2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
348
THE EFFECT OF LOCAL SKIN TEMPERATURE INCREASE ON
HUMAN DIVING RESPONSE
Cherouvim Evgenia and Geladas Nickos
Exercise Physiology Laboratory, Department of Sport Medicine and Biology of Exercise,
Faculty of Physical Education and Sport Science, University of Athens, Athens, Greece
Contact person: echerouv@phed.uoa.gr
INTRODUCTION
Apnea induces physiological changes, which are known as the diving response. The human
diving response involves bradycardia, hypertension and peripheral vasoconstriction. Factors
such as stimulation of facial cold receptors, lung volume, alterations of the intrathoracic
pressure, levels of physical fitness, age, long and short term training and psychological events
have been shown to influence the magnitude of diving response. In addition, many studies
have found a relationship between the magnitude of the human diving response and both
water and/or ambient temperature (Andersson et al., 2000; Schagatay et al., 1996). However,
it is not known whether a local skin temperature increase would affect the human diving
response. The present study wass designed to elucidate the effect of a limited skin
temperature increase on the human diving response. We hypothesized that mild local heating
would modify the diving responses. Furthermore, it was assumed that repeated breath hold
trials might reverse this phenomenon.
METHODS
Seven healthy, non-smoking males (age: 26.86 ± 1.4 years) participated in this study. None
of the subjects was experienced in apnea diving. The experimental protocol included 8
repeated breath hold efforts with face immersion, with 2 min intervals between each effort,
under two different conditions: a) without (AC) and b) with an ultraviolent lamp (AL) in
order to increase hand skin temperature, in a counterbalanced order. Subjects were instructed
to perform apnea manoeuvres without prior hyperventilation, after a deep but not maximal
inspiration and a relaxed chest throughout effort. Apnea was terminated upon maximum
individual tolerance, without any feedback being offered.
Cardiovascular parameters, such as heart rate (HR), systolic (SBP), diastolic (DBP) and mean
arterial blood pressure (MAP), and total peripheral resistance (TPR) were recorded
continuously during the test with a finger photoplethysmograph (Finometer 2300, FMS,
Netherlands). Skin and forearm temperatures were measured with a thermistor (Yellow
Spring, Inc. USA) every 15 sec. Apnea time was measured with an electronic stopwatch
(LCD Quartz, Citizen) and determined by close observation of termination and resumption of
breathing. Room temperature was kept at 21 ± 1 ο C and water temperature was maintained at
15 ± 1 ο C.
RESULTS
Heating the hand with the lamp resulted in an increase of fingure temperature to 34.12(±
0.34) ο C, whereas the temperature of the control hand was lower (28.04 ± 0.9 ο C, p0.05), a sufficiently long period for a
diving response to be established. Breath hold time gradually increased by 37 ± 10.26 sec
from the 1 st to the 8 th apnea without significant difference between the two conditions (Table
1). Local skin temperature increase affected heart rate response only during the four initial
trails where limited bradycardia was observed (AL: 59.36 ± 2.83 beats·min -1 vs. AC: 57.21 ±
2.32 beats·min -1 , p