Aunola, S. and Rusko, H., Aerobic and Anaerobic. Thresholds Determined from Venous Lactate Or from. Ventilation and Gas Exchange in Relation to Muscle.
ISSN 03621197, Human Physiology, 2013, Vol. 39, No. 2, pp. 171–177. © Pleiades Publishing, Inc., 2013. Original Russian Text © O.S. Tarasova, A.S. Borovik, S.Y. Kuznetsov, D.V. Popov, O.I. Orlov, O.L. Vinogradova, 2013, published in Fiziologiya Cheloveka, 2013, Vol. 39, No. 2, pp. 70–78.
The Pattern of Changes in Physiological Parameters in the Course of Changes in Physical Exercise Intensity O. S. Tarasovaa,b, A. S. Borovika, S. Y. Kuznetsova,c, D. V. Popova, O. I. Orlova, and O. L. Vinogradovaa,b a
Instituite for Biomedical Problems, Russian Academy of Sciences, Moscow, 123007 Russia b Moscow State University, Moscow, 119992 Russia c Moscow Institute of Physics and Technology, Moscow, 117871 Russia Received September 23, 2012
Abstract—It is well known that metabolic, cardiovascular, and respiratory indices during exercise of moder ate intensity are linearly related to the power of the exercise. After the load reaches a definite level, this rela tionship becomes nonlinear. Different methods for evaluating the intensity of load at which this transition takes place are discussed. The methods for investigating the time course of the transitional process in the sys tems of energy supply for muscle contractions with the changing intensity of the contractions are described. The dependence of the dynamic characteristics of physiological indices on the fitness level, which, in turn, depends on the age and level of physical activity, is discussed. Keywords: aerobic performance, lactate, aerobic–anaerobic transition, oxygen consumption DOI: 10.1134/S0362119713020163
Physical load is a powerful adaptogenic impact that triggers a series of regulatory mechanisms in systems of autonomic support of the functioning of, mainly, car diovascular and respiratory systems. Tests with physi cal load are widely used in the physiology of muscle activity, sports medicine, as well as in the functional testing of patients. However, as a rule, during this test ing, only stationary values of the measured parameters are estimated, whereas transitional processes arising upon a change in the intensity of the load receive little attention. At the same time, it is well known that the dynamic characteristics of regulatory processes, in many cases, better reflect the functioning of regulatory systems than static characteristics; i.e., they are more informative. This explains the wide use of intermittent physical loads for the functional testing of the state of the cardiovascular system. Pattern of Changes in Physiological Indices during Gradual Increase in the Intensity of Physical Exercise During a physical load of moderate intensity typi cal of everyday life and also used in trainings in popular sports and in rehabilitation procedures, the main source of energy supply of muscles are aerobic meta bolic processes [1]. At this load intensity, many physi ological indices characterizing the functioning of sys tems of the autonomic support of work linearly depend on the power of the load. With increasing load, muscle fibers are recruited in correspondence with Henneman’s rule [2]. At the beginning of the test, at the minimal power, typeI muscle fibers are mainly activated. With an increase in load, more highthreshold locomotor units, i.e., fibers of types IIA and IIX, are involved. By analyzing biop
tic samples of muscle tissue taken from the m. vastus lateralis during exercises at a cycle ergometer, it was shown that, at a moderate load, the exhaustion of gly cogen reserve occurs mainly in typeI muscle fibers, and, at a submaximum aerobic load, in both types of muscular fibers [3]. Muscle fibers of type I are characterized by the high volume density of mitochondria and the activity of oxidative enzymes, as well as a great number of lipid inclusions [4, 5]. In these fibers, aerobic reactions mainly occur whose substrates are muscle glycogen, blood glucose, as well as intramusular lipids and lipids brought with blood. During weak muscle contrac tions, lipids are used as the main energy substrate, which is supported by the low values of the respiratory coefficient (from 0.7 to 0.8). At these loads, the con centration of H+ in working muscles slightly increases [6]; however, in blood, the concentration of H+ and lactate does not change even during the activity of a large mass of muscles [7]. Note that an increase in the load is accompanied by an increase in the oxygen demanded by working muscles; therefore, pulmonary ventilation and oxygen consumption by the whole body increase. Note that, in the range of low and moderate values of a physical load, many physiological indices, such as pulmonary ventilation and oxygen consumption by the body [8, 9], concentration of deoxygenated hemo globin in working muscles [10], concentration of adrenaline and noradrenaline in blood [11], blood pressure [12], heart rate (HR) [13, 14], and elec tromyographic indices of muscles [15], linearly depend on its intensity.
