industrialized societies. Experts believe that lifestyle, and in particular its nutritional aspects, plays a decisive role in increasing the burden of these chronic conditions. Dietary habits would, therefore, be modified to exert a positive impact on the prevention and treatment of chronic diseases of lifestyle. It is believed that the state of hyperglycaemia that is observed following food intake under certain dietary regimes contributes to the development of various metabolic conditions. This is not only true for individuals with poor glycaemic control such as some diabetics, but could also be true for healthy individuals. It would, therefore, be helpful to be able to reduce the amplitude and duration of postprandial hyperglycaemia. Selecting the correct type of carbohydrate (CHO) foods may produce less postprandial hyperglycaemia, representing a possible strategy in the prevention and treatment of chronic metabolic diseases. At the same time, a key focus of sport nutrition is the optimal amount of CHO that an athlete should consume and the optimal timing of consumption. The most important nutritional goals of the athlete are to prepare body CHO stores pre-exercise, provide energy during prolonged exercise and restore glycogen stores during the recovery period. The ultimate aim of these strategies is to maintain CHO availability to the muscle and central nervous system during prolonged moderate to high intensity exercise, since these are important factors in exercise capacity and performance. However, the type of CHO has been studied less often and with less attention to practical concerns than the amount of CHO. The glycaemic index (GI) refers to the blood glucose raising potential of CHO foods and, therefore, influences secretion of insulin. In several metabolic disorders, secretion of insulin is inadequate or impossible, leading to poor glycaemic control. It has been suggested that low GI diets could potentially contribute to a significant improvement of the conditions associated with poor glycaemic control. Insulin secretion is also important to athletes since the rate of glycogen synthesis depends on insulin due to it stimulatory effect on the activity of glycogen synthase. Objectives: Three main objectives were identified for this study. The first was to conduct a meta-analysis of the effects of the GI on markers for CHO and lipid metabolism with the emphasis on randomised controlled trials (RCT's). Secondly, a systematic review was performed to determine the strength of the body of scientific evidence from epidemiological studies combined with RCT's to encourage dieticians to incorporate the GI concept in meal planning. Finally, a systematic review of the effect of the GI in sport performance was conducted on all available literature up to date to investigate whether the application of the GI in an athlete's diet can enhance physical performance. Methodology: For the meta-analysis, the search was for randomised controlled trials with a cross-over or parallel design published in English between 1981 and 2003, investigating the effect of low GI vs high GI diets on markers of carbohydrate and lipid metabolism. The main outcomes were serum fructosamine, glycosylated haemoglobin (HbA1c), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), total cholesterol (TC) and triacylglycerols (TG). For the systematic review, epidemiological studies as well as RCT's investigating the effect of LGI vs HGI diets on markers for carbohydrate and lipid metabolism were used. For the systematic review on the effect of the GI on sport performance, RCT's with either a cross-over or parallel design that were published in English between January 1981 and September 2004 were used. All relevant manuscripts for the systematic reviews as well as meta-analysis were obtained through a literature search on relevant databases such as the Cochrane Central Register of Controlled Trials, MEDLINE (1981 to present), EMBASE, LILACS, SPORTDiscus, ScienceDirect and PubMed. This thesis is presented in the article format. Results and conclusions of the individual manuscripts: For the meta-analysis, literature searches identified 16 studies that met the strict inclusion criteria. Low GI diets significantly reduced fructosamine (p<0.05), HbA1c, (p<0.03), TC(p<0.0001) and tended to reduce LDL-c (p=0.06) compared to high GI diets. No changes were observed in HDL-c and TG concentrations. Results from this meta analysis, therefore, support the use of the GI concept in choosing CHO-containing foods to reduce TC and improve blood glucose control in diabetics. The systematic review combined the results of the preceding meta-analysis and results from epidemiological studies. Prospective epidemiological studies