Article Text

Download PDFPDF
Effect of a multistage ultra-endurance triathlon on body composition: World Challenge Deca Iron Triathlon 2006
  1. B Knechtle1,
  2. O Salas Fraire2,
  3. J L Andonie3,
  4. G Kohler4
  1. 1
    Gesundheitszentrum St Gallen, St Gallen, Switzerland
  2. 2
    Universidad Autónoma de Nuevo León, Monterrey, Nuevo Leon, Mexico
  3. 3
    Multisport Andonie, Monterrey, Nuevo Leon, Mexico
  4. 4
    Division of Biophysical Chemistry, Biozentrum, University of Basel, Basel, Switzerland
  1. Beat Knechtle, Vadianstr. 26, St Gallen, Switzerland; beat.knechtle{at}


Objective: To investigate the effect of a multistage ultra-endurance triathlon on body composition in ultra-triathletes.

Design: Descriptive field study.

Setting: The “World Challenge Deca Iron Triathlon 2006” in Monterrey, Mexico, in which every day for 10 consecutive days athletes had to perform the distance of one Ironman triathlon.

Subjects: Eight male ultra-endurance athletes (mean (SD) age 40.6 (10.7) years, weight 76.4 (8.4) kg, height 175 (4) cm and body mass index (BMI) 24.7 (2.2) kg/m2).

Interventions: None.

Main outcome measurements: Determination of body mass, protein mass, body fat, per cent body fat, mineral mass, total body water, intracellular water, extracellular water and lean body mass with a direct segmental multifrequency bioelectrical impedance method before the race and after each stage in order to show changes in body composition.

Results: A statistically significant decrease of body mass (−2.4 kg, p = 0.014), body fat (−5 kg, p = 0.0078) and per cent body fat (−6.4%, p = 0.0078) occurred at the end of the first day compared to values taken in the pre-race period. In contrast, at the same time, a statistically significant increase of protein mass (+0.7 kg, p = 0.035), mineral mass (+0.2 kg, p = 0.04), total body water (+1.8 litres, p = 0.042), intracellular water (+1.6 litres, p = 0.034) and lean body mass (+2.6 kg, p = 0.023) was shown. After the first day until the end of the challenge, body fat (−3 kg, p>0.05) and per cent body fat (−3.9%, p>0.05) showed a statistically significant decrease, whereas the other parameters showed no changes.

Conclusions: Athletes taking part in a multistage ultra-endurance triathlon over 10 Ironman triathlon distances in 10 consecutive days lost 3 kg of body fat; skeletal muscle mass, mineral mass and body water were unchanged.

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


  • Competing interests: None declared.