Four weeks of supplementation with a multi-strain probiotic increased running time to fatigue in the heat. Further studies are required to elucidate the exact mechanisms for this performance benefit.

We examined whether daily hot water immersion (HWI) after exercise in temperate conditions induces heat acclimation and improves endurance performance in temperate and hot conditions. Seventeen non-heatacclimatized males performed a 6-day intervention involving a daily treadmill run for 40 min at 65% V O 2max in temperate conditions (18°C) followed immediately by either HWI (N = 10; 40°C) or thermoneutral (CON, N = 7; 34°C) immersion for 40 min. Before and after the 6-day intervention, participants performed a treadmill run for 40 min at 65% V O 2max followed by a 5-km treadmill time trial (TT) in temperate (18°C, 40% humidity) and hot (33°C, 40% humidity) conditions. HWI induced heat acclimation demonstrated by lower resting rectal temperature (T re , mean, À0.27°C, P < 0.01), and final T re during submaximal exercise in 18°C (À0.28°C, P < 0.01) and 33°C (À0.36°C, P < 0.01). Skin temperature, T re at sweating onset and RPE were lower during submaximal exercise in 18°C and 33°C after 6 days in HWI (P < 0.05). Physiological strain and thermal sensation were also lower during submaximal exercise in 33°C after 6 days in HWI (P < 0.05). HWI improved TT performance in 33°C (4.9%, P < 0.01) but not in 18°C. Thermoregulatory measures and performance did not change in CON. Hot water immersion after exercise on 6 days presents a simple, practical, and effective heat acclimation strategy to improve endurance performance in the heat.

To determine the diagnostic accuracy of state, minimally invasive clinical and physical signs (or sets of signs) to be used as screening tests for detecting impending or current water-loss dehydration, or both, in older people by systematically reviewing studies that have measured a reference standard and at least one index test in people aged 65 years and over. 1 Clinical and physical signs for identification of impending and current water-loss dehydration in older people (Protocol)

Objectives: Dehydration in older adults contributes to increased morbidity and mortality during hospitalization. As such, early diagnosis of dehydration may improve patient outcome and reduce the burden on healthcare. This prospective study investigated the diagnostic accuracy of routinely used physical signs, and non-invasive markers of hydration in urine and saliva. Design: Prospective diagnostic accuracy study. Setting: Hospital acute medical care unit and emergency department. Participants: One hundred and thirty older adults (59 males, 71 females, mean (SD) age = 78 (9) y). Measurements: Participants with any primary diagnosis underwent a hydration assessment within 30min of admittance to hospital. Hydration assessment comprised seven physical signs of dehydration (tachycardia (>100bpm), low systolic blood pressure (<100mmHg), dry mucous membrane, dry axilla, poor skin turgor, sunken eyes, and long capillary refill time (>2s)), urine color, urine specific gravity (USG), saliva flow rate (SFR) and saliva osmolality. Plasma osmolality (Posm) and the blood urea nitrogen to creatinine ratio (BUN:Cr) were assessed as reference standards of hydration, with 21% of participants classified with water-loss dehydration (Posm >295mOsm/kg), 19% classified with water-and-solute-loss dehydration (BUN:Cr >20) and 60% classified as euhydrated. Results: All physical signs showed poor sensitivity (0-44%) for detecting either form of dehydration, with only low systolic blood pressure demonstrating potential utility for aiding the diagnosis of water-and-solute-loss dehydration (diagnostic OR = 14.7). Neither urine color, USG, nor SFR could discriminate hydration status (area under the receiver operating characteristic curve, AUCROC = 0.49-0.57, P>0.05). In contrast, saliva osmolality demonstrated moderate diagnostic accuracy (AUCROC = 0.76, P<0.001) to distinguish both dehydration types (70% sensitivity, 68% specificity, OR =5.0 (95%CI 1.7-15.1) for water-loss dehydration, and 78% sensitivity, 72% specificity, OR =8.9 (95%CI 2.5-30.7) for water-and-solute-loss dehydration). Conclusions: With the exception of low systolic blood pressure, which could aid in the specific diagnosis of water-and-solute-loss dehydration, physical signs and urine markers show little utility to determine if an elderly patient is dehydrated. Saliva osmolality demonstrated superior diagnostic accuracy compared with physical signs and urine markers, and may have utility for the assessment of both water-loss and water-andsolute-loss dehydration in older individuals. It is particularly noteworthy that saliva osmolality was able to detect water-and-solute-loss dehydration, for which a measurement of plasma osmolality would have no diagnostic utility. Thankyou for allowing us to resubmit the above manuscript to your journal. We have responded to the reviewers comments (see below), with changes in the manuscript highlighted in red text. We hope you feel that these changes have improved the manuscript.Please don't hesitate to contact me if you require...

Unaccustomed strenuous physical exertion in hot environments can result in heat stroke and acute kidney injury (AKI). Both exercise-induced muscle damage and AKI are associated with the release of interleukin-6, but whether muscle damage causes AKI in the heat is unknown. We hypothesized that muscle-damaging exercise, before exercise in the heat, would increase kidney stress. Ten healthy euhydrated men underwent a randomized, crossover trial involving both a 60-min downhill muscle-damaging run (exercise-induced muscle damage; EIMD), and an exercise intensity-matched non-muscle-damaging flat run (CON), in random order separated by 2 wk. Both treatments were followed by heat stress elicited by a 40-min run at 33°C. Urine and blood were sampled at baseline, after treatment, and after subjects ran in the heat. By design, EIMD induced higher plasma creatine kinase and interleukin-6 than CON. EIMD elevated kidney injury biomarkers (e.g., urinary neutrophil gelatinase-associated lipocalin (NGAL) after a run in the heat: EIMD-CON, mean difference [95% CI]: 12 [5, 19] ng/ml) and reduced kidney function (e.g., plasma creatinine after a run in the heat: EIMD-CON, mean difference [95% CI]: 0.2 [0.1, 0.3] mg/dl), where CI is the confidence interval. Plasma interleukin-6 was positively correlated with plasma NGAL (r = 0.9, P = 0.001). Moreover, following EIMD, 5 of 10 participants met AKIN criteria for AKI. Thus for the first time we demonstrate that muscle-damaging exercise before running in the heat results in a greater inflammatory state and kidney stress compared with non-muscle-damaging exercise. Muscle damage should therefore be considered a risk factor for AKI when performing exercise in hot environments.