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With the subsequent increase in intensity, the grad ual involvement of more highthreshold locomotor units (IIA and IIX) takes place. Fibers of type II, espe cially IIX, have far lower oxidation capacities, they have a low volume density of mitochondria, low activ ity of oxidizing enzymes, and high activity of glycolytic enzymes [4, 5]. The resynthesis of adenosine triphos phate (ATP) in them takes place mainly due to glyco gen reactions whose end products are hydrogen ions and lactate. Therefore, when muscular fibers IIA and IIX are involved in functioning, i.e., at a submaximum aerobic power, a considerable increase in the concen tration of hydrogen ions and lactate in the muscle [16] and in blood [7] occurs. The substrate for glycolysis are carbohydrates (glycogen and glucose) and the propor tion of lipids participating in the resynthesis of ATP decreases. The decline in the utilization of lipids is promoted also by the inhibition of reactions of βoxi dation of fatty acids due to the decrease in pH and the increase in the concentration of acetylCoA [17, 18]. The transition to a greater use of carbohydrates is reflected in an increase in the respiratory coefficient whose values shift to the range 0.85–0.95. Hydrogen ions are transported into the blood, where they interact with bicarbonate ions. As a result of this reaction, nonmetabolic carbon dioxide is formed, whose effect leads to an additional stimula tion of receptors of the medullar respiratory center and an extensive increase in pulmonary ventilation. Respi ratory ventilation increases also due to the metabore flex mechanism, i.e., as a result of the stimulation of the chemoreceptors in muscles by the accumulation of metabolites (including glycolysis products) [19]. The subsequent increase in power leads to the activation of the most highthreshold locomotor units, and the contribution of glycolysis to the energy support of muscular functioning (resynthesis of ATP in muscle fibers) increases substanitally. In muscular fibers themselves, muscular interstition, and blood, a drastic decrease in pH and an increase in the lactate concen tration occur; the βoxidation of lipids, in this case, is completely inhibited. The activation of muscular metaboreflex leads to a drastic increase in respiratory ventilation and oxygen consumption by the body; the cardiac output and heart rate (HR) reach maximum values, the pH in working muscles decreases to the lowest level, which leads to a decrease in the contrac tion capacities of the muscles and breakdown in func tioning. General Approaches to Describing the Dynamic Characteristics of Linear Systems It is well known that a stationary linear system can be described by an impulse reaction [20]. Knowing its parameters, one can successively calculate the output signal for any input signal. Thus, the impulse reaction completely determines the system’s behavior. Another method of studying the dynamic behavior of linear systems involves the study of the response to harmon
ically changing input signals with the subsequent con struction of frequency characteristics (transmission function) [20]. The transfer function is one of the standard methods of the mathematical description of a dynamic system. In the case of the linear system, the output signal of a system exposed to sinusoidal action will have the same frequency, and its amplitude and phase shift will be determined by the dynamic charac teristics of the system. Knowledge of the input signal and transfer function permit the unambiguous deter mination of the output signal of the linear system. Thus, the task of determining the dynamic charac teristics of a complex system should be solved in two stages: (1) finding the range of changes in the input signal in which the given system can be regarded as lin ear; and (2) determination of the transfer function by studying the response of the system to an impulse or harmonically changing external action. Methods for Revealing the Linear Range of Change in Physiological Indices Depending on the Power of the Load As mentioned above, the accumulation of the end products of glycolysis leads to pronounced changes in the dependence of the most important physiological indices on the power of the load. Most physiological indices in response to an increase in the load change rather fast (within several minutes); therefore, the detection of the mainly aerobic (linear) range of met abolic support of muscular functioning can be per formed in a test with a stepwise increase in the load in the duration of steps from 2 to 3 min. The transition from mainly aerobic to aerobic–anaerobic metabo lism of muscles can be also assessed in a test with a progressively increasing load, in which the gradient of the load increase is comparable to the averaged profile of the load increase in a stepwise test. Such tests are usually conducted using bicycle ergometers, tread mills, and other controlledload devices. On reaching a definite level of load, the dynamics of these physiological indices considerably change and become nonlinear. In this respect, during the study of the dynamics of systemic and local physiological indi ces at a physical load of varying power, it is important to determine the value of the load power (or the corre sponding oxygen consumption by the body) at which the aerobic–anaerobic transition is observed. Below, the most frequently used indices characterizing such a transition are described. Aerobic threshold is the power (oxygen consump tion) during a test with an increasing load at which the transition from aerobic energy support to aerobic– anaerobic energy support is observed. At a small load, the lactate concentration in blood (index characteriz ing glycolysis activity) does not change with an increase in power. At a definite value of the load, the lactate concentration begins to increase. The empiri cally selected value of 0.5 mM, recorded in response to an increase in power of 30 W, is considered to be the HUMAN PHYSIOLOGY
