Aim. The purpose of this study was to determine the response of circulating markers of lipid and protein oxidation following an incremental test to exhaustion before and after 4 weeks of high-intensity interval training performed in the heat. Methods. To address this question, 16 physically active men (age = 23 ± 2 years; body mass = 73 ± 12 kg; height = 173 ± 6 cm; % body fat = 12.5 ± 6 %; body mass index = 24 ± 4 kg/m2) were allocated into 2 groups: control group (n = 8) performing high-intensity interval training at 22°C, 55% relative humidity and heat group (n = 8) training under 35°C, 55% relative humidity. Both groups performed high-intensity interval training 3 times per week for 4 consecutive weeks, accumulating a total of 12 training sessions. Before and after the completion of 4 weeks of high-intensity interval training, participants performed an incremental cycling test until exhaustion under temperate environment (22°C, 55% relative humidity) where blood samples were collected after the test for determination of exercise-induced changes in oxidative damage biomarkers (thiobarbituric acid reactive species and protein carbonyls). Results. When high-intensity interval training was performed under control conditions, there was an increase in protein carbonyls (p < 0.05) following the incremental test to exhaustion with no changes in thiobarbituric acid reactive species. Conversely, high-intensity interval training performed in high environmental temperature enhanced the incremental exercise-induced increases in thiobarbituric acid reactive species (p < 0.05) with no changes in protein carbonyls. Conclusion. In conclusion, 4 weeks of high-intensity interval training performed in the heat enhances exercise-induced lipid peroxidation, but prevents protein oxidation following a maximal incremental exercise in healthy active men.

Abstract-The aim of the present study was to assess the effects of prior ingestion of coconut water on fluid retention and exercise capacity in the heat as well as signs of gastrointestinal distress. Eight physically active men were recruited (age 23 ± 3 years, height 176 ± 6 cm, body mass 78 ± 7 kg) and performed three exercise capacity trials on a cycle ergometer in the heat (34 ± 1°C) after the ingestion of one of the following drinks: a) plain water (PW), b) flavored drink (FD), and c) coconut water (CW). Ingestion of CW resulted in a longer time to exhaustion (p=0.029). Likewise, participants achieved a higher heart rate in the CW session when compared to the other trials (PW 183 ± 5 bpm, FD 184 ± 8 bpm, and CW 189 ± 8 bpm, p<0.05) and a reduced urine output after the coconut water ingestion (PW 214 ± 85 ml, FD 267 ± 90 ml, and CW 161 ± 73 ml, p<0.05) indicating a higher fluid retention of coconut water in comparison to plain water and the flavored drink. These results demonstrate that previous ingestion of coconut water improves exercise capacity in the heat and provide a reduced urine output in comparison to plain water and flavored drink. Also there is no evidence for GI distress. Keywords: hydration, performance, temperatureResumo-O objetivo do presente estudo foi avaliar os efeitos da ingestão prévia de água de coco sobre a retenção de líquidos e capacidade de resistência ao exercício no calor, bem como sinais de desconforto gastrointestinal. Oito homens fisicamente ativos foram recrutados (idade 23 ± 3 anos, altura 176 ± 6 cm, massa corporal 78 ± 7 kg) e realizaram três sessões de capacidade de exercício em uma bicicleta ergométrica no calor (34 ± 1° C) após a ingestão de uma das seguintes bebidas: a) água pura (PW), b) bebida com sabor (FD), e c) água de coco (CW). A ingestão de CW resultou num maior tempo até a exaustão (p = 0,029). Da mesma forma, os participantes alcançaram uma frequência cardíaca mais alta na sessão de CW quando comparado com as outras sessões (PW 183 ± 5 bpm, FD 184 ± 8 bpm, e CW 189 ± 8 bpm, p <0,05) e uma taxa de produção de urina reduzida após a ingestão de água de coco (PW 214 ± 85 ml, FD 267 ± 90 ml, e CW 161 ± 73 ml, p <0,05), indicando uma maior retenção de líquidos na sessão água de coco em comparação com água pura e bebida com sabor. Estes resultados demonstram que a ingestão prévia de água de coco melhora a capacidade de exercício no calor e proporciona uma menor produção de urina em comparação com a água pura e bebida com sabor. Também não houve nenhuma evidência de desconforto gastrointestinal. Palavras-chave: hidratação, desempenho, temperaturaResumen-El objetivo del presente estudio fue evaluar los efectos de la ingesta previa de agua de coco en la retención de líquidos y la capacidad de ejercicio al calor, así como señales de malestar gastrointestinal. Ocho hombres físicamente activos fueron reclutados (edad 23 ± 3 años, altura 176 ± 6 cm, la masa corporal de 78 ± 7 kg) y se realizaron tres ensayos de capacidad de ejercicio en un cicloergómetro con el calor (34 ± ...

The optimal hydration plan [i.e., drink to thirst, ad libitum (ADL), or personalized plan] to be adopted during exercise in recreational athletes has recently been a matter of debate and, due to conflicting results, consensus does not exist. In the present investigation, we tested whether a personalized hydration strategy based on sweat rate would affect cardiovascular and thermoregulatory responses and exercise capacity in the heat. Eleven recreational male cyclists underwent two familiarization cycling sessions in the heat (34°C, 40% RH) where sweat rate was also determined. A fan was used to enhance sweat evaporation. Participants then performed three randomized time-to-exhaustion (TTE) trials in the heat with different hydration strategies: personalized volume (PVO), where water was consumed, based on individual sweat rate, every 10 min; ADL, where free access to water was allowed; and a control (CON) trial with no fluids. Blood osmolality and urine-specific gravity were measured before each trial. Heart rate (HR), rectal, and skin temperatures were monitored throughout trials. Time to exhaustion at 70% of maximal workload was used to define exercise capacity in the heat, which was similar in all trials (p = 0.801). Body mass decreased after ADL (p = 0.008) and CON (p < 0.001) and was maintained in PVO trials (p = 0.171). Participants consumed 0 ml in CON, 166 ± 167 ml in ADL, and 1,080 ± 166 ml in PVO trials. The increase in mean body temperature was similar among trials despite a lower increase in skin temperature during PVO trial in comparison with CON (2.1 ± 0.6 vs. 2.9 ± 0.5°C, p = 0.0038). HR was lower toward the end of TTE in PVO (162 ± 8 bpm) in comparison with ADL (168 ± 12 bpm) and CON (167 ± 10 bpm), p < 0.001. In conclusion, a personalized hydration strategy can reduce HR during a moderate to high intensity exercise session in the heat and halt the increase in skin temperature. Despite these advantages, cycling capacity in the heat remained unchanged.

| Schoolbag weight and mode of carrying it can contribute to postural deviations and back pain. Therefore, our objective was to determine and compare, among the school grades and between sexes, the schoolbag weight relative to body weight and the mode of carrying it of Elementary School students, who leave their books on