Investigation of the breathing pattern structure in competitive exercises of kettlebell lifters

The goal of the research was to determine the characteristics of the breathing pattern in kettlebell lifters. The following main indicators of external respiration were recorded during exercise performance: respiratory rate (RR, f), tidal volume (TV, V _T ), and respiratory minute volume (RMV, V _E ). The dependence of these parameters on the qualification of athletes and competitive exercise intensity was estimated. An SMP-21/01-“R-D” spirograph was used for qualitative and quantitative assessment of the main indicators of breathing patterns in kettlebell lifters. The characteristic changes in breathing of masters of sports (MS) and candidate masters of sport (CMS) were shown mainly for the three parameters, respiratory rate and tidal volume, as well as in the number of breathing cycles per cycle of exercise. Respiratory rate increases and tidal volume decreases at a high-intensity exercise. In international masters of sports (MSIC), the number of breathing cycles per cycle of competitive exercise and, consequently, respiratory rate remain constant independent of physical load. They show the predominance of only one index, tidal volume, which increases from 0.7 ± 0.1 L to 1.2 ± 0.1 L (p < 0.01) with increasing intensity of exercise. We have found transitional forms of breathing patterns in the competitive exercises of kettlebell lifting. The results lay the basis for the development of a novel concept of training and improvement of breathing technique in kettlebell lifting.     

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.     

腹式呼吸训练法对COPD伴Ⅱ型呼吸衰竭患者肺通气状态、血气指标及运动耐力的影响

摘要 目的：探讨腹式呼吸训练法对慢性阻塞性肺疾病（COPD）伴Ⅱ型呼吸衰竭患者肺通气状态、血气指标及运动耐力的影响。方法：选择我院2020年07月2022年12月期间收治的100例COPD伴Ⅱ型呼吸衰竭患者,根据随机数字表法将患者分为对照组[常规治疗基础上接受双水平气道正压（BIPAP）辅助通气,n=50]和研究组（对照组的基础上接受腹式呼吸训练法干预,n=50）。对比两组临床相关指标、肺通气状态、血气指标及运动耐力指标。结果：研究组的喘憋消失时间、体温恢复正常时间、住院时间、肺部啰音消失时间短于对照组（P<0.05）。两组干预1周后第1秒呼气的最大容积（FEV₁）、最大自主分钟通气量（MVV）、用力肺活量（FVC）均升高,且研究组高于对照组（P<0.05）。两组干预1周后氧分压（PaO2₂）、血氧饱和度（SpO₂）均升高,且研究组高于对照组;二氧化碳分压（PaCO₂）下降,且研究组低于对照组（P<0.05）。两组干预1周后6 min步行距离（6MWT）升高,且研究组高于对照组（P<0.05）。结论：腹式呼吸训练法有助于改善COPD伴Ⅱ型呼吸衰竭患者的临床症状,调节肺通气状态、血气指标,提高运动耐力。     

Effects of interval training at the ventilatory threshold on clinical and cardiorespiratory responses in elderly humans

This study assessed clinical and cardiorespiratory responses after an interval training programme in sedentary elderly adults using the ventilatory threshold (V _th) as the index of exercise training intensity. A selection of 22 subjects were randomized into two groups: 11 subjects served as the training group (TG) and the others as controls (CG). Maximal exercise tests were performed on a treadmill before (T₀), each month (T₁, T₂) and after the 3-month interval training programme period (T₃). The TG subjects were individually trained at the heart rate corresponding to V _th measured at T₀, T₁ and T₂ as the breakpoint in the oxygen uptake-carbon dioxide production relationship. Their training programme consisted of walking/jogging sessions on a running track twice a week. The sessions consisted of varying durations of exercise alternating with active recovery in such a way that the subjects slowly increased their total exercise time from an initial duration of 30 min to a final duration of 1 h. During training the heart rate was continuously monitored by a cardiofrequency meter. Compared with the daily activities of the controls, no training programme-related injuries were observed in TG. Moreover, programme adherence (73%) and attendance (97.3%) were high. The maximal oxygen uptake and V _th were increased in TG, by 20% (P<0.05) and 26% (P<0.01), respectively. Interval training at V _th also significantly increased maximal O₂ pulse (P<0.05) and maximal ventilation (P<0.01). A significant decrease in submaximal ventilation (P<0.05) and heart rate (P<0.01) was also noted. These results would suggest that for untrained elderly adults, an interval training programme at the intensity of V _th may be well-tolerated clinically and may significantly improve both maximal aerobic power and submaximal exercise tolerance. Accepted: 6 January 1998     

