Assessments of training load in elite youth soccer

One of the most popular sports globally, soccer has seen a rise in the demands of the game over recent years. An increase in intensity and playing demands, coupled with growing social and economic pressures on soccer players means that optimal preparation is of paramount importance. Recent research has found the modern game, depending on positional role, to consist of approximately 60% more sprint distance in the English Premier League, which was also found to be the case for frequency and success of discrete technical actions (Bush et al., 2015). As a result, the focus on soccer training and player preparedness is becoming more prevalent in scientific research. By designing the appropriate training load, and thus periodization strategies, the aim is to achieve peak fitness in the most efficient way, whilst minimising the risk of injury and illness. Traditionally, training intensity has been based on heart rate responses, however, the emergence of tracking microtechnology such as global positioning system (GPS) and inertial sensors are now able to further quantify biomechanical load as well as physiological stress. Detailed pictures of internal and external loading indices such as these then combine to produce a more holistic view of training load experience by the player during typical drills and phases of training in soccer. The premise of this research is to gain greater understanding of the physical demands of common training methodologies in elite soccer to support optimal match performance. The coaching process may then benefit from being able to prescribe the most effective training to support these. The first experimental chapter in this thesis began by quantify gross training loads of the pre-season and in-season phases in soccer. A broader picture of the training loads inherent in these distinct phases brought more detail as to the type and extent of external loading experienced by soccer players at these times, and how the inclusion of match play influences weekly training rhythms. Training volume (total distance) was found to be high at the start compared to the end of pre-season (37 kilometres and 28 kilometres), where high cardiovascular loads were attained as part of the conditioning focus. This progressed transiently, however, to involve higher-speed, acceleration and change-of-direction stimuli at the end of pre-season compared to the start and to that in-season (1.18 kilometres, 0.70 kilometres and 0.42 kilometres high-intensity running; with 37, 25 and 23 accelerations >3m/s2 respectively) . The decrease in volume and increase in maximal anaerobic activity was evident in the training focus as friendly matches were introduced before the competitive season. The influence of match-play as being a large physical dose in the training week may then determine the change in weekly periodisation and how resulting training loads applied and tapered, if necessary. The focus of research was then directed more specifically to the most common mode of training in soccer, that also featured regularly in the pre-season period in the present study, small-sided games (SSG). The subsequent studies examined numerous manipulations of this specific form of soccer conditioning, such as player numbers as well as absolute and relative playing space available. In contrast to some previous literature, changing the number of players did not seem to influence training responses significantly, although playing format in the possession style brought about larger effects for heart rate (89.9%HRmax) and average velocity (7.6km/h-1). However, the following studies (Chapters 5, 6 and 7) revealed a greater influence of relative playing space available to players in SSG. The larger area at their disposal brought about greater aerobic responses (~90%HRmax), by allowing higher average and peak velocities (>25km/h-1), as well as greater distance acceleration behaviour at greater thresholds (>2.8m/s2). Furthermore, the data points towards space as being a large determinant in strategy of the player in small-sided games (SSG), subsequently shaping their movement behaviour and resulting physical responses. For example, higher average velocities in a possession format (8km/h-1) reflects higher work rate and heart rate load but makes achieving significant neuromuscular accelerations at a high level difficult given higher starting velocities prior to the most intense accelerations (4.2km/h-1). By altering space available and even through intentional numerical imbalances in team numbers, it may be easier for coaches to achieve the desired stimulus for the session or individual player, whether that is for aerobic and neuromuscular conditioning. Large effects were found for heart rate being higher in the underloaded team (85-90%HRmax) compared to the team with more players (80-85%HRmax) as well as for RPE (5AU versus 7AU). This was also apparent for meterage and therefore average velocity. It would also seem neuromuscular load through high acceleration and deceleration efforts were more pronounced with less numbers (given the need to press and close down opponents, and in a larger area relative to the number of players on the underloaded team. The peak accelerations and deceleration achieved was also higher when playing with less players (3-6.2m/s2 and 3-6.1m/s2) Having detailed ways in which to reach desired physical loading responses in common small training formats, Chapter 8 compared SSG to larger 9v9 formats with full-size 11v11 friendly matches. This enabled absolute and relative comparisons to be made and to understand the extent to which smaller training formats are able to replicate the required movements to be successful in competition. In relative terms, it was revealed that relative acceleration distance and Player Load were higher in smaller 4v4 games than match-play (1.1m.min-1 and 0.3m.min-1 >3m/s2; 16.9AU versus 12AU). Although the smallest format did not replicate the high-velocity demands of matches, the results confirmed their efficacy in providing significant neuromuscular load during the training week, which may then be supplemented by high-intensity interval running in order to gain exposure to more maximal speed work. In summary, the data presented provide valuable information from GPS and inertial sensor microtechnology which may then be used to understand training better to manipulate types of load according to physical conditioning objectives. For example, a library of resources to direct planning of drills of varying cardiovascular, neuromuscular and perceptual load can be created to give more confidence in session outcomes. Combining external and internal load data of common soccer training drills, and their application across different phases and training objectives may give coaches a powerful tool to plan and periodize training.

