2007, Piran, Slovenia

Acute and chronic heat exposure
EFFECTS OF HAND COOLING ON INTERMITTENT EXERCISE
PERFORMANCE IN THE HEAT.
Mike Price, Doug Thake, Alsadair O’Doherty,
Department of Biomolecular and Sports Sciences, Coventry Univerity, UK
Contact person: m.price@coventry.ac.uk
INTRODUCTION
The human body functions inefficiently during exercise and, as a result, between 70-80% of
energy produced during exercise is lost as heat (Marino, 2002) causing strain on the
thermoregulatory system. When performing high intensity exercise in the heat, such as that
experienced during team sports, the strain on the thermoregulatory system is increased,
resulting in core body temperature exceeding 40°C, and a decrease in exercise performance
(Nybo and Nielsen, 2001). Consequently, various cooling methods have been examined to try
and improve performance (Marino, 2002). Hand cooling is a practical method of reducing the
onset of heat strain (House et al., 1997) due to a large number of capillaries in the hands that
can be exposed to the cold when submerged, leading to cooling of the blood and consequently
core temperature (Livingstone et al., 1989). However, the effectiveness of hand cooling has
not yet been reported during intermittent exercise to alleviate heat strain. Therefore the aim of
this study was to determine the effects of different hand cooling regimens on intermittent
exercise performance in the heat.
METHODS.
Nine male team sport players volunteered for this study (mean (± SD) 22.3 ±2.3 y, 181.1 ±8.6
cm, 82.9 ±5.7 kg, and VO2max 52.6 ±6.3 mL.kg -1 .min -1 ). The study was approved by the
University Faculty of Health and Life Sciences Ethics Committee. All participants provided
written informed consent and completed a health screen questionnaire prior to each exercise
test. Each subject performed a preliminary test for maximal oxygen uptake (VO2max) test on a
motorised treadmill (Price and Halabi, 2005). Heart rate (HR) was measured by a Polar Heart
Rate Monitor every minute of the test. Expired gas was measured by an online breath by
breath gas analyser (Metamax 3b), via a face mask and sample line. The velocity at V & O2max
(v-V & O2max) was used to determine the treadmill speeds that each subject would exercise at
during the subsequent intermittent exercise protocols. Participants visited the laboratory on
three further occasions to perform either; no cooling control (CON), one handed (1-HC) or
two-handed (2-HC) cooling in a randomised and counterbalanced order. The intermittent
protocol consisted of a 5 min warm-up (8km.h -1 , 1% incline) followed by 20 min intermittent
running (repeated bouts of 15 s running at 100% v-V & O2max and 15 s passive recovery). After
the 20 min exercise period, a 15 min simulated halftime was undertaken where cooling or no
cooling was undertaken. Cooling involved placing either one hand or two hands into a bucket
containing 9 litres of cooled water (19.1 ±1.0°C) continuously stirred with an aquatic pump.
Heat lost via the hands into the water was calculated by the equation (Livingstone et al.,
1995). Once the cooling / control period had been completed participants undertook a
performance trial (repeated outs of 20 s running at 120% v-V & O2max followed by 20 s of rest).
At least 48 hr separated each trial. Subjects were asked to refrain from maximal exercise or
consumption of alcohol and caffeine 24 hr prior to testing, and arrive at the laboratory fully
hydrated. All experimental conditions were performed at 34.6 ±0.3°C. Subjects wore a rugby
shirt, shorts, socks and training shoes throughout each trial.
Subjects entered the air conditioned laboratory regulated at 21°C. Nude body weight was
measured (Seca balance scales). Thermistors (Edale Ltd) were attached for the measurement
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