An ultratriathlon leads to a decrease of body fat and skeletal muscle mass--the Triple Iron Triathlon Austria 2006.

We investigated the effects on body composition in triathletes at the Triple Iron Triathlon Austria in 2006, where athletes had to perform 11.6 km swimming, 540 km cycling, and 126.6 km running within 58 h. In 16 male triathletes, body mass (BM), skinfold thicknesses, and circumferences of extremities were measured before and after the competition in order to calculate body mass index (BMI), percent body fat (%BF), fat mass (FM), and skeletal muscle mass (SM). Body mass, BMI, %BF, FM, and SM decreased statistically significantly (p < 0.01). The loss of BM is associated neither with the decrease of %BF (p > 0.05, r(2)= 0.00) nor with the decrease of SM (p> 0.05, r(2)= 0.06). There is no association between total race time and the loss of BM (r(2) = 0.06), %BF (r(2) = 0.10), and SM (r2 = 0.11). No significant correlation (p > 0.05, r(2)= 0.43) was found between the initial SM and loss of SM.