Roelands, B., de Koning, J., Hettinga, F., & Meeusen, R. (2012). Different pacing strategies during time-trials in 18°C and 30°C. Presentation 1934 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

This study examined differences in pacing strategies during a time-trial in normal and high ambient temperatures preceded by exercise. Ss (endurance-trained males) performed 60 minutes of fixed intensity exercise at 55% maximum work rate preceding a time-trial in 18°C (N = 37) and 30°C (N = 41). During the time-trial, a predetermined amount of work had to be completed. The time-trial was started at 75% maximum work rate but Ss were free to change resistance as desired from the onset of exercise. Power output was collected every second and averaged in 5% segments of the total time-trial performance.

The average time-trial time in 18°C was ~30.7 minutes, while in 30°C it was ~37.8 minutes. In 18°C there were no differences between the 5% segments and average power output (indicating that it was even paced). In 30°C, Ss decreased power output during the initial 15% of the time-trial, followed by a slight decrease in power output until it was significantly lower compared to average power at 85% of the time-trial when an end spurt commenced. In the heat, final power was significantly higher compared to the average power.

Implication. Different pacing strategies were used for the same task in different environmental temperatures. After fixed intensity exercise in 18°C, Ss choose an even-paced strategy until the last 5% of the time-trial when a non-significant end spurt was attempted. In the heat, Ss significantly decreased power at the start and an end sprint was obvious in the last 15% of the time-trial. Ss anticipated voluntarily adapted pacing strategies to different environmental circumstances.

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