Alcohol and respiratory and body temperature changes during tepid water immersion

Resting subjects were immersed for 30 min in water at 22 and 30 degrees C after drinking alcohol. Total ventilation, end-tidal PCO2, rectal temperature, aural temperature, mean skin temperature, heart rate, and oxygen consumption were recorded during the experiments. Blood samples taken before the immersion period were analyzed by gas-liquid chromatography. The mean blood alcohol levels were 82.50 +/- 9.93 mg.(100 ml)-1 and 100.6 +/- 12.64 mg (100 ml)-1 for the immersions at 22 and 30 degrees C, respectively. There was no significant change in body temperature measured aurally or rectally, mean surface skin temperature, or heart rate at either water temperature tested. Total expired ventilation was significantly attenuated for the last 15 min of the immersion at 22 degrees C, after alcohol consumption as compared to the ventilation change in water at 22 degrees C without ethanol. This response was not consistently significantly altered during immersion in water at 30 degrees C. It is evident that during a 30-min immersion in tepid water with a high blood alcohol level, body heat loss is not affected but some changes in ventilation do occur.     

Maximal oxygen uptake and erythropoietic responses after training at moderate altitude

Six well-trained male cross-county skiers trained for 7 days at 2700 m above sea level, their accommodation being at 1695 m. Blood samples for haemoglobin concentration [Hb], erythropoietin concentration [EPO] and reticulocyte count were collected before, during and after altitude exposure. Packed cell volume (PCV), red blood cell count (RBC), transferrin-iron saturation, mean red cell volume (MCV), mean corpuscular haemoglobin concentration (MCHC), maximal oxygen uptake, maximal achieved ventilation and heart rate were determined pre- and postaltitude exposure. The [EPO] increased significantly from pre-altitude (mean 36 mU.ml-1, SD 5) to maximal altitude values (mean 47 mU.ml-1, SD 3). The [Hb] had increased significantly above pre-altitude values (mean 8.8 mmol.l-1, SD 0.5) on day 2 (mean 9.1 mmol.l-1, SD 0.4) and day 7 (mean 9.4 mmol.l-1, SD 0.4) at altitude and on day 4 postaltitutde (mean 9.2 mmol.l-1, SD 0.4). The reticulocyte counts had increased significantly above pre-altitude values (mean 6%, SD 3%) on day 3 at altitude (mean 12%, SD 8%) and day 4 postaltitude (mean 10%, SD 5%). The RBC counts had increased on the 4th postaltitude day. The transferrin-iron saturation had decreased below pre-altitude values (mean 23%, SD 4%) on day 4 postaltitude (mean 14%, SD 5%) and had increased on day 11 postaltitude (mean 22%, SD 7%). There were no significant changes in MCV, MCHC, PCV, maximal oxygen uptake and maximal achieved ventilation, and heart rate pre- to postaltitude. These observations demonstrated an erythropoietic response to the altitude training which was not sufficient to increase the postaltitude maximal oxygen uptake.     

The physiological costs of box lifting

Thirteen male subjects lifted boxes of three different weights for 20 min periods each. Ventilation, oxygen uptake and heart rates were measured. Each subject made subjective estimates of the degree of difficulty of the work he was doing. Oxygen uptake and ventilation were found to reach steady state after about four minutes and remain there for the rest of the work session. Heart rate for the two lighter boxes reached steady state after about thirteen minutes while the heart rate continued to rise when lifting was done with the heaviest box. The relationships between oxygen uptake, heart rate and work load tended to be curvilinear, whereas the ventilation was linear when compared to work load. The heart rate and oxygen uptake relationship was also curvilinear, while ventilation and oxygen uptake had a linear relationship. The subjective ratings were expected to be about one-tenth of the heart rate. Only the ratings made while lifting the lightest box reflected this. The heavier boxes were rated as being more difficult to lift than 10 times the heart rate per minute. The mechanical efficiencies were found to range between 4.4% and 6.2%.     