Estimation of the anaerobic threshold from the data on lung ventilation and heart rate variability

The goal of the study was to develop methods for estimating the anaerobic threshold from the rate of lung ventilation and heart rate variability during bicycle ergometer and treadmill tests with a stepwise increasing load. At the first stage, the method of estimation of the anaerobic threshold from lung ventilation data was developed. Forty-nine skilled ski racers participated in the experiment. They performed a treadmill ski-walking test with poles, with the slope gradually increasing from 0 to 25 degrees at a rate of one degree per minute. At the second stage, we developed a method for determining the anaerobic threshold from heart rate data. Eighty-six athletes of different sports specialties performed pedaling on a Monarch bicycle ergometer until exhaustion. The initial power was 25 W; the power increased by 25 W every 2 min. The pedaling rate remained constant (75 rpm). The lung ventilation, as well as oxygen consumption and carbon dioxide exhalation parameters, were measured using a COSMED K4 gas analyzer. Arterial blood was sampled from an earlobe or a finger; the blood lactate concentration was determined using an Akusport instrument. The RR intervals were recorded using a Polar s810i heart rate monitor. The results showed that the onset of ventilation anaerobic threshold (VAnT) determined by the graphical method coincided with the moment when blood lactate accumulated to 3.8 ± 0.1 mM in the treadmill test and 4.1 ± 0.6 mM in the bicycle ergometer test. The oxygen consumption at the VAnT level was found to be related to the variance of RR intervals (SD ₁). The following regression equation was derived: VO₂ AnT = 0.35 + 0.01SD ₁ W + 0.0016SD ₁ HR + 0.106SD ₁ (ms), l/min; (R = 0.98, function estimation error, 0.26 l/min, p < 0.001), where W (W) is power, HR is heart rate (bpm), and SD ₁ is the variance of RR intervals (ms) at the moment of recording of the heart rate threshold.     

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).     

Oxygen Demand and Energy Cost of Intense Muscular Activity in Humans

Changes in the kinetics of aerobic and anaerobic metabolism were studied in 26 highly profiled athletes performing bicycle ergometer exercise. The different intensity exercise sessions included those with a critical intensity corresponding to the maximum oxygen consumption up to value of the maximum anaerobic intensity of about 10 MMR units. The maximal aerobic metabolism was maintained in the exercises with a relative intensity of 1.0 to 2.5 MMR units. At the higher values of the exercise relative intensity, the oxygen current consumption exponentially decreased. An increase in the rate of anaerobic glycolytic energy production, which was first recorded at the threshold of anaerobic metabolism (W _AT = 0.5 MMR units), increased linearly with a further increase in the exercise relative intensity up to the level of the exhaustion intensity (W _ex = 4.7 MMR units). A sharp increase in the rate of an alactic anaerobic process was found at the relative intensity values of 2.5 MMR units, and this increase grew linearly up to values of the maximal anaerobic intensity (W _max = 9.5 MMR units).     

Response of subjects trained to hold their breath to intermittent normobaric hypoxia

The change in the external respiration parameters was studied in individuals engaging in sports (swimming) combined with training in voluntary cyclic breath holding during a session of intermittent normobaric hypoxia (three cycles of 5 min breathing a gas mixture containing 10.7% O₂ alternating with 5 min breathing ordinary air). It was shown that they differed from the control group in sharp variations in the oxygen consumption rate, which were accompanied by equally marked changes in the effectiveness of oxygen binding in the lungs with a slightly increased stable level of pulmonary ventilation and a bradypneic type of breathing. An increase in the alveolar concentration of carbonic acid and a dramatic increase in the effectiveness of its elimination are significant features of the adaptive process in the mechanism of regulation of external respiration in this training.     

Ventilatory and metabolic adaptations to walking and cycling in patients with COPD.

