Regulation of electrolyte and fluid metabolism in multi-stage ultra-marathoners.

The purposes of this study were (i) to determine the prevalence of exercise-associated hyponatremia (EAH) in multi-stage ultra-marathoners and (ii) to gain more insight into fluid and electrolyte regulation during a multi-stage race. Body mass, sodium concentration ([Na⁺]), potassium concentration ([K⁺]), creatinine, urea, specific gravity, and osmolality in urine were measured in 25 male ultra-marathoners in the 'Swiss Jura Marathon' 2008 with 11,000 m gain of altitude over 7 stages covering 350 km, before and after each stage. Haemoglobin, haematocrit, creatinine, urea, [Na⁺], [K⁺], and osmolality were measured in plasma before stage 1 and after stages 1, 3, 5, and 7. Two athletes (8%) showed plasma [Na⁺] <135 mmol/l. Body mass, plasma [Na⁺], and plasma [K⁺] remained unchanged (p>0.05). Urine specific gravity (p<0.001) and osmolality in both plasma (p<0.01) and urine (p<0.001) were increased and haematocrit (p<0.0001), haemoglobin (p<0.0001) and plasma albumin were decreased (p<0.001). Plasma volume (p<0.01) and plasma urea (p<0.001) were increased. The K⁺/Na⁺ ratio in urine increased >1.0 after each stage and returned to <1.0 the morning of the next stage (p<0.001). To summarize, more sodium than potassium was excreted during rest. The increased urinary sodium losses during rest are compatible with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) or the cerebral salt-wasting syndrome (CSWS). Further studies are needed to determine the antidiuretic hormone (ADH) and both the atrial natriuretic peptide (ANP) and the brain natriuretic peptide (BNP) during multi-stage races.

A comparison of fat mass and skeletal muscle mass estimation in maleultra-endurance athletes using bioelectrical impedance analysis anddifferent anthropometric methods / Comparación de la masa grasa y muscular estimada en atletas varones de ultra-resistencia utilizando la bioimpedancia eléctrica y diferentes métodos antropométricos

Two hundred and fifty seven male Caucasian ultraendurance athletes were recruited, pre-race, before different swimming, cycling, running and triathlon races. Fat mass and skeletal muscle mass were estimated using bioelectrical impedance analysis (BIA) and anthropometric methods in order to investigate whether the use of BIA or anthropometry would be useful under field conditions. Total body fat estimated using BIA was significantly high (P < 0.001) compared with anthropometry. When the results between BIA and anthropometry were compared, moderate to low levels of agreement were found. These results were in accordance with the differences found in the Bland-Altman analysis, indicating that the anthropometric equation of Ball et al. had the highest level of agreement (Bias = -3.0 ± 5.8 kg) with BIA, using Stewart et al. (Bias = -6.4 ± 6.3 kg), Faulkner (Bias = -4.7 ± 5.8 kg) and Wilmore-Siri (Bias = -4.8 ± 6.2 kg). The estimation of skeletal muscle mass using BIA was significantly (P < 0.001) above compared with anthropometry. The results of the ICC and Bland-Altman method showed that the anthropometric equation from Lee et al. (Bias = -5.4 ± 5.3 kg) produced the highest level of agreement. The combined method of Janssen et al. between anthropometry and BIA showed a lower level of agreement (Bias = -12.5 ± 5.7 kg). There was a statistically significant difference between the results derived from the equation of Lee et al. and Janssen et al. (P < 0.001). To summarise, the determination of body composition in ultra-endurance athletes using BIA reported significantly high values of fat and skeletal muscle mass when compared with anthropometric equations (AU)

