Dynamic pacing strategies during the cycle phase of an Ironman triathlon.
BACKGROUND
A nonlinear dynamic systems model has previously been proposed to explain pacing strategies employed during exercise.


OBJECTIVE
This study was conducted to examine the pacing strategies used under varying conditions during the cycle phase of an Ironman triathlon.


METHODS
The bicycles of six well-trained male triathletes were equipped with SRM power meters set to record power output, cadence, speed, and heart rate. The flat, three-lap, out-and-back cycle course, coupled with relatively consistent wind conditions (17-30 km x h(-1)), enabled comparisons to be made between three consecutive 60-km laps and relative wind direction (headwind vs tailwind).


RESULTS
Participants finished the cycle phase (180 km) with consistently fast performance times (5 h, 11 +/- 2 min; top 10% of all finishers). Average power output (239 +/- 25 to 203 +/- 20 W), cadence (89 +/- 6 to 82 +/- 8 rpm), and speed (36.5 +/- 0.8 to 33.1 +/- 0.8 km x h(-1)) all significantly decreased with increasing number of laps (P < 0.05). These variables, however, were not significantly different between headwind and tailwind sections. The deviation (SD) in power output and cadence did not change with increasing number of laps; however, the deviations in torque (6.8 +/- 1.6 and 5.8 +/- 1.3 N x m) and speed (2.1 +/- 0.5 and 1.6 +/- 0.3 km x h(-1)) were significantly greater under headwind compared with tailwind conditions, respectively. The median power frequency tended to be lower in headwind (0.0480 +/- 0.0083) compared with tailwind (0.0531 +/- 0.0101) sections.


CONCLUSIONS
These data show evidence that a nonlinear dynamic pacing strategy is used by well-trained triathletes throughout various segments and conditions of the Ironman cycle phase. Moreover, an increased variation in torque and speed was found in the headwind versus the tailwind condition.
Abbiss
Chris R
CR
School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia. c.abbiss@ecu.edu.au
Quod
Marc J
MJ
Martin
David T
DT
Netto
Kevin J
KJ
Nosaka
Kazunori
K
Lee
Hamilton
H
Surriano
Rob
R
Bishop
David
D
Laursen
Paul B
PB