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Introduction: We investigated two athletes swimming in 4°C for 23min (1.3km, swimmer 1) and 42min (2.2km, 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 20min after getting out of the water, and 35.5°C 80min 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

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 2.2kg (p=0.0009) and fat mass decreased by 0.5kg (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 1.022g/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

We investigated participation and performance trends in duathletes in the ‘Powerman Duathlon World Championship’ in Zofingen, Switzerland, from 2002 to 2011, regarding the nationality of the finishers. Sex and nationality at the time of the competition and overall race times of both women and men finishers at the ‘Powerman Zofingen’ (10 km run, 150 km cycle, 30 km run) were analysed from 2002 to 2011 using linear regression analysis. In total, 272 women and 1,964 men finished the race. Participation increased across years in women (r2=0.73, P<0.01), but not in men (r2=0.15, P>0.05). Most of the athletes originated from Switzerland, followed by participants from Germany, France, Italy, Belgium, the United States of America, Spain, Great Britain, the Netherlands and Denmark. Across the years, both German men (r2=0.55, P=0.01) and German women (r2=0.66, P<0.01) increased their participation. The top five athletes overall showed no changes in performance for both women and men where Swiss athletes achieved the fastest race times. Athletes from the five countries with the highest participation showed no changes in overall race time. To summarize, (i) European athletes from Switzerland and Germany dominated participation in the ‘Powerman World Championship’ where Swiss duathletes were the fastest and (ii) duathletes at world-class level showed no changes in performance in the last ten years. Future studies should investigate the participation and performance trends in other long distance duathlons of the ‘Powerman World Series’. Keywords: running, cycling, ultra, endurance, multi-sport

Background: Participation and performance trends have been investigated in ultramarathons and ultratriathlons but not in ultracycling. The aim of the present study was to investigate (1) participation and performance trends in ultraendurance cyclists, (2) changes in cycling speed over the years, and (3) the age of the fastest male and female ultraendurance cyclists. Methods: Participation and performance trends in the 5000 km Race Across America (RAAM) and in two RAAM-qualifier races – the 818 km Furnace Creek 508 in the United States and the 715 km Swiss Cycling Marathon in Europe – were investigated using linear regression analyses and analyses of variance. Results: On average, ~41% of participants did not finish either the RAAM or the Furnace Creek 508, whereas ~26% did not finish the Swiss Cycling Marathon. Female finishers accounted for ~11% in both the RAAM and the Furnace Creek 508 but only ~3% in the Swiss Cycling Marathon. The mean cycling speed of all finishers remained unchanged during the studied periods. The winner’s average speed was faster for men than for women in the RAAM (22.6 ± 1.1 km · h-1 versus 18.4 ± 1.7 km · h-1, respectively; average speed difference between male and female winners, 25.0% ± 11.9%), the Swiss Cycling Marathon (30.8 ± 0.8 km · h-1 versus 24.4 ± 1.9 km · h-1, respectively; average speed difference between male and female winners, 27.8% ± 9.4%), and the Furnace Creek 508 (27.4 ± 1.6 km · h-1 versus 23.4 ± 3.0 km · h-1, respectively; average speed difference between male and female winners, 18.4% ± 13.9%). In both the Furnace Creek 508 and the Swiss Cycling Marathon, ~46% of the finishers were aged between 35 and 49 years. The mean age of winners, both male and female, across the years in the Furnace Creek 508 and in the Swiss Cycling Marathon was 37 ± 10 years. Conclusion: These findings in ultracycling races showed that (1) ~26%–40% of starters were unable to finish, (2) the percentage of female finishers was ~3%–11%, (3) the g