Monitoramento de parâmetros imunológicos em atletas adolescentes de basquetebol durante e após a temporada esportiva= : Monitoring of immunological parameters in adolescent basketball athletes during and after a sports season

Universidade Estadual de Campinas . Faculdade de Educação Física

Construct and concurrent validation of omni-kayak rating of perceived exertion scale

This study tested the concurrent and construct validity of a newly developed OMNI-Kayak Scale, testing 8 male kayakers who performed a flatwater load-incremented ""shuttle"" test over a 500-m course and 3 estimation-production trials over a 1,000-m course. Velocity, blood lactate concentration, heart rate, and rating of perceived exertion (RPE), using the OMNI-Kayak RPE Scale and the Borg 6-20 Scale were recorded. OMNI-Kayak Scale RPE was highly correlated with velocity, the Borg 6-20 Scale RPE, blood lactate, and heart rate for both load-incremented test (rs=.87-.96), and estimation trials (rs=.75-.90). There were no significant differences among velocities, heart rate and blood lactate concentration between estimation and production trials. The OMNI-Kayak RPE Scale showed concurrent and construct validity in assessing perception of effort in flatwater kayaking and is a valid tool for self-regulation of exercise intensity.

Mood states as an indication of staleness and recovery

Elite athletes repeatedly completed the Profile of Mood States (POMS) during a six month training season to determine whether athletes who are stale show different values from those who are intensely trained but not stale. Nineteen elite male and female swimmers were studied at five time points: three times during training (early-, mid-, and late-season), during tapering prior to, and then shortly after, major competition. Of the 14 subjects who completed the entire monitoring program, three were classified as stale based on several criteria including poorer performance and prolonged high level of fatigue. Two of the stale swimmers showed higher scores for several of the POMS measures throughout the season compared with the remainder who were classified as non-stale. However, the third stale swimmer showed similar scores to those of the non-stale swimmers. Several POMS measures were significantly correlated with training intensity but not with training volume. It was concluded that stale athletes may not always demonstrate different mood scores from non-stale athletes but that the total mood disturbance score (TMD) as evaluated by the POMS may be used to indicate those athletes predisposed to the condition long before the symptoms of poor performance and prolonged fatigue are observed. TMD scores were chosen to monitor staleness since they represent a synthesis of the six specific mood states measured by the POMS.

Reabilitação respiratória na DPOC : efeito de duas intensidades de treino de exercício aeróbio nos resultados centrados no doente

