Changes in energy balance, body composition, metabolic profile and physical performance in a 62-day Army Ranger training in a hot-humid environment.

OBJECTIVES: To determine the physiological effects of multiple stressors including energy deficit during a 62-day Ranger course in a hot-humid environment. DESIGN: Prospective cohort design. METHODS: Food intake data were collected daily and energy expenditure at each of the three phases of the course was estimated by the doubly-labeled water method. Anthropometry, hydration status, stress and metabolic hormones, handgrip strength and lower explosive power were measured at the start and at the end of each phase. RESULTS: Seventeen male participants (age: 24.5 ±â€¯3.2 years, height: 173.9 ±â€¯5.1 cm, body mass: 69.3 ±â€¯3.2 kg, BMI: 22.9 ±â€¯0.9 kg/m2, percent body fat: 14 ±â€¯5%) completed the study. Mean total daily energy expenditure was 4756 kcal/day and mean daily energy intake was 3882 kcal/day. An 18% energy deficit resulted in an average body mass loss of 4.6 kg, comprising mostly fat mass. Participants with higher baseline adiposity (>15% body fat) lost more fat mass and gained (rather than lost) muscle mass compared to those with lower baseline adiposity. Handgrip strength declined only at the end of Phase I, while lower body explosive power declined progressively throughout the course. Lean mass in arms and legs was correlated with initial grip strength and lower body explosive power, but only at the start of the course. CONCLUSIONS: Physiologically demanding Ranger training in an equatorial environment is at least as metabolically demanding and stressful as other similar high-risk training courses, as demonstrated by the stress and metabolic endocrine responses, changes in body composition, and reduction in explosive power. Moreover, the smaller body size of Asian soldiers may confer an energetic advantage over larger sized Western counterparts.

A Novel Dimeric Exoglucanase (GH5_38): Biochemical and Structural Characterisation towards its Application in Alkyl Cellobioside Synthesis.

An exoglucanase (Exg-D) from the glycoside hydrolase family 5 subfamily 38 (GH5_38) was heterologously expressed and structurally and biochemically characterised at a molecular level for its application in alkyl glycoside synthesis. The purified Exg-D existed in both dimeric and monomeric forms in solution, which showed highest activity on mixed-linked ß-glucan (88.0 and 86.7 U/mg protein, respectively) and lichenin (24.5 and 23.7 U/mg protein, respectively). They displayed a broad optimum pH range from 5.5 to 7 and a temperature optimum from 40 to 60 °C. Kinetic studies demonstrated that Exg-D had a higher affinity towards ß-glucan, with a Km of 7.9 mg/mL and a kcat of 117.2 s-1, compared to lichenin which had a Km of 21.5 mg/mL and a kcat of 70.0 s-1. The circular dichroism profile of Exg-D showed that its secondary structure consisted of 11% α-helices, 36% ß-strands and 53% coils. Exg-D performed transglycosylation using p-nitrophenyl cellobioside as a glycosyl donor and several primary alcohols as acceptors to produce methyl-, ethyl- and propyl-cellobiosides. These products were identified and quantified via thin-layer chromatography (TLC) and liquid chromatography-mass spectrometry (LC-MS). We concluded that Exg-D is a novel and promising oligomeric glycoside hydrolase for the one-step synthesis of alkyl glycosides with more than one monosaccharide unit.

The Use of Candida pyralidae and Pichia kluyveri to Control Spoilage Microorganisms of Raw Fruits Used for Beverage Production.

Undesired fermentation of fruit-derived beverages by fungal, yeast and bacterial spoilage organisms are among the major contributors of product losses in the food industry. As an alternative to chemical preservatives, the use of Candida pyralidae and Pichia kluyveri was assessed for antimicrobial activity against several yeasts (Dekkera bruxellensis, Dekkera anomala, Zygosaccharomyces bailii) and fungi (Botrytis cinerea, Colletotrichum acutatum and Rhizopus stolonifer) associated with spoilage of fruit and fruit-derived beverages. The antagonistic properties of C. pyralidae and P. kluyveri were evaluated on cheap solidified medium (grape pomace extract) as well as on fruits (grapes and apples). Volatile organic compounds (VOCs) from C. pyralidae and P. kluyveri deemed to have antimicrobial activity were identified by gas chromatography-mass spectrometry (GC-MS). A cell suspension of C. pyralidae and P. kluyveri showed growth inhibition activity against all spoilage microorganisms studied. Direct contact and extracellular VOCs were two of the mechanisms of inhibition. Twenty-five VOCs belonging to the categories of alcohols, organic acids and esters were identified as potential sources for the biocontrol activity observed in this study. This study reports, for the first time, the ability of C. pyralidae to inhibit fungal growth and also for P. kluyveri to show growth inhibition activity against spoilage organisms (n = 6) in a single study.