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criterion of a significant increase in lactate concentra tion. As a criterion of glycolysis activation, the fixed value of lactate concentration in blood equal to 2 mM, as an upper boundary of the norm for lactate concen tration at rest, is also used [21]. Threshold of anaerobic metabolism (TAM) is the power (oxygen consumption) during a test with an increasing load at which the lactate concentration in blood equal to 4 mM is recorded, which corresponds to the population’s average value of the maximum lac tate concentration at which the equilibrium between the release of products of glycolysis into blood and their utilization is observed [21]. The shortcoming of this index is that the maximum stationary lactate con centration in individual subjects may noticeably differ from the population’s mean value. Several studies performed with the participation of qualified athletes have shown that the indices charac terizing aerobic–anaerobic transition are more closely related to sports performance than the value of maxi mum oxygen consumption by the body ( V· O2msx )[22– 24]. These observations agree with the results of stud ies of muscular tissue samples: it turned out that the values of indices characterizing aerobic–anaerobic transition were correlated with the activity of enzymes of Krebs’ cycle in muscle fibers and with the percent age concentration of fibers of type I [22, 23, 25]. At the same time, between index V· O2msx and the activity of oxidizing enzymes, a significant relationship is not always revealed [26]. Note also that the difference in the level of the aerobic working capacity between trained and untrained subjects assessed according to TAM is more pronounced than when they are com pared according to V· O2msx [22, 27]. For instance, the specific (relative to the body weight) oxygen consump tion or specific power at the level of TAM in triathletes is higher by a factor of 2.5 than in untrained men, while the difference in V· O2msx is noticeably smaller— from 70 to 80%. As a result of prolonged training, oxygen consump tion at the level of TAM approaches the level of V· O2msx . In athletes, the relation of these indices is 80–95% versus 60–70% in untrained men. In wellprepared athletes who train their endurance (e.g., in triath letes), oxygen consumption at the level of TAM when they are in top competitive shape can reach 95–99% of V· O2msx [27]. We can assume that the physical aerobic training leads to the extension of the range of the linear relationship of physiological indices with the indices of a physical load. Study of Transitional Processes in the Human Body via Studying the Response of Physiological Indices to an Impulse Load One of the first integrated studies on the dynamics of physiological indices on the stimulating effect of an impulse was performed by Miyamoto et al. [28]. In HUMAN PHYSIOLOGY
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experiments with the participation of young healthy men, the authors studied the dynamics of changes in the stroke volume, HR, cardiac output, respiratory volume, respiration rate, pulmonary ventilation, and indices of gas exchange during performance of a bicy cle ergometer exercise at a power lower than TAM and during the recovery. For most indices, the delay in response did not exceed 5 s, except the respiration vol ume, whose increase was recorded only after 20 s. The changes in most indices were described by exponential functions, except changes in HR and cardiac output, which were described by the sum of two exponents whose values of the time constant differed by more than an order of magnitude. Judging from the value of the time constants, for the HR, cardiac output, respi ratory volume, pulmonary ventilation, О2 consump tion and СО2 evolution, the dynamics of restoration are comparable to the dynamics of the change in response to a load; for the stroke volume and respira tory rate, the time constant of restoration was far greater than at an increase in load. The data obtained by these authors indicate that the dynamics of the change of various physiological indices in response to an impulse load considerably differ; the HR and respi ration rate are also the most labile. Subsequently, the results of this study were sup ported by the results of other studies. For instance, later [29], it was shown that changes in cardiac output develop faster than change in О2 consumption by the body. However, we note that the values of the time parameters of the response, according to the data of various papers, may differ [28–30]. Probably, this is related to the selection of the parameters of the testing load or to specific features of the functional state of subjects whose effect on the dynamic characteristics of physiological indices will be considered below. It has been shown [29] that the dynamics of cardiac output is well described by a twophase model, which, according to the opinion of the authors, reflects a