不同功率递增速率对正常人心肺运动试验整体功能的影响Ⅱ—亚极限运动相关指标的影响*

目的: 观察健康志愿者不同功率递增速率完成症状限制性极限心肺运动试验（CPET）对CPET亚极限运动相关核心指标的影响。方法: 选择12名健康志愿者在一周内不同工作天随机完成中等适度程度（30 W/min）及比较低（10 W/min）和比较高（60 W/min）3种不同功率递增速率CPET。按标准方法比较12名志愿者CPET亚极限运动相关核心指标：无氧阈（AT）、单位功率摄氧量（ΔVO₂/ΔWR）、摄氧通气有效性峰值平台（OUEP）、二氧化碳通气当量平均90 s最低值（Lowest VE/ VCO₂）、二氧化碳通气当量斜率（VE/ VCO₂ Slope）及截距（intercept）和无氧阈时的摄氧通气效率值（VO₂/ VE@AT）和无氧阈时的二氧化碳通气当量值（VE/ VCO₂@AT）。对三组不同功率递增速率下各个指标的差异组间两两比较。结果: 中等适度功率递增速率组与比较低和比较高功率递增速率组相比摄氧通气有效性峰值平台（42.22±4.76 vs 39.54±3.30 vs 39.29±4.29）和二氧化碳通气当量平均90 s最小值（24.13±2.88 vs 25.60±2.08 vs 26.06±3.05）明显好,差异有统计学意义（P<0.05）;比较低、比较高功率递增速率组与中等适度功率递增速率组相比,单位功率摄氧量显著升高和降低（（8.45±0.66 vs 10.04±0.58 vs 7.16±0.60）ml/（min·kg））,差异有统计学意义（P<0.05）;无氧阈值没有发生明显改变（（0.87±0.19 vs 0.87±0.19 vs 0.89±0.19）L/min）,差异无统计学意义（P>0.05）;结论: 比较低、比较高功率递增速率可以明显改变摄氧通气有效性、二氧化碳排出通气有效性、单位功率摄氧量等CPET亚极限运动相关指标;选择比较低和比较高的功率递增速率和适度功率递增速率CPET相比明显降低了健康个体的摄氧通气有效性和二氧化碳排出通气有效性。CPET规范化操作要求选择适合受试者的功率递增速率,这样得到的CPET亚极限相关指标才最能反应受试者的真实功能状态。     

Morphofunctional properties of red blood cells in humans during seven-day “Dry” immersion

Healthy male volunteers were subjected to seven-day “dry” immersion. After that, morphological and biochemical features of erythrocytes, erythropoiesis intensity, including the indices of iron metabolism and erythropoietin, lipid and phospholipid spectrum of the plasma membrane of erythrocytes, and the efficiency of binding and release of oxygen by hemoglobin were studied. The studies were performed before immersion, at the last seventh day of immersion, and on the 7th and 15th days of the recovery period. We found that seven-day “dry” immersion tended to change morphological composition of red blood, erythropoiesis intensity, and metabolic indices in erythrocytes. Seven-day simulated microgravity resulted in significant changes in the indices of oxygen-transporting function of erythrocytes, probably, due to changes at the membrane level and, particularly, in phospholipid fractions. These changes have no clinical importance, because all of them returned to the baseline after the 15-day recovery period. Substantial variability of data is related to an individual response of the body to stress induced by experimental conditions.     

Compensatory and adaptive rearrangement in the human respiratory system under acute hypoxic conditions

