The effect of double - blind carbohydrate ingestion during 60 km of self-paced exercise in warm ambient conditions

This study evaluated double blind ingestions of placebo (PLA) versus 6% carbohydrate (CHO) either as capsules (c) or beverage (b) during 60 km self-paced cycling in the heat (32&deg;C and 50% relative humidity). Ten well-trained males (mean &plusmn; SD: 26&plusmn;3 years; 64.5&plusmn;7.7 kg and 70.7&plusmn;8.8 ml.kg-1.min-1 maximal oxygen consumption) completed four separate 60 km time trials (TT) punctuated by 1 km sprints (14, 29, 44, 59 km) whilst ingesting either PLAb or PLAc or CHOb or CHOc. The TT was not different among treatments (PLAb 130.26 11.2 min, CHOb 140.5&plusmn;18.1 min, PLAc 143.1&plusmn;29.2 min, CHOc 137.3&plusmn;20.1 min; P&gt;0.05). Effect size (Cohen\u27s d) for time was only moderate when comparing CHOb - PLAb (d = 0.68) and PLAb - PLA c (d = 0.57) whereas all other ES were \u27trivial\u27 to \u27small\u27. Mean speed throughout the trial was significantly higher for PLAb only (P&lt;0.05). Power output was only different (P&lt;0.05) between the sprints and low intensity efforts within and across conditions. Core and mean skin temperatures were similar among trials. We conclude that CHO ingestion is of little or no benefit as a beverage compared with placebo during 60 km TT in the heat.<br /

PERFORMANCE OF SOCCER PLAYERS OF DIFFERENT PLAYING POSITIONS AND NACIONALITIES IN A 30-METER SPRINT TEST

The purpose of this study was to compare the performance of soccer players of different playing positions and different nationalities on a 30-meter sprint test. The players were instructed to run at full speed. Tests were performed on a Soccer field. The mean speed for 10 (V10), 10-30 (V20) and 30m (V30) were determined. The results of 75 Brazilian players of different positions were compared between themselves and 21 first division professional Brazilian players were compared with 18 J-League Japanese players. No difference was found between the performances of Brazilian players of different positions. The performance of Brazilian players in V20 and V30 (8.69 ± 0.64 and 7.68 ± 0.28m•s-1) was better than that of Japanese players (8.11 ± 0.26 and 7.42 ± 0.22m•s-1;

An exploratory study of short-term camping in Antarctica: Hormonal and mood states changes

Long-term Antarctic expedition’s studies indicated harmful or positive behavioral and psychophysiological adaptive changes that arise from adversities in isolated, confined, and extreme environments. Whereas most of the published studies focused on overwintering situations, most Brazilian Antarctic Program summer expeditions consist of short-term stays. We evaluated the influence of a permanence in Antarctic short-term (13-day) summer camp on the hormonal responses and mood states in eight volunteers. Data collection was carried out at the beginning (initial measure, days 3 to 5) and the end (final measurement, days 10 to 12) of the camping. Morning and evening samples of saliva were obtained to measure the testosterone and cortisol concentrations. Morning blood drops were used to determine thyroid-stimulating hormone (TSH) and thyroxine (T4) concentration. The volunteers also answered a mood states questionnaire. During the short-term camp, T4 (3.92 ± 0.75 vs 2.21 ± 0.71 μg.dL-1) and T4/TSH (3.16 ± 0.97 vs 1.79 ± 0.74 AU) reduced, without concomitant changes in TSH (1.28 ± 0.17 vs 1.30 ± 0.09 μU.mL-1), and salivary cortisol increased (2,392 ± 1,153 vs 4,440 ± 1,941 pg.mL-1) resulting in greater cortisol amplitude (calculated from the difference between morning and evening measurement, 1,400 ± 1,442 vs 3,230 ± 2,046). In men, testosterone increased as well (26.2 ± 12.5 vs 67.8 ± 45.8, all differences with P&lt;0.05). There was a moderate effect in mood states evidenced by increased anger and fatigue, and reduced vigor. At the end of the camp, the change in cortisol correlated with anger, and the final cortisol values with anger and tension. We concluded that staying in a short-term summer camp in Antarctica induced endocrine and mood state changes, indicators of stress reaction