The prevalence of exercise-associated hyponatraemia (EAH) has been investigated in endurance athletes such as runners and Ironman triathletes, but not in ultra-endurance road cyclists. We assessed fluid intake and changes in body mass, urine specific gravity and plasma sodium concentration ([Na(+)]) in 65 ultra-endurance road cyclists in a 720-km ultra-cycling marathon, the 'Swiss Cycling Marathon'. The cyclists lost 1.5 (1.7)% body mass (P < 0.01). No athlete developed EAH. Fluid intake was associated with the change in plasma [Na(+)] (r = -0.32, P < 0.05) and the change in body mass (r = -0.30, P < 0.05). The change in plasma [Na(+)] was related to post-race plasma [Na(+)] (r = 0.63, P < 0.0001). To conclude, ad libitum fluid intake in ultra-endurance cyclists in a single-stage ultra-endurance road cycling race showed no case of EAH. Future studies regarding drinking behaviour in different ultra-endurance disciplines might give insights into why the prevalence of EAH is different in the different disciplines.

Triathlon, in particular the 18Ironman 19 distance, has become very popular in the field of ultra-endurance sports. The aim of the present study was to analyse the participation and performances at the 18Ironman Switzerland 19 in Zurich, Switzerland, regarding the nationality of the participants. Nationalities and performances of 21,399 athletes, originating from exactly 100 countries and competing between 1995 and 2011, were analysed. The mean total race times and changes across the years of the top ten athletes overall and of each country for both women and men triathletes were analysed using linear regression analyses. In total, 90% of the participants in 18Ironman Switzerland 19 originated from European countries, with triathletes from Switzerland (31.9%) and Germany (18.9%) presenting the majority, followed by participants from Great Britain (11.2%), France (7.9%), Italy (5.3%), USA (4.7%), Spain (3.5%), Belgium (2.7%) and Austria (2.6%). Switzerland presented the fastest triathletes in both sexes followed by athletes from Germany. Behind these two leading nations, triathletes from countries such as France, Belgium, Austria, Great Britain, Spain, Italy and USA competed slower. To summarize, 18Ironman Switzerland 19 has been dominated by central European triathletes regarding participation and performance. Most of the participants and the fastest finishers came from Switzerland, followed by triathletes from Germany. To assess these results, future studies need to investigate the leading nations in 18Ironman 19 qualifying races all over the world for 18Ironman Hawaii 19 and in the 18Ironman World Championship 19 in Hawaii.

The aims of this study were (i) to investigate the participation in Triple Iron ultra-triathlons covering 11.4 km swimming, 540 km cycling, and 126.6 km running between 1988 and 2011 and (ii) to analyze the nationalities of the athletes achieving the fastest swimming, cycling, running and overall race times. Six out of seven races worldwide were held in Europe. Participation of male Triple Iron ultra-triathlons increased over the 24-year period while the participation of females remained stable at ~8% of the total field. Out of the 1,258 participants, 1.077 athletes (85.6%) originated from Europe. The number of male European athletes (r2 = 0.23; P = 0.02) and male North American athletes (r2 = 0.35; P < 0.01) increased across years. European males (2.161 ± 168.5 min) were faster (P < 0.05) than both European females (2.615 ± 327.2 min) and North American males (2.850 ± 370.6 min). Male European athletes improved (r2 = 0.18; P = 0.043), while European females impaired (r2 = 0.48; P = 0.001) overall race time. To summarize, participation in Triple Iron ultra-triathlon increased across years where most of the participants originated from Europe. European males achieved the fastest overall race times and improved their performance across years. Future studies need to investigate what motivates these athletes to compete in these races.

Background: The age of peak performance in elite endurance athletes has been investigated for elite marathoners, but not for elite Ironman triathletes. The aim of this study was to analyze the age of peak performance in swimming (3.8 km), cycling (180 km), running (42 km), and overall race time for elite female and male Ironman triathletes competing in Ironman Switzerland, a qualifier for the Ironman world championship, known as the Ironman Hawaii. Methods: The age of the annual top ten overall swimmers, cyclists, runners, and annual overall finishers for both male and female elite triathletes and their corresponding split and overall race times at the Ironman Switzerland were analyzed between 1995 and 2011. Results: The mean age of the elite Ironman triathletes was 33 ± 3 years for men and 34 ± 4 years for women. For women, the age of peak performance was not significantly different between the three disciplines (P > 0.05), while for men, the best swimmers (29 ± 3 years) were significantly (P < 0.05) younger than the best runners (35 ± 5 years). During the study period, the age of peak performance remained unchanged for men at 31 ± 3 years (P > 0.05), but increased for women from 30 ± 4 years in 1995 to 36 ± 5 years in 2011 (P < 0.01). Conclusion: Although both women and men improved their overall race times during the 1995–2011 period, the age of peak performance was similar between women and men in the three disciplines and in overall race time. Future studies need to examine the change in age of peak performance across years in the Ironman Hawaii world championship event.

