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Biomedical subjects

R E Reinertsen

Publications and source records attributed to R E Reinertsen.

9 recordsLinked to original sources
PubMed1999

Salmeterol and physical performance at -15 degrees C in highly trained nonasthmatic cross-country skiers.

The aim of this double-blind, placebo-controlled, cross-over study was to investigate possible improvement in physical performance at an ambient temperature of -15 degrees C by an inhaled dose of 50 micrograms salmeterol in 8 highly trained nonasthmatic cross-country skiers. FEV1 was measured before, during and after the treadmill exercise protocol, which consisted of a warm-up run, runs of 10 min at 90% and 5 min at 80% VO2max, followed by a timed run to exhaustion. Despite a significant improvement in FEV1, salmeterol did not have a beneficial effect on heart rate, blood lactate concentration, respiratory exchange ratio, oxygen uptake or minute ventilation during the exercise protocol. Running time to exhaustion was not significantly different from placebo. This lack of enhancement of exercise performance in healthy endurance athletes further supports the recent approval of salmeterol for prophylactic use by asthmatic athletes during training and competition.

Adrenergic beta-Agonists↗
PubMed1998

Effect of cold exposure (-15 degrees C) and salbutamol treatment on physical performance in elite nonasthmatic cross-country skiers.

The effects of whole-body exposure to ambient temperatures of -15 degrees C and 23 degrees C on selected performance-related physiological variables were investigated in elite nonasthmatic cross-country skiers. At an ambient temperature of -15 degrees C we also studied the effects of the selective beta2-adrenergic agonist Salbutamol (0.4 mg x 3) which was administered 10 min before the exercise test. Eight male cross-country skiers with known maximal oxygen uptakes (VO2max) of more than 70 ml x kg(-1) x min(-1) participated in the study. Oxygen uptake (VO2), heart rate (fc), blood lactate concentration ([La-]b) and time to exhaustion were measured during controlled submaximal and maximal running on a treadmill in a climatic chamber. Lung function measured as forced expiratory volume in 1 s (FEV1) was recorded immediately before the warm-up period and at the conclusion of the exercise protocol. Submaximal VO2 and [La-]b at the two highest submaximal exercise intensities were significantly higher at -15 degrees C than at 23 degrees C. Time to exhaustion was significantly shorter in the cold environment. However, no differences in VO2max or fc were observed. Our results would suggest that exercise stress is higher at submaximal exercise intensities in a cold environment and support the contention that aerobic capacity is not altered by cold exposure. Furthermore, we found that after Salbutamol inhalation FEV1 was significantly higher than after placebo administration. However, the inhaled beta2-agonist Salbutamol did not influence submaximal and maximal VO2, fc, [La-]b or time to exhaustion in the elite, nonasthmatic cross-country skiers we studied. Thus, these results did not demonstrate any ergogenic effect of the beta2-agonist used.

Administration, Inhalation↗
PubMed1998

Effect of oxygen tension and rate of pressure reduction during decompression on central gas bubbles.

Reduction in ascent speed and an increase in the O2 tension in the inspired air have been used to reduce the risk for decompression sickness. It has previously been reported that decompression speed and O2 partial pressure are linearly related for human decompressions from saturation hyperbaric exposures. The constant of proportionality K (K = rate/partial pressure of inspired O2) indicates the incidence of decompression sickness. The present study investigated the relationship among decompression rate, partial pressure of inspired O2, and the number of central gas bubbles after a 3-h dive to 500 kPa while breathing nitrox with an O2 content of 35 kPa. We used transesophageal ultrasonic scanning to determine the number of bubbles in the pulmonary artery of pigs. The results show that, for a given level of decompression stress, decompression rate and O2 tension in the inspired air can be traded off against each other by using pulmonary artery bubbles as an end point. The results also seem to confirm that decompressions that have a high K value are more stressful.

Animals↗
PubMed1995

Heat production during cold water immersion: the role of shivering and exercise in the development of hypothermia.

