**4. Muscle function energy supply development**

Muscle activity is the most energy-intensive function: even for a person engaged in mental work about half of daily energy expenditure is used to provide a contracting activity of somatic muscles. One of the first works researching ontogenesis of the muscle function energy supply was made by Robinson (1938), who discovered age changes in maximum oxygen consumption in children, teenagers and adults. The research of P.-O. Astrand (1952), still a classic, presents data of maximal aerobic capacity of people from 6 up to 60 years old.

As compared with other tissues, skeletal muscles have the greatest functional range (Fig.4) – metabolic process can change its velocity in muscles by a factor of dozens. Such amplitude of metabolic activity change is impossible to be explained through the work of mitochondrial apparatus; therefore muscles can get the energy required for contraction even from the glycolysis process in cytoplasm and macroergs reserves accumulated in cells in the form of ATP and creatine phosphate. It forms a specific character of muscle tissue energetics. These specifics were expressed by Margaria (1963) in his conception of three energy sources for the muscle activity: aerobic (oxidative, mitochondrial); anaerobic glycolytic (lactacide); anaerobic phosphagenic (alactacide). In combination with the anaerobic threshold conception (Mader & Heck, 1986; Skinner, 1993), these presentations are now the theoretic base of muscle bioenergetics (Volkov, 2010).

Ample data prove an uneven development of aerobic and both anaerobic sources with age, like, for example, heterochrony determines a qualitative peculiarity of skeletal muscles energetics at separate stages of ontogenesis (Guminskiy et al., 1985; Demin, 1983; Kornienko, 1979; Kornienko et al., 2000, 2005; Son'kin, 1988; 2007; Tambovtseva, 2003; Van Praagh, Dore, 2002).

#### **4.1 Aerobic (oxidative) source**

Facilities of aerobic energy supply in skeletal muscles are considerably changed in the course of individual development. It is provided by both the change in content of most important oxidizing ferments in the somatic muscle tissue (Kornienko, 1979), and structural change in the oxidative chain of mitochondria (Demin, 1983, 1985; Demin et al., 1987; Son'kin & Tambovtseva, 2011). Naturally, the most important factor is absolute and relative age increase in mass of somatic muscles. Generally, the maximum oxygen consumption

mechanisms of physical thermoregulation are incomplete. Only in youths after pubescence do thermoregulation facilities reach their final level. Increase in tissue heat insulation to the level of 1.1 CLO allows to function without activating the chemical thermoregulation (meaning extra heat production) even when the environment temperature falls down by 10-15 degrees

The given data prove that in the process of postnatal ontogenesis the primary line of the system development providing temperature homeostasis is indirect (Falk, 1998). At each stage of individual organism development there is a complex dependence of thermoregulation active mechanisms on growth and development, the rate of metabolic processes and conditions of some autonomic functions. It is this dependence that determines a primary activity of physical or chemical thermoregulation mechanisms, providing

Muscle activity is the most energy-intensive function: even for a person engaged in mental work about half of daily energy expenditure is used to provide a contracting activity of somatic muscles. One of the first works researching ontogenesis of the muscle function energy supply was made by Robinson (1938), who discovered age changes in maximum oxygen consumption in children, teenagers and adults. The research of P.-O. Astrand (1952), still a classic, presents data of maximal aerobic capacity of people from 6

As compared with other tissues, skeletal muscles have the greatest functional range (Fig.4) – metabolic process can change its velocity in muscles by a factor of dozens. Such amplitude of metabolic activity change is impossible to be explained through the work of mitochondrial apparatus; therefore muscles can get the energy required for contraction even from the glycolysis process in cytoplasm and macroergs reserves accumulated in cells in the form of ATP and creatine phosphate. It forms a specific character of muscle tissue energetics. These specifics were expressed by Margaria (1963) in his conception of three energy sources for the muscle activity: aerobic (oxidative, mitochondrial); anaerobic glycolytic (lactacide); anaerobic phosphagenic (alactacide). In combination with the anaerobic threshold conception (Mader & Heck, 1986; Skinner, 1993), these presentations are

Ample data prove an uneven development of aerobic and both anaerobic sources with age, like, for example, heterochrony determines a qualitative peculiarity of skeletal muscles energetics at separate stages of ontogenesis (Guminskiy et al., 1985; Demin, 1983; Kornienko, 1979; Kornienko et al., 2000, 2005; Son'kin, 1988; 2007; Tambovtseva, 2003; Van Praagh,

Facilities of aerobic energy supply in skeletal muscles are considerably changed in the course of individual development. It is provided by both the change in content of most important oxidizing ferments in the somatic muscle tissue (Kornienko, 1979), and structural change in the oxidative chain of mitochondria (Demin, 1983, 1985; Demin et al., 1987; Son'kin & Tambovtseva, 2011). Naturally, the most important factor is absolute and relative age increase in mass of somatic muscles. Generally, the maximum oxygen consumption

below thermoneutral. Such body reaction is naturally more economical and efficient.

temperature homeostasis at the corresponding stage of development.