Relationships between the parameters of external respiration (minute volume and respiration rate) and those of internal, tissue respiration (oxygen consumption, arteriovenous oxygen difference and efficiency of oxygen uptake) were studied during a period of acute hypoxia and upon its completion. The subjects were exposed to hypoxia for 25 min using oxygen-nitrogen hypoxic gas mixtures (HGMs) differing in oxygen content (8 and 12%, HGM-8 and HGM-12, respectively). From the third to the fifth minutes of exposure to HGM-8, the respiration minute volume (RMV) was found to increase by 51 ± 33% as compared to the background value; however, the body’s oxygen consumption (OC) was 35 ± 22% reduced. Afterwards, OC grew to reach, from the 20th to the 25th min of hypoxia, 108 ± 21% of the background value and 181% of the value determined from the third to the fifth minutes of hypoxia. OC growth was accompanied by an insignificant RMV increase (by 12%) as compared to the level determined from the third to the fifth minutes of hypoxia, whereas the efficiency of oxygen uptake from the arterial blood increased by 75% for the same period. RMV growth from the third to the fifth minutes of hypoxia occurred as expense result of a higher breathing depth; at the same time, the respiration rate decreased as compared to the background value. By the period from the 20th to the 25th min of exposure to HGM-8, the respiration rate increased by 21% as compared to the period from the third to the fifth minutes of hypoxia. The efficiency of oxygen uptake from the arterial blood remained higher than the background value for at least 5 min after completion of the exposure to HGM-8. During the same period, the ventilation equivalent, an indicator of the efficiency of external respiration, i.e., of oxygen supply to the body, was significantly lower than the background value. During the exposure to HGM-12, RMV increased to a lesser extent than on exposure to HGM-8, however, the efficiency of oxygen uptake was higher during exposure to HGM-12; therefore, OC was also higher in the latter case. Therefore, the assumption that, during hypoxia, intensified external respiration (ventilatory response) itself compensates oxygen deficiency in inhaled air is revised. Ventilatory response is only a portion of the entire functional system of respiration (both external and tissue respiration). The role of ventilatory response is important for conditioning the tissue respiration rearrangement to eliminate deficiency of oxygen consumption during hypoxia. The retained higher oxygen uptake from the arterial blood during the period after completion of hypoxic treatment testifies to the adaptive implication of changes in tissue respiration; the same is confirmed by a reduced ventilation equivalent after hypoxia, which is indicative of the growing efficiency of external respiration, i.e., of an improved oxygen supply to the body.     

代谢、血液碱化和纯氧影响呼吸调控的人体实验研究I:运动试验*

目的: 在整体整合生理学医学理论的指导下,通过分析正常人运动期间心肺代谢等多系统功能整体整合的连续动态变化,探讨正常环境运动状态下呼吸反应模式的调控机理。方法: 选正常志愿者5名,在美国洛杉矶加州大学Harbor-UCLA医学中心分别进行动脉置管,在常温室内空气状态下完成症状限制性最大极限心肺运动试验(CPET)。在运动过程中,连续测定肺通气指标及每分钟动脉取样的血气分析指标的变化,对CPET期间呼吸气体交换和血气指标的动态变化进行统计分析。结果: 在CPET期间,随着运动功率逐步递增,分钟摄氧量(每呼吸摄氧量×呼吸频率=每搏摄氧量×心率）和分钟通气量(潮气量×呼吸频率)均呈现近于线性渐进性递增(与静息状态比较,P<0.05~0.001);在运动超过无氧阈和呼吸代偿点后,分钟通气量的上升反应更加显著。结论: 人体在运动过程中,为了克服自行车功率计的阻力而发生代谢率改变,呼吸随代谢改变而变化,高强度运动时酸性代谢产物堆积更加加剧呼吸反应。     

Respiratory,cardiovascular, and hemolymph acid‐base changes in the amphibious crab,Cardisoma guanhumi,during immersion and emersion

The cardiorespiratory and hemolymph acid base status of bimodal breathing crabs, Cardisoma guanhumi, was monitored during the transition from breathing air to breathing water. Upon immersion, oxygen uptake (MO₂) decreased by half. Ventilatory frequency (fsc) increased more than 5 fold, causing a decrease in hemolymph carbon dioxide partial pressure (PCO₂). This was nearly fully compensated for by a gradual decrease in hemolymph bicarbonate concentration ([HCO₃ ^‐]) over 96 hours post‐immersion. After one to two weeks of immersion, when crabs were removed from the water, oxygen uptake initially increased, but eventually returned to the initial immersed value. Heart rate was unchanged but fsc slowed dramatically. The decreased ventilation resulted in a buildup of hemolymph PCO₂, causing a respiratory acidosis that was slowly compensated for by increased hemolymph [HCO₃ ^‐]. C. guanhumi appears to be a truly amphibious crab with respiratory and acid‐base adaptations found in both fully aquatic and fully terrestrial species.     