showed improvements in HDL-c concentrations over longer time periods with low GI diets vs. high GI diets, while the RCT's failed to show an improvement in HDL-c over the short-term. This could be attributed to the short intervention period during which the RCT's were conducted. Furthermore, epidemiological studies failed to show positive relationships between LDL-c and TC and low GI diets, while RCT's reported positive results on both these lipids with low GI diets. However, the epidemiological studies, as well as the RCT's showed positive results with low GI diets on markers of CHO metabolism. Taken together, convincing evidence from RCT's as well as epidemiological studies exists to recommend the use of low GI diets to improve markers of CHO as well as of lipid metabolism. 3 From the systematic review regarding the GI and sport performance it does not seem that low GI pre-exercise meals provide any advantages over high GI pre-exercise meals. Although low GI pre-exercise meals may better maintain CHO availability during exercise, low GI pre-exercise meals offer no added advantage over high GI meals regarding performance. Furthermore, the exaggerated metabolic responses from high GI compared to low GI CHO seems not be detrimental to exercise performance. However, athletes who experience hypoglycaemia when consuming CHO-rich feedings in the hour prior to exercise are advised to rather consume low GI pre-exercise meals. No studies have been reported on the GI during exercise. Current evidence suggests a combination of CHO with differing Gl's such as glucose (high GI), sucrose (moderate GI) and fructose (low GI) will deliver the best results in terms of exogenous CHO oxidation due to different transport mechanisms. Although no studies are conducted on the effect of the GI on short-term recovery it is speculated that high GI CHO is most effective when the recovery period is between 0-8 hours, however, evidence suggests that when the recovery period is longer (20-24 hours), the total amount of CHO is more important than the type of CHO. Conclusion: There is an important body of evidence in support of a therapeutic and preventative potential of low GI diets to improve markers for CHO and lipid metabolism. By substituting high GI CHO-rich with low GI CHO-rich foods improved overall metabolic control. In addition, these diets reduced TC, tended to improve LDL-c and might have a positive effect over the long term on HDL-c. This confirms the place for low GI diets in disease prevention and management, particularly in populations characterised by already high incidences of insulin resistance, glucose intolerance and abnormal lipid levels. For athletes it seems that low GI pre-exercise meals do not provide any advantage regarding performance over high GI pre-exercise meals. However, low GI meals can be recommended to athletes who are prone to develop hypoglycaemia after a CHO-rich meal in the hour prior to exercise. No studies have been reported on the effect of the GI during exercise. However, it has been speculated that a combination of CHO with varying Gl's deliver the best results in terms of exogenous CHO oxidation. No studies exist investigating the effect of the GI on short-term recovery, however, it is speculated that high GI CHO-rich foods are suitable when the recovery period is short (0-8 h), while the total amount rather than the type of CHO is important when the recovery period is longer (20-24 h). Therefore, the GI is a scientifically based tool to enable the selection of CHO-containing foods to improve markers for CHO and lipid metabolism as well as to help athletes to prepare optimally for competitions. Recommendations: Although a step nearer has been taken to confirm a place for the GI in human health, additional randomised, controlled, medium and long-term studies as well as more epidemiological studies are needed to investigate further the effect of low GI diets on LDL-c. HDL-c and TG. These studies are essential to investigate the effect of low GI diets on endpoints such as CVD and DM. This will also show whether low GI diets can reduce the risk of diabetic complications such as neuropathy and nephropathy. Furthermore, the public at large must be educated about the usefulness and application of the GI in meal planning. For sport nutrition, randomised controlled trials should be performed to investigate the role of the GI during exercise as well as in sports of longer duration such as cricket and tennis. More studies are needed to elucidate the short-term effect of the GI post-exercise as well as to determine the mechanism of lower glycogen storage with LGI meals post-exercise. / Thesis (Ph.D. (Dietetics))--North-West University, Potchefstroom Campus, 2005.