Body Mass Index is associated with endurance performance in athletes. Reported and measured values of body mass and body height in 1,607 endurance athletes (1,352 men, 255 women) showed that men and women both underestimated their body mass and overestimated their body height, leading to an underestimation of Body Mass Index. There were age and sex differences in estimates of height and weight; for both women and men, underestimation of Body Mass Index amounted to 0.4 kg/m2. Master athletes tended to underestimate their body mass and overestimate their body height thus leading to significant differences between estimated and measured Body Mass Index. However, the magnitude of underestimation of BMI probably has a negligible influence on performance predictions. The differences between measured and estimated body mass, height, and BMI were within the range of normal daily variation, and for body height even within the precision of the measurement (0.5 cm).

Background: A recent study showed that European triathletes performed faster in Double Iron ultratriathlons than North American athletes. The present study analyzed triathletes participating in Double Iron ultratriathlons to determine the origin of the fastest Double Iron ultratriathletes, focusing on European countries. Methods: Participation and performance trends of finishers in Double Iron ultratriathlons from 1985–2011 of the different countries were investigated. Additionally, the performance trends of the top three women and men overall from 2001–2011 were analyzed. Results: A total of 1490 finishers originated from 24 different European countries and the United States. The number of European triathletes increased for both women (r2 = 0.56; P , 0.01) and men (r2 = 0.63; P , 0.01). The number of the North American triathletes increased for women (r2 = 0.25; P , 0.01), but not for men (r2 = 0.02; P . 0.05). Hungarian triathletes showed a significant improvement in both overall race times and in cycling split times, Swiss triathletes improved both their swim and run times, and French triathletes improved their swim times. Conclusion: Men and women triathletes from Central European countries such as France, Germany, Switzerland, and Hungary improved Double Iron ultratriathlon overall race times and split times during the 26-year period. The reasons might be the social and economic factors required to be able to participate in such an expensive and lavish race. Also, a favorable climate may provide the ideal conditions for successful training. Future studies need to investigate the motivational aspects of European ultraendurance athletes.

Clavicle fractures are frequent injuries in athletes and midshaft clavicle fractures in particular are well-known injuries in Ironman triathletes. In 2000, Auzou et al. described the mechanism leading to an isolated truncular paralysis of the musculocutaneous nerve after a shoulder trauma. It is well-known that nerve palsies can lead to an atrophy of the associated muscle if they persist for months or even longer. In this case report we describe a new case of an Ironman triathlete suffering from a persistent isolated atrophy of the brachialis muscle. The atrophy occurred following a displaced midshaft clavicle fracture acquiring while falling off his bike after hitting a duck during a competition.

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.

The aim of this study was to investigate predictor variables of anthropometry, training, and previous experience in order to predict a half marathon race time for future novice recreational male half marathoners. Eighty-four male finishers in the ‘Half Marathon Basel’ completed the race distance within (mean and standard deviation, SD) 103.9 (16.5) min, running at a speed of 12.7 (1.9) km/h. After multivariate analysis of the anthropometric characteristics, body mass index (r = 0.56), suprailiacal (r = 0.36) and medial calf skin fold (r = 0.53) were related to race time. For the variables of training and previous experience, speed in running of the training sessions (r = –0.54) were associated with race time. After multivariate analysis of both the significant anthropometric and training variables, body mass index (P = 0.0150) and speed in running during training (P = 0.0045) were related to race time. Race time in a half marathon might be partially predicted by the following equation (r2 = 0.44): Race time (min) = 72.91 + 3.045 * (body mass index, kg/m2) –3.884 * (speed in running during training, km/h) for recreational male runners. To conclude, variables of both anthropometry and training were related to half marathon race time in recreational male half marathoners and cannot be reduced to one single predictor variable.

