Cardiorespiratory and metabolic adaptation during the swimming and cycling sectors of an olympic triathlon

Introduction

The aim of this study is to analyse the metabolic and cardiorespiratory adaptation in swimming and cycling, and the first transition of a simulated olympic triathlon at race pace intensity.
Methods
6 triathletes of international level swam 1500m, a transition, and one hour on a cycle ergometer at race pace. Central and periferic adaptation were measured by indirect calorimetry and continuous ECG. Heart rate was recorded by a cardiotachometer, and seriated blood lactates samples were taken.

Results

Mean speed in the swimming sector was 1.29  0.07 m•s-1, 98%  2% of the maximal aerobic speed (MAS). Mean power during the cycling sector was equal to 264  28 W, 77%  6% of the maximal aerobic power (MAP). MAS was highly correlated to the performance in the swimming sector (r = 0.944; P < 0.05). We observed statistically significative differences between weight before and after the experimental protocol (71.7  3.7 kg vs. 69.7  3.4 kg; p < 0.01). At 45 min of the cycling sector, power, speed, and cadence were minimum. At this point these values increased progressively. No differences on blood lactate level, VO2 and VE, were observed during the two sectors and the transition.

Discussion/Conclusion

Although triathlon is considered a continuous workout, it seems to be necessary to study the performance for every sector independently. Results showed that the relative intensities in the two sectors were different. The weight lowering and the possible dehydration did not decrease the triathlete economy during the cycling sector. The work accomplished during the swimming sector affected the cycling performance only during the first ten minutes of the sector. The intensity during the cycling sector was very near to the individual lactate threshold, at which intensity, theoretically, more lactate is being removed. Future studies should focus to determine if performance during the cycling sector could modify the running sector performance.