Aeration, Agitation and Cell Immobilization on Corncobs and Oak Wood Chips Effects on Balsamic-Styled Vinegar Production.

Optimum fermentor conditions are essential for desired microbial growth and activity in fermentations. In balsamic vinegar fermentation systems, the microorganisms used must endure several stressful conditions including high sugar concentration, low water activity, high osmotic pressure and high acetic acid concentration. Consequently, the present study was aimed at improving the performance of a microbial consortium of non-Saccharomyces yeast and acetic acid bacteria during balsamic-styled vinegar fermentation. Cell immobilization via adsorption on corncobs and oak wood chips in combination with aeration and agitation effects, have never been tested during balsamic-styled vinegar fermentation. Therefore, fermentations were initially conducted under static conditions without aeration with successive fermentations also being subjected to low (0.15 vvm min-1) and high (0.3 vvm min-1) aeration. The results showed improved acetification rates when cells were immobilized on corncobs under static conditions. Low aeration showed better acetification rates (1.45-1.56 g·L·day-1), while only free-floating cells were able to complete fermentations (1.2 g·L·day-1) under high aeration conditions. Overall, cells immobilized on corncobs showed higher acetification rates of 1.56 and 2.7 g·L·day-1 under low aeration and static fermentations, respectively. Oak wood chips were determined to be less efficient adsorbents due to their relatively smooth surface, while the rough surface and porosity of corncobs led to improved adsorption and, therefore, enhanced acetification rates.

Grape Pomace Extracts as Fermentation Medium for the Production of Potential Biopreservation Compounds.

Microbial spoilage causes food losses in the food industry and as such, the use of synthetic chemical preservatives is still required. The current study proposes the use of agro-waste, i.e., grape pomace extracts (GPE), as production medium for biopreservation compounds. Production kinetics, subsequent to optimization using response surface methodology (RSM) for biopreservation compounds production was studied for three yeasts using GPE broth as a fermentation medium. The results showed that the highest volumetric zone of inhibition (VZI) was 1.24 L contaminated solidified media (CSM) per mL biopreservation compounds used (BCU) when Candida pyralidae Y1117 was inoculated in a pH 3-diluted GPE broth (150 g L-1) incubated at 25 °C for 24 h. Similar conditions were applied for Pichia kluyveri Y1125 and P. kluyveri Y1164, albeit under slightly elongated fermentation periods (up to 28 h), prior to the attainment of a maximum VZI of only 0.72 and 0.76 L CSM mL-1 ACU, respectively. The potential biopreservation compounds produced were identified to be isoamyl acetate, isoamyl alcohol, 2-phenyl ethylacetate and 2-phenyl ethanol.

Ad libitum water consumption prevents exercise-associated hyponatremia and protects against dehydration in soldiers performing a 40-km route-march.

