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Biomedical subjects

B Ulicný

Publications and source records attributed to B Ulicný.

4 recordsLinked to original sources
PubMed1996

Changes in thermal homeostasis in humans due to repeated cold water immersions.

The purpose of this study was to monitor changes in body and skin temperatures, heat production, subjective shivering, cold sensation and body fat content in humans after intermittent cold water immersion. Repeated exposures of young sportsmen to cold water (head out, 14 degrees C, 1 h, 3 times per week for 4-6 weeks) induced changes in regulation of thermal homeostasis. "Cold acclimated" subjects exhibited an hypothermic type of adaptation. Central and peripheral body temperatures at rest and during cold immersion were lowered. The metabolic response to cold was delayed and subjective shivering was attenuated. The observed hypothermia was due to the shift of the threshold for induction of cold thermogenesis to lower body temperatures. "Cold acclimated" subjects also showed a lowered cold sensation. Because of the observed physiological changes, about 20% of the total heat production was saved during one cold water immersion of "cold acclimated" subjects. Maximal aerobic and anaerobic performances were not altered. No change in the thermosensitivity of the body temperature controller, as assessed from the unchanged slope of the relation between the deep body temperature and total heat production, was observed. Changes in cold sensation and regulation of cold thermogenesis were noticed first after four cold water immersions and persisted for at least 2 weeks after termination of the adaptation procedure. A trend towards a small increase in the body fat content was also observed. This finding, as well as the increased vasoconstriction, evidenced by the lowered skin temperature, indicate that slight changes in body insulation may also occur after "cold acclimation" in humans.

Acclimatization↗
PubMed1995

[Nutrient utilization during cold exposure and adaptation].

BACKGROUND: Repeated exposure to cold leads to a decline in the intensity of physiological defence reactions. In the complex of adaptational responses metabolic, thermogenic and insulation reactions predominate. The objective of the present investigation was to provide evidence of the predominating type of response of sportsmen exposed repeatedly to cold in an aqueous environment and to elucidate metabolic processes which serve to meet the energy demands of a certain type of adaptation to cold. METHODS AND RESULTS: The examination was made in a group of volunteers (men, mean age 21.0 +/- 1.8 years, height 1.80 +/- 0.04 m, body weight 77.0 +/- 3.1 kg, body fat 13.2 +/- 1.7%, anaerobic capacity expressed as maximum oxygen consumption 4.5 +/- 0.43 l.min-1). The cold acclimation programme involved immersion of the body into water 14 +/- 1 degree C 3 times a week for 1 month. During cold exposure the median body temperature before the acclimation programme dropped by 3.9 degrees C, after the acclimation programme by 4.1 degrees C. The total metabolic turnover after the programme declined by a 0.23 multiple of the metabolism at rest, at the end of the programme merely by a multiple of 0.07. During immersion the oxygen consumption doubled regardless of the stage of adaptation and an insignificant rise of non-esterified fatty acids occurred before the onset of the programme as well as after its termination. After the first exposure to cold a significant drop of the blood sugar was observed, while after the acclimation programme it increased insignificantly. The serum level of the thyroid stimulating hormone and triiodothyronine were affected only insignificantly by exposure to cold, the thyroxine level only at the borderline of significance before the onset of the acclimation programme. CONCLUSIONS: From values of the blood sugar level, respiratory quotient RQ, the non-esterified fatty acid level and body temperature at the periphery we may conclude that there is a restriction of the carbohydrate component as regards meeting energy demands of cold exposure before adaptation and a mixed type of meeting energy demands after termination of the cold acclimation programme.

Adaptation, Physiological↗
PubMed1993

[Changes in body fluids and minerals after cold adaptation].

To characterize fluid and ion shifts during 5-weeks cold adaptation, 6 nonadapted volunteers underwent cold acclimation programme (CAP), consisted of 1 h head-out immersion in water 14 +/- 1 degrees C 3 times a week. Blood samples were analyzed before/after the immersion and in the first and in the last week of CAP. Urine was collected for 10 h before, during, and after immersion for 4 h. Plasma volume (PV) decreased during first immersion (-18%) and less after CAP (-12). Blood volume reduction was 8.5% before and 5.2% after the CAP. Mean corpuscular volume was not changed either after the cold exposition or after the cold adaptation. The concentration of serum proteins increased by 12.1% after first immersion and by 8.1% after the CAP. The changes in serum concentration of Na+, K+ and Cl- before and after the CAP were not significant. Urine flow increased by 102% after first immersion, and by 165% after CAP. Urinary excretion of Na+ increased by 167% and 283%, excretion of K+ by 222% and 362% during first immersion and after CAP, respectively. Serum concentration of aldosterone increased nonsignificantly (+30%) during immersion before CAP and it did not changed after CAP. After the cold adaptation we observed the reduction of PV decrease, and increased diuresis with higher excretions of cations.

Acclimatization↗