Incidence of Hyponatremia During a Continuous 246-km Ultramarathon Running Race.

Purpose: The purpose of this observational study was to examine the incidence of exercise-associated hyponatremia (EAH) in a 246-km continuous ultra-marathon. Methods: Over 2 years, 63 male finishers of the annual Spartathlon ultra-marathon foot race from Athens to Sparta, Greece were included in the data analysis. A blood sample was drawn from an antecubital vein the day before the race as well as within 15 min post-race and analyzed for sodium concentration. During the second year of data collection, blood was also drawn at the 93-km checkpoint (n = 29). Height and weight were measured pre and post-race. Results: Mean race time of all subjects was 33 ± 3 h with a range of 23.5 and 36.0 h. Of the 63 finishers recruited, nine began the race with values indicative of mild hyponatremia. Seven runners were classified as hyponatremic at the 93-km checkpoint, three of whom had sodium levels of severe hyponatremia. After the race, 41 total finishers (65%) developed either mild (n = 27, 43%) or severe hyponatremia (n = 14, 22%). Mean change in bodyweight percentage and serum sodium from pre-race to post-race was -3.6 ± 2.7% (-2.5 ± 1.9 kg) and -6.6 ± 5.6 mmol·L-1, respectively. Pre-race serum sodium level was not a significant predictor of post-race serum sodium levels (ß = 0.08, R 2 = 0.07, P = 0.698), however, there was a significant negative association between change in bodyweight percentage and post-race serum sodium concentration (ß = -0.79, R 2 = 0.29, P = 0.011). Conclusion: The incidence of EAH of 52 and 65%, when excluding or including these individuals with pre-race hyponatremia, was the highest reported in current literature.

Breast milk fat concentration and fatty acid pattern during the first six months in exclusively breastfeeding Greek women.

PURPOSE: To determine fat and fatty acid (FA) profile of Greek mother's milk during the first 6 months of exclusive breastfeeding and to examine their correlation with dietary and other maternal characteristics. METHODS: Milk samples and dietary records were obtained by mothers at 1st (n = 64), 3rd (n = 39), and 6th (n = 24) month postpartum. Fatty acid methylesters were separated and quantified by gas chromatography (GC/FID) and fat concentration by the creamatocrit method. RESULTS: At the 3 time points, milk fat concentration ranged between 26.3 and 30.2 g/l (p > 0.05). Milk's FA composition was expressed as weight percentage (% wt/wt of all FAs detected with a C6 to C22 chain length). Maternal macronutrient and FA dietary intake, as well as the FAs' profile in maternal milk, remained constant over the 6 months. Saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) represented approx. 46, 35, and 18 % of all FAs, while ω6 and ω3 PUFA were 17.4 and 0.8 %, respectively. Body weight gain during pregnancy was positively related to breast milk's concentration in SFA (p < 0.01) and negatively to milk's concentration in MUFA (p < 0.01). Age and parity were also independent factors affecting the FA profile in maternal milk. A strong positive effect was found during the first month postpartum, between mother's PUFA intake and the concentration of PUFA, ω3 fatty acids, docosahexaenoic and linoleic acid (LA) in the milk, while MUFA intake was strongly correlated with the concentration of PUFA, ω6 fatty acids, and LA. CONCLUSION: This study is among few in literature to determine FA profile of breast milk in European populations and verified certain dietary factors that influence this profile. Maternal PUFA and MUFA intake were found to be important factors affecting breast milk's FA profile.

One day of moderate energy deficit reduces fasting and postprandial triacylglycerolemia in women: the role of calorie restriction and exercise.

BACKGROUND & AIMS: Fasting and postprandial hypertriacylglycerolemia are important cardiovascular risk factors in women. We sought to examine the effects of acute (1 day), moderate ( approximately 2 MJ) energy deficit induced by calorie restriction, exercise, or combination of both on fasting and postprandial triacylglycerol (TAG) metabolism in women. METHODS: Six healthy premenopausal women performed four oral fat tolerance tests in the morning after a day of a) rest (control), b) calorie restriction ( approximately 2 MJ), c) exercise (net deficit of approximately 2 MJ) and d) calorie restriction-plus-exercise (total energy deficit of approximately 2 MJ). RESULTS: All energy deficit trials significantly reduced fasting and postprandial total plasma TAG concentrations by 15-23% and 12-23%, respectively, and triacylglycerol-rich lipoprotein TAG concentrations by 37-43% and 25-39%, respectively, compared with the control condition (P<0.05). Postprandial, but not fasting, total TAG concentrations were approximately 12% lower after exercise compared with diet-induced energy deficit (P=0.05). CONCLUSIONS: Acute, moderate energy deficit independently of its origin (i.e. diet or exercise or combination of both) reduces fasting and postprandial triacylglycerolemia in women. Exercise elicits a somewhat greater effect than calorie restriction in the postprandial state. The acute effect of diet and exercise should be taken into account when studying the long-term effects of weight loss and exercise training on TAG metabolism.