rapid decrease in vagal effects and a delay in the acti vation of sympathetic effects. For investigating the effect of the two divisions of the autonomic nervous system on the dynamics of cardiac output, the next study [31] was performed under the conditions of moderate normobaric hypoxia (such impact causes a decrease in vagal cardiotropic effects and, correspond ingly, offsets the parasympathetic component of heart regulation). Based on the results, they concluded that the first rapid phase of an increase in cardiac output only partly depends on the appearance of vagal effects; it is also influenced by another rapid mechanism, apparently related to an increase in the venous return of blood to the heart because of the activation of the muscle pump. Miyamoto [32] compared the results of assessing the dynamic characteristics of changes in pulmonary ventilation, indices of gas exchange, cardiac output, and HR obtained using various patterns of a specific load: step, impulse, and with a ramp profile. As noted
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above, in the case of the step pattern, no differences in time characteristics of the response of most indices to an increase or a decrease in the load are observed. At the same time, in the case of the ramp pattern, the typ ical time of response in the phase of load increase increases upon a decrease in the gradient of the increase, while, at the initial stage, it decreases. Such changes of time characteristics depending on the pro file of the load increase may be related to a change in metabolic processes in working muscles. In order to explain the asymmetry of the responses, the authors suggested a nonlinear model of blood circulation in muscles that considers the dynamics of the accumula tion and washout of metabolites from muscle tissue in which receptors responding to metabolites are present. Note also that the dynamics of changes in physio logical indices may depend on the mode of the load, which is seen from the comparison of the responses during exercises on a bicycle ergometer and a treadmill [33]. This may be related to a higher intramuscular pressure during the bicycle ergometer exercise and/or to a greater eccentric component of the load during running. Study of Transitional Processes in the Human Body Using Frequency Characteristics In several studies, frequency transitional functions of the indices characterizing the functioning of the human cardiorespiratory system at a load whose power changed according to the sinusoidal law were studied. In one of the first studies on this subject [34], the dynamic characteristics of regulating HR in untrained young men and women during a bicycle ergometer exercise at a sinusoidal change in the power of the load in a range lower than the power corresponding to TAM were studied. The average power of the load was 90 W for men and 60 W for women, and the amplitude of changes in power was 50 and 30 W, respectively. The linear behavior of HR in a wide range of the period of changes in power (from 0.5 to 15 min) was found, the amplitude of the fluctuations of HR decreased with an increase in the frequency of the changes in the power of the load. In another study [35], changes not only in HR but also in the pulmonary ventilation and indices of gas exchange at a cycle ergometric load with an average value of power 1.5 W/kg and amplitude of 0.9 W/kg (calculated on the leanweight basis) were studied. The power of load changed according to the sinusoidal law with periods of 12 to 0.75 min. The amplitude of changes of all studied physiological indices decreased with an increase in the frequency of changes in the power of the load. In contrast, the phase shift increased with an increase in frequency. In several studies, another pattern of the sinusoi dally changing load was used: throughout the test, the power of the load remained constant, and according to the sinusoidal law, the rate of rhythmic contractions of muscles changed (by varying the pedal rate). This
approach permits studying the regulation of physio logical indices depending on the state of the muscle receptors, excluding the effect of metabolic demands of the body upon a change in the power of load. The study of respiration regulation during the bicycle ergo meter exercise with a constant power of load (50 W) and the pedal rate varying according to the sinusoidal law (in the range from 40 to 80 rpm) was performed in [36]. Each subject performed 5 tests with a duration of 30 min, differing in the value of the period of changes in the pedal rate. Lowamplitude fluctuations in the O2 consumption and CO2 release were recorded in the test. Pulmonary ventilation varied in phase with the CO2 release, and the values of the amplitude of peri odic changes in these two indices were correlated to each other, as a result of which the concentration of CO2 in the expired air remained almost constant. Based on these observations, the authors concluded that the function of respiration is controlled mainly by the tension of CO2 in blood and, to a smaller extent, depends on signals coming from receptors of the work ing muscles. Of interest is the series of studies on the frequency characteristics of the thermoregulatory processes by measuring cutaneous blood flow and the rate of sweat ing. The authors of one of these papers [37] studied the dynamics of changes in the temperature of the core of the body (measured using a sensor located in the esophagus) and skin, as well as of the rate of sweating on