Distribution of power output during the cycling stage of a Triathlon World Cup

The aim of this study was to evaluate the power output (PO) during the cycle phase of the Beijing World Cup test event of the Olympic triathlon in China 2008.

Ten elite triathletes (5 females, 5 males) performed two laboratory tests: an incremental cycling test during which PO, HR at ventilatory thresholds (VT1 and VT2), and maximal aerobic power (MAP) were assessed, and a brief all-out test to determine maximal anaerobic power output (MAnP). During the cycle part of competition, PO and HR were measured directly with portable device. The amount of time spent below PO at VT1 (zone 1), between PO at VT1 and VT2 (zone 2), between PO at VT2 and MAP (zone 3) and above MAP (zone 4) was analyzed.

A significant decrease in PO, speed, and HR values was observed during the race. The distribution of time was 51 +/- 9% for zone 1, 17 +/- 6% for zone 2, 15 +/- 3% for zone 3, and 17 +/- 6% was performed at workloads higher than MAP (zone 4). From HR values, the triathletes spent 27 +/- 12% in zone 1, 26 +/- 8% in zone 2, and 48 +/- 14% above VT2.

This study indicates a progressive reduction in speed, PO, and HR, coupled with an increase in variability during the event. The Olympic distance triathlon requires a higher aerobic and anaerobic involvement than constant-workload cycling exercises classically analyzed in laboratory settings (i.e., time trial) or Ironman triathlons. Furthermore, monitoring direct PO could be more suitable to quantify the intensity of a race with pacing strategies than classic HR measurements.