Intensidade de sessões de treinamento e jogos oficiais de futebol

The intensity of individual workout sessions is one of the most determinant components of the training load. However, only a few studies have investigated the intensity of the effort (IE) of training sessions frequently used by soccer and conditioning coaches. The purpose of this study was to compare the IE of two different training sessions, training game (TG) and modified game (MG), with the IE of official soccer matches. The heart rate (HR) of eight U-17 players, from first division Brazilian Soccer club, was measured and registered during two training sessions (TG and MG) and during 6 matches of an official competition. The IE during the matches of the official competition (166 ± 3 bpm and 84 ± 1.3 %HRmax) was higher than TG (150 ± 3 bpm and 75 ± 1.8 %HRmax). However, no difference was found between the IE of official soccer matches and MG (157 ± 5 bpm and 79 ± 2.6 %HRmax). Considering that the IE of the MG was similar to that found in official games, it may be considered as being a specific training stimulus for developing the aerobic capacity of soccer players.No treinamento esportivo, a intensidade é um dos componentes mais determinantes da carga de treinamento. Entretanto, poucos estudos investigaram a intensidade de esforço (IE) de sessões de treinamento freqüentemente utilizadas por treinadores e preparadores físicos de futebol. O objetivo desse estudo foi identificar e comparar a IE de duas sessões de treinamento (coletivo e campo reduzido) com a IE de jogos de uma competição oficial de futebol. A freqüência cardíaca (FC) de oito atletas juvenis, pertencentes a um clube da primeira divisão do futebol brasileiro, foi medida e registrada durante duas sessões de treinamento (coletivo e campo reduzido) e durante seis jogos de uma competição oficial. A IE registrada nos jogos da competição oficial (166 ± 3 bpm e 84 ± 1,3 %FCmáx) foi maior em comparação com a IE registrada durante o treinamento coletivo (150 ± 3 bpm e 75 ± 1,8 %FCmáx). Não houve diferença entre a IE dos jogos da competição oficial e a IE do treinamento em campo reduzido (157 ± 5 bpm e 79 ± 2,6 %FCmáx). A semelhança entre as IEs do treinamento em campo reduzido e dos jogos oficiais registradas no presente estudo sugere que esta atividade pode ser utilizada como um estímulo específico de treinamento aeróbico para o futebol

Time required to stabilize thermographic images at rest

Thermography for scientific research and practical purposes requires a series of procedures to obtain images that should be standardized; one of the most important is the time required for acclimatization in the controlled environment. Thus, the objective of this study was to identify the appropriate acclimatization time in rest to reach a thermal balance on young people skin. Forty-four subjects participated in the study, 18 men (22.3 ± 3.1 years) and 26 women (21.7 ± 2.5 years). Thermographic images were collected using a thermal imager (Fluke ®), totaling 44 images over a period of 20 minutes. The skin temperature (TSK) was measured at the point of examination which included the 0 minute, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20. The body regions of interest (ROI) analyzed included the hands, forearms, arms, thighs, legs, chest and abdomen. We used the Friedman test with post hoc Dunn?s in order to establish the time at rest required to obtain a TSK balance and the Mann-Whitney test was used to compare age, BMI, body fat percentage and temperature variations between men and women, considering always a significance level of pmenor que0.05. Results showed that women had significantly higher temperature variations than men (pmenor que0.01) along the time. In men, only the body region of the abdomen obtained a significant variance (pmenor que0.05) on the analyzed period, both in the anterior and posterior part. In women, the anterior abdomen and thighs, and the posterior part of the hands, forearms and abdomen showed significant differences (pmenor que0.05). Based on our results, it can be concluded that the time in rest condition required reaching a TSK balance in young men and women is variable, but for whole body analysis it is recommended at least 10 minutes for both sexes

Avaliação de parâmetros de hidratação após jogos de futebol de diferentes categorias.