Immersed in cold water, the body loses heat to the external environment. Heat production rises in order to compensate for heat loss by shivering or exercise. The aim of this study was to determine whether heat production is more successfully maintained over a long period of time by physical activity than by shivering when a human being is wearing an insulated survival suit and is immersed in cold water, and whether increased insulation of those parts of the suit exposed to water improves protection against heat loss with all-around standard insulation of the suit. Nine men participated in four series of experiments each lasting six hours. They were immersed in water at 3.6 degrees C and wore survival suits. One series of trials was made at rest, one series with periods of work, one series at rest where the insulation on the back was increased by 10 mm, and one series at rest with a survival suit featuring a new type of insulation. The results showed that periods of work give better chances of survival than continuous heat production by shivering in a well insulated suit. Furthermore, an extra layer of insulation in the back region significantly improved the thermal status of the subjects. When both rectal and skin temperature change at the same time in the same direction, there is a stronger influence on thermoregulation than when rectal temperature alone changes.

Body Temperature↗
PubMed1995

Metabolic changes during cold water immersion.

This study was conducted in order to compare the metabolic responses of individuals exposed to long duration cold water immersion under two experimental conditions: 1) Heat loss compensated by shivering thermogenesis, and 2) heat loss compensated by intermittent periods of exercise. Nine subjects participated in two experimental trials 1) Subjects wearing insulated survival suits who did perform mild leg cycling during immersion 2) Subjects wearing insulated survival suits who did not perform exercise. Blood was sampled pre- and postimmersion. Blood was assayed for free fatty acids (FFA), lactate, creatine kinase and glucose. Intermittent periods of physical activity during cold water immersion resulted in a higher increase in FFA than during inactivity. In lactate, glucose, and creatine kinase there were no significant differences between the changes from pre- to postimmersion under the two conditions.

Adult↗
PubMed1992

Cardiovascular responses to thoracic skin cooling: comparison of incubating and non-incubating Bantam hens.

Body temperatures, metabolic rate, haemostatic parameters, and cardiovascular reactions to thoracic skin cooling were compared between incubating (broody) and non-broody Bantam hens. Under resting conditions, without thoracic skin cooling, cardiac output of broody hens was twice that of non-broody hens. However, their metabolic rate (VO2) was increased by only one-third over that of non-broody hens, and the arteriovenous difference in oxygen concentration was smaller for broody birds. This indicates a higher rate of non-nutrient blood flow during incubation. A higher thoracic skin temperature (Tths) for broody hens compared to non-broody hens suggests that brood patches are the probable site of this increased flow through arteriovenous anastomoses (AVAs). Thoracic skin cooling increased metabolic rate and Q significantly more in broody hens, but did not increase AVA blood flow. The relation between metabolic rate and total peripheral resistance indicated more intense vasodilation for broody hens at the relatively low metabolic rates during moderate cooling, and more intense vasoconstriction for the broody hens at the high metabolic rates during stronger cooling. This corresponds to Tths measurements indicating dilation of brood patch AVAs with moderate cooling and AVA constriction with severe cooling. During moderate cooling, vasoconstriction in the feet and wattles of broody hens (but not of non-broody hens) freed non-nutrient blood flow for redistribution to the brood patches. Thus, the cardiovascular system of the hen seems to adjust to the special demands of incubation by a permanent increase of AVA flow in the brood patch, and by an additional capacity for brood patch vasodilation induced by cold stimuli in the range from 35 to 25 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Adaptation of homeostatic thermoregulation: comparison of incubating and non-incubating bantam hens.

Incubating and non-incubating Bantam hens were exposed to identical thoracic skin cooling to study the difference between their physiological responses with regard to thermoregulatory adaptation to incubation. Under resting conditions thoracic skin temperature (Tths) and metabolic heat production (M) were significantly higher in broody than in non-broody hens, indicating a permanently increased conductance of the brood patch. Thoracic skin cooling from 35 to 25 degrees C decreased Tths less in broody than in non-broody hens. In broody hens, these coolings induced a large, immediate increase in M, no constriction of brood patch vasculature, and a decrease in colonic temperature (Tc). This decrease in Tc triggered no further increase in M, but induced vasoconstriction in the feet. The coolings induced a smaller increase in M in the non-broody hens, accompanied by pronounced vasoconstriction, and did not affect Tc and foot temperature, Tf. The effects of more severe thoracic skin cooling (between 25 and 15 degrees C) differed much less between non-broody and broody hens. Vasoconstriction of the brood patch also occurred in the latter. It is concluded that in adaptation to incubation the thoracic skin becomes more sensitive, and its input signal becomes stronger for the control of certain effector systems of thermoregulation, allowing a controlled heat transfer to the eggs.

Adaptation, Biological↗