Mariann Sandsund

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

Abstract The effects of whole-body exposure to ambient temperatures of −15°C and 23°C on selected performance-related physiological variables were investigated in elite nonasthmatic cross-country skiers. At an ambient temperature of −15°C we also studied the effects of the selective β2-adrenergic agonist Salbutamol (0.4u2009mgu2009×u20093) which was administered 10 min before the exercise test. Eight male cross-country skiers with known maximal oxygen uptakes (V˙O2max) of more than 70u2009mlu2009·u2009kg−1u2009·u2009min−1 participated in the study. Oxygen uptake (V˙O2), 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 V˙O2 and [La−]b at the two highest submaximal exercise intensities were significantly higher at −15°C than at 23°C. Time to exhaustion was significantly shorter in the cold environment. However, no differences in V˙O2max 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 β2-agonist Salbutamol did not influence submaximal and maximal V˙O2, 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 β2-agonist used.

Comparison of thermal manikins of different body shapes and size

Differences between manikins may be present due to manikin body shapes (male versus female). In order to examine such differences a study was designed. Comparisons were carried out based on: (1) tight versus loose clothing; (2) serial versus parallel calculation models; (3) even versus uneven clothing (insulation) distribution; and (4) the effect of donning clothes. Differences were observed between female and male manikins depending on body shape. However, these differences were within the range that was observed in the Subzero project, and were comparable with differences between manikins of male body shapes. Manikins behaved differently according to clothing adjustments. Tight-fitting clothes resulted in smaller differences. The effects of donning clothes were more pronounced with the serial calculation model, while the results generated by the serial and parallel calculation models differed more if the insulation was unevenly distributed (24% and 12% respectively). In order to examine the effect of body size, two baby manikins were compared to an adult manikin. The experimental conditions involved air layer insulation measurements (AL), lying on the back on an insulating surface (OB), and lying on the back on an insulating surface, covered with a sheet (OBS, baby manikins only). The acquired AL insulation for all manikins were very similar. The insulation value of adult manikin tested under condition OB differed from the others. This was related to flexible joints allowing the arms and legs to be in contact with the insulating surface, while baby manikins retained their arms and legs in the air. The baby manikins performed similarly in OBS tests.

Comparison of three different prehospital wrapping methods for preventing hypothermia - a crossover study in humans

BackgroundAccidental hypothermia increases mortality and morbidity in trauma patients. Various methods for insulating and wrapping hypothermic patients are used worldwide. The aim of this study was to compare the thermal insulating effects and comfort of bubble wrap, ambulance blankets / quilts, and Hiblers method, a low-cost method combining a plastic outer layer with an insulating layer.MethodsEight volunteers were dressed in moistened clothing, exposed to a cold and windy environment then wrapped using one of the three different insulation methods in random order on three different days. They were rested quietly on their back for 60 minutes in a cold climatic chamber. Skin temperature, rectal temperature, oxygen consumption were measured, and metabolic heat production was calculated. A questionnaire was used for a subjective evaluation of comfort, thermal sensation, and shivering.ResultsSkin temperature was significantly higher 15 minutes after wrapping using Hiblers method compared with wrapping with ambulance blankets / quilts or bubble wrap. There were no differences in core temperature between the three insulating methods. The subjects reported more shivering, they felt colder, were more uncomfortable, and had an increased heat production when using bubble wrap compared with the other two methods. Hiblers method was the volunteers preferred method for preventing hypothermia. Bubble wrap was the least effective insulating method, and seemed to require significantly higher heat production to compensate for increased heat loss.ConclusionsThis study demonstrated that a combination of vapour tight layer and an additional dry insulating layer (Hiblers method) is the most efficient wrapping method to prevent heat loss, as shown by increased skin temperatures, lower metabolic rate and better thermal comfort. This should then be the method of choice when wrapping a wet patient at risk of developing hypothermia in prehospital environments.

Effect of ambient temperature on endurance performance while wearing cross-country skiing clothing

This study assessed the effects of exposure to cold (−14 and −9xa0°C), cool (−4 and 1xa0°C) and moderate warm (10 and 20xa0°C) environments on aerobic endurance performance-related variables: maximal oxygen consumption (VO2max), running time to exhaustion (TTE), running economy and running speed at lactate threshold (LT). Nine male endurance athletes wearing cross-country ski racing suit performed a standard running test at six ambient temperatures in a climatic chamber with a wind speed of 5xa0mxa0s−1. The exercise protocol consisted of a 10-min warm-up period followed by four submaximal periods of 5xa0min at increasing intensities between 67 and 91xa0% of VO2max and finally a maximal test to exhaustion. During the time course mean skin temperature decreased significantly with reduced ambient temperatures whereas Tre increased during all conditions. Tre was lower at −14xa0°C than at −9 and 20xa0°C. Running economy was significantly reduced in warm compared to cool environments and was also reduced at 20xa0°C compared to −9xa0°C. Running speed at LT was significantly higher at −4xa0°C than at −9, 10 and 20xa0°C. TTE was significantly longer at −4 and 1xa0°C than at −14, 10 and 20xa0°C. No significant differences in VO2max were found between the various ambient conditions. The optimal aerobic endurance performance wearing a cross-country ski racing suit was found to be −4 and 1xa0°C, while performance was reduced under moderate warm (10 and 20xa0°C) and cold (−14 and −9xa0°C) ambient conditions.

Effects of montelukast on physical performance and exercise economy in adult asthmatics with exercise-induced bronchoconstriction

Leukotriene antagonists are effective in the treatment of exercise‐induced bronchoconstriction. Montelukast is a specific cysteinyl‐leukotriene receptor1 antagonist without known effects on the pulmonary vessels, which in theory should be advantageous with respect to gas exchange.