In male high-level long-distance runners over 10,000 m, a positive association between both the front thigh and medial calf skin-fold thickness and running performance has been demonstrated. It is assumed that the thickness of skin-folds of the lower limb is related to training in highly trained runners. We investigated in 22 male ultra-endurance runners in a 24-hour run the relationship between skin-fold thicknesses and race performance. The 22 runners achieved a total of 154 (47) km during the 24 hours, varying from 73.079 km to 231.956 km. No association for both the skin-fold thicknesses and the training variables with race performance could be demonstrated. Furthermore, skin-fold thicknesses showed no relationship with both volume and intensity during training. We must assume that in ultra-endurance runners in a 24-hour run, other variables such as motivation and nutrition must be associated with race outcome.

Purpose. The association between anthropometric and training characteristics on an athlete’s performance has been investigated in swimmers, cyclists and runners, but not in inline skaters. The aim of this study was to investigate the relationship between anthropometry, pre race preparation and equipment in the finishers of the longest inline race in Europe, the ‘Inline One eleven’ over 111 km in Switzerland. Basic procedures. We investigated the association of anthropometry, training, and equipment variables with race times in 84 male ultraendurance inline skaters using bi- and multivariate analysis. Main findings. In the multivariate analysis, percent body fat, duration per training unit, and personal best time in the ‘Inline One eleven’ was related to the race time for all finishers. Out of the 84 finishers, 58 had already finished an ‘Inline One eleven’ while 26 participated for the first time. Speed in training and the kind of skates worn were related to race times of the 26 inexperienced finishers. The inexperienced finishers skating with custom made skates were significantly faster with 229.1 (12.7) min compared to inexperienced finishers using ordinary skates finishing within 290.8 (35.4) min ( p < 0.001). For experienced inliners, body mass, the sum of skin-folds and percent body fat correlated to race time. Conclusions. We assume that inexperienced athletes in ultra-endurance skating need time to gain the experience necessary in choosing the correct equipment and doing the training in order to successfully finish a long-distance inline race. Experienced inliners can only improve race performance in an ultra-endurance inline race such as the ‘Inline One eleven’ through a reduction of their body fat.

Anthropometric and training variables were related to half-marathon race time in recreational female runners. Skin-fold thicknesses at various upper body locations were related to training intensity. High running speed in training appears to be important for fast half-marathon race times and may reduce upper body skin-fold thicknesses in recreational female half marathoners.

Background: The purpose of this study was to investigate the effect of short-term supplementation of amino acids before and during a 100 km ultra-marathon on variables of skeletal muscle damage and muscle soreness. We hypothesized that the supplementation of amino acids before and during an ultra-marathon would lead to a reduction in the variables of skeletal muscle damage, a decrease in muscle soreness and an improved performance. Methods: Twenty-eight experienced male ultra-runners were divided into two groups, one with amino acid supplementation and the other as a control group. The amino acid group was supplemented a total of 52.5 g of an amino acid concentrate before and during the 100 km ultra-marathon. Pre- and post-race, creatine kinase, urea and myoglobin were determined. At the same time, the athletes were asked for subjective feelings of muscle soreness. Results: Race time was not different between the groups when controlled for personal best time in a 100 km ultra-marathon. The increases in creatine kinase, urea and myoglobin were not different in both groups. Subjective feelings of skeletal muscle soreness were not different between the groups. Conclusions: We concluded that short-term supplementation of amino acids before and during a 100 km ultra-marathon had no effect on variables of skeletal muscle damage and muscle soreness.