To test the hypothesis that in chronic obstructive pulmonary disease (COPD) patients the ventilatory and metabolic requirements during cycling and walking exercise are different, paralleling the level of breathlessness, we studied nine patients with moderate to severe, stable COPD. Each subject underwent two exercise protocols: a 1-min incremental cycle ergometer exercise (C) and a "shuttle" walking test (W). Oxygen uptake (VO(2)), CO(2) output (VCO(2)), minute ventilation (VE), and heart rate (HR) were measured with a portable telemetric system. Venous blood lactates were monitored. Measurements of arterial blood gases and pH were obtained in seven patients. Physiological dead space-tidal volume ratio (VD/VT) was computed. At peak exercise, W vs. C VO(2), VE, and HR values were similar, whereas VCO(2) (848 +/- 69 vs. 1,225 +/- 45 ml/min; P < 0. 001) and lactate (1.5 +/- 0.2 vs. 4.1 +/- 0.2 meq/l; P < 0.001) were lower, DeltaVE/DeltaVCO(2) (35.7 +/- 1.7 vs. 25.9 +/- 1.3; P < 0. 001) and DeltaHR/DeltaVO(2) values (51 +/- 3 vs. 40 +/- 4; P < 0.05) were significantly higher. Analyses of arterial blood gases at peak exercise revealed higher VD/VT and lower arterial partial pressure of oxygen values for W compared with C. In COPD, reduced walking capacity is associated with an excessively high ventilatory demand. Decreased pulmonary gas exchange efficiency and arterial hypoxemia are likely to be responsible for the observed findings.     

Cycling efficiency and pedalling frequency in road cyclists

The purpose of this study was to determine the influence of pedalling rate on cycling efficiency in road cyclists. Seven competitive road cyclists participated in the study. Four separate experimental sessions were used to determine oxygen uptake (VO(2)) and carbon dioxide output (VCO(2)) at six exercise intensities that elicited a VO(2) equivalent to 54, 63, 73, 80, 87 and 93% of maximum VO(2) (VO(2max)). Exercise intensities were administered in random order, separated by rest periods of 3-5 min; four pedalling frequencies (60, 80, 100 and 120 rpm) were randomly tested per intensity. The oxygen cost of cycling was always lower when the exercise was performed at 60 rpm. At each exercise intensity, VO(2) showed a parabolic dependence on pedalling rate (r = 0.99-1, all P < 0.01) with a curvature that flattened as intensity increased. Likewise, the relationship between power output and gross efficiency (GE) was also best fitted to a parabola (r = 0.94-1, all P < 0.05). Regardless of pedalling rate, GE improved with increasing exercise intensity (P < 0.001). Conversely, GE worsened with pedalling rate (P < 0.001). Interestingly, the effect of pedalling cadence on GE decreased as a linear function of power output (r = 0.98, n = 6, P < 0.001). Similar delta efficiency (DE) values were obtained regardless of pedalling rate [21.5 (0.8), 22.3 (1.2), 22.6 (0.6) and 23.9 (1.0)%, for the 60, 80, 100 and 120 rpm, mean (SEM) respectively]. However, in contrast to GE, DE increased as a linear function of pedalling rate (r = 0.98, P < 0.05). The rate at which pulmonary ventilation increased was accentuated for the highest pedalling rate (P < 0.05), even after accounting for differences in exercise intensity and VO(2) (P < 0.05). Pedalling rate per se did not have any influence on heart rate which, in turn, increased linearly with VO(2). These results may help us to understand why competitive cyclists often pedal at cadences of 90-105 rpm to sustain a high power output during prolonged exercise.     

Relationships of Oxygen Consumption, Hemodynamics, and Heart Rate Variability with the Functional Class of Coronary Artery Disease Patients