Exercise of low energy expenditure along with mild energy intake restriction acutely reduces fasting and postprandial triacylglycerolaemia in young women.

A single bout of prolonged, moderate-intensity endurance exercise lowers fasting and postprandial TAG concentrations the next day. However, the TAG-lowering effect of exercise is dose-dependent and does not manifest after light exercise of low energy cost ( < 2 MJ). We aimed to investigate whether superimposing mild energy intake restriction to such exercise, in order to augment total energy deficit, potentiates the hypotriacylglycerolaemic effect. Eight healthy, sedentary, premenopausal women (age 27.1 (sem 1.3) years; BMI 21.8 (sem 0.9) kg/m2) performed two oral fat tolerance tests in the morning on two different occasions: once after a single bout of light exercise (100 min at 30 % of peak oxygen consumption; net energy expenditure 1.04 (sem 0.01) MJ) coupled with mild energy intake restriction (1.39 (sem 0.22) MJ) on the preceding day, and once after resting coupled with isoenergetic feeding on the preceding day (control). Fasting plasma TAG, TAG in the TAG-rich lipoproteins (TRL-TAG) and serum insulin concentrations were 18, 34 and 30 % lower, respectively, after exercise plus diet compared with the control trial (P < 0.05). Postprandial concentrations of plasma TAG and TRL-TAG were 19 and 27 % lower after exercise plus diet compared with the control condition (P < 0.01), whereas postprandial insulin concentrations were not different. It is concluded that a combination of light exercise along with mild hypoenergetic diet may be a practical and feasible intervention to attenuate fasting and postprandial triacylglycerolaemia, especially for people who cannot exercise for prolonged periods of time at moderate-to-high intensities, such as many sedentary individuals.

The Gene-Diet Attica investigation on childhood obesity (GENDAI): overview of the study design.

BACKGROUND: There is limited evidence on the role of genetic and environmental factors in the etiology of childhood obesity, a major health problem worldwide. METHODS: The Gene-Diet Attica Investigation on childhood obesity (GENDAI) evaluates the contributions to and pivotal interactions of genetic, dietary and physical activity variables on children's weight. We describe the design, methodology, and present preliminary data. So far, 920 participants have been enrolled and the final projected sample is 1000 fifth- and sixth-grade students from selected elementary schools in Attica (10-14 years). In this school-based cross-sectional study, more than 400 variables describing anthropometric, dietary, clinical, genetic, sociodemographic and other lifestyle characteristics were collected from participating children and their families. RESULTS: Increased body mass index was identified in 39.3% of subjects (30.5% overweight and 8.8% obese), with males presenting a more unfavorable metabolic profile, i.e., higher blood lipids, glucose, and insulin, compared to females. Normal-weight children had a significant advantage when compared to all children of increased weight in terms of lipid profile and insulin, as well as behaviors examined. Specifically, normal-weight children exhibited less skipping of meals and less sedentary activities. CONCLUSIONS: The overall high prevalence of overweight and obesity in the current population is significant and underscores the need for environmental and genetic information that will shed light on the phenomenon of childhood obesity.

Exertional Rhabdomyolysis during a 246-km continuous running race.

BACKGROUND: To evaluate the effect of continuous, moderate-intensity ultra-endurance running exercise on skeletal muscle and hepatic damage, as indicated by serum enzyme activity measured immediately following the race. METHODS: Thirty-nine runners of the Spartathlon race (a 246-km continuous race from Athens to Sparta, Greece) who managed to complete the race within the 36-h limit participated in this study. Mean finishing time of the study participants was 33.3+/-0.5 h and their average age, height, and body mass were 41+/-1 yr, 174+/-1 cm, and 67.5+/-1.1 kg, respectively. Blood samples, taken a day before and immediately after completion of the race, were assayed for the following variables: creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyltransferase (gamma-GT). RESULTS: A dramatic increase in most of muscle and liver damage indicators was observed. The mean values for CK, LDH, AST, and ALT after the race were 43,763+/-6,764, 2,300+/-285, 1,182+/-165, and 264+/-37 IU.L, respectively. These values were 29,384+/-4,327, 585+/-89, 5,615+/-902, and 1,606+/-331% higher than the corresponding values before the race (P<0.001) for CK, LDH, AST, and ALT, respectively. However, there was not a significant increase in gamma-GT levels. CONCLUSION: Muscle and liver damage indicators were elevated at the highest level ever reported as a result of prolonged exercise, although no severe symptoms that required hospitalization were observed in any of the participants. The data suggest that even moderate-intensity exercise of prolonged duration can induce asymptomatic exertional rhabdomyolysis.