La réalisation d’une performance sportive dans un environnement chaud est un challenge majeur que doivent surmonter les athlètes de haut niveau notamment à l’occasion des Jeux Olympiques d’été. Depuis plusieurs décennies, les scientifiques ont tenté de trouver des solutions innovantes. Parmi les réponses proposées, on distingue aujourd’hui le refroidissement corporel préalable ou consécutif à l’effort (le pré et le post-cooling, respectivement), qui permettrait de minimiser les risques d’hyperthermie et améliorerait la récupération de l’athlète. Cependant, les modalités d’utilisation de ces méthodes et leur efficacité font l’objet de conclusions pour le moins contradictoires en raison notamment des techniques de refroidissement mises en œuvre (refroidissement par immersion, vêtements thermorégulants, brumisation…), de la durée d’application, du type d’exercice réalisé et des conditions environnementales explorées. La préparation des Jeux Olympiques à Pékin, en Août 2008, a été une occasion unique de faire un état de l’art sur les méthodes existantes. Nous avons testé chez des cyclistes de haut niveau l’hypothèse selon laquelle une stratégie de refroidissement utilisant une veste garnie d’accumulateurs thermiques permettrait d’améliorer le confort thermique et la performance lors d’un exercice de type anaérobie (Wingate test) et lors d’une épreuve d’endurance de 20 minutes. L’étude menée sur le test de Wingate ne montre aucun effet significatif du pré-cooling sur le pic de puissance ni sur la puissance moyenne mais permet néanmoins d’améliorer significativement (P < 0,05) l’indice de fatigue des athlètes testés. Sur l’épreuve de 20 minutes, le pré-cooling permet une amélioration significative (P < 0,05) de la puissance moyenne développée, du confort thermique et une baisse significative des températures cutanées et rectales. Une autre étude portant sur l’influence de différents maillots sur les réponses physiologiques et perceptives de coureurs cyclistes a montré qu’un maillot constitué de larges mailles offrait un meilleur confort thermique en diminuant significativement (P < 0,05) la température cutanée, mais sans modifier la perception de l’effort. Les bénéfices observés chez les cyclistes de haut niveau nous ont orientés vers la mise en œuvre d’un protocole similaire appliqué à des personnes atteintes de pathologies affectant la thermorégulation. Ainsi, nous avons débuté un protocole de recherche clinique exploratoire visant à étudier les effets du port d’une veste thermorégulante sur les performances motrices et cognitives de patients atteints de sclérose en plaques. Ce protocole, qui a obtenu l’accord du Comité de Protection des Personnes du Grand Est –II, devrait commencer fin 2012. / Abstract: Exercising in the heat and high relative humidity is a major challenge that athletes have to overcome, especially during the summer Olympic Games. For decades, scientists investigated innovative solutions amongst which the body cooling before competing (pre-cooling) or after competing (post-cooling) seemed to be a valuable mean of minimizing hyperthermia threats and increasing the recovery of the athletes. However, contradictory results have been reported concerning body cooling protocols (cold water immersion, cooling vests, water sprays, etc.), exposure time, exercise duration, environmental conditions and their efficiency. By preparing the 2008 Beijing Olympic Games, we managed to review the existing literature on those methods. We hypothesized that a cooling vest combined with a cooling headband would increase thermal comfort of elite cyclists and their performances on an anaerobic (Wingate Test) and endurance (20 minutes time-trial) exercises. The Wingate Test study showed no significant effect of pre-cooling on peak or mean power output despite a significant increase (P < 0.05) of fatigue indexes. During the endurance study, pre-cooling maneuvers induced significant improvement (P < 0.05) of the mean power output, of the thermal comfort and a significant decrease in rectal and skin temperatures. Another study concerning the influence of wearing different cycling shirt on perceived and physiological responses of cyclists showed that a large knitted shirt provided a better thermal comfort by decreasing significantly (P < 0.05) skin temperatures, but without affecting perceived exertion. Those positive results on elite athletes lead us to apply similar cooling strategies on a population experiencing disease-related thermoregulation troubles. We decided to initiate an exploratory clinical study aiming at investigating the effects of a cooling vest on motor and cognitive skills of patients with multiple sclerosis disease. This protocol obtained the clearance of the French National Ethics Committee – East Section II, and should start on the late of 2012.