RESUMO: Introdução: O treino de exercício assume uma importância fundamental nos programas de reabilitação respiratória, contudo permanece desconhecida qual a intensidade de treino efectiva na mudança dos resultados centrados no doente. Objectivos: Foram estudados os efeitos de duas intensidades de treino aeróbio na qualidade de vida relacionada com a saúde, no controlo de sintomas e na tolerância ao exercício, num programa de reabilitação respiratória para doentes com DPOC. Métodos: Trinta e quatro doentes com DPOC de estádios GOLD de ligeiro a muito grave, foram alocados aleatoriamente a intensidades de treino de exercício aeróbio de 60% ou 80% da intensidade máxima avaliada na prova de esforço num programa ambulatório de reabilitação respiratória de 20 sessões. Foram avaliados resultados centrados no doente pela aplicação do questionário respiratório de St.George, do índice de dispneia de Mahler, do questionário de actividades da vida diária do London Chest, da prova de 6 minutos, da prova de endurance a carga constante e da prova de esforço máxima incremental. Resultados: Apesar de existirem melhorias significativas em todos os resultados para ambos os grupos, a diferença média intergrupal por efeito da intensidade de treino aeróbio a 60% ou 80% da carga máxima em prova de esforço não foi significativa no questionário respiratório de St.George (p=0,306), no índice de dispneia de Mahler (p=0,378), no questionário de actividades da vida diária do London Chest (p=0,425), na prova de marcha de 6 minutos (p=0,917), na prova de endurance a carga constante (p=0,504) e na prova de esforço máxima incremental (p=0,117). Verificou-se ainda que a média das diferenças intergrupais na prova de endurance a carga constante e na prova de marcha de 6 minutos não apresentou qualquer associação com a idade dos doentes. Conclusões: O estudo permite concluir que não existem diferenças significativas nas alterações médias da qualidade de vida relacionada com a saúde, do controle de sintomas e da tolerância ao exercício em doentes com DPOC como efeito de duas intensidades de treino aeróbio. Os autores propõem para a prática clínica em reabilitação respiratória, a aplicação de intensidades de treino aeróbio individualmente adaptadas, de pelo menos 60% da carga máxima na prova de esforço inicial. -------------------------------ABSTRACT: Introduction: Exercise training is an important component of pulmonary rehabilitation, but it remains questionable as how training intensity changes patient-centered outcomes. Aims and objectives: The effects of two aerobic exercise training intensities in health-related quality of life, symptoms control and exercise tolerance in COPD patients were studied. Methods: Thirty-four COPD patients from mild to very severe GOLD stages were randomly assigned to a 60% or 80% aerobic exercise training intensity in a twenty-session outpatient pulmonary rehabilitation program. Patient-centered outcomes were assessed with St.George's respiratory questionnaire, Mahler dyspnoea index, London Chest activity of daily living, six minute walk test, constant work rate test and maximal incremental test. Results: Although there were significant improvements in all outcomes for both groups, there were no differences in mean change in St.George's respiratory questionnaire (p=0,306), Mahler dyspnoea index (p=0,378), London Chest activity of daily living (p=0,917), six-minute walk test (p=0,504), constant work rate test (p=0,504) and maximal incremental test (p=0,117), as an effect of aerobic exercise training intensity of 60% or 80%. Mean changes in constant work rate and six-minute walk test were not age-related. Conclusions: It is concluded that there are no differences in mean changes in health-related quality of life, symptoms control and exercise tolerance in COPD patients as an effect of two aerobic exercise training intensities. Therefore, the authors suggest that individually tailored exercise intensities above 60% should guide clinical practice in pulmonary rehabilitation.

Effect of acute and chronic exercise on fat oxidation and hormonal and plasma metabolite kinetics in obese and severely obese men