the forearm skin. The subjects performed a bicycle ergometer exercise with the power changing according to the sinusoidal law between values corresponding to 10 and 60% of the level of V· O2msx , and with periods equal to 1.3, 4, and 8 min. At longer periods, sinusoi dal changes in all the indices studied were observed, and the changes in sweating took place before the phase of the change in the body temperature. We note that the use of the sinusoidal pattern of load made it possible to detect changes in sweating not related to thermoregulation. In the case of a short period (1.3 min), the temperature values of the core and skin were stable; however, harmonic changes were observed in the rate of sweating determined in all likelihood by the psychoemotional tension or stimulation of recep tors other than thermoreceptors. In two subsequent studies [38, 39], the same group of authors analyzed the vasomotor responses of vessels located in various sites of the skin. The fluctuations of the conduction of vessels on the dorsal side of the hand, as compared to vessels of the palm, were charac terized by a smaller amplitude in the case of short peri ods of the sinusoidal effect (from 1 to 4 min) and a smaller phase shift at a longer duration of the period (8 and 16 min). These differences in frequency char acteristics agree with concepts on the difference between the mechanisms of regulating the tone of the skin vessels at hairy and glabrous skin. At glabrous sites (such as the palm), the tone of the vessels is regulated HUMAN PHYSIOLOGY
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exclusively by sympathetic effects, and at these skin sites there are many arteriovenous shunts. At hairy skin sites, the tone of the vessels is also regulated through active vasodilation, which probably has a cho linergic nature. Changes in Dynamic Characteristics Depending on Age To date, the accumulated data showe that the dynamic characteristics of physiological indices can change depending on the functional state of the body, which, in turn, depends on the age and level of the physical activity. During the study of the relationship between the change in the power of the load on a bicycle ergometer and the response of HR in a sufficiently large group of apparently healthy subjects, a negative correlation between the time of the response of HR and age was found [40]. Similar agerelated changes in the dynamic characteristics of HR were detected in the study [41]: it was shown that, in subjects aged 65 to 70 years, as com pared to young people (aged 20 to 25 years), upon a change in the load, the amplitude of change in HR is smaller, and the rate of increase in pulmonary ventila tion is lower. The deceleration of the mechanisms regulating heart activity with age correlates to a decrease in the density of sympathetic innervation and an increase in the role of slower humoral regulation [42]. The para sympathetic component of heart regulation is retained for a longer time, but it also attenuates with age [42]. In connection with changes in the mechanisms of ner vous regulation, with age, the dynamic characteristics of vagal regulation of the heart change, which mani fests itself in the decrease in the power of moderate frequency (~0.1 Hz) and highfrequency (~0.4 Hz) fluctuations of heart rhythm [43]. A comprehensive study of agerelated changes in the regulation of the respiratory system was performed in [44] with a comparison of the dynamics of changes in physiological indices in young (aged 22 to 28 years) and elderly (aged 62 to 72 years) women. Mathemati cal analysis was performed of the time series of values of HR, pulmonary ventilation, and indices of gas exchange, recorded during bicycle ergometer exercises at a sinusoidally changing power of the load with a period in the range from 45 to 600 s; the intensity of the load was lower than TAM. It was shown that, with age, the amplitude of fluctuations of all indices char acterizing the function of respiration noticeably decreases, while the time delay of the response consid erably increases [44]. A comparative study of age changes in the systemic and local mechanisms of the oxygentransport system was performed [45]. In experiments with the partici pation of two groups of different ages (about 25 years of age and about 68 years of age), the consumption of О2 by the body as a whole and by an individual working muscle upon an increase in the load from 20 W to a power corresponding to 80% of the power at the level HUMAN PHYSIOLOGY
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of TAM was measured. Subjects of the older group were characterized by a slower increase in the con sumption of О2 upon the load, although the values of the time delay and the time constant of the increase in the concentration of desoxygenated hemoglobin in the working muscle did not differ from the corresponding values in young subjects. The authors assume that the agerelated delay in the systemic dynamics of О2 con sumption is explained by the change in heart activity and a slower dilatation of blood vessels in the working muscles. Note that the slow kinetics of О2 consumption is also typical of subjects who underwent heart trans plantation and patients with obesity, mitochondrial dysfunctions, McArdle’s disease (glycogenosis as a result of the low activity of muscular glycogen phos phorylase), and some other diseases [46, 47]. These slow kinetics are associated with a decrease in the working capacity of muscles as a result of a decrease