BACKGROUND: It remains unclear if ad libitum water drinking, as a hydration strategy, prevents exercise-associated hyponatremia (EAH) during prolonged exercise. The aim of this study was to determine the incidence of EAH within the broader context of fluid regulation among soldiers performing a 40-km route-march ingesting water ad libitum. METHODS: Twenty-eight healthy male soldiers participated in this observational trial. Pre- and post-exercise body mass, blood and urine samples were collected. Blood samples were assessed for serum sodium ([Na+]), glucose, creatinine, urea nitrogen (BUN), plasma osmolality, creatine kinase (CK), and plasma arginine vasopressin (AVP) concentrations. Plasma volume (PV) was calculated using hematocrit and hemoglobin. Urine samples were analyzed for osmolality and [Na+]. Water intake was assessed by weighing bottles before, during and after the march. The mean relative humidity was 55.7% (21.9-94.3%) and the mean dry bulb temperature was 27.1 °C (19.5 °C - 37.0 °C) during the exercise. RESULTS: Twenty-five soldiers (72 ± 10 kg) (Mean ± SD) completed the march in 09:11 ± 00:43 (hr:min). Participants consumed 736 ± 259 ml/h of water and lost 2.8 ± 0.9 kg (4.0% ± 1.4%, P < 0.05) of body mass. Significant (pre-march vs. post-march; P < 0.05) decreases in serum [Na+] (141 mmol/L vs. 136 mmol/L), plasma osmolality (303 mOsmol/kg H2O vs. 298 mOsmol/kg H2O), and serum creatinine (111 µmol/L vs. 101 µmol/L) and urine [Na+] (168 mmol/L vs. 142 mmol/L), as well as significant increases in plasma AVP (2 pg/ml vs. 11 pg/ml), plasma CK (1423 U/L vs. 3894 U/L) and urine osmolality (1035 mOsmol/kg H2O vs. 1097 mOsmol/kg H2O) were found. The soldier (72 kg) with the lowest post-exercise sodium level completed the march in 08:38. He drank 800 ml/h, lost 2% body mass, and demonstrated (pre-post) increases in plasma osmolality (294-314 mOsmol/kg H2O), BUN (20-30 mg/dl), AVP (2-16 pg/ml) and PV (41%). His urine osmolality decreased from 1114 mOsmol/kg H2O to 1110 mOsmol/kg H2O. No participants finished the route-march with a serum [Na+] indicating hypernatremia (range, 134-143 mmol/L). CONCLUSIONS: Ad libitum drinking resulted in 4% body mass loss with a 2 mmol/L serum [Na+] reduction in conjunction with high urine osmolality (> 1000 mOsmol/kg H2O) and plasma AVP. No single hydration strategy likely prevents EAH, but hypernatremia (cellular dehydration) was not seen despite > 2% body mass losses and high urine osmolality.

Body composition and somatotypes of male Zimbabwean Premier League football referees.

BACKGROUND: Elite athletes need to optimize their body composition to deliver world class performances and this argument could be extended to elite referees as well. Unfortunately, there is a scarcity of body composition information among football referees. The aim of the study was to determine and compare the body composition and somatotypes of male football referees and assistant referees who officiated in the 2013 Zimbabwe Premier Football League. METHODS: Forty-one participants (21 referees, 20 assistant referees; 8 FIFA, 33 ZIFA licensed referees) with a mean age of 34.89±5.13 years took part. They had on average 10.85±3.85 years of refereeing experience. The ISAK restricted anthropometric profile was used to measure body mass, height, skinfolds, girths and bone breadths, from which Body Mass Index (BMI), waist-to-hip ratio (WHR), percentage body fat and somatotype were calculated. RESULTS: The referees were significantly taller than the assistant referees. The FIFA referees had moderately more desirable anthropometric profiles than the ZIFA referees. With a mean somatotype of 2.62-4.65-2.65, the total sample could be classified as balanced mesomorphs. They had lower BMI and body fat percentages than that observed among referees from other nationalities in the available literature. CONCLUSIONS: The results add to the paucity of information on the body composition of football officials. Referees aiming to excel at higher levels need to obtain and maintain an ideal body composition since elite level football is intense and requires high fitness levels.

Kinetic modelling and optimisation of antimicrobial compound production by Candida pyralidae KU736785 for control of Candida guilliermondii.

Biological antimicrobial compounds from yeast can be used to address the critical need for safer preservatives in food, fruit and beverages. The inhibition of Candida guilliermondii, a common fermented beverage spoilage organism, was achieved using antimicrobial compounds produced by Candida pyralidae KU736785. The antimicrobial production system was modelled and optimised using response surface methodology, with 22.5 ℃ and pH of 5.0 being the optimum conditions. A new concept for quantifying spoilage organism inhibition was developed. The inhibition activity of the antimicrobial compounds was observed to be at a maximum after 17-23 h of fermentation, with C. pyralidae concentration being between 0.40 and 1.25 × 109 CFU ml-1, while its maximum specific growth rate was 0.31-0.54 h-1. The maximum inhibitory activity was between 0.19 and 1.08 l contaminated solidified media per millilitre of antimicrobial compound used. Furthermore, the antimicrobial compound formation rate was 0.037-0.086 l VZI ml-1 ACU h-1, respectively. The response surface methodology analysis showed that the model developed sufficiently described the antimicrobial compound formation rate 1.08 l VZI ml-1 ACU, as 1.17 l VZI ml-1 ACU, predicted under the optimum production conditions.

