Effects of warm-up and precooling on endurance
performance in the heat
Sandra U¨ckert, Winfried Joch
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See end of article for
Dr S U¨ckert, Institute of
Sports Science, University of
Dortmund, Otto-Hahn-Str 3,
44227 Dortmund, Germany;
Accepted 4 December 2006
Published Online First
15 January 2007
Br J Sports Med 2007;41:380–384. doi: 10.1136/bjsm.2006.032292
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
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
30˚C brought about a decrease of 2.3% in the performance of a
10 min exercise bout.2The question, however, as to what
strategies could be applied to compensate for this heat-induced
decrease in performance has been left largely unanswered.
Sufficient fluid intake is a possible answer, and application of
cold provides another one.3 4In the context of endurance in
heat a further question arises—namely, whether warm-up
(WU; including the concomitant increase in core temperature
(CT)) is a sensible measure, taking into consideration the
additional thermal stress.5
For this reason, it is useful to compare the effects of WU and
precooling (PC) to optimise endurance performance. The
practical relevance of the objective lies in the fact that
competitions—for example, the Olympic Games 2008 in
Beijing—will be held in high ambient temperatures, exceeding
30˚C at all times of day, and there is no coherent (systematically
and experimentally tested) position in the literature on the
implications of WU6 7for endurance performance in such
temperatures. Although PC has been discussed more widely
during the last two decades,8–10it has not yet been studied in
comparison with active WU.
t is well established that high ambient temperatures have a
detrimental effect on endurance performance.1 2Compared
with temperate conditions (20˚C), an ambient temperature of
METHODS AND PROCEDURES
Twenty male subjects were tested in this study. They were
physical education students at the University of Muenster,
Muenster, Germany, and regularly practised types of sport with
high endurance and strength components at a high level
(soccer, athletics). All gave their informed consent to partici-
pate in this study after the University of Muenster Human
Ethics Committee had approved of the procedures used. Mean
(SD) values for age, height and weight were 25.6 (3.5) years,
183.4 (7.6) cm and 77.9 (9.5) kg.
After attending a familiarisation session, subjects performed
three testing sessions, five days apart. In every session, subjects
performed the same test, after WU, after PC (with a cooling vest)
or without any thermoregulatory preparation (TPP; control (C)).
The tests were set in randomised order to avoid any order effects.
In each test, subjects performed an incremental running test
on a treadmill until exhaustion. They wore running shoes,
sports socks, shorts and a T-shirt. Subjects were required to
refrain from vigorous exercise for 48 h before testing and to
avoid any food, drink, cigarettes or caffeinated products for 3 h
before the start of a testing session.
The effect of the different TPP procedures was tested using an
incremental step test on a treadmill. Testing commenced at a
pace of 9 km/h, which was increased by 1 km/h every 5 min.
Subjects performed up to the point of volitional fatigue (break-
off or inability to sustain the pace).
Before the familiarisation session and all three tests, the body
height and weight of the subjects were measured. Before each
testing session, to analyse the heart rate (HR), the HR
transmitter and receiver were adjusted and started in the same
temperate conditions. Subjects then entered the heated
Abbreviations: 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,