Acute exercise increases energy expenditure (EE) during exercise and post-exercise recovery [excess post-exercise oxygen consumption (EPOC)] and therefore may be recommended as part of the multidisciplinary management of obesity. Moreover, chronic exercise (training) effectively promotes an increase in insulin sensitivity, which seems to be associated with increased fat oxidation rates (FORs). The main purpose of this thesis is to investigate 1) FORs and extra-muscular factors (hormones and plasma metabolites) that regulate fat metabolism during acute and chronic exercise; and 2) EPOC during acute post-exercise recovery in obese and severely obese men (class II and III). In the first study, we showed that obese and severely obese men present a lower exercise intensity (Fatmax) eliciting maximal fat oxidation and a lower reliance on fat oxidation at high, but not at low and moderate, exercise intensities compared to lean men. This was most likely related to an impaired muscular capacity to oxidize non-esterified fatty acids (NEFA) rather than decreased plasma NEFA availability or a change in the hormonal milieu during exercise. In the second study, we developed an accurate maximal incremental test to correctly and simultaneously evaluate aerobic fitness and fat oxidation kinetics during exercise in this population. This test may be used for the prescription of an appropriate exercise training intensity. In the third study, we demonstrated that only 2 wk of exercise training [continuous training at Fatmax and adapted high-intensity interval training (HIIT)], matched with respect to mechanical work, may be effective to improve aerobic fitness, FORs during exercise and insulin sensitivity, which suggest that FORs might be rapidly improved and that adapted HIIT is feasible in this population. The increased FORs concomitant with the lack of changes in lipolysis during exercise suggest an improvement in the mismatching between NEFA availability and oxidation, highlighting the importance of muscular (oxidative capacity) rather than extra-muscular (hormones and plasma metabolites) factors in the regulation of fat metabolism after a training program. In the fourth study, we observed a positive correlation between EE during exercise and EPOC, suggesting that a chronic increase in the volume or intensity of exercise may increase EE during exercise and during recovery. This may have an impact in weight management in obesity. In conclusion, these findings might have practical implications for exercise training prescriptions in order to improve the therapeutic approaches in obesity and severe obesity. -- L'exercice aigu augmente la dépense énergétique (DE) pendant l'exercice et la récupération post-exercice [excès de consommation d'oxygène post-exercise (EPOC)] et peut être utilisé dans la gestion multidisciplinaire de l'obésité. Quant à l'exercice chronique (entraînement), il est efficace pour augmenter la sensibilité à l'insuline, ce qui semble être associé à une amélioration du débit d'oxydation lipidique (DOL). Le but de cette thèse est d'étudier 1) le DOL et les facteurs extra-musculaires (hormones et métabolites plasmatiques) qui régulent le métabolisme lipidique pendant l'exercice aigu et chronique et 2) l'EPOC lors de la récupération aiguë post-exercice chez des hommes obèses et sévèrement obèses (classe II et III). Dans la première étude nous avons montré que les hommes obèses et sévèrement obèses présentent une plus basse intensité d'exercice (Fatmax) correspondant au débit d'oxydation lipidique maximale et un plus bas DOL à hautes, mais pas à faibles et modérées, intensités d'exercice comparé aux sujets normo-poids, ce qui est probablement lié à une incapacité musculaire à oxyder les acides gras non-estérifiés (AGNE) plutôt qu'à une diminution de leur disponibilité ou à un changement du milieu hormonal pendant l'exercice. Dans la deuxième étude nous avons développé un test maximal incrémental pour évaluer simultanément l'aptitude physique aérobie et la cinétique d'oxydation des lipides pendant l'exercice chez cette population. Dans la troisième étude nous avons montré que seulement deux semaines d'entraînement (continu à Fatmax et intermittent à haute intensité), appariés par la charge de travail, sont efficaces pour améliorer l'aptitude physique aérobie, le DOL pendant l'exercice et la sensibilité à l'insuline, ce qui suggère que le DOL peut être rapidement amélioré chez cette population. Ceci, en absence de changements de la lipolyse pendant l'exercice, suggère une amélioration de la balance entre la disponibilité et l'oxydation des AGNE, ce qui souligne l'importance des facteurs musculaires (capacité oxydative) plutôt que extra-musculaires (hormones et métabolites plasmatiques) dans la régulation du métabolisme lipidique après un entraînement. Dans la quatrième étude nous avons observé une corrélation positive entre la DE pendant l'exercice et l'EPOC, ce qui suggère qu'une augmentation chronique du volume ou de l'intensité de l'exercice pourrait augmenter la DE lors de l'exercice et lors de la récupération post-exercice. Ceci pourrait avoir un impact sur la gestion du poids chez cette population. En conclusion, ces résultats pourraient avoir des implications pratiques lors de la prescription des entraînements dans le but d'améliorer les approches thérapeutiques de l'obésité et de l'obésité sévère.