[Mild head injuries in the elderly]. / Leichtes Schädel-Hirn-Trauma im Alter.

In the elderly, particularly those over 80 years old, head injuries often occur as a result of falls. The majority suffer from mild head injury. After clarification of the initial symptoms in these patients, the main aim is to recognize or exclude intracranial injuries (bleeding). Demonstration of intracranial bleeding is possible with cranial computed tomography (CCT), which in contrast to magnetic resonance imaging (MRI) can be quickly carried out in most cases; however, most patients with mild head injury show no intracranial bleeding. The performance of CCT and the often necessary hospital admission place a severe physical and psychological burden on the elderly. The plasma parameter S100B, combined with the clinical findings, is a valuable instrument for decision making in the management of elderly patients with mild head injury.

Atypical Femoral Fractures-Ongoing and History of Bone-Specific Therapy, Concomitant Diseases, Medications, and Survival.

Although atypical femoral fractures (AFFs) are generally rare events; several studies have indicated a potential link between AFF and long-term bone-specific therapies (BSTs). The aim of this study was to analyze the frequency of AFF and potential associations with prior or ongoing BST. A total of 8851 Caucasian female and male patients with de novo hip fractures treated in the largest Austrian level 1 trauma center from 2000 to 2013 were selected. Of the total, 194 patients with a de novo low-traumatic subtrochanteric or shaft fractures were identified: 35 atypical and 159 typical fractures. Of these patients, concomitant diseases, medication, previous fractures, and survival data were retrieved and analyzed. Female patients in both groups were significantly older. The median survival was significantly shorter in patients with AFF (9 vs 18 months; p < 0.0001). Cardiovascular disease, sarcopenia, chronic kidney disease, type 2 diabetes, smoking (past or current history), and prevalent fragility fractures were more frequent in AFF patients, as well as the concomitant use of phenprocoumon, furosemide, and sulfonylurea. Although the number of patients with current BST was less in (14.5%) both groups, more patients in the AFF group were previously treated with BST (71% vs 49%; p = 0.016), and they received these therapies for a longer time period. A combination of severe comorbidities, long-term pharmaceutical therapies, and a history of previous or ongoing BST was associated with an increased individual risk for AFF.

Total Body Water, Electrolyte, and Thermoregulatory Responses to Ad Libitum Water Replacement Using Two Different Water Delivery Systems During a 19-km Route March.

Hands-free hydration systems are often advocated for improved hydration and performance in military populations. The aim was to assess whether such systems indeed result in improved hydration in exercising soldiers. Subjects were required to complete a route march while consuming water ad libitum from either a hydration bladder (BG) or traditional canteen (CG). Water intakes of 538 ml·h⁻¹ (BG) and 533 ml·h⁻¹ (CG) resulted in no differences for changes in body mass, serum [Na], plasma osmolality, total body water, or time required to complete the march. There were no differences between peak exercise core temperature of the BG (38.9° C) and CG (38.7° C) groups. There were no differences between the groups for fluid balance, thermoregulation, or performance. This is a not a surprising finding because the amount of fluid consumed ad libitum is determined by changes in serum osmolality and not the fluid delivery system as often proposed.

Exercise-associated hyponatremic encephalopathy and exertional heatstroke in a soldier: High rates of fluid intake during exercise caused rather than prevented a fatal outcome.

Athletes are often advised to drink in order to "fully replace bodyweight losses" in order to prevent exertional heatstroke (EHS) during exercise in the heat. There is little evidence that "dehydration" in the range experienced by athletes adversely affects thermoregulation or is the exclusive cause of EHS. In contrast it is established that excess fluid intake can cause exercise-associated hyponatremia (EAH) sometimes associated with encephalopathy (EAHE). As part of a series of experiments to determine optimal fluid replacement during exercise in the heat, we studied a group of exceptionally well-conditioned and heat-adapted members of the South African National Defence Force. A 20 year old male started a time restricted 50 km route-march in a dry bulb temperature that reached 37.5°C (WBGT of 33.6°C, relative humidity of 85%). Pre-march plasma osmolality, serum [Na(+)] and total body water measures indicated euhydration. Fluid was available ad libitum and isotonic sports drinks at 5 km intervals. Fluid intake and core body temperature (Tc) were recorded throughout while he was tracked by a global positioning system measuring distance travelled, position and speed. Comparing the total fluid intake of the soldier (12930 mL) to the rest of the participants (mean intake of 9 038 mL) up to 40 km, it is evident that his intake was 3892 mL (approximately 300 mL h(-1)) more than the mean for group. At approximately 17h14 the soldier was found lying by himself at the side of the route, 2.24 km from the finish point. He passed away the next day in a medical care facility. This tragic event provides the valuable opportunity to present data on the pacing, temperature regulation and fluid consumption of an exceptional athlete during the development of a fatal case of combined EAHE and EHS. Pacing, fluid intake, Tc and environmental condition data are presented for 5 km intervals throughout the march. We propose a novel hypothesis on the possible contribution of EAHE to the development of EHS.

