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.