2007, Piran, Slovenia
2007, Piran, Slovenia 2007, Piran, Slovenia
Environmental Ergonomics XII Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007 calorimeter. The accuracy criterion was the quantity of heat insertion/extraction and relationship with core temperature and skin temperature topography. The findings demonstrated a high correspondence between the thermal status of the body core and the temperature/heat flux of the finger as registered by the finger calorimeter under both cooling/warming sites. To assess the stability of the Tfing data transmitted by the calorimeter in extreme cold conditions, subjects wore the NASA Phase VI glove while grasping a highly cold rail. Placement of the finger sensor on the proximal vs. distal phalanx was compared. Tfing data obtained from the proximal phalanx did not exhibit the swings noted at the periphery of the fingers, indicating that the proximal area is less influenced by direct contact with a cold surface, and therefore is a more accurate location for the finger sensor in terms of reflecting body thermal status. DISCUSSION Based on zonal principles of heat transfer and the optimization of regimes of garment cooling/warming, it is possible to reduce the space garment’s weight and volume, quantity of circulating water and energy consumption, thus increasing reliability and safety. Comfort support of the extremities relying on heat delivery through optimal contact of the heating elements with the blood vessels on the hands and feet, or direct heat bypasses between body zones with high to low heat content is highly feasible. Through the use of a finger calorimeter functioning as a heat flux/temperature dynamic controller, it is possible to more accurately evaluate and regulate astronaut thermal status during EVA and onboard emergencies. ACKNOWLEDGEMENT This research was supported by NASA grants NAG5-3555, NAG9-1218, and NAG9- 1521 awarded to Victor S. Koscheyev, principal investigator. The first two authors are co-inventors of a patent on the shortened LCWG and the finger calorimeter. 36
Gravitational Physiology THE EXERCISE-INDUCED SWEATING RESPONSE AFTER 35 DAYS OF HORIZONTAL BED REST Igor B. Mekjavic 1 , Stelios Kounalakis 1,2 , Michail E. Keramidas 1,2 , Gianni Biolo 3 , Pietro E. di Prampero 4 , Marco Narici 5 , Rado Pisot 6 , and Ola Eiken 7 1 Jozef Stefan Institute, Ljubljana, Slovenia; 2 National and Kapodistrian University of Athens, Greece; 3 Università di Trieste - Ospedale di Cattinara, Trieste, Italy; 4 MATI Centro di Eccellenza - Università di Udine, Udine, Italy; 5 Manchester Metropolitan University, Alsager Campus, Cheshire, UK; 6 Institute for Kinesiology Research, University of Primorska, Koper, Slovenia; 7 Swedish Defence Research Agency, Karolinska Institutet, Stockholm, Sweden Contact person: igor.mekjavic@ijs.si INTRODUCTION We have demonstrated that for a given combination of core and skin temperatures the exercise sweating response may be modified by the magnitude of the relative work rate (Eiken and Mekjavic 2004; Kacin et al. 2007). These studies were conducted by manipulating the oxygen delivery to the working muscles either by experimentally inducing ischaemia (Eiken and Mekjavic 2004), or with hypoxia (Kacin et al. 2007). The aim of the present study was to evaluate whether the potentiation of the exercise sweating response with increased relative work rate prevails, in conditions where the ratio of relative:absolute work rate is changed while oxygen delivery to the working muscles is not limited, either by perfusion or diffusion. The exercise sweating response was compared prior to, and immediately after a 35-day horizontal bed rest period, which induces cardiovascular and muscular deconditioning, resulting in a decrease in aerobic capacity and muscle strength (Eiken and Mekjavic, 2002). By conducting the exercise at the same absolute work rate, the post-bed rest exercise induces a much greater relative work rate. If the potentiated sweating response previously observed during ischaemic and hypoxic exercise is associated with increased relative work rate per se, then the post-bed rest exercise sweating response should be potentiated at given core and skin temperatures. METHODS Ten healthy male subjects with average ± SD age of 23.0±1.7 yrs, height 181.2±5.2 cm, body mass 76.3±9.0 kg, and V & O2max 4.1±0.7 L·min -1 participated in the study. Following a medical examination they were housed in a ward at the Orthopaedic Hospital Valdoltra. Subjects remained in a horizontal position for the entire 35-day period, and were under 24-hour medical supervision during the study. Prior to the bed rest, subjects conducted an incremental-rate exercise to exhaustion on a cycle ergometer (Schiller CS-200, Switzerland), and a 40-min submaximal exercise test, conducted at a work rate equivalent to 30% of the maximal work rate. Following the bed rest, the subjects repeated the incremental-rate exercise to exhaustion, and also conducted two submaximal exercises. One was conducted at the same absolute level as in the pre-bed rest trial (Trial A), and the other at an absolute work rate, which would induce the same amount of relative work rate in the post-bed rest exercise (Trial R). During the submaximal exercise we monitored rectal temperature (Tre; MSR 12, Switzerland) 12 cm beyond the anal sphincter, skin temperatures (MSR 12, 37
- Page 1 and 2: ENVIRONMENTAL ERGONOMICS XII Procee
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Environmental Ergonomics XII<br />
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana <strong>2007</strong><br />
calorimeter. The accuracy criterion was the quantity of heat insertion/extraction and<br />
relationship with core temperature and skin temperature topography. The findings<br />
demonstrated a high correspondence between the thermal status of the body core and<br />
the temperature/heat flux of the finger as registered by the finger calorimeter under<br />
both cooling/warming sites. To assess the stability of the Tfing data transmitted by the<br />
calorimeter in extreme cold conditions, subjects wore the NASA Phase VI glove<br />
while grasping a highly cold rail. Placement of the finger sensor on the proximal vs.<br />
distal phalanx was compared. Tfing data obtained from the proximal phalanx did not<br />
exhibit the swings noted at the periphery of the fingers, indicating that the proximal<br />
area is less influenced by direct contact with a cold surface, and therefore is a more<br />
accurate location for the finger sensor in terms of reflecting body thermal status.<br />
DISCUSSION<br />
Based on zonal principles of heat transfer and the optimization of regimes of garment<br />
cooling/warming, it is possible to reduce the space garment’s weight and volume,<br />
quantity of circulating water and energy consumption, thus increasing reliability and<br />
safety. Comfort support of the extremities relying on heat delivery through optimal<br />
contact of the heating elements with the blood vessels on the hands and feet, or direct<br />
heat bypasses between body zones with high to low heat content is highly feasible.<br />
Through the use of a finger calorimeter functioning as a heat flux/temperature<br />
dynamic controller, it is possible to more accurately evaluate and regulate astronaut<br />
thermal status during EVA and onboard emergencies.<br />
ACKNOWLEDGEMENT<br />
This research was supported by NASA grants NAG5-3555, NAG9-1218, and NAG9-<br />
1521 awarded to Victor S. Koscheyev, principal investigator. The first two authors<br />
are co-inventors of a patent on the shortened LCWG and the finger calorimeter.<br />
36
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