Thermal Responses from Repeated Exposures to Severe Cold with Intermittent Warmer Temperatures.

Abstract

This study was conducted to evaluate physiological reaction and manual performance during exposure to warm (30 degrees C) and cool (10 degrees C) environments after exposure to very low temperatures (-25 degrees C). Furthermore, this experiment was conducted to study whether it is desirable to remove cold-protective jackets in warmer rooms after severe cold exposure. Eight male students remained in an extremely cold room for 20 min, after which they transferred into either the warm room or the cool room for 20 min. This pattern was repeated three times, and the total cold exposure time was 60 min. In the warm and cool rooms, the subjects either removed their cold-protective jackets (Condition A), or wore them continuously (Condition B). Rectal temperature, skin temperatures, manual performance, blood pressure, thermal, comfort and pain sensations were measured during the experiment. The effects of severe cold on almost all measurements in the cool (10 degrees C) environment were greater than those in the warm (30 degrees C) environment under both clothing conditions. The effects of severe cold on all measurements under Condition A except rectal temperature and toe skin temperature were significantly greater than those under Condition B in the cool environment but, not at all differences between Condition A and Condition B in the warm environments were significant. It was recognized that to remove cold-protective jackets in the cool room (10 degrees C) after severe cold exposure promoted the effects of severe cold. When rewarming in the warm resting room (30 degrees C), the physiological and psychological responses and manual performance were not influenced by the presence or absence of cold-protective clothing. These results suggest that it is necessary for workers to make sure to rewarm in the warm room outside of the cold storage and continue to wear cold-protective clothing in the cool room.

Blood pressure and thermal responses to repeated whole body cold exposure: effect of winter clothing

“…The level of maximal blood pressure was reached 5 min after the starting of the cold exposure, and blood pressure stayed almost at the same level during the 15-min cold exposure. SBP and DBP responses in the present study were in accordance with previous studies (Ozaki et al 1998(Ozaki et al , 2001, which have been carried out with normotensive participants in warmer winter clothing (2.3 clo) under colder test conditions. SBP has been reported to increase from 118 to 126, 129, and 128.5 mmHg after the first, second and third 20-min exposure to -25°C with 20-min warm up in 30°C between two cold exposures (Ozaki et al 1998).…”

“…Numerous studies have been conducted to demonstrate the effects of long-term exposure to cold (Leppaluoto et al 2001;Makinen et al 2006;Reynolds et al 2007). On the other hand, investigations of the effects of short-term repeated cold exposures on health and physiological responses are limited in number (Ozaki et al 1998(Ozaki et al , 2001Tochihara 2005;Kim et al 2007). However, these short cold exposures are very common in daily life during winter and have become more increasingly common in industry.…”

Protection of Feet in Cold Exposure

“…The rewarming of toes started only after 15-20 min of exercise. Other authors have also observed the later onset of the recovery of toe skin temperature 6) .…”

“…This effect can be related to slower warm-up of toes in footwear with a steel toe cap that has a higher thermal inertia (ca 100 g extra mass). After cold exposure the toe temperatures start to warm up after 5-15 min of a warm break or exercise 5,6,12,[26][27][28] .…”

Brief Rewarming Blunts Hypothermia-Induced Alterations in Sensation, Motor Drive and Cognition

“…Even exposure to less severe cold, which does not lower core temperature markedly, may produce cognitive (Palinkas, 2001; Mäkinen et al, 2006; Muller et al, 2012) and physical (Drinkwater and Behm, 2007) decrements, which may adversely affect performance and health (Tanaka et al, 1993; Palinkas, 2001). Brief periodic rewarming breaks throughout the day are recommended for restoring or preventing impairments in physiological and psychological performance for people exposed to the cold in occupational or leisure activities (Ceron et al, 1995; Ozaki et al, 1998; Brown et al, 2012). For example, in a protocol involving 3 sets of alternating 20-min exposure to −25°C in an industrial freezer with 20-min rewarming at 30°C or rest at 10°C, the protocol involving rewarming had a more positive effect than rest at 10°C on body temperature, hand tremor, counting task performance, and thermal and pain sensations.…”