Motivation: The prevalence of non-communicable diseases such as diabetes mellitus (DM) and cardiovascular disease (CVD) is rapidly increasing in industrialized societies. Experts believe that lifestyle, and in particular its nutritional aspects, plays a decisive role in increasing the burden of these chronic conditions. Dietary habits would, therefore, be modified to exert a positive impact on the prevention and treatment of chronic diseases of lifestyle. It is believed that the state of hyperglycaemia that is observed following food intake under certain dietary regimes contributes to the development of various metabolic conditions. This is not only true for individuals with poor glycaemic control such as some diabetics, but could also be true for healthy individuals. It would, therefore, be helpful to be able to reduce the amplitude and duration of postprandial hyperglycaemia. Selecting the correct type of carbohydrate (CHO) foods may produce less postprandial hyperglycaemia, representing a possible strategy in the prevention and treatment of chronic metabolic diseases. At the same time, a key focus of sport nutrition is the optimal amount of CHO that an athlete should consume and the optimal timing of consumption. The most important nutritional goals of the athlete are to prepare body CHO stores pre-exercise, provide energy during prolonged exercise and restore glycogen stores during the recovery period. The ultimate aim of these strategies is to maintain CHO availability to the muscle and central nervous system during prolonged moderate to high intensity exercise, since these are important factors in exercise capacity and performance. However, the type of CHO has been studied less often and with less attention to practical concerns than the amount of CHO. The glycaemic index (GI) refers to the blood glucose raising potential of CHO foods and, therefore, influences secretion of insulin. In several metabolic disorders, secretion of insulin is inadequate or impossible, leading to poor glycaemic control. It has been suggested that low GI diets could potentially contribute to a significant improvement of the conditions associated with poor glycaemic control. Insulin secretion is also important to athletes since the rate of glycogen synthesis depends on insulin due to it stimulatory effect on the activity of glycogen synthase. Objectives: Three main objectives were identified for this study. The first was to conduct a meta-analysis of the effects of the GI on markers for CHO and lipid metabolism with the emphasis on randomised controlled trials (RCT's). Secondly, a systematic review was performed to determine the strength of the body of scientific evidence from epidemiological studies combined with RCT's to encourage dieticians to incorporate the GI concept in meal planning. Finally, a systematic review of the effect of the GI in sport performance was conducted on all available literature up to date to investigate whether the application of the GI in an athlete's diet can enhance physical performance. Methodology: For the meta-analysis, the search was for randomised controlled trials with a cross-over or parallel design published in English between 1981 and 2003, investigating the effect of low GI vs high GI diets on markers of carbohydrate and lipid metabolism. The main outcomes were serum fructosamine, glycosylated haemoglobin (HbA1c), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), total cholesterol (TC) and triacylglycerols (TG). For the systematic review, epidemiological studies as well as RCT's investigating the effect of LGI vs HGI diets on markers for carbohydrate and lipid metabolism were used. For the systematic review on the effect of the GI on sport performance, RCT's with either a cross-over or parallel design that were published in English between January 1981 and September 2004 were used. All relevant manuscripts for the systematic reviews as well as meta-analysis were obtained through a literature search on relevant databases such as the Cochrane Central Register of Controlled Trials, MEDLINE (1981 to present), EMBASE, LILACS, SPORTDiscus, ScienceDirect and PubMed. This thesis is presented in the article format. Results and conclusions of the individual manuscripts: For the meta-analysis, literature searches identified 16 studies that met the strict inclusion criteria. Low GI diets significantly reduced fructosamine (p<0.05), HbA1c, (p<0.03), TC(p<0.0001) and tended to reduce LDL-c (p=0.06) compared to high GI diets. No changes were observed in HDL-c and TG concentrations. Results from this meta analysis, therefore, support the use of the GI concept in choosing CHO-containing foods to reduce TC and improve blood glucose control in diabetics. The systematic review combined the results of the preceding meta-analysis and results from epidemiological studies. Prospective epidemiological studies showed improvements in HDL-c concentrations over longer time periods with low GI diets vs. high GI diets, while the RCT's failed to show an improvement in HDL-c over the short-term. This could be attributed to the short intervention period during which the RCT's were conducted. Furthermore, epidemiological studies failed to show positive relationships between LDL-c and TC and low GI diets, while RCT's reported positive results on both these lipids with low GI diets. However, the epidemiological studies, as well as the RCT's showed positive results with low GI diets on markers of CHO metabolism. Taken together, convincing evidence from RCT's as well as epidemiological studies exists to recommend the use of low GI diets to improve markers of CHO as well as of lipid metabolism. 