ECSS Paris 2023: CP-PN02
INTRODUCTION: This study examined the effect of the follicular (FP) and luteal phases (LP) of the menstrual cycle on sweat rate, estimated sweat sodium concentration, heart rate, hydration status, fluid intake, and perceived exertion in first-division university female football players METHODS: Eight athletes completed two monitored training sessions, one in each men-strual phase, following a repeated-measures field-based design under habitual training conditions. Sweat rate was determined using pre- to post-exercise body mass changes and microfluidic sweat patches, while es-timated sweat sodium concentration was obtained via wearable colorimetric sensors. Heart rate was continuously monitored, hydration status was assessed using urine specific gravity, fluid intake was recorded, and perceived exertion was evaluated using the Borg CR-10 scale. RESULTS: Sweat rate was significantly higher during LP compared with FP (0.83 ± 0.20 vs. 0.55 ± 0.25 L·h⁻¹, p = 0.026), alongside greater estimated sweat sodium concentration (695 ± 305 vs. 404 ± 159 mg·L⁻¹, p = 0.031) and higher perceived exertion (4.63 ± 1.41 vs. 3.13 ± 0.83, p = 0.021). Fluid intake was also significantly greater during LP (0.99 ± 0.19 vs. 0.49 ± 0.25 L, p < 0.001). No significant differences were observed for urine specific gravity, mean heart rate, or total body mass change (p > 0.05). CONCLUSION: These findings indicate that the luteal phase is associated with increased thermoregulatory strain, electrolyte loss, and perceived effort during football training, emphasizing the importance of menstrual cycle–informed hydration and training management strategies in female athletes.
Read CV Valentin E. Fernandez-EliasECSS Paris 2023: CP-PN02
INTRODUCTION: Exercise-induced dehydration can negatively impact mood and cognitive performance. Solutions containing electrolytes and glucose (sugar) are commonly used to support rehydration and mitigate cognitive decrements, potentially due to the role of glucose in energy provision. However, previously published findings from the present trial demonstrate that sugar-free electrolyte formulations are effective rehydration strategies. METHODS: Thirty participants enrolled and 22 participants (n = 18 F; n = 4 M) completed a double-blinded, randomized, placebo-controlled, crossover trial. As previously reported, participants completed an exercise-induced dehydration protocol (30°C, 50% rh) to elicit ~2% body mass loss (1.70 ± 0.29%), followed by a 60-minute rehydration period providing 150% of fluid lost using three electrolyte rehydration formulations (A = allulose, B = blend of amino acids, C = sugar alcohol) or placebo (flavour-matched water). Mood was assessed as a secondary outcome using four visual analogue scales (thirst, fatigue, positivity of mood, readiness to perform) and cognitive performance was assessed as a secondary outcome using a three-minute Psychomotor Vigilance Task and a two-minute Simon task. Assessments were completed hourly across the five-hour recovery period. RESULTS: Perceptual responses did not differ between conditions (p > 0.05; d <0.20; trivial effects). On the PVT, mean reaction time was slower for placebo compared with Formula A at three hours (p = 0.020, d = 0.12 [0.04, 0.21]) and Formula B at one hour (p = 0.025, d = 0.12 [0.04, 0.21]), with median reaction time mirroring this pattern for placebo versus Formula B at one hour (p = 0.024, d = 0.12 [0.04, 0.21]). No differences were observed for transformed number of lapses (p > 0.05). On the Simon task, placebo demonstrated slower overall and congruent mean reaction time compared with Formula A at two hours (p = 0.029, d = 0.12 [0.03, 0.20]), with no differences observed for remaining outcomes (p > 0.05). CONCLUSION: Cognitive performance following exercise-induced dehydration was largely comparable across conditions, with some small positive effects observed for sugar-free electrolyte formulations. When considered alongside the previously reported hydration outcomes, these findings suggest that sugar-free hydration solutions can effectively support rehydration without compromising post-exercise cognitive performance. Direct comparisons with sugar-containing formulations and assessment under more cognitively demanding conditions, such as decision-making tasks or dehydration resulting in greater than 2% body mass loss, may help further clarify the efficacy of sugar-free electrolyte solutions for mood and cognitive performance.
Read CV Stacy HawkinsECSS Paris 2023: CP-PN02
INTRODUCTION: We recently reported that carbonation of water reduces beverage consumption compared to non-carbonated water, likely due to sensory effects such as oral stimulation. However, despite this reduction, hydration efficiency as assessed by changes in body weight and plasma volume was comparable to that of plain water. These findings suggest that carbonated water may offer similar hydration benefits to plain water, even when consumed in smaller volumes. However, the previous study was conducted under conditions where food intake was restricted. Since hydration occurs through both food and fluid consumption, it is practically important to investigate whether carbonation of water affects both drinking and eating behaviour, as well as hydration status, following exercise in the heat. METHODS: Twelve healthy young adults (six women) exercised at 50% of their peak oxygen uptake in a hot environment (35 °C) until they reached a 2% reduction in body mass. They then rested in a seated position in a cooler environment (25 °C) and were given a 30-min ad libitum eating and drinking period. During this time, participants were allowed to consume either non-carbonated or carbonated water, along with a standardized food item (bread). In the non-carbonated water trial, participants consumed non-carbonated water during the 30-min period, whereas in the carbonated water trial, they consumed carbonated water. The two trials were conducted on separate days. Venous blood and urine samples were collected throughout the protocol. RESULTS: In the carbonated water trial, fluid intake during the first 5 min after the onset of drinking was lower than in the non-carbonated water trial. Total fluid intake also tended to be lower under the carbonated water condition, whereas no difference was observed in total food intake between the two conditions. Cumulative urine volume did not differ between the water and carbonated water conditions. However, the degree of body mass recovery was lower in the carbonated water condition. In contrast, recovery of plasma volume and plasma osmolality was comparable between conditions. The carbonated water condition elicited a greater sensation of drinking-related stimulation and a greater reduction in hunger. CONCLUSION: Carbonated water reduces total fluid intake after exercise in the heat without affecting eating behavior, ultimately impairing the recovery of body fluid compared with the condition in which non-carbonated water is consumed. This attenuated recovery of body fluid with carbonated water contrasts with our previous study, in which participants followed the same protocol but did not consume food. In the present study, the inclusion of food particularly due to its sodium content may have helped retain ingested water in the body, a response that was absent in our earlier study. On the other hand, carbonated water intake suppresses hunger sensation, which may be beneficial for avoiding excessive calorie intake.
Read CV Naoto FujiiECSS Paris 2023: CP-PN02