Parameters of bone health and fracture risk in older female fall victims: what do they tell us?

INTRODUCTION: A common and severe osteoporotic type fracture in older women is a hip fracture. It is not clear whether bone turnover parameters measured in blood can be a useful tool to predict fracture risk in older persons. The aim of the current study was to assess the association between serum vitamin D (25OHD) levels, parathyroid hormone (PTH), total osteocalcin, carboxy-terminal collagen crosslinks (CTX) and hip fractures in older fallers. MATERIAL AND METHODS: A single centre, prospective cohort study of bone parameters was carried out in 400 female patients aged > 70 years including 200 with a hip fracture and 200 without fractures, admitted after a fall between January 2005 and December 2007. RESULTS: Serum total osteocalcin levels were significantly lower in the fracture group compared to the non-fracture group (20.4 ng/ml vs 26.1 ng/ml, respectively, p = 0.01). This finding remained significant after exclusion of the patients on bisphosphonates (p = 0.003). There were no significant differences in 25OHD, PTH or CTX levels between the two groups. CONCLUSION: In the current study there was an association between the presence of a hip fracture and lower total serum osteocalcin concentrations. This could be indicative of low bone turnover osteoporosis in these women. An association for other bone turnover markers was lacking.

Effects of a carbohydrate-electrolyte solution on cognitive performance following exercise-induced hyperthermia in humans.

BACKGROUND: There is limited information on the effects of sports drinks on cognitive function after exercise in the heat. We aimed to investigate the effects of ingesting a commercially available carbohydrate-electrolyte (CHO) solution on cognitive performance following exercise-induced hyperthermia. METHODS: Twelve participants completed three practices of cognitive tests, one full familiarisation and two experimental trials in an environmental chamber (dry bulb temperature: 30.2 ± 0.3°C, relative humidity: 70 ± 3%). The experimental trials consisted of five cognitive tests (symbol digit matching, search and memory, digit span, choice reaction time and psychomotor vigilance test) performed before and after a 75-min run on a treadmill at 70% VO2 max. One ml/kg body mass of a 6.8% CHO solution or placebo was consumed at the start, every 15 min during exercise and between cognitive tests after exercise. Core temperature, heart rate, blood glucose concentrations, subjective ratings and cognitive performance were assessed (symbol digit matching, search and memory, digit span, choice reaction time and psychomotor vigilance). RESULTS: Participants were hyperthermic at the end of the run (placebo: 39.5 ± 0.4°C, CHO: 39.6 ± 0.5°C; Mean ± SD; p = 0.37). The change in blood glucose was higher with CHO ingestion (1.6, 0.7 to 4.5 mmol/L) (median, range) than with placebo ingestion (0.9, -0.1 to 4.7 mmol/L; p < 0.05). CHO ingestion reduced the maximum span of digits memorized, in contrast to an increase in maximum span with placebo ingestion (p < 0.05). CHO solution had no effect on other cognitive tests (p > 0.05). CONCLUSIONS: These results suggest that CHO solution ingestion may impair short-term memory following exertional heat stress.

[Procedural organisation: surgical and anaesthesiological management in hip fractures]. / Ablauforganisation - unfallchirurgisches und anästhesiologisches Management bei Hüftfrakturen.