Se reclutaron a 257 hombres caucasianos que eran atletas de alto rendimiento, antes de competir en diferentes pruebas triatlón de natación, ciclismo y carrera. Se estimaron la masa grasa y la masa de músculo esquelético utilizando un análisis de impedancia bioeléctrica (BIA) y métodos antropométricos con el fin de investigar si el uso de BIA o de la antropometría sería útil en tales condiciones de campo. La grasa corporal total estimada por BIA fue significativamente mayor en comparación con la antropometría (P < 0,001). Cuando se compararon los resultados entre BIA y antropometría, se encontraron niveles de concordancia bajos a moderados. Estos resultados concuerdan con las diferencias halladas con el análisis Bland-Altman, lo que indica que la ecuación antropométrica de Ball et al. posee el mayor grado de concordancia (desviación = -3,0 ± 5,8 kg) con BIA, con Stewart et al. (desviación = -6,4 ± 6,3 kg), Faulkner (desviación = -4,7 ± 5,8 kg) y Wilmore-Siri (desviación = -4,8 ± 6,2 kg). La estimación de la masa de músculo esquelético fue significativamente superior con BIAS que con antropometría (P < 0,001). Los resultados de la ICC y del método Bland-Altman muestran que la ecuación antropométrica de Lee et al. (desviación = -5,4 ± 5,3 kg) produjo el mayor grado de concordancia. El método combinado de Janssen et al. entre antropometría y BIA mostró el menor grado de concordancia (desviación = -12,5 ± 5,7 kg). Hubo una diferencia estadísticamente significativa entre los resultados derivados de la ecuación de Lee et al. y de la de Janssen et al. (P < 0,001). En resumen, la determinación de la composición corporal en atletas de alto rendimiento utilizando BIA produjo valores significativamente mayores de masa grasa y músculo esquelético en comparación con las ecuaciones antropométricas (AU)

Maintained serum sodium in male ultra-marathoners--the role of fluid intake, vasopressin, and aldosterone in fluid and electrolyte regulation.

Exercise-associated hyponatremia (EAH) is a well know electrolyte disorder in endurance athletes. Although fluid overload is the most like etiology, recent studies, however, argued whether EAH is a disorder of vasopressin secretion. The aims of the present study were to investigate (i) the prevalence of EAH in male ultra-marathoners and (ii) whether fluid intake, aldosterone or vasopressin, as measured by copeptin, were associated with post-race serum sodium concentration ([Na+]). In 50 male ultra-marathoners in a 100 km ultra-marathon, serum [Na+], aldosterone, copeptin, serum and urine osmolality, and body mass were measured pre- and post-race. Fluid intake, renal function parameters and urine excretion were measured. No athlete developed EAH. Copeptin and aldosterone increased; a significant correlation was found between the change in copeptin and the change in serum [Na+], no correlation was found between aldosterone and serum [Na+]. Serum [Na+] increased by 1.6%; body mass decreased by 1.9 kg. The change in serum [Na+] and body mass correlated significantly and negatively. The fluid intake of ~ 0.58 l/h was positively related to the change in body mass and negatively to both post-race serum [Na+] and the change in serum [Na+]. We conclude that serum [Na+] was maintained by both the mechanisms of fluid intake and the hormonal regulation of vasopressin.

Do ultra-runners in a 24-h run really dehydrate?

BACKGROUND: Loss of body mass during a 24-h run was considered to be a result of dehydration. AIMS: We intended to quantify the decrease in body mass as a loss in fat mass or skeletal muscle mass and to quantify the change in hydration status. METHODS: Body mass, fat mass, skeletal muscle mass, haematocrit, plasma sodium and urinary specific gravity were measured in 15 ultra-marathoners in a 24-h run. RESULTS: Body mass decreased by 2.2 kg (p = 0.0009) and fat mass decreased by 0.5 kg (p = 0.0084). The decrease in body mass correlated to the decrease in fat mass (r = 0.72, p = 0.0024). Urinary specific gravity increased from 1.012 to 1.022 g/mL (p = 0.0005). CONCLUSIONS: The decrease in body mass and the increase in urinary specific gravity indicate dehydration. The decrease in body mass was correlated to the decrease in fat mass and therefore not only due to dehydration.

A comparison of fat mass and skeletal muscle mass estimation in male ultra-endurance athletes using bioelectrical impedance analysis and different anthropometric methods.

Two hundred and fifty seven male Caucasian ultra-endurance athletes were recruited, pre-race, before different swimming, cycling, running and triathlon races. Fat mass and skeletal muscle mass were estimated using bioelectrical impedance analysis (BIA) and anthropometric methods in order to investigate whether the use of BIA or anthropometry would be useful under field conditions. Total body fat estimated using BIA was significantly high (P < 0.001) compared with anthropometry. When the results between BIA and anthropometry were compared, moderate to low levels of agreement were found. These results were in accordance with the differences found in the Bland-Altman analysis, indicating that the anthropometric equation of Ball et al. had the highest level of agreement (Bias = -3.0 ± 5.8 kg) with BIA, using Stewart et al. (Bias = -6.4 ± 6.3 kg), Faulkner (Bias = -4.7 ± 5.8 kg) and Wilmore-Siri (Bias = -4.8 ± 6.2 kg). The estimation of skeletal muscle mass using BIA was significantly (P < 0.001) above compared with anthropometry. The results of the ICC and Bland-Altman method showed that the anthropometric equation from Lee et al. (Bias = -5.4 ± 5.3 kg) produced the highest level of agreement. The combined method of Janssen et al. between anthropometry and BIA showed a lower level of agreement (Bias = -12.5 ± 5.7 kg). There was a statistically significant difference between the results derived from the equation of Lee et al. and Janssen et al. (P < 0.001). To summarise, the determination of body composition in ultra-endurance athletes using BIA reported significantly high values of fat and skeletal muscle mass when compared with anthropometric equations.

