Effects of Precooling on 30-km Cycling Performance and Pacing in Hot and Temperate Environments.

This study examined the effects of precooling on performance and pacing during 30-km cycling exercise in hot and temperate environments. 8 trained male cyclists performed 4 trials involving either cooling (PRECTEMP and PRECHOT) or no-cooling interventions (TEMP and HOT) prior to a 30-km self-paced cycling exercise in either a hot (35°C, 68% relative humidity) or temperate environment (24°C, 68% relative humidity). Exercise time was longer in HOT (60.62±3.47 min) than in TEMP (58.28±3.30 min; P<0.001), and precooling attenuated this thermal strain performance impairment (PRECHOT 58.28±3.30 min; P=0.048), but it was still impaired compared with TEMP (P=0.02). Exercise performance in PRECTEMP (54.58±4.35 min) was no different from TEMP. Initial power output was sustained until the end of the exercise in both TEMP and PRECTEMP, but was reduced from the 12th km until the end of the trial in HOT (P<0.05). This reduction was delayed by precooling because power output was reduced only after the 20th km during PRECHOT (P<0.05). Heart rate was similar in all conditions throughout almost the entire exercise, suggesting the maintenance of similar relative intensities. In conclusion, precooling was effective in attenuating, but not completely reversing thermal strain performance impairment and offered no ergogenic effect in the temperate environment.

Assessment of acute physiological demand for soccer / Avaliação da demanda fisiológica aguda no futebol

Soccer is a sport practiced worldwide, on all continents. It is considered an intermittent activity of high intensity and long duration, in which movements that require great strength and speed, such as jumps and sprints, result in high levels of muscle microtrauma, hampering athletes' training and recovery. The present study aimed to evaluate the magnitude of changes in different markers of physiological demand resulting from a soccer match in healthy individuals. Ten healthy male physical education students participated in the study and were evaluated in two matches: the semi-final and final games of the college tournament at the federal university where they studied. Blood samples were collected from each volunteer pre- and post-match. Cortisol, IL-6 and CK concentrations were increased after the match (p < 0.05). Testosterone and alpha-actin concentrations did not change. Our results indicate that changes in some of the acute response markers evaluated in players before and after competitive soccer matches provide important information for planning training or recovery, as well as nutritional strategies for improving performance.

O futebol é um esporte de abrangência mundial praticado em todos os continentes.É considerada uma atividade intermitente, de alta intensidade e longa duração, na qual as ações de grande força e velocidade como saltos e sprints implicam altos níveis de microtrauma muscular, atrapalhando o treinamento e a recuperação dos atletas. O propósito deste trabalho foi avaliar a magnitude das alterações de diferentes marcadores da demanda fisiológica em indivíduos saudáveis decorrentes de um jogo de futebol. Participaram do estudo, dez homens considerados saudáveis, estudantes de Educação Física. Os indivíduos foram avaliados em dois jogos, sendo a semifinal e a final do torneio universitário da universidade federal onde estudavam. A amostra sanguínea foi retirada de cada voluntário nos momentos pré e pós-jogo. Resultados: As concentrações de Cortisol, IL-6 e CK, apresentaram aumento pós-jogo (p<0,05). As concentrações de Testosterona e alfa-actina não se alteraram. Pode-se concluir que as alterações em parte dos marcadores das respostas agudas avaliados em jogos competitivos de futebol fornecem informações importantes para o planejamento de métodos de treinamento, recuperação ou estratégias nutricionais para o aperfeiçoamento do esporte.

Efeitos do calor no OBLA: comparação entre ambiente quente e temperado / Effects of heat on OBLA: comparison between warm and temperate environments

O OBLA (onset of blood lactate accumulation) é um método utilizado para estimar o limiar de lactato (LL). Entretanto, ainda não está claro o efeito da temperatura ambiente sobre o OBLA. O objetivo do presente estudo foi comparar o OBLA em ambiente quente (40ºC) e temperado (22ºC). Nove homens (idade: 23,9±2,4 anos; massa corporal: 75,9±7,3 kg e VO2máx: 47,8±4,9 mL•kg-1•min-1) realizaram teste progressivo em cicloergômetro para determinação da potência máxima (Wmáx) e do OBLA nos dois ambientes. A Wmáx (195±25W vs 225±28W) e a potência no OBLA (153±30W vs 165±32W) foram menores no ambiente quente do que no temperado. A frequência cardíaca no OBLA-40 foi maior do que no OBLA-22 (171±8 vs 153±10 bpm, respectivamente). Não foi observada diferença no consumo de oxigênio no OBLA-22 e OBLA-40 (31,65±5,21 vs 31,12±6,82 mL•kg-1•min-1). Estes resultados indicam que as condições ambientais influenciam a determinação do OBLA.

The OBLA (onset of blood lactate accumulation), is a method used to estimate the lactate threshold (LT). However, It is unclear the effect of ambient temperature on OBLA. The aim of this study was to compare OBLA determined in warm (40°C) and temperate (22ºC) environments. Nine men (age: 23.9±2.4 years, body mass: 75.9±7.3kg and VO2máx: 47.8±4.9 mL•kg-1•min-1) performed an incremental test in cycle ergometer to determine the maximal power output (Wmax) and OBLA in the heat (OBLA-40) and temperate (OBLA-22) environments. The Wmax (195±25W vs 225±28W) and the power output associated with the OBLA (153±30 W vs 165±32W) were lower in warm than in temperate experiments. The heart rate at OBLA-40 was higher than in OBLA-22 (171±8 vs 153±10 bpm, respectively). No difference was found in oxygen uptake at OBLA-22 and OBLA-40 (31.65±5.21 vs 31.12±6.82 mL•kg-1•min-1). The results indicate that environmental conditions influence the OBLA determination.