Exercise may cause myocardial ischemia at the anaerobic threshold in cardiac rehabilitation programs

Myocardial ischemia may occur during an exercise session in cardiac rehabilitation programs. However, it has not been established whether it is elicited when exercise prescription is based on heart rate corresponding to the anaerobic threshold as measured by cardiopulmonary exercise testing. Our objective was to determine the incidence of myocardial ischemia in cardiac rehabilitation programs according to myocardial perfusion SPECT in exercise programs based on the anaerobic threshold. Thirty-nine patients (35 men and 4 women) diagnosed with coronary artery disease by coronary angiography and stress technetium-99m-sestamibi gated SPECT associated with a baseline cardiopulmonary exercise test were assessed. Ages ranged from 45 to 75 years. A second cardiopulmonary exercise test determined training intensity at the anaerobic threshold. Repeat gated-SPECT was obtained after a third cardiopulmonary exercise test at the prescribed workload and heart rate. Myocardial perfusion images were analyzed using a score system of 6.4 at rest, 13.9 at peak stress, and 10.7 during the prescribed exercise (P < 0.05). The presence of myocardial ischemia during exercise was defined as a difference ≥2 between the summed stress score and summed rest score. Accordingly, 25 (64%) patients were classified as ischemic and 14 (36%) as nonischemic. MIBI-SPECT showed myocardial ischemia during exercise within the anaerobic threshold. The 64% prevalence of ischemia observed in the study should not be looked on as representative of the whole population of patients undergoing exercise programs. Changes in patient care and exercise programs were implemented as a result of our finding of ischemia during the prescribed exercise.

La relation entre la formation des ressources humaines et la performance organisationnelle : l’effet modérateur du roulement du personnel

La présente recherche a comme premier objectif d’étudier l’effet de la formation des ressources humaines sur la performance organisationnelle. Le concept de formation des ressources humaines, tel que considérée ici, comporte deux dimensions : l’intensité et l’incidence de la formation mesurées respectivement par la proportion des coûts investis et par la proportion d’employés formés. Les dimensions de la performance organisationnelle retenues sont la productivité et la rentabilité financière. Le second objectif de cette recherche est d’étudier l’effet modérateur du roulement du personnel dans la relation entre la formation et la performance organisationnelle. Les données de la présente recherche sont de nature secondaire. Il s’agit des données colligées par Jalette (1998) auprès de la Fédération des Caisses Desjardins de Montréal et de l’Ouest-du-Québec pour sa thèse de doctorat. Au total, 288 caisses ont été considérées pour la présente étude. Les analyses de régression multiple ont été effectuées dans le but de vérifier l’effet de chaque dimension de la formation sur chaque dimension de la performance organisationnelle. Quatre analyses de régression hiérarchiques nous ont permis de tester l’effet modérateur du roulement du personnel dans la relation entre la formation des ressources humaines et la performance organisationnelle. Les résultats de cette recherche indiquent que les relations examinées sont plus complexes qu’il n’y paraissait à première vue. Tout d’abord, l’effet de la formation sur la performance organisationnelle n’était pas significatif ou allait dans le sens contraire de nos attentes. Par contre, un effet modérateur significatif du roulement du personnel a été identifié dans trois régressions. Ainsi, la relation négative entre l’intensité de la formation et la rentabilité financière est moins prononcée dans un milieu où le roulement est élevé que dans un milieu où il est faible. Aussi, dans un milieu où le roulement est élevé, la relation entre l’incidence de la formation et la productivité est positive tandis qu’elle est négative dans un contexte où le roulement est bas. Ces deux effets modérateurs vont cependant dans le sens contraire à celui attendu. Cependant, l’hypothèse huit a été vérifiée : ainsi, dans un contexte où le roulement du personnel est élevé, la relation entre l’incidence de la formation et la rentabilité financière est négative tandis qu’elle est positive dans un contexte où le roulement est bas.

Efeito do treinamento resistido na pressão arterial e capacidade funcional de idosas hipertensas