Upper body skinfold thickness is related to race performance in male Ironman triathletes.

We investigated the association between skinfold thickness and race performance in male and female Ironman triathletes. Skinfold thicknesses at 8 sites and percent body fat were correlated to total race time including the split times for the 3 sub disciplines, for 27 male and 16 female Ironman athletes. In the males, percent body fat (r=0.76; p<0.0001), the sum of upper body skinfolds (r=0.75; p<0.0001) and the sum of all 8 skinfolds (r=0.71; p<0.0001) were related to total race time. Percent body fat (r=-0.67; p<0.001), the sum of upper body skinfolds (r=-0.63, p=0.0004) and the sum of all 8 skinfolds (r=-0.59; p<0.001) were also associated with speed in cycling during the race. In the females, none of the skinfold thicknesses showed an association with total race time, average weekly training volume or speed in the sub disciplines in the race. The results of this study indicate that low skinfold thicknesses of the upper body are related to race performance in male Ironman triathletes, but not in females.

Participation and performance trends in ultra-triathlons from 1985 to 2009.

We examined the changes in participation and performance trends in ultra-triathlons, from the Double Iron (7.6 km swimming, 360 km cycling, 84.4 km running) to the Deca Iron (38 km swimming, 1800 km cycling, 422 km running), between 1985 (first year of a Double Iron) and 2009 (25 years). The mean finish rate for all distances and races was 75.8%. Women accounted for ∼8-10% of the ultra-triathlons starters. For Double and Triple Iron, the number of finishers per year increased, from 17 to 98 and from 7 to 41, respectively. In the Deca Iron, the finishers per race have remained <20 since the first event was held, up to 2009. Concerning World best performances, the men were ∼19% faster than the women in both the Double and Triple Iron, and ∼30% faster in a Deca Iron. With the increasing length of ultra-triathlons, the best women became relatively slower compared with the best men. Further investigations are required to understand why this gender difference in total performance time increased with the distance in ultra-triathlons.

Swimming in ice cold water.

INTRODUCTION: We investigated two athletes swimming in 4°C for 23 min (1.3 km, swimmer 1) and 42 min (2.2 km, swimmer 2), respectively. MATERIALS AND METHODS: Pre swim, percent body fat was determined; post swim, core temperature was measured. RESULTS: The core temperature of swimmer 2 was: 37.0°C immediately before the start, 32°C 20 min after getting out of the water, and 35.5°C 80 min after finishing the swim. CONCLUSION: We assume that the higher skin-fold thickness and body fat of swimmer 2 enabled him to perform longer. In addition to this, mental power and experience in cold water swimming must be considered. In any athlete aiming at swimming in water of less than 5°C, body core temperature and heart rate should be continuously monitored in order to detect a body core temperature below 32°C and arrhythmia to pull the athlete out of the water before life-threatening circumstances occur.

Skin-fold thickness and training volume in ultra-triathletes.

We investigated the relationship between variables of anthropometry and training volume on race performance in 29 male non-professional ultra-triathletes. Anthropometric variables were determined in order to calculate body mass index, sum of skin-folds and percent body fat. Participants kept a comprehensive training diary recording their training volume in hours and kilometres in the 3 months before the race. The relationship of anthropometry and average weekly training volume with race performance was investigated with linear regression analysis. The sum of 8 skin-fold thicknesses was associated with total race time (r (2)=0.33, p<0.001), whereas the average weekly training volume was not (r (2)=0.00, p>0.05). The training volume showed no association with the sum of 8 skin-folds (r (2)=0.00, p>0.05). The sum of 8 skin-folds was neither associated with speed in the swim (r (2)=0.10, p>0.05) nor in the bike split (r (2)=0.10, p>0.05) but showed a significant association with speed in the run split (r (2)=0.38, p<0.0001). We concluded that anthropometry was of more importance than training volume in male Triple Iron triathletes and that these athletes were close to runners regarding the relationship of anthropometry with race performance.