The association of skinfold thicknesses with race performance has been investigated in runners competing over distances of ≤50 km. This study investigated a potential relation between skinfold thicknesses and race performance in male ultra-marathoners completing >50 km in 24 hours. Variables of anthropometry, training, and previous performance were related to race performance in 63 male ultra-marathoners aged 46.9 (standard deviation [SD] 10.3) years, standing 1.78 (SD 0.07) m in height, and weighing 73.3 (SD 7.6) kg. The runners clocked 146.1 (SD 43.1) km during the 24 hours. In the bivariate analysis, several variables were associated with race performance: body mass (r = -0.25); skinfold thickness at axilla (r = -0.37), subscapula (r = -0.28), abdomen (r = -0.31), and suprailiaca (r = -0.30); the sum of skinfold thicknesses (r = -0.32); percentage body fat (r = -0.32); weekly kilometers run (r = 0.31); personal best time in a marathon (r = -0.58); personal best time in a 100-km ultra-run (r = -0.31); and personal best performance in a 24-hour run (r = 0.46). In the multivariate analysis, no anthropometric or training variable was related to race performance. In conclusion, in contrast to runners up to distances of 50 km, skinfold thicknesses of the lower limbs were not related to race performance in 24-hour ultra-marathoners.

We investigated the change in body composition and hydration status in one male ultra-endurance swimmer during a 24-hour swim. Body mass, percent body fat and skeletal muscle mass using the anthropometric method as well as total body water using bioelectrical impedance analysis were determined pre race, every 6 hours and after the race. Parameters of hydration status (urinary specific gravity, haematocrit, plasma sodium) and skeletal muscle damage (plasma urea) were measured at the same time. The swimmer achieved a total distance of 41.1 km. Body mass decreased by 1.6 kg, skeletal muscle mass by 1.5 kg, body fat by 2.4 kg and total body water by 3.9 l. Urinary specific gravity remained unchanged at 1.015 g/ml. Haematocrit increased from 46 to 47, plasma volume decreased by 4 % and plasma sodium by 4.0 mmol/l. We found in this ultra-swimmer a decrease in body mass of 1.7 % and a consistent urinary specific gravity of 1.015 g/ml. According to the general concept of dehydration, this corresponds to minimal dehydration.

Purpose: The aim of this study was to evaluate predictor variables of race time in female ultra-endurance inliners in the longest inline race in Europe. Methods: We investigated the association between anthropometric and training characteristics and race time for 16 female ultraendurance inline skaters, at the longest inline marathon in Europe, the ‘Inline One-eleven’ over 111 km in Switzerland, using bi- and multivariate analysis. Results: The mean (SD) race time was 289.7 (54.6) min. The bivariate analysis showed that body height (r=0.61), length of leg (r=0.61), number of weekly inline skating training sessions (r=-0.51)and duration of each training unit (r=0.61) were significantly correlated with race time. Stepwise multiple regressions revealed that body height, duration of each training unit, and age were the best variables to predict race time. Conclusion: Race time in ultra-endurance inline races such as the ‘Inline One-eleven’ over 111 km might be predicted by the following equation (r2 = 0.65): Race time (min) = -691.62 + 521.71 (body height, m) + 0.58 (duration of each training unit, min) + 1.78 (age, yrs) for female ultra-endurance inline skaters.

We investigated the relationship between selected variables of anthropometry and training with race performance during a 26.4 km open-water ultra-endurance swim at 23 °C in male master ultra-swimmers. Basic procedures. Fifteen non-professional male open-water ultra-endurance swimmers who were (mean ± SD) 40.0 (8.2) years of age with 83.7 (10.3) kg body mass, 1.80 (0.08) m body height and a BMI of 25.5 (2.5) kg/m2 finished the race within the time limit. Body mass, percent body fat, thickness of 7 skin folds, body height, length of arm, and length of leg were measured prior to race. The number of years as active swimmer, average weekly training volume in hours and kilometres and average speed in training were recorded. The variables were then correlated to total race time. Main findings. Study participants had mean finish times of 551 (100) min and an average speed of 3.0 (0.5) km/h. Speed in swimming during training was the only variable related to total race time (r = –0.66, p = 0.0037) whereas none of the other investigated variables showed an association. Conclusions. We conclude that anthropometry was not related to race performance in these male ultra-endurance swimmers whereas speed in training showed a moderate association with total race time.