The results of studies about the ideal resistance training intensity for reduction of resting blood pressure levels, as well as this type of training to increase the functional capacity of hypertensive older women are still unclear, since the few investigations usually analyze young individuals normotensive, and the literature lacks precise information in elderly hypertensive subjects. Objectives: To determine the effect of two resistance training intensities on resting blood pressure and the effect of resistance training on functional capacity in elderly women with systemic arterial hypertension, analyzing these variables before and after eight weeks of intervention. Methods: Patients underwent eight weeks of resistance training, with a frequency of three times per week on alternate days, in the afternoon. The exercises performed were: leg press, bench press, knee extension, lat pull-down, knee flexion, shoulder abduction, standing cable hip abduction and biceps curl. Results: It was found that patients who underwent training with moderate resistance, showed a reduction on resting values of diastolic blood pressure (DBP) p<0.03 and of mean arterial pressure (MAP) p<0.03. Patients who underwent mild resistance training showed reduction in resting values of MAP (p<0.03) and a tendency to decrease in DBP (p<0.06). With regard to functional capacity, the results showed significant increase in the strength of arms and legs, agility and aerobic endurance (p<0.001) and maintaining flexibility (p>0.05). Conclusion: The data indicated that both mild and moderate resistance training, even when started in old age, promoted cardiovascular benefits and also improve the functional capacity of hypertensive older women.

Respostas agudas pós-exercício dos níveis de lactato sanguíneo e creatinofosfoquinase de atletas adolescentes

O crescente interesse de crianças e adolescentes por esportes competitivos induz a uma maior preocupação em prescrever treinamentos adequados a essa população específica. O conhecimento do impacto da intensidade de treinamento físico competitivo sobre a saúde de adolescentes são ainda incipientes na literatura científica. Este estudo objetivou investigar as respostas agudas do lactato sanguíneo (Lac) e da creatinofosfoquinase (CPK) após uma sessão de treinamento físico em atletas jovens treinados em diferentes modalidades esportivas. Participaram 43 adolescentes do sexo masculino entre 9 e 17 anos, distribuídos em três grupos: nadadores, tenistas, jogadores de futebol de salão. Os protocolos para cada modalidade seguiram o planejamento normal de uma sessão específica. A dieta no dia anterior à coleta foi padronizada e as 24 horas que precediam a avaliação foram dedicadas ao repouso dos atletas. Foram coletados 5ml de sangue da veia antecubital imediatamente antes da realização da sessão de treinamento, repetindo coleta idêntica, imediatamente após a sessão. Foi obtida a idade óssea para a avaliação da maturação esquelética pelo método de Greulich & Pyle. Análise de variância Kruskal-Wallis e teste U-de Mann-Whitney foram utilizados para comparações entre os grupos. Valores de p < 0,05 foram considerados significantes. em todas as modalidades esportivas estudadas os valores prévios do Lac e da CPK foram inferiores aos valores pós-sessão. Com relação aos três grupos de faixas etárias, tanto para o Lac como para a CPK, os valores na pré-sessão foram inferiores aos obtidos na pós-sessão, assinalando que para o grupo de 9 aos 11 anos, tanto na situação pré como na pós, os valores foram inferiores aos observados nos grupos de idade superior. Os resultados indicaram que a magnitude de aumento da CPK e do Lac foram similares aos valores encontrados na literatura e demonstraram um aumento em função da faixa etária, indicando ser maturação biológica dependente.

O exercício físico potencializa ou compromete o crescimento longitudinal de crianças e adolescentes? Mito ou verdade?

A sociedade atual tem valorizado de forma significativa a aparência alta e esbelta. Essa constituição física tem sido reforçada desde a infância e atinge a população adolescente, que deseja enquadrar-se nos estereótipos, particularmente aqueles veiculados pela mídia. Nesse sentido, profissionais de saúde são questionados rotineiramente sobre os efeitos positivos que o exercício físico exerce sobre o crescimento longitudinal de crianças e adolescentes. Procurou-se revisar a literatura especializada a respeito dos principais efeitos que o exercício físico exerceria sobre a secreção e atuação do hormônio de crescimento (GH) nos diversos tecidos corporais, durante a infância e adolescência. Através dessa revisão, foi possível verificar que o exercício físico induz a estimulação do eixo GH/IGF-1. Embora muito se especule quanto ao crescimento ósseo ser potencializado pela prática de exercícios físicos, não foram encontrados na literatura científica específica estudos bem desenvolvidos que forneçam sustentação a essa afirmação. No tocante aos efeitos adversos advindos do treinamento físico durante a infância e adolescência, aparentemente, esses foram independentes do tipo de esporte praticado, porém resultantes da intensidade do treinamento. A alta intensidade do treinamento parece ocasionar uma modulação metabólica importante, com a elevação de marcadores inflamatórios e a supressão do eixo GH/IGF-1. Entretanto, é importante ressaltar que a própria seleção esportiva, em algumas modalidades, recruta crianças e/ou adolescentes com perfis de menor estatura, como estratégia para obtenção de melhores resultados, em função da facilidade mecânica dos movimentos. Através dessa revisão, fica evidente a necessidade de realização de estudos longitudinais, nos quais os sujeitos sejam acompanhados antes, durante e após sua inserção nas atividades esportivas, com determinação do volume e da intensidade dos treinamentos, para que conclusões definitivas relativas aos efeitos sobre a estatura final possam ser emanadas.