Effect of prolonged running on physiological responses to subsequent exercise

The purpose of this study was to compare metabolic and cardiopulmonary responses for submaximal and maximal exercise performed several days preceding (pre-test) and 45 min after (post-test) 21 miles of high intensity (70% VO2 max) treadmill running. Seven aerobically trained subjects' oxygen uptake, oxygen pulse, respiratory exchange ratio, heart rate, pulmonary ventilation, ventilatory equivalent of oxygen, and blood lactate concentration were determined for exercise during the pre- and post-test sessions. No differences were found for submaximal oxygen uptake, oxygen pulse, pulmonary ventilation and ventilatory equivalent of oxygen between the pre- and post-test values. Generally, submaximal heart rate responses were higher, and respiratory exchange ratio values were lower during the post-test. Reductions of maximal work time (12%), maximal oxygen uptake (6%) and maximal blood lactate concentration (47%) were found during the post-test. Thermal stress and glycogen depletion are possible mechanisms which may be responsible for these observed differences.     

Physiological adaptations to head-out aquatic exercises with different levels of body immersion

The purpose of this study was to compare the physiological adaptations to basic head-out aquatic exercises with different levels of body immersion. Sixteen young and clinically healthy subjects (9 women and 7 men) volunteered to participate in this study. Each subject performed 3 repetitions (on land, immersed to the hip, and immersed to the breast) of the aquatic exercise "rocking horse" for 6 minutes. The rating of perceived effort (RPE), the maximal heart rate achieved during the exercitation (HRmax), the percentage of the maximal theoretical heart rate estimated (%HRmax), the peak of oxygen uptake during the exercise (V(.-)O2peak), and the energy expenditure (EE) were evaluated. The RPE was significantly higher when exercising immersed to the hip than on land (p < 0.01) and immersed to the breast (p = 0.03). The HRmax and %HRmax were significantly lower when exercising with immersion to the breast than on land (p < 0.01) and with immersion to the hip (p < 0.01). The V(.-)O2peak was significantly different between all conditions. The lower mean value was verified when exercising immersed to the breast, followed by immersion to the hip and on land. The EE was significantly higher when performing aquatic exercises on land than when immersed to the hip (p = 0.02) and the breast (p < 0.01). So, physiological responses when exercising immersed to the hip are higher than when immersed to the breast. The physiological responses when exercising on land are higher than when exercising with immersion to the hip and to the breast.     

Effects of water temperature on cardiac autonomic nervous system modulation during supine floating

It is well known that heart rate, oxygen uptake and body temperature during exercise in water are affected by water temperature, buoyancy, hydrostatic and so on. It has been reported that the central blood volume during immersion was affected by the increased external hydrostatic pressure and cold-induced peripheral vasoconstriction, and intrathoratic blood volume should be greater during cold than warm water immersion (Epstein, 1992). The purpose of this presentation study was to make clear heart rate, blood pressure, oxygen uptake and cardiac autonomic nervous system modulation during supine floating at water temperatures of 25, 35 and 41 degrees C.     

Effects of experimental ventilation and ambient Po2 on O2 uptake of the isolated cutaneous tissue in the carp,Cyprinus carpio

Effects of experimental ventilation and ambient Po₂ on cutaneous O₂ uptake in vitro were studied in the carp, Cyprinus carpio. Oxygen uptake rate of the isolated cutaneous tissue was determined by ventilating the epidermis side of the skin with normoxic water in flow-through respirometers. Oxygen uptake rate of the skin increased with ventilation rate across the skin between 2.5 and 40 ml/min and became 3.2 nmol/cm²/min at a flow rate of 40 ml/min, which corresponds to an apparent water velocity of 1.1 cm/sec. At a ventilation rate of 10 ml/min, oxygen uptake rate of the skin increased with the ambient Po₂ between 115 and 230 Torr and became constant (3.8 nmol/cm²/min) between 230 and 295 Torr. When both sides of the skin were ventilated with normoxic water, oxygen uptake rate of the skin increased and became 3.7 nmol/cm²/min at a flow rate of 20–40 ml/min. These results suggest that the oxygen requirement of the skin is 3.7–3.8 nmol/cm²/min at 21.3°C and that cutaneous O₂ uptake in vitro depends on experimental ventilation and ambient Po₂, consistent with values measured in vitro in the carp (ref).     