An ultra-cycling race leads to no decrease in skeletal muscle mass.

Ultra-endurance races lead to an enormous energy deficit, and a decrease in body mass in the form of fat mass as well as skeletal muscle mass can be found. The decrease in skeletal muscle mass has been demonstrated in ultra-runners. We investigated therefore, in an ultra-cycling race, whether ultra-cyclists also suffered a decrease in body mass and whether we could find changes in skeletal muscle mass and/or fat mass. The anthropometric method was used to determine body mass, skeletal muscle mass and fat mass in 28 male Caucasian, non-professional, ultra-cyclists before and after a 600 km ultra-cycling race. In order to quantify hydration status, we measured total body water, haematocrit, plasma sodium and urinary specific gravity. In addition, plasma urea was determined as a marker of protein catabolism. Body mass as well as fat mass decreased highly significantly (p<0.01) whereas skeletal muscle mass did not change (p>0.05). The post race minus pre race difference (Delta) in body mass was associated with Delta fat mass (p<0.05). Urea increased highly significantly (p<0.01); however Delta urea was not associated with Delta skeletal muscle mass. We concluded that ultra-cycling in contrast to ultra-running leads to no reduction in skeletal muscle mass.

[Change of body composition in an 81 year old runner in a 100 km run]. / Das Verhalten der Körpermasse bei einem 81-jährigen Läufer an einem 100-km-Lauf.

An 81-year-old runner completed successfully a 100-km-run within 19 h 45 min one year after coronary artery bypass surgery in recently diagnosed atherosclerotic coronary heart disease. Prior and shortly after the run, percent body fat, lean body mass, skeletal muscle mass and percent body water were determined non invasively both by the bioelectrical impedance analysis (BIA) and the traditional anthropometrical method. In addition, blood and urine samples were collected in order to evaluate fluid homeostasis. Proton nuclear magnetic resonance ((1)H-NMR) spectroscopy of the urine was performed in order to detect changes in metabolites of carbohydrate, fat and protein metabolism. Body mass increased by 1.9 kg, calculated skeletal muscle mass increased by 0.1 kg, calculated fat mass from anthropometric method decreased by 0.2 kg and from BIA by 3.1 kg. Calculated body water from BIA increased by 1.2 l and plasma volume decreased by 19%. Haematocrit, nitrogen urea, urinary specific gravity decreased whilst sodium increased. (1)H-NMR spectroscopy revealed an increase of ketone bodies after the run. To demonstrate a decrease of skeletal muscle mass after a 100-km-run, we should wait with the measurements of body masses until body water has reached pre race value. The increase of body water is unclear. In future studies, additional methods should be performed to provide information whether skeletal muscle mass decreased after endurance performance and whether metabolites of skeletal muscle mass degradation may impair renal function.

Personal best marathon performance is associated with performance in a 24-h run and not anthropometry or training volume.

OBJECTIVE: In this study, the influence of anthropometric and training parameters on race performance in ultra-endurance runners in a 24-h run was investigated. DESIGN: Descriptive field study. SETTING: 24-h run in Basel 2007. PARTICIPANTS: 15 male Caucasian ultra-runners (mean (SD) 46.7 (5.8 years), 71.1 (6.8 kg), 1.76 (0.07 m), body mass index 23.1 (1.84 kg/m(2))). INTERVENTIONS: None. MAIN OUTCOME MEASURES: Age, body mass, body height, length of lower limbs, skin-fold thicknesses, circumference of extremities, skeletal muscle mass, body mass, percentage of body fat, and training volume in 15 successful finishers were determined to correlate anthropometric and training parameters with race performance. RESULTS: No significant association (p>0.05) was found between the reached distance and the anthropometric properties. There was also no significant association between the reached distance with the weekly training hours, running years, the number of finished marathons and the number of finished 24-h runs. The reached distance was significantly (p<0.05) positively correlated with the personal best marathon performance (r(2) = 0.40) and the personal best 24-h run distance (r(2) = 0.58). Furthermore, the personal best marathon performance was significantly and positively correlated (p<0.01) with the best personal 24-h run distance (r(2) = 0.76). CONCLUSIONS: Anthropometry and training volume does not seem to have a major effect on race performance in a 24-h run. Instead, a fast personal best marathon time seems to be the only positive association with race performance in a 24-h run.