3 From the systematic review regarding the GI and sport performance it does not seem that low GI pre-exercise meals provide any advantages over high GI pre-exercise meals. Although low GI pre-exercise meals may better maintain CHO availability during exercise, low GI pre-exercise meals offer no added advantage over high GI meals regarding performance. Furthermore, the exaggerated metabolic responses from high GI compared to low GI CHO seems not be detrimental to exercise performance. However, athletes who experience hypoglycaemia when consuming CHO-rich feedings in the hour prior to exercise are advised to rather consume low GI pre-exercise meals. No studies have been reported on the GI during exercise. Current evidence suggests a combination of CHO with differing Gl's such as glucose (high GI), sucrose (moderate GI) and fructose (low GI) will deliver the best results in terms of exogenous CHO oxidation due to different transport mechanisms. Although no studies are conducted on the effect of the GI on short-term recovery it is speculated that high GI CHO is most effective when the recovery period is between 0-8 hours, however, evidence suggests that when the recovery period is longer (20-24 hours), the total amount of CHO is more important than the type of CHO. Conclusion: There is an important body of evidence in support of a therapeutic and preventative potential of low GI diets to improve markers for CHO and lipid metabolism. By substituting high GI CHO-rich with low GI CHO-rich foods improved overall metabolic control. In addition, these diets reduced TC, tended to improve LDL-c and might have a positive effect over the long term on HDL-c. This confirms the place for low GI diets in disease prevention and management, particularly in populations characterised by already high incidences of insulin resistance, glucose intolerance and abnormal lipid levels. For athletes it seems that low GI pre-exercise meals do not provide any advantage regarding performance over high GI pre-exercise meals. However, low GI meals can be recommended to athletes who are prone to develop hypoglycaemia after a CHO-rich meal in the hour prior to exercise. No studies have been reported on the effect of the GI during exercise. However, it has been speculated that a combination of CHO with varying Gl's deliver the best results in terms of exogenous CHO oxidation. No studies exist investigating the effect of the GI on short-term recovery, however, it is speculated that high GI CHO-rich foods are suitable when the recovery period is short (0-8 h), while the total amount rather than the type of CHO is important when the recovery period is longer (20-24 h). Therefore, the GI is a scientifically based tool to enable the selection of CHO-containing foods to improve markers for CHO and lipid metabolism as well as to help athletes to prepare optimally for competitions. Recommendations: Although a step nearer has been taken to confirm a place for the GI in human health, additional randomised, controlled, medium and long-term studies as well as more epidemiological studies are needed to investigate further the effect of low GI diets on LDL-c. HDL-c and TG. These studies are essential to investigate the effect of low GI diets on endpoints such as CVD and DM. This will also show whether low GI diets can reduce the risk of diabetic complications such as neuropathy and nephropathy. Furthermore, the public at large must be educated about the usefulness and application of the GI in meal planning. For sport nutrition, randomised controlled trials should be performed to investigate the role of the GI during exercise as well as in sports of longer duration such as cricket and tennis. More studies are needed to elucidate the short-term effect of the GI post-exercise as well as to determine the mechanism of lower glycogen storage with LGI meals post-exercise. / Thesis (Ph.D. (Dietetics))--North-West University, Potchefstroom Campus, 2005.

Subject: The knowledge of the sport performance structure with individual identification of the sport training model is a prerequisite for the effective management of sport training. Achieving the sports top limit performance in sport is possible by adapting the training plan to the athlete's individuality by his physiological and psychological prerequisites. To achieve the highest sports performance, sports training analysis is an indispensable tool for international competitiveness. This case study deals with the description of sports training models identified by the composition and dynamics of the training load predictors. A retrospective longitudinal study provides with insights into the possibilities of influencing sports training, which made national, Czech, records on the course of 800 m men and 3,000 m of women's steeplechase. Probandé (n=2) at the age of 21 (runner 1) and 28 resp. 29 years old (runner 2) reached limiting sports performances. The track record dates originates from 1995 to 2012. Runners were participants or medalists from top world or European athletic competitions. Objectiv: The aim of the thesis is to identify retrospectively through the found predictors, by whom were reached limit sports performance and sporting performance in the middle distances run. Methods: The...