We investigated in 27 male Ironman triathletes aged 30.3 (9.1) years, with 77.7- (9.8) kg body mass, 1.78- (0.06) m body height, 24.3- (2.2) kg·m⁻² body mass index (BMI), and 14.4 (4.8) % body fat and in 16 female Ironman triathletes aged 36.6 (7.0) years, with 59.7- (6.1) kg body mass, 1.66- (0.06) m body height, 21.5 (1.0) kg·m⁻² BMI, and 22.8 (4.8) % body fat to ascertain whether anthropometric or training variables were related to total race time. The male athletes were training 14.8 (3.2) h·wk⁻¹ with a speed of 2.7 (0.6) km·h⁻¹ in swimming, 27.3 (3.0) in cycling, and 10.6 (1.4) in running. The female athletes trained for 13.9 (3.4) h·wk⁻¹ at 2.1 (0.8) km·h⁻¹h in swimming, 23.7 (7.6) km·h⁻¹ in cycling, and 9.0 (3.7) km·h⁻¹ in running, respectively. For male athletes, percent body fat was highly significantly (r² = 0.583; p < 0.001) associated with total race time. In female triathletes, training volume showed a relationship to total race time (r² = 0.466; p < 0.01). Percent body fat was unrelated to training volume for both men (r² = 0.001; p > 0.05) and women (r² = 0.007; p > 0.05). We conclude that percent body fat showed a relationship to total race time in male triathletes, and training volume showed an association with total race time in female triathletes. Presumably, the relationship between percent body fat, training volume, and race performance is genetically determined.

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.

In 219 recreational male runners, we investigated changes in body mass, total body water, haematocrit, plasma sodium concentration ([Na(+)]), and urine specific gravity as well as fluid intake during a 100-km ultra-marathon. The athletes lost 1.9 kg (s = 1.4) of body mass, equal to 2.5% (s = 1.8) of body mass (P < 0.001), 0.7 kg (s = 1.0) of predicted skeletal muscle mass (P < 0.001), 0.2 kg (s = 1.3) of predicted fat mass (P < 0.05), and 0.9 L (s = 1.6) of predicted total body water (P < 0.001). Haematocrit decreased (P < 0.001), urine specific gravity (P < 0.001), plasma volume (P < 0.05), and plasma [Na(+)] (P < 0.05) all increased. Change in body mass was related to running speed (r = -0.16, P < 0.05), change in plasma volume was associated with change in plasma [Na(+)] (r = -0.28, P < 0.0001), and change in body mass was related to both change in plasma [Na(+)] (r = -0.36) and change in plasma volume (r = 0.31) (P < 0.0001). The athletes consumed 0.65 L (s = 0.27) fluid per hour. Fluid intake was related to both running speed (r = 0.42, P < 0.0001) and change in body mass (r = 0.23, P = 0.0006), but not post-race plasma [Na(+)] or change in plasma [Na(+)] (P > 0.05). In conclusion, faster runners lost more body mass, runners lost more body mass when they drank less fluid, and faster runners drank more fluid than slower runners. AbstractWe investigated in 219 recreational male runners the changes (Δ) in body mass, total body water, haematocrit, plasma sodium concentration ([Na + ]) and urine specific gravity as well as fluid intake during a 100-km ultra-marathon. The athletes lost 1.9 (s = 1.4) kg of body mass, equal to 2.5 (s = 1.8) % in body mass (P < 0.001), 0.7 (s = 1.0) kg of predicted skeletal muscle mass (P < 0.001), 0.2 (s = 1.3) kg of predicted fat mass (P < 0.05) and 0.9 (s = 1.6) L of predicted total body water (P < 0.001). Haematocrit decreased (P < 0.001), urine specific gravity (P < 0.001), plasma volume (P < 0.05), and plasma [Na + ] (P < 0.05) increased.

We investigated whether ultraendurance runners in a 100-km run suffer a decrease of body mass and whether this loss consists of fat mass, skeletal muscle mass, or total body water. Male ultrarunners were measured pre- and postrace to determine body mass, fat mass, and skeletal muscle mass by using the anthropometric method. In addition, bioelectrical impedance analysis was used to determine total body water, and urinary (urinary specific gravity) and hematological parameters (hematocrit and plasma sodium) were measured in order to determine hydration status. Body mass decreased by 1.6 kg (p < .01), fat mass by 0.4 kg (p < .01), and skeletal muscle mass by 0.7 kg (p < .01), whereas total body water increased by 0.8 L (p < .05). Hematocrit and plasma sodium decreased significantly (p < .01), whereas plasma urea and urinary specific gravity (USG) increased significantly (p < .01). The decrease of 2.2% body mass and a USG of 1.020 refer to a minimal dehydration. Our athletes seem to have been relatively overhydrated (increase in total body water and plasma sodium) and dehydrated (decrease in body mass and increase in USG) during the race, as evidenced by the increased total body water and the fact that plasma sodium and hematocrit were lower postrace than prerace. The change of body mass was associated with the change of total body water (p < .05), and we presume the development of.

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.