in their socalled metabolic stability, i.e., accelerated accumulation of products of metabolism, which leads to fatigue. Changes in Dynamic Characteristics as a Result of Physical Training Regular physical activity can hinder or even pre vent the agerelated delay in the HR regulation. It has been shown that the duration of the time delay in the response of HR to a change in a physical load is nega tively correlated to the physical activity of a subjects that was assessed according to the daily number of steps [20]. The parameters of the response of HR to sinusoidal changes in the power of the load depend on the level of physical training of the subject: the value of the time shift of HR is inversely dependent on index PWC170 (power of the load at which HR increases to 170 beats/min) [34]. During the study of the effects of six weeks of aerobic training on a treadmill, it was shown that such training leads to a change in the dynamics of О2 consumption in response to a step increase in the rate of running [48]. As a result of the training, the dynamic characteris tics of the thermoregulation system may also change. In the case of a bicycle ergometric exercise with a sinu soidal load, the time of response of the temperature of the core and surface of the body in longdistance run ners does not differ from the values recorded in untrained subjects; however, the time of the response of sweating in athletes is considerably shorter [49]. These changes in the regulation of sweating in athletes are related to a less pronounced temperature increase in the body at an increase in a load, i.e., as a result of training, the lability of the regulation of sweating increases, which results in a smaller increase in tem perature during work. In addition, athletes are characterized by differ ences in the regulation of cutaneous blood flow [39]. It has been shown that the amplitudes of fluctuations of
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the vascular conductance in trained and untrained subjects do not differ; however, the phase shift of vasodilatation response in athletes is greater than in untrained subjects; i.e., a slower vascular response is typical of trained subjects. These specific features of vasomotor regulation may be related to a less pro nounced increase in body temperature in athletes under a physical load [49]. The published data indicate that the effect of train ings on the dynamic characteristics of physiological indices depends on the direction of the training pro cess [50]. The authors of this paper used frequency transfer functions of cardiorespiratory indices in tests with a sinusoidal pattern of change in the load during bicycle ergometer exercises in athletes of two special izations—football players and longdistance run ners—as compared to untrained subjects. The ampli tude of fluctuations and the phase shift in О2 con sumption in football players did not differ from those in untrained subjects, but, in longdistance runners, the values of these parameters were considerably higher than in the remaining two groups. Thus, in players, despite the considerably greater value of V· O2msx , no changes in the dynamic characteristics of the gas exchange indices are observed. The authors conclude that athletes of various sports have different dynamic characteristics of cardiorespiratory system regulation. CONCLUSIONS Analysis of the literature demonstrated that, despite a longterm history of the study of transitional processes in systems supporting muscle work under a change in the intensity of load, many issues have not been solved up to now, and the data cited by different authors are often contradictory. This is apparently mainly determined by the complexity of these pro cesses: the dynamics of changes in various physiologi cal indices may differ significantly, which depends on both the specific features of their regulation in the body and the pattern of setting the variable physical load. In addition, the discrepancy of the published data may be related to methodological differences between the experimental studies. For instance, in many studies, the change in the intensity of the load is not related to individual physical capacities—the dynamic characteristics of response of these or other physiological indices to a given load are studied in a group of subjects, although it is obvious that the dynamics of the studied transitional processes in each particular subject depend not only on the pattern of the load but also on the functional state of the body and the individual level of physical training. REFERENCES 1. Holloszy, J.O., Regulation by Exercise of Skeletal Mus cle Content of Mitochondria and GLUT4, J. Physiol. Pharmacol., 2008, vol. 59, Suppl. 7, p. 5.