In patients with hip fractures, in order to reduce the high number of general complications and those associated with the specific treatment, the functional loss and cognitive impairment, implementation of co-ordinated, multidisciplinary treatment pathways, and rehabilitation, is mandatory. The imminent treatment of proximal femoral fracture consists of major orthopaedic surgery in most cases (total or partial hip arthroplasty, osteosynthesis). After the diagnosis of a hip fracture, an adequate pain medication should be initiated. The decision making for the fracture treatment includes fracture type, patient's age, cognitive function, mobility before the fall and functional demands of the patient in the context of patients life expectancy and goals of care. The anaesthesiological evaluation focuses on risk assessment. Medical abnormalities should be optimized within 24 to 48 h, or an increased perioperative risk due to comorbidities has to be accepted. The timing and the course of further preoperative diagnostic examinations and therapeutic interventions should be co-ordinated between the involved medical disciplines. After the operation a structured screening for delirium should be initiated and further evaluation of patient's nutrition, fall-associated medication, living conditions and osteoporosis treatment has to be performed.

Ad libitum vs. restricted fluid replacement on hydration and performance of military tasks.

INTRODUCTION: The primary objective was to evaluate the effect of ad libitum vs. restricted fluid replacement protocol on hydration markers and performance in selected military tasks. The secondary objective was to determine if 300 ml x h(-1) could be considered a safe minimum fluid intake under the experimental conditions. METHODS: Data were collected simulating a route march over 16 km. There were 57 subjects who participated in the study. RESULTS: The mean pre-exercise body mass of the ad libitum group was 70.4 +/- 13.3 (SD) kg compared to 69.3 +/- 8.9 kg in the restricted group. The mean total fluid intake of the ad libitum group was 2.1 +/- 0.9 L compared to 1.2 +/- 0.0 L in the restricted group. The ad libitum and restricted intake groups, respectively, lost a mean of 1.05 kg +/- 0.77 (1.5%) and 1.34 kg +/- 0.37 (1.9%). Calculated sweat rate was 608 +/- 93 ml x h(-1) compared to 762 +/- 162 ml x h(-1) in the ad libitum group. DISCUSSION: There were no significant differences for either urine specific gravity (USG) or urine osmolality (UOsm) before or after the exercise. It is not clear whether fluid intake and calculated sweat rates are causally related or explained by their codependence on a third variable; for example, the exercising metabolic rate. Thus, 300 ml x h(-1) intake could be considered a current safe minimum water intake for soldiers of similar mass under similar experimental conditions, namely similar exercise durations at equivalent exercise intensities in a moderate, dry climate.

Solid organ transplantation: technical progress meets human dignity: a review of the literature considering elderly patients' health related quality of life following transplantation.

INTRODUCTION: Many transplant studies in elderly patients focus on survival and mortality rates. It was the aim of this review to evaluate publications dealing with individual patient performance and independence. METHODS: The literature search included all articles retrievable for the hit "transplantation in elderly recipients" between 1960 and 2010. For quality search the inclusion criteria were as follows: older than 60 years and transplanted kidney, liver, heart, lung or pancreas from a deceased or living donor. We focussed on parameters concerning quality of life, frailty, nutritional status/weight loss, drugs/interactions/polypharmacy, gait/osteoporosis/fracture, delirium/dementia and geriatric assessment to address physical and psychosocial functionality of elderly recipients. RESULTS: The initial hit list contained 1427 citations from electronic databases. 249 abstracts thereof were selected for full review. A total of 60 articles met final inclusion criteria. Finally, only five studies met the qualitative inclusion criteria as listed above. CONCLUSION: The number of elderly patients placed on waiting lists has increased dramatically and will further grow. Interdisciplinary collaboration and distinct patient selection is recommended in most of the studies. However, data concerning quality of life and related parameters in elderly transplant recipients are rare.

Trained humans can exercise safely in extreme dry heat when drinking water ad libitum.

Guidelines to establish safe environmental exercise conditions are partly based on thermal prescriptive zones. Yet there are reports of self-paced human athletic performances in extreme heat. Eighteen participants undertook a 25-km route march in a dry bulb temperature reaching 44.3°C. The mean (± s) age of the participants was 26.0 ± 3.7 years. Their mean ad libitum water intake was 1264 ± 229 mL · h(-1). Predicted sweat rate was 1789 ± 267 mL · h(-1). Despite an average body mass loss of 2.73 ± 0.98 kg, plasma osmolality and serum sodium concentration did not change significantly during exercise. Total body water fell 1.47 kg during exercise. However, change in body mass did not accurately predict changes in total body water as a 1:1 ratio. There was a significant relationship (negative slope) between post-exercise serum sodium concentration and changes in both body mass and percent total body water. There was no relationship between percent body mass loss and peak exercise core temperature (39 ± 0.9°C) or exercise time. We conclude that participants maintained plasma osmolality, serum sodium concentration, and safe core temperatures by (1) adopting a pacing strategy, (2) high rates of ad libitum water intake, and (3) by a small reduction in total body water to maintain serum sodium concentration. Our findings support the hypothesis that humans are the mammals with the greatest capacity for exercising in extreme heat.