Cardiac output variations in supine resting subjects during head-out cold water immersion

Five men, aged 31.2 years (SD 2.3), under semi-nude conditions and resting in a dorsal reclining position, were exposed to thermoneutral air for 30 min, followed immediately by a cold water (15°C) immersion for 60 min. Cardiac output was measured using a dualbeam Doppler flow meter. During immersion in cold water, cardiac frequency (f _c) showed an initial bradycardia. The lowest values were reached at about 10 min after immersion, 58.3 (SD 2.5) to 48.3 (SD 7.8) beats min^–1 (P < 0.05). By the 20th min of exposure,f _c had gradually risen to 70.0 beats min^–1 (SD 6.6,P < 0.05). This change could be due to the inhibition of the initial vagal reflex by increased catecholamine concentration. Stroke volume (V _s) was significantly increased (P < 0.05) during the whole cold immersion period. Cardiac output, increased from 3.57 (SD 0.50) to 6.26 (SD 1.33)1 min^–1 (P < 0.05) and its change with time was a function of bothV _s andf _c. On the other hand, systolic flow acceleration was unchanged during the period of immersion. The changes in the respiratory variables (ventilation, oxygen uptake, carbon dioxide output and respiratory exchange ratio) during immersion showed an initial hyperventilation followed, as immersion proceeded, by a slower metabolic increase due to shivering.     

Respiratory behaviour of larvae of four species of the Family Polycentropodidae (Trichoptera)

Larvae of Plectrocnemia conspersa and Polycentropus flavomaculatus from flowing water and Cyrnus flavidus and Holocentropus picicornis from still water were selected for study. In the above sequence, these larvae are associated with increasing ranges of temperature in their natural habitats. Experimental determination of lethal temperatures and investigations on ventilation frequency indicated that the larvae were increasingly tolerant of temperature in the same sequence of species. C. flavidus and H. picicornis showed infrequent ventilation which was little affected over wide ranges of temperature and dissolved oxygen but was stimulated erratically by water flow. P. conspersa and P. flavomaculatus showed more active ventilation which was more sensitive to changes in temperature and dissolved oxygen and was decreased by water flow. Consideration of ventilation in relation to oxygen uptake in P. conspersa and P. flavomaculatus suggests that ventilation activity may account for some 60–70% of active oxygen uptake. Differences in ventilation behaviour may thus be important in limiting larval distribution in stream systems.     

Cardiovascular and respiratory responses to apneas with and without face immersion in exercising humans.

The effect of the diving response on alveolar gas exchange was investigated in 15 subjects. During steady-state exercise (80 W) on a cycle ergometer, the subjects performed 40-s apneas in air and 40-s apneas with face immersion in cold (10 degrees C) water. Heart rate decreased and blood pressure increased during apneas, and the responses were augmented by face immersion. Oxygen uptake from the lungs decreased during apnea in air (-22% compared with eupneic control) and was further reduced during apnea with face immersion (-25% compared with eupneic control). The plasma lactate concentration increased from control (11%) after apnea in air and even more after apnea with face immersion (20%), suggesting an increased anaerobic metabolism during apneas. The lung oxygen store was depleted more slowly during apnea with face immersion because of the augmented diving response, probably including a decrease in cardiac output. Venous oxygen stores were probably reduced by the cardiovascular responses. The turnover times of these gas stores would have been prolonged, reducing their effect on the oxygen uptake in the lungs. Thus the human diving response has an oxygen-conserving effect.     

The use of opercular muscle electromyograms as an indicator of the metabolic costs of fish activity in rainbow trout, Salmo gairdneri Richardson, as determined by radiotelemetry

Averages of electromyogram (EMG) signals emanating from the levator arcus palatini , a small muscle involved in the operation of the operculum in rainbow trout, Salmo gairdneri , were analysed in terms of their relationship to the fish's oxygen consumption rates under various activity levels. The EMG signals were detected and transmitted with a radio-telemetry system. The EMG values showed a good correlation with corresponding oxygen consumption rates for fish under forced-swimming conditions but not when the fish was swimming spontaneously; this is attributed to an ability to regulate oxygen uptake at the gill surfaces by other means than increasing the ventilation volume, including alterations in the gill blood flow dynamics (e.g. secondary lamellar recruitment), and changes in the cardiac output. Under forced-swim conditions, where the oxygen demands by the respiring muscles were higher, increased ventilation volume, as indicated by increased opercular muscle activity, was directly related to swimming speed and oxygen uptake.     