[The effect of a multi-stage ultra-endurance triathlon over ten times an iron-man-triathlon on fat mass and skeletal muscle mass--the world challenge deca iron 2006]. / Der Einfluss von zehn aufein- ander folgenden Langdistanz- TriathLons auf Körperfett und Muskelmasse--World Challenge Deca Iron 2006.

The present study investigated the change of body composition in 8 ultra-endurance triathletes during a multi-stage ultra-endurance triathlon, where athletes had to perform one Ironman distance over 3.8 km swimming, 180 km cycling and 42.2 km running per day for 10 consecutive days. In the only 8 male successful finishers, body mass, skin fold thicknesses and circumferences of extremities were measured pre and post race in order to calculate skeletal muscle mass, percent body fat and fat mass. Bioelectrical impedance analysis was performed at the same time to determine lean body mass, percent body fat and total body water. Body mass did not change (p > 0.05), whereas skeletal muscle mass statistically significantly decreased by 1.1 kg (p < 0.05) and fat mass significantly decreased by 0.9 kg (p < 0.05).

Upper arm circumference is associated with race performance in ultra-endurance runners.

OBJECTIVE: To investigate the association of anthropometric parameters to race performance in ultra-endurance runners in a multistage ultra-endurance run. DESIGN: Descriptive field study. SETTING: The Deutschlandlauf 2006 race in Germany, where athletes had to run 1200 km within 17 consecutive days. There were no interventions. SUBJECTS: In total, there were 19 male Caucasian ultra-endurance runners (mean (SD) 46.2 (9.6) years, 71.8 (5.2) kg, 179 (6) cm, BMI 22.5 (1.9) kg/m(2)). MAIN OUTCOME MEASUREMENTS: Determination of body mass, body height, length of lower limbs, skin-fold thicknesses, circumference of limbs, body mass index (BMI), percentage skeletal muscle mass (%SM), and percentage body fat (%BF) in 19 successful finishers in order to correlate anthropometric parameters with running performance. RESULTS: A significant association of upper arm circumference with the total running time was found (p<0.05, r2 = 0.26). No significant association was found with the directly measured anthropometric properties body height, body mass, average skin-fold thickness and the circumference of thigh and calf (p>0.05). Furthermore, no significant association was observed between the running time and the calculated parameters BMI, %BF, and %SM (p>0.05). CONCLUSIONS: In an ultra-endurance run over 1200 km within 17 consecutive days, circumference of the upper arm was the only factor associated with performance in well-experienced ultra-endurance runners. Body mass, BMI, body height, length of limbs, skin-fold thicknesses, circumference of limbs and the calculated percentage body composition of skeletal muscle mass and body fat showed no association with running performance.

Decrease in body fat during an ultra-endurance triathlon is associated with race intensity.

OBJECTIVE: To investigate whether adipose subcutaneous tissue or skeletal muscle mass decreased during a non-stop ultra-endurance triathlon. DESIGN: Descriptive field study. SETTING: The Triple Iron Triathlon Germany 2006 in Lensahn: 11.6 km swimming, 540 km cycling and 126.6 km running. SUBJECTS: 17 male Caucasian triathletes, mean (SD) age 39.2 (7.5) years, height 178 (5) cm, body mass 80.7 (8.9) kg and body mass index (BMI) 25.4 (2.4) kg/m(2). INTERVENTIONS: None. MAIN OUTCOME MEASUREMENTS: Determination of body mass, skin-fold thicknesses, limb circumference, skeletal muscle mass and percentage body fat in order to show changes after the race. RESULTS: A significant decrease was shown for body mass (p<0.001), BMI (p<0.001) and calculated percentage body fat (p<0.001) whereas skeletal muscle mass did not change significantly (p>0.05). Circumferences of the thigh, upper arm and calf did not decrease significantly (p>0.05), whereas all skin-fold thicknesses decreased significantly (p<0.05), with the exception of those at the chest and thigh. A significant correlation was found between the loss of percentage body fat and the loss of body mass (p<0.01, r(2) = 0.55) as well as change in percentage body fat with race performance (p<0.05, r(2) = 0.24). CONCLUSIONS: Ultra-endurance triathletes at the Triple Iron Triathlon Germany 2006 showed a significant decrease in body mass and percentage body fat, where decrease in percentage body fat was associated with race intensity.

Effects of a Deca Iron Triathlon on body composition: a case study.

