BHI may be a useful measure to identify the short-term hydration potential of different beverages when ingested in a euhydrated state. This trial was registered at www.isrctn.com as ISRCTN13014105.

colon; Saliva osmolality and total protein appear to be as sensitive as urine osmolality to track hydration changes during hypertonic-hypovolemia. These results also suggest that dehydration has a greater involvement in the decrease in saliva flow rate during prolonged exercise than neuroendocrine regulation.

This review outlines recent advancements in the understanding of athlete immune health. Controversies discussed include whether high levels of athletic training and environmental stress (for example, heat acclimation, cryotherapy and hypoxic training) compromise immunity and increase upper respiratory tract infection (URTI). Recent findings challenge early exercise immunology doctrine by showing that international athletes performing high-volume training suffer fewer, not greater, URTI episodes than lower-level performers and URTI incidence decreases, not increases, around the time of competition compared with heavy training. Herein we raise the possibility of host genetic influences on URTI and modifiable behavioural and training-related factors underpinning these recent observations. Continued controversy concerns the proportion of URTI symptoms reported by athletes that are due to infectious pathogens, airway inflammation or as yet unknown causes and indeed whether the proportion differs in athletes and non-athletes. Irrespective of the cause of URTI symptoms (infectious or non-infectious), experts broadly agree that self-reported URTI hinders high-volume athletic training but, somewhat surprisingly, less is known about the influence on athletic performance. In athletes under heavy training, both innate and acquired immunity are often observed to decrease, typically 15-25%, but whether relatively modest changes in immunity increase URTI susceptibility remains a major gap in knowledge. With the exception of cell-mediated immunity that tends to be decreased, exercising in environmental extremes does not provide an additional threat to immunity and host defence. Recent evidence suggests that immune health may actually be enhanced by regular intermittent exposures to environmental stress (for example, intermittent hypoxia training).

The aim was to test the hypothesis that one night of sleep deprivation will impair pre-loaded 30 min endurance performance and alter the cardio-respiratory, thermoregulatory and perceptual responses to exercise. Eleven males completed two randomised trials separated by 7 days: once after normal sleep (496 (18) min: CON) and once following 30 h without sleep (SDEP). After 30 h participants performed a 30 min pre-load at 60% [VO(2 max) followed by a 30 min self-paced treadmill distance test. Speed, RPE, core temperature (T(re)), mean skin temperature (T(sk)), heart rate (HR) and respiratory parameters VO(2 max), VCO(2), VE, RER pre-load only) were measured. Less distance (P = 0.016, d = 0.23) was covered in the distance test after SDEP (6037 (759) 95%CI 5527 to 6547 m) compared with CON (6224 (818) 95%CI 5674 to 6773 m). SDEP did not significantly alter T(re) at rest or thermoregulatory responses during the pre-load including heat storage (0.8 degrees C) and T(sk). With the exception of raised VO(2) at 30 min on the pre-load, cardio-respiratory parameters, RPE and speed were not different between trials during the pre-load or distance test (distance test mean HR, CON 174 (12), SDEP 170 (13) beats min(-1): mean RPE, CON 14.8 (2.7), SDEP 14.9 (2.6)). In conclusion, one night of sleep deprivation decreased endurance performance with limited effect on pacing, cardio-respiratory or thermoregulatory function. Despite running less distance after sleep deprivation compared with control, participants' perception of effort was similar indicating that altered perception of effort may account for decreased endurance performance after a night without sleep.

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...