Winke, M., & Yates, J. W. (2008). Precooling and running economy. ACSM 55th Annual Meeting Indianapolis. Presentation number 800.

"Precooling, or a reduction in core temperature has been demonstrated to be a potent enhancer of endurance running performance, however there is no known mechanism for this improvement. By holding the exercise workload constant, changes in variables such as running economy, heart rate, and ventilation can be determined as a result of pre-cooling. Improved running economy, or a reduced oxygen cost of a specific workload, is linked to improved exercise performance."

This investigation determined changes in flexibility, running economy, heart rate, ventilation, and core temperature during running at a constant workload following cool water immersion. Gender-specific responses were also evaluated. Well-trained runners (M = 8; F = 6) completed four treadmill runs at a gender-specific velocity (8.0 mph for females and 8.6 mph for males). The first two runs served as accommodation trials. The third and fourth runs were preceded by either cool water immersion (24.8°C) for 40 minutes or quiet sitting. Oxygen consumption, heart rate, core temperature, ventilation, and flexibility were measured during both experimental trials.

Running economy did not change as a result of the pre-cooling treatment. There was a reduction in core temperature (0.4°C) and heart rate (5 bpm) among all Ss. Gender differences were apparent in all variables other than running economy. The core temperature response was similar between groups with the exception of a reduced core temperature in male Ss at the onset of the control trial (mean reduction of 0.2°C). Minute ventilation was reduced in female Ss only (1.4 l/min) while male Ss demonstrated a reduced heart rate (6 bpm) during the precooling treatment. Females were more flexible than the male Ss at all times.

Implication. While pre-cooling was effective in reducing core temperature and heart rate, running economy did not change. Thus, improvements in running economy cannot explain notable enhancements of endurance running performance that often occur post-cooling. Differences between male and female Ss in response to pre-cooling were identified, most notably in ventilation.

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