The functional classes (FCs) established according to the criteria of the New York Heart Association were tested for association with oxygen consumption, the state of central hemodynamics, and heart rate (HR) variability in coronary artery disease (CAD) patients. Oxygen consumption, central hemodynamics, and HR variability at rest and during exercise were assayed in 146 CAD patients and 30 healthy individuals (the control group). It was established that the peak oxygen consumption (VO_2max), anaerobic threshold, pulmonary ventilation, systolic and minute blood volume at the threshold load (TL), and HR variability in a supine position significantly decrease and the total vascular peripheral resistance at rest and during exercise increases with increasing FC in CAD patients. The closest correlation of FC was revealed with physical working capacity, anaerobic threshold, age, and peak oxygen consumption. Moderate correlations were established with the chronotropic function of the heart at the threshold load, HR variability, the high- and low-frequency components of the cardiac rhythm at TL, pulmonary ventilation, stroke volume at rest and at TL, and the carbon dioxide ventilation equivalent at TL. In healthy individuals, the peak oxygen consumption closely correlated with the HR variability, the very low frequency component at TL, and physical capacity. With an increase in FC in CAD patients, peak oxygen consumption became more tightly associated with the chronotropic function and the hemodynamic components at TL than with the HR variability in a supine position or at TL.     

机械通气新生儿撤机失败的危险因素分析及预防对策探讨

摘要 目的：分析机械通气新生儿撤机失败的危险因素,并探讨预防对策。方法：回顾性选取2018年4月~2021年3月在我院接受机械通气治疗的256例新生儿的临床资料。根据是否发生撤机失败将患儿分为撤机成功组与撤机失败组。撤机失败的影响因素采用单因素及多因素Logistic回归分析,并探讨预防对策。结果：256例接受机械通气的新生儿中,有29例发生撤机失败,撤机失败率为11.33%。单因素分析结果显示：撤机成功组与撤机失败组在胎龄、出生体重、Apgar评分、产伤情况、呼吸机相关性肺炎、多脏器功能损害、肺部感染、败血症、营养支持、撤机时血氧分压（PO₂）、撤机时心率、撤机时二氧化碳分压（PCO₂）方面对比差异有统计学意义（P<0.05）。多因素Logistic回归分析结果显示：撤机时PO₂偏低、撤机时心率较高、撤机时PCO₂较高、多脏器功能损害、无营养支持、伴有肺部感染、发生呼吸机相关性肺炎、胎龄＜37周是导致机械通气新生儿撤机失败的危险因素（P<0.05）。结论：导致机械通气新生儿撤机失败的危险因素较多,临床应针对危险因素进行干预,并在撤机前进行充分评估以减少撤机失败率。     

Influence of aeration intensity on mature aerobic granules in sequencing batch reactor

Aeration intensity is well known as an important factor in the formation of aerobic granules. In this research, two identical lab-scale sequencing batch reactors with aeration intensity of 0.8 (R1) and 0.2 m³/h (R2) were operated to investigate the characteristics and kinetics of matured aerobic granules. Results showed that both aeration intensity conditions induced granulation, but they showed different effects on the characteristics of aerobic granules. Compared with the low aeration intensity (R2), the aerobic granules under the higher aeration intensity (R1) had better physical characteristics and settling ability. However, the observed biomass yield (Y _obs) in R1 [0.673 kg mixed liquor volatile suspended solids (MLVSS)/kg chemical oxygen demand (COD)] was lower than R2 (0.749 kg MLVSS/kg COD). In addition, the maximum specific COD removal rates (q _max) and apparent half rate constant (K) of mature aerobic granular sludge under the two aeration intensities were at a similar level. Therefore, the matured aerobic granule system does not require to be operated in a higher aeration intensity, which will reduce the energy consumption.     

Physiological Comparison of Concentric and Eccentric Arm Cycling in Males and Females

Lower body eccentric exercise is well known to elicit high levels of muscular force with relatively low cardiovascular and metabolic strain. As a result, eccentric exercise has been successfully utilised as an adaptive stressor to improve lower body muscle function in populations ranging from the frail and debilitated, to highly-trained individuals. Here we investigate the metabolic, cardiorespiratory, and energy costs of upper body eccentric exercise in a healthy population. Seven men and seven women performed 4-min efforts of eccentric (ECC) or concentric (CON) arm cycling on a novel arm ergometer at workloads corresponding to 40, 60, and 80% of their peak workload as assessed in an incremental concentric trial. The heart rate, ventilation, cardiac output, respiratory exchange ratio, and blood lactate concentrations were all clearly greater in CON condition at all of the relative workloads (all p<0.003). Effect size calculations demonstrated that the magnitude of the differences in VO₂ and work economy between the ECC and CON exercise ranged from very large to extremely large; however, in no case did mechanical efficiency (η_MECH) differ between the conditions (all p>0.05). In contrast, delta efficiency (η_Δ), as previously defined by Coyle and colleagues in 1992, demonstrated a sex difference (men>women; p<0.05). Sex differences were also apparent in arteriovenous oxygen difference and heart rate during CON. Here, we reinforce the high-force, low cost attributes of eccentric exercise which can be generalised to the muscles of the upper body. Upper body eccentric exercise is likely to form a useful adjunct in debilitative, rehabilitative, and adaptive clinical exercise programs; however, reports of a shift towards an oxidative phenotype should be taken into consideration by power athletes. We suggest delta efficiency as a sensitive measure of efficiency that allowed the identification of sex differences.     