We intended to compare the anthropometry of male and female Ironman triathletes with the anthropometry of male and female ultra-swimmers. Body mass, body mass index and body fat were lower in both male and female triathletes compared to swimmers. Body height and length of limbs were no different between the two groups. In the multi-variate analysis, in male triathletes, body mass (p=0.015) and percent body fat (p=0.0003) were related to race time; percent body fat was also related to the swim split (p=0.0036). In male swimmers, length of the arm was related to race time (p=0.0089). In female triathletes and swimmers, none of the investigated anthropometric variables showed an association with race time. We concluded that Ironman triathletes and ultra-swimmers were different regarding anthropometry and that different anthropometric variables were related to race time. We assume that other factors, such as training and equipment, as opposed to anthropometry, may better predict race time in male and female Ironman triathletes.

The relationship of anthropometric and training characteristics with race time were investigated in 39 male and 24 female open-water ultra-endurance swimmers in a 26.4 km open-water ultra-swim, using bi- and multivariate analyses. For the men, body height, Body Mass Index, length of arm, and swimming speed during training were related to race time in the bivariate analysis. For the women, swimming speed during training was associated with performance in the bivariate analysis. In the multivariate analysis for the men, Body Mass Index and swimming speed during training were related to race time.

OBJECTIVE: To investigate the influence of anthropometric and training parameters on race performance in ultra-endurance runners in a 24-hour-run. DESIGN: Descriptive field study. SETTING: The 24-hour-run in Basel 2007. SUBJECTS: Fifteen male Caucasian ultra runners (mean +/- SD; 46.7 +/- 5.8 y, 71.1 +/- 6.8 kg, 1.76 +/- 0.07 m, BMI 23.1 +/- 1.84 kg/m2). INTERVENTIONS: None. MAIN OUTCOME MEASUREMENTS:Determination of age, body mass, body height, length of lower limbs, skin-fold thicknesses, circumference of extremities, skeletal muscle mass, BMI and percent body fat as well as training volume in 15 successful finishers in order 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 of the reached distance with the weekly training hours, running years, the number of finished marathons and the number of finished 24-hour-runs. The reached distance is significantly (p<0.05) positively correlated with the personal best marathon performance (r2=0.40) and the personal best 24-hour-run distance (r2=0.58). Furthermore, the personal best marathon performance is highly significantly and positively correlated (p<0.01) with the best personal 24-hour-run distance (r2=0.76). CONCLUSIONS: Anthropometry as well as training volume does not seem to have a major effect on race performance in a 24-hour-run. Instead, a fast personal best marathon time seems to be the only positive association with race performance in a 24-hour-run.

A multistage ultraendurance triathlon over five times the Ironman distance within five consecutive days leads in one ultraendurance triathlete to minimal changes in body mass (BM; -0.3 kg), fat mass (FM; -1.9 kg), skeletal muscle mass (SM; no change), and total body water (TBW; +1.5 l). This might be explained by the continuously slower race times throughout the race every day and the positive energy balance (8,095 kcal), although he suffered an average energy deficit of -1,848 kcal per Ironman distance. The increase of TBW might be explained by the increase of plasma volume (PV) in the first 3 days. The increase of PV and TBW could be a result of an increase of sodium, which was increased after every stage. We presume that this could be the result of an increased activity of aldosterone.

Introduction: We investigated two athletes swimming in 4°C for 23min (1.3km, swimmer 1) and 42min (2.2km, 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 20min after getting out of the water, and 35.5°C 80min 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

Introduction: We investigated two athletes swimming in 4°C for 23min (1.3km, swimmer 1) and 42min (2.2km, 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 20min after getting out of the water, and 35.5°C 80min 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

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 2.2kg (p=0.0009) and fat mass decreased by 0.5kg (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 1.022g/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