Changes in total body water content during running races of 21.1 km and 56 km in athletes drinking ad libitum.

OBJECTIVE: To measure changes in body mass (BM), total body water (TBW), fluid intake, and blood biochemistry in athletes during 21.1-km and 56-km foot races. DESIGN: Observational study. SETTING: 2009 Two Oceans Marathon, South Africa. PARTICIPANTS: Twenty-one (21.1 km) and 12 (56 km) participants were advised to drink according to thirst or their own race drink plan (ad libitum). MAIN OUTCOME MEASURES: Body mass, TBW, plasma osmolality, plasma sodium (p[Na]), and plasma total protein ([TP]) concentrations were measured before and after race. Fluid intake was recorded from recall after race. RESULTS: Significant BM loss occurred in both races (21.1 km; -1.4 ± 0.6 kg; P < 0.000 and 56 km; -2.5 ± 1.1 kg; P < 0.000). Total body water was reduced in the 56-km race (-1.4 ± 1.1 kg; P < 0.001). A negative linear relationship was found between percentage change (%Δ) in TBW and %Δ in BM in the 56-km runners (r = 0.6; P < 0.01). Plasma osmolality and [TP] increased significantly in the 56-km runners (6.8 ± 8.2 mOsm/kg H2O; P < 0.05 and 5.4 ± 4.4 g/L; P < 0.01, respectively), but all other biochemical measures were within the normal range. CONCLUSIONS: Although TBW decreased in the 56-km race and was maintained in the 21.1-km race, the change in TBW over both races was less than the BM, suggesting that not all BM lost during endurance exercise is a result purely of an equivalent reduction in TBW. These findings support the interpretation that the body primarily defends p[Na] and not BM during exercise and that a reduction in BM can occur without an equivalent reduction in TBW during prolonged exercise. Furthermore, these data support that drinking without controlling for BM loss may allow athletes to complete these events.

Nutritional supplementation affects postoperative oxidative stress and duration of hospitalization in patients with hip fracture.

OBJECTIVE: The objective of this prospective randomized controlled study was to investigate the effect of nutritional supplementation on postoperative oxidative stress and duration of hospitalization in elderly patients with hip fracture. METHODS: A total of fourteen women (= SG) with hip fracture received individually adapted supplements enriched with protein and antioxidants postoperatively, nine served as unsupplemented controls (= CG). Blood samples were taken preoperatively (T1), on the day of discharge from hospital (T2) and three weeks thereafter (T3). Plasma concentrations of albumin and total protein (TP) were measured by autoanalysis, advanced oxidation protein products (AOPP) and the total antioxidant capacity (TAC) were determined photometrically. Malondialdehyde (MDA) levels were analyzed by HPLC. RESULTS: Postoperatively, there was a significant (T1 > T2, p< 0.01) decrease in plasma albumin, TP and TAC, followed by a significant (p< 0.05) increase in the period T2-T3 in the CG, but not in the SG. This resulted in significant differences in TP (T2: SG > CG, p< 0.05) and TAC (T2: SG > CG, p< 0.01) between the investigated groups. Postoperatively, the plasma levels of AOPP and MDA increased significantly (T1 < T2, p< 0.01) in both groups, and remained at the significantly (AOPP: T1 < T3, p< 0.05; MDA: T1 < T3, p< 0.01) elevated level in the CG, but not in the SG (T2 > T3, p< 0.01). Consequently, the oxidant markers MDA and AOPP were significantly positively (p< 0.01), TAC and albumin significantly negatively (p< 0.05) related to duration of hospital stay in both groups. CONCLUSIONS: Individualized nutritional supplementation may reduce postoperative oxidative stress and shorten duration of hospitalization in patients with hip fracture.