An increased carbon dioxide production in transient hypoxia in healthy subjects at rest

Indices of pulmonary gas exchange and heart rate (HR) have been measured in 24 healthy subjects not adapted to hypoxia after hypoxic aerial mixture (HAM) (17, 15, 13 vol % of oxygen) respiration for 15 min. Using group data analysis, it has been shown that hypoxia under the conditions of inhalation of 17 and 15 vol % of O₂ caused no significant changes. Hypoxia under the conditions of 13 vol % of O₂ inhalation is a threshold one, when ventilation (SpO₂) drops below 85%. A significant increase in the lung ventilation (Ve) (10–14%, p < 0.05) and HR (11–15%, p < 0.05) have been observed in this case. Hyperpnea was accompanied by an increase in the oxygen uptake rate by 10% and carbon dioxide release rate (10–18%, p < 0.05). On the contrary, individual data analysis showed changes in the pulmonary gas exchange indices in 90% of subjects in the case of inhalation of 17 vol % of O₂ HAM. Four response types have been found: ventilation (increase in lung ventilation), hypoxic hypometabolism (decrease in oxygen consumption rate), and mobilization response (increase in oxygen utilization in the lungs), and anaerobic response, which is expressed in an increase in the carbon dioxide release rate along with an increase in the respiratory quotient. All these responses are of an individual type, but the ventilation response is developed in response to hypoxia caused by inhalation of 13 vol % of O₂ HAM and a decrease in SpO₂ below 85% in more than 60% of cases.     

Dynamic hyperinflation is associated with a poor cardiovascular response to exercise in COPD patients

Background

Pulmonary hyperinflation has the potential for significant adverse effects on cardiovascular function in COPD. The aim of this study was to investigate the relationship between dynamic hyperinflation and cardiovascular response to maximal exercise in COPD patients.

Methods

We studied 48 patients (16F; age 68 yrs ± 8; BMI 26 ± 4) with COPD. All patients performed spirometry, plethysmography, lung diffusion capacity for carbon monoxide (TLco) measurement, and symptom-limited cardiopulmonary exercise test (CPET). The end-expiratory lung volume (EELV) was evaluated during the CPET. Cardiovascular response was assessed by change during exercise in oxygen pulse (ΔO₂Pulse) and double product, i.e. the product of systolic blood pressure and heart rate (DP reserve), and by the oxygen uptake efficiency slope (OUES), i.e. the relation between oxygen uptake and ventilation.

Results

Patients with a peak exercise EELV (%TLC) ≥ 75% had a significantly lower resting FEV₁/VC, FEF₅₀/FIF₅₀ ratio and IC/TLC ratio, when compared to patients with a peak exercise EELV (%TLC) < 75%. Dynamic hyperinflation was strictly associated to a poor cardiovascular response to exercise: EELV (%TLC) showed a negative correlation with ΔO₂Pulse (r = - 0.476, p = 0.001), OUES (r = - 0.452, p = 0.001) and DP reserve (r = - 0.425, p = 0.004). Furthermore, according to the ROC curve method, ΔO₂Pulse and DP reserve cut-off points which maximized sensitivity and specificity, with respect to a EELV (% TLC) value ≥ 75% as a threshold value, were ≤ 5.5 mL/bpm (0.640 sensitivity and 0.696 specificity) and ≤ 10,000 Hg · bpm (0.720 sensitivity and 0.783 specificity), respectively.

Conclusion

The present study shows that COPD patients with dynamic hyperinflation have a poor cardiovascular response to exercise. This finding supports the view that in COPD patients, dynamic hyperinflation may affect exercise performance not only by affecting ventilation, but also cardiac function.     