2. Henneman, E., Somjen, G., and Carpenter, D.O., Functional Significance of Cell Size in Spinal Motoneu rons, J. Neurophysiol., 1965, vol. 28, p. 560. 3. van Loon, L.J., Greenhaff, P.L., ConstantinTeodo siu, D., et al., The Effects of Increasing Exercise Inten sity on Muscle Fuel Utilisation in Humans, J. Physiol., 2001, vol. 536, p. 295. 4. Schiaffino, S., Fibre Types in Skeletal Muscle: a Personal Account, Acta Physiol. (Oxf.), 2010, vol. 199, p. 451. 5. Schiaffino, S. and Reggiani, C., Fiber Types in Mamma lian Skeletal Muscles, Physiol. Rev., 2011, vol. 91, p. 1447. 6. Richardson, R.S., Noyszewski, E.A., Kendrick, K.F., et al., Myoglobin O2 Desaturation during Exercise. Evi dence of Limited O2 Transport, J. Clin. Invest., 1995, vol. 96, p. 1916. 7. Wasserman, K., Beaver, W.L., and Whipp, B.J., Gas Exchange Theory and the Lactic Acidosis (Anaerobic) Threshold, Circulation, 1990, vol. 81, p. II14. 8. Korzeniewski, B. and Zoladz, J.A., Possible Factors Determining the NonLinearity in the VO2Power Out put Relationship in Humans: Theoretical Studies, Jpn. J. Physiol., 2003, vol. 53, p. 271. 9. Usaj, A. and Kandare, F., The Oxygen Uptake Thresh old during Incremental Exercise Test, Pflugers Arch., 2000, vol. 440, p. R200. 10. Grassi, B., Quaresima, V., Marconi, C., et al., Blood Lactate Accumulation and Muscle Deoxygenation Dur ing Incremental Exercise, J. Appl. Physiol., 1999, vol. 87, p. 348. 11. Dickhuth, H.H., Yin, L., Niess, A., et al., Ventilatory, LactateDerived and Catecholamine Thresholds during Incremental Treadmill Running: Relationship and Reproducibility, Int. J. Sports Med., 1999, vol. 20, p. 122. 12. Omiya, K., Itoh, H., Harada, N., et al., Relationship between Double Product Break Point, Lactate Thresh old, and Ventilatory Threshold in Cardiac Patients, Eur. J. Appl. Physiol., 2004, vol. 91, p. 224. 13. Volkov, N.I., Popov, O.I., Gabrys’, T., and Shmatlyan Gabrys’, U., Physiological Criteria in Defining the Stan dards for Training and Competition Loads in Elite Sports, Hum. Physiol., 2005, vol. 31, p. 606. 14. Ribeiro, J.P., Fielding, R.A., Hughes, V., et al., Heart Rate Break Point May Coincide with the Anaerobic and Not the Aerobic Threshold, Int. J. Sports Med., 1985, vol. 6, p. 220. 15. Hug, F., Faucher, M., Kipson, N., and Jammes, Y., EMG Signs of Neuromuscular Fatigue Related to the Ventilatory Threshold During Cycling Exercise, Clin. Physiol. Funct. Imaging, 2003, vol. 23, p. 208. 16. Roussel, M., Mattei, J.P., Le, F.Y., et al., Metabolic Determinants of the Onset of Acidosis in Exercising Human Muscle: a 31PMRS Study, J. Appl. Physiol., 2003, vol. 94, p. 1145. 17. Kiens, B. and Roepstorff, C., Utilization of LongChain Fatty Acids in Human Skeletal Muscle during Exercise, Acta Physiol. Scand., 2003, vol. 178, p. 391. 18. Venables, M.C., Achten, J., and Jeukendrup, A.E., Determinants of Fat Oxidation During Exercise in Healthy Men and Women: a CrossSectional Study, J. Appl. Physiol., 2005, vol. 98, p. 160. 19. Vinogradova, O.L., Popov, D.V., Tarasova, O.S., et al., Ergoreflex: Essence and Mechanisms of the Phenome non, Aviakosmich. Ekol Med., 2008, vol. 42, p. 5. HUMAN PHYSIOLOGY
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THE PATTERN OF CHANGES IN PHYSIOLOGICAL PARAMETERS 20. Ljung, L., System Identification. Theory for the User, N.J.: Prentice Hall, 1991. 21. Faude, O., Kindermann, W., and Meyer, T., Lactate Threshold Concepts: How Valid Are They?, Sports Med., 2009, vol. 39, p. 469. 22. Popov, D.V., Missina, S.S., Lemesheva, Yu.S., et al., Final Blood Lactate Concentration after Incremental Test and Aerobic Performance, Hum. Physiol., 2010, vol. 36, p. 335. 23. Seluyanov, V.N., Podgotovka beguna na srednie distantsii (Training of a ShortDistance Runner), Moscow: Spor tAkademPress, 2001. 24. Denis, C., Fouquet, R., Poty, P., et al., Effect of 40 Weeks of Endurance Training on the Anaerobic Threshold, Int. J. Sports Med., 1982, vol. 3, p. 208. 25. Aunola, S. and Rusko, H., Aerobic and Anaerobic Thresholds Determined from Venous Lactate Or from Ventilation and Gas Exchange in Relation to Muscle Fiber Composition, Int. J. Sports Med., 1986, vol. 7, p. 161. 26. Rusko, H., Rahkila, P., and Karvinen, E., Anaerobic Threshold, Skeletal Muscle Enzymes and Fiber Compo sition in Young Female CrossCountry Skiers, Acta Physiol. Scand., 1980, vol. 108, p. 263. 27. Popov, D.V., Netreba, A.I., Orlov, O.I., et al., Assessment of the Functional State of the Human Body at Solving Tasks of Mass Sports and Elite Sports, in Nauka o sporte. Entsiklopediya sistem zhizneobespecheniya, (Sports Sci ence. Encyclopedia of Life Support Systems), Stolyarov, V.I., Eds., UNESCO, EOLSS, MagistrPress, 2011, p. 520. 28. Miyamoto, Y., Hiura, T., Tamura, T., et al., Dynamics of Cardiac, Respiratory, and Metabolic Function in Men in Response to Step Work Load, J. Appl. Physiol., 1982, vol. 52, p. 1198. 29. Lador, F., Azabji, K.M., Moia, C., et al., Simultaneous Determination of the Kinetics of Cardiac Output, Sys temic O(2) Delivery, and Lung O(2) Uptake at Exercise Onset in Men, Am. J. Physiol. Regul. Integr. Comp. Phys iol., 2006, vol. 290, p. R1071. 30. McKay, B.R., Paterson, D.H., and Kowalchuk, J.M., Effect of ShortTerm HighIntensity Interval Training vs. Continuous Training on O2 Uptake Kinetics, Muscle Deoxygenation, and Exercise Performance, J. Appl. Physiol., 2009, vol. 107, p. 128. 31. Lador, F., Tam, E., Azabji, K.M., et al., Phase I Dynam ics of Cardiac Output, Systemic O2 Delivery, and Lung O2 Uptake at Exercise Onset in Men in Acute Nor mobaric Hypoxia, Am. J. Physiol. Regul. Integr. Comp. Physiol., 2008, vol. 295, p. R624. 32. Miyamoto, Y., Kinetics of Respiratory and Circulatory Responses to Step, Impulse, Sinusoidal and Ramp Forc ings of Exercise Load in Humans, Front Med. Biol. Eng., 1992, vol. 4, p. 3. 33. Carter, H., Jones, A.M., Barstow, T.J., et al., Oxygen Uptake Kinetics in Treadmill Running and Cycle Ergom etry: A Comparison, J. Appl. Physiol., 2000, vol. 89, p. 899. 34. Tiedt, N., Wohlgemuth, B., and Wohlgemuth, P., Dynamic Characteristics of HeartRate Responses to SineFunction WorkLoad Patterns in Man, Pflugers Arch., 1975, vol. 355, p. 175. 35. Bakker, H.K., Struikenkamp, R.S., and De Vries, G.A., Dynamics of Ventilation, Heart Rate, and Gas HUMAN PHYSIOLOGY
Vol. 39
No. 2
2013
36.
