Objective: To examine the effects of different thermoregulatory preparation procedures (warm-up (WU), precooling (PC), control (C)) on endurance performance in the heat.
Methods: 20 male subjects completed three treadmill runs to exhaustion (5 days apart). In each session, all subjects performed an incremental running test after WU (20 min at 70% maximum heart rate (HR)), after PC (wearing a cooling vest (0°C–5°C) for 20 min at rest) or without particular preparation (C). After a 5-min break, the exercise protocol commenced at a workload of 9 km/h and was increased by 1 km/h every 5 min until the point of volitional fatigue. Running performance, HR, blood lactate concentration, tympanic temperature and skin temperature were measured in each trial.
Results: In the PC condition, the running performance (32.5 (5.1) min; mean (SD)) was significantly (p<0.05) higher than in WU (26.9 (4.6) min) and in C conditions (30.3 (4.3) min). During the first 30 min of testing, HR, tympanic temperature and skin temperature were significantly (p<0.05) lower after PC than after WU. There were no significant differences in lactate concentration; however, there was a trend to lower values after WU.
Conclusions: The use of an ice-cooling vest for 20 min before exercising improved running performance, whereas the 20 min WU procedure had a distinctly detrimental effect. Cooling procedures including additional parts of the body such as the head and the neck might further enhance the effectiveness of PC measures.
- BL, blood lactate
- bpm, beats per minute
- C, control
- CT, core temperature
- HR, heart rate
- PC, precooling
- ST, skin temperature
- TPP, thermoregulatory preparation
- Tt, tympanic temperature
- WU, warm-up
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Published Online First 15 January 2007
Competing interests: None declared.