The response of runners to arduous triathlon competition

  • G. Rogers
  • C. Goodman
  • D. Mitchell
  • J. Hattingh


As very few of the competitors in a triathlon are truly specialist in more than one of the three disciplines, high levels of physical (and mental) stress may result during the course of the event. We investigated some of the physiological responses occurring in runners participating in an “Iron Man” triathlon consisting of canoeing (20 km), cycling (90 km) and running (42 km), in that sequence.

Twenty-one male entrants volunteered as subjects for the study. Prior to the competition, maximal oxygen consumption (\(\dot V_{{\text{O}}_{{\text{2max}}} }\)) was determined. Basal venous blood samples were collected on the day prior to the competition and post-exercise venous blood samples were collected within 5 minutes of completion of the race.

Serum iron was significantly reduced from a mean basal value of 20.6 Μmol · l−1 to a mean value of 8.4 Μmol · l−1 after the race. Cortisol levels showed a 3 fold increase after the race. Gross \(\dot V_{{\text{O}}_{{\text{2max}}} }\) (l · min−1) and mass standardised \(\dot V_{{\text{O}}_{{\text{2max}}} }\) (ml · min−1 · kg−1) were both negatively correlated to cortisol levels after the race (p<0.05). Total performance time was not related to gross \(\dot V_{{\text{O}}_{{\text{2max}}} }\) (l · min−1) but was well correlated to mass corrected \(\dot V_{{\text{O}}_{{\text{2max}}} }\) (ml · min−1 · kg−1).

The marked fall in serum iron may have been related to heavy sweating or prelatent iron deficiency. Chronic iron deficiency (without frank anaemia) can impair physical performance, although we were unable to show any significant correlation between serum iron level after the race and time taken to complete the event. The subjects with a lower \(\dot V_{{\text{O}}_{{\text{2max}}} }\) (ml · min−1 · kg−1) had a higher cortisol concentration. In spite of a longer performance time, these subjects were apparently still exposed to greater physiological strain.

Key words

Cortisol Iron Maximal oxygen consumption Performance Endurance exercise 


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Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • G. Rogers
    • 1
  • C. Goodman
    • 1
  • D. Mitchell
    • 1
  • J. Hattingh
    • 2
    • 1
  1. 1.Department of PhysiologyUniversity of the Witwatersrand Medical SchoolJohannesburgSouth Africa
  2. 2.Department of General PhysiologyUniversity of the Witwatersrand Dental SchoolJohannesburg

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