37. 38. 39.
40.
41.
42.
43. 44.
45.
46.
47.
48.
49.
50.
177
Exchange: Sinusoidal and Impulse Work Loads in Man, J. Appl. Physiol., 1980, vol. 48, p. 289. Casaburi, R., Whipp, B.J., Wasserman, K., and Koyal, S.N., Ventilatory and Gas Exchange Responses to Cycling with Sinusoidally Varying Pedal Rate, J. Appl. Physiol., 1978, vol. 44, p. 97. Yamazaki, F., Sone, R., and Ikegami, H., Responses of Sweating and Body Temperature to Sinusoidal Exercise, J. Appl. Physiol., 1994, vol. 76, p. 2541. Yamazaki, F., Vasomotor Responses in Glabrous and Nonglabrous Skin During Sinusoidal Exercise, Med. Sci. Sports Exerc., 2002, vol. 34, p. 767. Yamazaki, F. and Sone, R., Skin Vascular Response in the Hand during Sinusoidal Exercise in Physically Trained Subjects, Eur. J. Appl. Physiol., 2003, vol. 90, p. 159. Fukuoka, Y., Nakagawa, Y., Ogoh, K., et al., Dynamics of the Heart Rate Response to Sinusoidal Work in Humans: Influence of Physical Activity and Age, Clin. Sci. (Lond.), 2002, vol. 102, p. 31. Ishida, K., Sato, Y., Katayama, K., and Miyamura, M., Initial Ventilatory and Circulatory Responses to Dynamic Exercise Are Slowed in the Elderly, J. Appl. Physiol., 2000, vol. 89, p. 1771. Shvalev, V.N., Guski, G., Tarskii, N.A., and Sosu nov, A.A., Transformation of the SympatheticAdrena line System at an Elderly and Old Age as a Risk Factor of Cardiovascular Diseases, Kazan. Med. Zh., 2003, no. 6, p. 401. Shvalev, V.N. and Tarskii, N.A., Phenomen of Early Age Involution of the Sympathetic Region of the Autonomic Nervous System, Kardiol., 2001, no. 2, p. 10. Cunningham, D.A., Himann, J.E., Paterson, D.H., and Dickinson, J.R., Gas Exchange Dynamics with Sinuso idal Work in Young and Elderly Women, Respir. Physiol., 1993, vol. 91, p. 43. DeLorey, D.S., Kowalchuk, J.M., and Paterson, D.H., Effect of Age on O(2) Uptake Kinetics and the Adapta tion of Muscle Deoxygenation at the Onset of Moderate Intensity Cycling Exercise, J. Appl. Physiol., 2004, vol. 97, p. 165. Grassi, B., Porcelli, S., Salvadego, D., and Zoladz, J.A., Slow VO(2) Kinetics During ModerateIntensity Exer cise As Markers of Lower Metabolic Stability and Lower Exercise Tolerance, Eur. J. Appl. Physiol., 2011, vol. 111, p. 345. Salvadego, D., Lazzer, S., Busti, C., et al., Gas Exchange Kinetics in Obese Adolescents. Inferences on Exercise Tolerance and Prescription, Am. J. Physiol. Regul. Integr. Comp. Physiol., 2010, vol. 299, p. R1298. Carter, H., Jones, A.M., Barstow, T.J., et al., Effect of Endurance Training on Oxygen Uptake Kinetics during Treadmill Running, J. Appl. Physiol., 2000, vol. 89, p. 1744. Yamazaki, F., Fujii, N., Sone, R., and Ikegami, H., Responses of Sweating and Body Temperature to Sinu soidal Exercise in Physically Trained Men, J. Appl. Phys iol., 1996, vol. 80, p. 491. Fukuoka, Y., Gwon, O., Sone, R., and Ikegami, H., Characterization of Sports by the VO2 Dynamics of Ath letes in Response to Sinusoidal Work Load, Acta Physiol. Scand., 1995, vol. 153, p. 117.