We investigated energy balance and change of body composition in one athlete in a multistage triathlon, the World Challenge Deca Iron Triathlon 2006, where athletes had to perform one Ironman triathlon of 3.8 km swimming, 180 km cycling and 42.195 km running per day for ten consecutive days. In one well-experienced male ultra-endurance triathlete, we measured body mass, skinfold thicknesses and perimeters of extremities, in order to calculate skeletal muscle mass, fat mass and percentage of body fat. Energy intake was measured by analysis of nutrition, and energy expenditure was calculated using a portable heart rate monitor. This was performed to quantify energy deficit. In addition, bio-impedance measurements were performed to determine fluid metabolism. The athlete finished the race in 128 hours, 22 minutes and 42 seconds in 3rd position. Body mass decreased by 1 kilogram, skeletal muscle mass decreased by 0.9 kilograms and calculated fat mass decreased by 0.8 kilograms. Total body water increased by 2.8 liters. Total energy expenditure for the Deca Iron was 89,112 kilocalories and a total energy deficit of 11,480 kilocalories resulted. We presume that energy deficit was covered by consumption of adipose subcutaneous tissue as well as skeletal muscle mass; the degradation of muscle mass seems to lead to hypoproteinemic edemas.

[Swimming for 12 hours leads to no reduction of adipose subcutaneous tissue--a case study]. / Ein 12-Stunden-Schwimmen führt zu keinem nachweisbaren Verlust an subkutanem Fett--eine Fallstudie.

In a 12-hour swimming event, an athlete with constant body weight lost 1.1 kg of muscle mass and 21 of total body fluids whereas fat mass remained stable. Based both on the urine's specific gravity and haematological parameters, the athlete did not suffer from dehydration. We assume that loss of skeletal muscle mass occurred due to degradation of intramyocellular lipids and muscle glycogen. In order to confirm these results obtained in a case study regarding the decrease of skeletal muscle mass with stable fat mass during prolonged swimming exercise, a larger number of athletes would have to be analyzed.

[12 hours running results in a decrease of the subcutaneous adipose tissue]. / Zwölf Stunden Laufen führt zu einem nachweisbaren Abbau des subkutanen Fettgewebes.

A runner has completed 80 km in a 12-hour run. Prior and shortly after the run, fat and skeletal muscle mass were determined non invasively both by the bioelectrical impedance analysis and the classic skin fold method. In addition, blood and urine samples were taken in order to assess fluid balance. By applying the bioelectrical impedance analysis, the runner has increased body mass by 1.5 kg, fat-free body mass by 4.2 kg and muscle mass by 1.0 kg, whereas fat mass decreased by 4.4 kg. Since body water increased by 4.9 l, the determination of haematocrit, haemoglobin and sodium showed a haemodilution and the specific gravity of urine indicated no dehydration, we assume a substantial decrease of subcutaneous adipose tissue for energy production and intracellular oedemas. The difference between determining fat mass with the skin fold method or with the bioelectrical impedance analysis is discussed.

[A 12 hour indoor cycling marathon leads to a measurable decrease of adipose subcutaneous tissue]. / Ein 12-stunden-Indoor-Cycling-Marathon führt zu einem messbaren Abbau des subkutanen Fettgewebes.

In a 12 hour indoor cycling marathon, an athlete has lost 0.4 to 1.2 kg of body mass depending on the time of measurement. Fat mass has decreased by 0.9 kg independent of the time of measurement. Calculated skeletal muscle mass increased by 0.27 to 0.67 kg - depending on the time of measurement. Due to the specific weight of urine, a possibly minimum dehydration was objectified, whereas specific weight right after exercise and 24 h after exercise had the same value. We assume that there was a substantial loss of fat mass, since repeated measurements after exercise showed an increasingly lower body weight and a constantly lower fat mass after exercise independent of the time of measurement. Increase of calculated muscle mass is considered to be due to an intramuscular oedema. In order to confirm results obtained in a case study, a larger number of athletes would have to be analyzed. A possible oedema would have to be objectified by a bioelectrical impedance analysis.

[Effect of ultra-endurance swimming on body composition--marathon swim 2006 from Rapperswil to Zurich]. / Einfluss von einem Langstreckenschwimmen auf die Körperzusammensetzung-- das Marathonschwimmen 2006 von Rapperswil nach Zürich.

We measured, during a marathon swimming event 2006 in the lake of Zurich, load intensity, energy intake, energy expenditure and impact on both muscle and fat mass in a trained long-distance swimmer. The swimmer had a load intensity of 125 bpm corresponding to 51% VO2(max). Despite adequate energy intake during the load, an energy deficit of 500 kcal per hour occurred, which resulted in a loss of 1.1 kg body mass within 9 hours of swimming.