Changes in the oxygen consumption of cysts of Globodera rostochiensis associated with the hatching of juveniles

The oxygen consumption of single cysts (90–110 /tg dry wt) was measured with an oxygen electrode microrespirometer. The mean oxygen consumption of nine cysts after 7 days in tap-water, was 0–48 + 0–05 mm³ 0₂ mg dry wt^-1 h^-1. After transfer to potato root diffusate for 1 day the mean oxygen consumption of the same cysts showed a significant increase to 159±7% of the rate recorded before they were removed from water. After 3 and 7 days in diffusate the corresponding means were 131±9% and 127±12% respectively. Cysts that remained in water throughout the experiments did not show any significant change in their oxygen consumption from the rate recorded after 7 days. The initial increase in oxygen uptake after the addition of diffusate was shown not to be due to the presence of microorganisms. Comparison of hatching data with the changes in oxygen consumption of similar cysts after 24 h in diffusate suggests that the increased oxygen uptake cannot be attributed solely to locomotor activity of the juveniles during the hatching process. The increased rate of respiration may precede other known changes that follow after the juveniles within a cyst are stimulated to hatch.     

Development of a telemetry system for measuring oxygen uptake during sports activities

A new system for continuous measurement of oxygen uptake by means of a telemeter has been developed. Oxygen uptake and pulmonary ventilation during rest and exercise were determined using a portable oxygen consumption meter (Oxylog). A small interface circuit between the Oxylog and the transmitter of a frequency modulated bio-telemeter system was designed and installed inside the Oxylog. Data from the transmitter were passed to a receiver and were fed into a microcomputer system. The microcomputer system displayed and printed out minute values of ventilation and oxygen uptake. The accuracy and reliability of the new system were checked by comparison with the traditional (Douglas bag) method. In the range less than 80 l.min-1 of ventilation and less than 2 l.min-1 of oxygen uptake, the system was not inferior to the Douglas bag method. The new system was applied for field continuous measurement of oxygen uptake during a doubles tennis game. The results of the application indicate that the telemetry system developed here is a very practical and useful way of measuring oxygen uptake during sports activities.     

Disturbance of sports performance after partial sleep deprivation

The changes in cardiac and ventilatory responses were measured in 7 endurance athletes during physical exercise on a bicycle ergometer, taking place after a control night and after a night with partial sleep deprivation in the middle of the night. The results show that, despite the maximal work load was not modified with control, heart rate, ventilation and VE/VO2 ratio (ERO2) were greater at the submaximal (75% of the VO2 max) and maximal work load and oxygen consumption decreased at maximal work, after the night of partial sleep deprivation as compared to the control. These findings suggest that acute sleep loss may contribute to alter the endurance performance by impairment of aerobic pathways.     

Effects of temperature and dissolved oxygen on heart rate,ventilation rate and oxygen consumption of spangled perch,Leiopotherapon unicolor (Günther 1859), (Percoidei,Teraponidae)

Summary Heart, ventilation and oxygen consumption rates ofLeiopotherapon unicolor were studied at temperatures ranging from 5 to 35°C, and during progressive hypoxia from 100% to 5% oxygen saturation. Biopotentials recorded from the water surrounding the fish corresponded to ventilation movements, and are thought to originate from the ventilatory musculature. Cardio-respiratory responses to temperature and dissolved oxygen follow the typical teleost pattern, with bradycardia, increased ventilation rate and reduced oxygen consumption occurring during hypoxia. However, ventilation rate did not increase at 15°C and below. Ventilation rate showed a slower response to increasing temperature (normoxic Q₁₀=1.39) than heart rate and oxygen consumption (normoxic Q₁₀=2.85 and 2.38).L. unicolor is unable to survive prolonged hypoxia by utilising anaerobic metabolism, but has a large gill surface area which presumably facilitates oxygen uptake in hypoxic environments. Periodic ventilation during normoxia in restingL. unicolor may improve ventilation efficiency by increasing the oxygen diffusion gradient across the gills.Abbreviations EBG electrobranchiogram - ECG electrocardiogram