O objetivo do presente estudo foi avaliar o padrão de hidratação e respostas termorregulatórias de jogadores de futebol de diferentes categorias ao longo de um jogo oficial. Participaram desse estudo jogadores de futebol das categorias sub-15 (N 36) e sub-17 anos (N 14). Os jogadores foram divididos em grupos de acordo com o tempo de atuação em nos jogos: grupo principal, o grupo parcial, grupo intermediário grupo controle. As respostas termorregulatórias decorrentes dos jogos e o estatus de hidratação foram determinados e comparados entre os grupos apresentados. Os grupos principal e parcial apresentaram maiores valores de consumo de água, perda de peso e taxa de sudorese em comparação aos grupos intermediário e controle (p<0,05). A diferença de peso pré e pós-jogo entre as categorias foi maior nos atletas da categoria sub17 em comparação com os atletas sub 15 no mesmo grupo (p<0,05). Conclui-se que um jogo de futebol foi capaz de alterar de forma significativa os parâmetros de hidratação dos jogadores de futebol tendo relação direta com o tempo de atuação em campo.The purpose of this study was to evaluate the hydration status and thermoregulatory responses, during official soccer matches, of soccer players in different categories. The participants of the under-15 (U-15, n=36) and of the under-17 category (U-17, n=14) were placed into different groups according to the amount of time spent in the field: Main group; Partial group; Intermediate group; Control group. The thermoregulatory responses and hydration status were measured. The Main group and the Partial group presented significantly higher water intake, weight loss and sweat rate compared with the Intermediate and Control group (p<0.05). The under-17 players of the Main group had a larger weight difference pre and post match compared with the under-15 players of the same group (p<0.05). It was concluded that an official soccer match altered significantly the hydration status of the players, and it was related with the time spent in the match

Limiar anaeróbio de jogadores de futebol de diferentes categorias

Diferentes variáveis podem ser utilizadas para a identificação e monitoramento da capacidade aeróbia em esportes coletivos, sendo o limiar anaeróbio (LAN) muito utilizado em atividades como futebol, basquete, handebol entre outros. O objetivo do estudo foi determinar a intensidade do LAN de jogadores de futebol de diferentes categorias, avaliando os parâmetros velocidade, freqüência cardíaca (FC) e percentual da FC máxima (%FCmáx), bem como comparar estas intensidades entre as categorias. Participaram do estudo 19 jogadores da categoria sub-17, 12 jogadores Sub-20 e 14 profissionais. O LAN foi determinado a partir da intensidade de 4mM obtida em um teste de campo. Este consistiu em corridas de 1000m, em velocidades constantes a cada tentativa. A FC e lactato ([Lactato]) obtidos no teste foram analisados através de interpolação linear. Foram determinados a velocidade, a FC e %FCmáx correspondentes à intensidade do LAN. Identificou-se que a FCmáx dos jogadores Sub-17 (202 ± 7bpm) foi maior quando comparada à categoria Profissional (193 ± 10bpm) (p<0,05). O LAN expresso em %FCmáx dos jogadores Sub-17 (87,0 ± 1,1) e Sub-20 (86,3 ± 0,8) foi menor quando comparado à categoria Profissional (91,2 ± 1,1) (p<0,05). A intensidade média do LAN foi 87% FCmáx. Não foram identificadas diferenças entre as categorias quando o LAN foi considerado em bpm e como velocidade de corrida. Concluiu-se que a intensidade do LAN neste grupo pode ser considerada alta, sendo que os jogadores profissionais apresentam LAN mais alto em comparação com as categorias Sub-17 e Sub-20