Possible influences of exercise-intensity-dependent increases in non-cortical hemodynamic variables on NIRS-based neuroimaging analysis during cognitive tasks: Technical note

[Purpose]

Functional near-infrared spectroscopy (fNIRS) provides functional imaging of cortical activations by measuring regional oxy- and deoxy-hemoglobin (Hb) changes in the forehead during a cognitive task. There are, however, potential problems regarding NIRS signal contamination by non-cortical hemodynamic (NCH) variables such as skin blood flow, middle cerebral artery blood flow, and heart rate (HR), which are further complicated during acute exercise. It is thus necessary to determine the appropriate post-exercise timing that allows for valid NIRS assessment during a task without any increase in NCH variables. Here, we monitored post-exercise changes in NCH parameters with different intensities of exercise.

[Methods]

Fourteen healthy young participants cycled 30, 50 and 70% of their peak oxygen uptake (Vo_2peak) for 10 min per intensity, each on different days. Changes in skin blood flow velocity (SBFv), middle cerebral artery mean blood velocity (MCA V_mean) and HR were monitored before, during, and after the exercise.

[Results]

Post-exercise levels of both SBFv and HR in contrast to MCA V_mean remained high compared to basal levels and the times taken to return to baseline levels for both parameters were delayed (2-8 min after exercise), depending upon exercise intensity.

[Conclusion]

These results indicate that the delayed clearance of NCH variables of up to 8 min into the post-exercise phase may contaminate NIRS measurements, and could be a limitation of NIRS-based neuroimaging studies.     

Oxidative stress and nitrite dynamics under maximal load in elite athletes: relation to sport type

Maximal workload in elite athletes induces increased generation of reactive oxygen/nitrogen species (RONS) and oxidative stress, but the dynamics of RONS production are not fully explored. The aim of our study was to examine the effects of long-term engagement in sports with different energy requirements (aerobic, anaerobic, and aerobic/anaerobic) on oxidative stress parameters during progressive exercise test. Concentrations of lactates, nitric oxide (NO) measured through stabile end product-nitrites (NO₂ ^?), superoxide anion radical (O₂ ^??), and thiobarbituric reactive substances (TBARS) as index of lipid peroxidation were determined in rest, after maximal workload, and at 4 and 10th min of recovery in blood plasma of top level competitors in rowing, cycling, and taekwondo. Results showed that sportmen had similar concentrations of lactates and O₂ ^?? in rest. Nitrite concentrations in rest were the lowest in taekwondo fighters, while rowers had the highest levels among examined groups. The order of magnitude for TBARS level in the rest was bicycling > taekwondo > rowing. During exercise at maximal intensity, the concentration of lactate significantly elevated to similar levels in all tested sportsmen and they were persistently elevated during recovery period of 4 and 10 min. There were no significant changes in O₂ ^??, nitrite, and TBARS levels neither at the maximum intensity of exercise nor during the recovery period comparing to the rest period in examined individuals. Our results showed that long term different training strategies establish different basal nitrites and lipid peroxidation levels in sportmen. However, progressive exercise does not influence basal nitrite and oxidative stress parameters level neither at maximal load nor during the first 10 min of recovery in sportmen studied.     

The respiratory function of blood in elderly and old age and the factors that determine it

Indices of pulmonary gas exchange, blood gases, the oxyhemoglobin dissociation curve, and intraerythrocytic metabolic parameters were analyzed in 62 apparently healthy elderly and senile subjects (60–92 years old) and 18 young healthy subjects (19–30 years old). PaO₂ was found to decrease in elderly and senile subjects. Arterial hypoxemia in old age is caused by an increase in the alveoloarterial PO₂ gradient, primarily as a result of the malcoordination of pulmonary ventilation and blood flow. A rightward compensatory shift of the oxyhemoglobin dissociation curve was observed, which was due to facilitated oxygen release in tissues owing to a pH decrease in erythrocytes (the Bohr effect). However, the facilitated oxygen release by oxyhemoglobin cannot compensate for the effect of factors deteriorating oxygen supply delivery to tissues, observed with aging, which is confirmed by the decrease in the partial pressure of oxygen in the venous blood of elderly and senile people, reflecting PO₂ in tissues.     

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。