Effects of breathing cold and warm air on lung function and physical performance in asthmatic and nonasthmatic athletes during exercise in the cold

Asthma and exercise-induced respiratory symptoms are frequently reported among elite cross-country skiers,-3 and the magnitude of the exercise-induced obstructive airway response in asthmatics is determined by the minute ventilation during exercise together with the temperature and humidity of the inspired air.4 Cold weather may exacerbate the symptoms because the low water content of the inspired low-temperature air will increase the osmolarity of the lining fluid of the airways. This in turn could lead to increased constriction of airway smooth muscles,6 resulting in impaired ventilatory function. Most previous studies of this problem have used an experimental protocol in which the test subjects were supplied with cold breathing air while exposed to warm environments (normal room temperature^).^-^ Few studies have investigated the effects of breathing cold air in an environmental chamber.0-12 However, in Scandinavia, winter athletes have to train and compete outdoors under severe cold stress during the winter months, and exercise in cold weather implies exposure of the entire body as well as the respiratory tract to cold. For asthmatic athletes this may cause problems associated with inhalation of the dry cold air. For a fixed ventilation, breathing warm humid air reduces the severity of the subsequent obstruction in asthmatics, while cooling the breathing air exacerbates it.4

Effect of ambient temperature on female endurance performance.

Ambient temperature can affect physical performance, and an ambient temperature range of -4 °C to 11 °C is optimal for endurance performance in male athletes. The few similar studies of female athletes appear to have found differences in response to cold between the genders. This study investigated whether ambient temperature affects female endurance performance. Nine athletes performed six tests while running on a treadmill in a climatic chamber at different ambient temperatures: 20, 10, 1, -4, -9 and -14 °C and a wind speed of 5 m s(-1). The exercise protocol consisted of a 10-min warm-up, followed by four 5-min intervals at increasing intensities at 76%, 81%, 85%, and 89% of maximal oxygen consumption. This was followed by an incremental test to exhaustion. Although peak heart rate, body mass loss, and blood lactate concentration after the incremental test to exhaustion increased as the ambient temperature rose, no changes in time to exhaustion, running economy, running speed at lactate threshold or maximal oxygen consumption were found between the different ambient temperature conditions. Endurance performance during one hour of incremental exercise was not affected by ambient temperature in female endurance athletes.

Performance on a work-simulating firefighter test versus approved laboratory tests for firefighters and applicants.

Aim. Firefighters must meet minimum physical demands. The Norwegian Labour Inspection Authority (NLIA) has approved a standardised treadmill walking test and 3 simple strength tests for smoke divers. The results of the Trondheim test were compared with those of the NLIA tests taking into account possible effects of age, experience level and gender. Methods. Four groups of participants took part in the tests: 19 young experienced firefighters, 24 senior male firefighters and inexperienced applicants, 12 male and 8 female. Results. Oxygen uptake (VO2) at exhaustion rose linearly by the duration of the treadmill test. Time spent on the Trondheim test was closely related to performance time and peak VO2 on the treadmill test. Senior experienced firefighters did not perform better than equally fit young applicants. However, female applicants performed poorer on the Trondheim test than on the treadmill test. Performance on the Trondheim test was not closely related to muscle strength beyond a minimum. Conclusion. Firefighters completing the Trondheim test in under 19 min fit the requirements of the NLIA treadmill test. The Trondheim test can be used as an alternative to the NLIA tests for testing aerobic fitness but not for muscular strength. Women’s result of the Trondheim test were poorer than the results of the NLIA treadmill test, probably because of their lower body mass.

Exercise-induced asthma in adolescents: Challenges for physical education teachers

Asthma is the most common chronic medical condition that school-teachers are likely to encounter among their pupils. This study aimed to identify the needs of physical education teachers in dealing with adolescents with exercise-induced asthma, study their self-reported knowledge of asthma and identify future topics for education about exercise-induced asthma. A questionnaire was drawn up on the basis of the requirements that had emerged in the course of interviews with 18 physical education teachers. One hundred and six physical education teachers at secondary schools in the city of Trondheim and colleges in Sør-Trøndelag County in Norway answered the questionnaire (65% response rate). Eighty-two physical education teachers (78.1%) had pupils with asthma in their sports classes, and 89.4% answered positively regarding their need for advice on teaching pupils with asthma. Twenty-seven (25.9%) reported that they had sufficient knowledge to teach adolescents with asthma. Topics about asthma, its management and activities suitable for asthmatics were given high priority by the teachers.

Evaluation of test protocols for smoke-divers working in the heat

Abstract Smoke diving is physically very demanding, and regular training is important. However, in small fire brigades realistic training situations may occur only rarely. The purpose of this study was therefore to evaluate various test protocols with the aim of developing a realistic protocol for use in training situations for smoke-divers. Each subject carried out six exercise trials on six different days. Trials 1–3 consisted of a standard 8-min walking test on a treadmill in a climatic chamber (the treadmill test). In trials 4–6 the subjects performed a job-related performance test in two special climatic chambers built for smoke-diver training (the Pyrosec test). The temperatures in both test series were 50, 100 and 130°C, and the subjects wore full protective clothing and breathing apparatus during the tests. These data suggest that strenuous smoke-diving efforts at 130°C produces greater thermal stress and results in a perception of greater effort than at lower temperatures. The stress is greater during the longer Pyrosec test, and this may have implications for smoke-divers decision-making ability. These physiological measurements should help to improve our understanding of the factors that are critical for the ability of smoke-divers to behave rationally with regard to their own safety and awareness of their limitations.