Efeitos do desempenho aeróbio na máxima fase estável de lactato sanguíneo determinada em protocolo intermitente na natação

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito do exercício físico contínuo e intervalado no peso e perfil bioquímico de ratas Wistar prenhes e consequências no peso da prole

INTRODUÇÃO: A prática de atividade física é reconhecida como fator importante para a preservação, recuperação e manutenção da saúde. O estímulo à prática de exercícios é crescente, mas quando relacionado à gravidez, dúvidas surgem sobre os efeitos deletérios ou salutares na mãe e no feto. OBJETIVO: O objetivo deste trabalho foi avaliar os efeitos do exercício físico intervalado e contínuo no perfil bioquímico de ratas Wistar prenhes e avaliar o efeito destes exercícios no peso da placenta e dos filhotes. MÉTODOS: Utilizou-se 45 ratas Wistar divididas em grupos de 15 animais segundo o tipo de exercício: controle (GC), exercício contínuo (GCO) e exercício intermitente (GIN). Os exercícios constituíram-se de natação forçada, cinco dias por semana, em piscinas individuais: exercício contínuo (duração de 45 minutos diários com sobrecarga de 5% do peso corporal) e intermitente (45 minutos com estímulos de 15 segundos de exercício e 15 de repouso com sobrecarga de 15% do peso corporal). O exercício foi praticado do primeiro ao 20º dia de prenhez. Após este período avaliou-se o peso e os níveis de glicemia, colesterol total, LDL-C, HDL-C e triglicérides das ratas, assim como o peso da placenta e dos filhotes. RESULTADOS: Não se observou modificação no peso das mães. Houve redução significativa nos níveis de LDL-C. O peso das placentas não variou, mas os pesos dos filhotes variaram estatisticamente entre os três grupos (4,153 ± 0,649; 3,682 ± 0,070 e 3,453 ± 0,052, respectivamente, para os filhos de mães do GC, GIN e GCO). CONCLUSÕES: Conclui-se que a prática do exercício físico contínuo e intermitente por ratas prenhes, neste modelo experimental, não interferiu no peso corpóreo das mesmas, mas interferiu no peso dos filhotes ao nascer

Long-term creatine supplementation improves the aerobic capacity of horses

The aim of the present study was to investigate the effect of long-term oral supplementation of creatine on the physiological responses to aerobic training. Twelve purebred Arabian horses were submitted to aerobic training for 90 days, with and without creatine supplementation which consisted of the daily administration of 75g of creatine monohydrate mixed into the ration for 90 days of training. Physical conditioning was conducted on a high performance treadmill and training intensity was stipulated by calculating the V 4 (velocity at which blood lactate reaches 4mmol L -1) determined monthly for each animal. The individual intensity of physical force at 80% of aerobic threshold was established. An incremental exercise test was used to set the individual V4. After a warm up period of 4 min at 4m s -1), the speed was increased at 2min intervals to 6, 8 and 10m s -1). The blood samples were collected 15s before the end of each step to determine the concentration of lactate, packed cell volume, hemoglobin and red cell values. The results demonstrated a significant increase (P<0.05) in V4 in the groups that received creatine supplementation for 60 days or more when compared to the animals without creatine supplememntation. The other hematological variables were similar to all groups. The results showed that the prolonged creatine supplementation may have a beneficial al effect on the equine athletic performance.

Influência do treinamento físico intervalado nas pressões respiratórias na concentração de nitrito/nitrato e do receptor de leptina solúvel em mulheres na pós-menopausa

Pós-graduação em Ciências da Motricidade - IBRC