**4. Muscle function energy supply development** 

now the theoretic base of muscle bioenergetics (Volkov, 2010).

up to 60 years old.

Dore, 2002).

**4.1 Aerobic (oxidative) source** 

(MOC) rises proportionally to the muscle mass growth (Kornienko et al., 2000), but it lacks information about qualitative changes in muscle energy supply of children and teenagers (Son'kin & Tambovtseva, 2011).


Table 2. Age changes in cytochrome **a** content in thigh muscle and human aerobic capacity (After: Kornienko, 1979)

Fig. 5. Dynamics of aerobic capacity indices in schoolboys

Age dynamics of cytochrome **a** content – a terminal site of the oxidative chain – in human skeletal muscles (Kornienko, 1979; Demin et al., 1987) is given in Table 2. Calculations of the estimated value for specific MOC (per 1 kg of somatic muscle mass) are shown. As obvious from the given data, the highest cytochrome **a** concentration is registered in skeletal muscles for boys 9-11 years old. It is also proved by data of electron microscopic researches (Kornienko, 1979; Kornienko et al, 1987): the number of mitochondria in relation to the area of myofibrils for 11-year old boy is considerably more than in an adult man (Table 3). It is remarkable, that, according to data of morphologists, a capillary network in the muscles of extremities turns out to be more developed in children of 9-11 years (Topol'sky, 1951), which is the age when there is the highest content of oxidizing ferments in the muscle tissue. Thus, an age development of the energy production aerobic source in skeletal muscles does not happen monotonously, but gets the expressed maximum during prepubescence (Fig.5). These conditions have a considerable effect on the functioning of the muscle energy supply system.

Energy Metabolism in Children and Adolescents 133

the structure of large skeletal muscles in human extremities, achieved by the method of

It turns out that all large human skeletal muscles are characterized by the same age tendency: undifferentiated embryo fibers are changed by fibers with a slow actomyosin ATP-ase, by 4-7 years an "aerobic profile" of mixed muscles is formed, which prevails up to 11-12 years. Then, with start of pubescence there is a two-phase transformation of the muscle structural-functional composition, which results in considerable reduction in a share of red oxidizing fibers (I type), some increase in a share of intermediate fibers (IIA type), and

Fig. 6. Age changes of muscle fiber composition in men (% of each fiber type). By X-line – age from 4 months intrauterine development up to 70 years. By Y-line –fiber share (%%): MB undifferentiated, MB I type, MB IIA type, MB IIB type. UDF – undifferentiated fibers.

Only by 17-18 years is a definite picture formed, which is characterized by predominance of anaerobic – glycolytic fibers in all large muscles. Such muscle structure is likely to be preserved up to the start of involutive processes at the old age, which might be connected

It should be noted that in the world literature there is no definite view on the age development of somatic muscle structural components. The relatively scarce researches of age features in human skeletal muscles provide conflicting results (Blimkie & Sale, 1998; Van Praagh, 2000). According to some authors, there is a relatively large share of undifferentiated fibers at birth (10-20%). Amount of I-type fibers grows rapidly after birth, and II-type fibers reduces. By the age of one year the structure which is similar to adults is formed (Bell et al., 1980; Colling-Saltin, 1980; Elder & Kakulas, 1993). The ratio of IIA-type and IIB-type fibers is also disputable (Colling-Saltin, 1980; du Plessis et al., 1985; Jansson, 1996). But, according to other authors, children until pubescence are more characterized by I type than adults (Eriksson & Saltin, 1974; Lexell et al., 1992; Lundberg et al., 1979). According to Jansson (1996), development of muscles from birth up to 35 years old for men corresponds to ∩-model: from birth up to 9 years old a substantial increase in percent of Itype fibers is observed, at the age of about 9 there is a maximum, whereupon their share is reduced considerably by 19 years old. It is evident that this model is very close to results

histochemical revelation of ATP myosin activity.

with decreased activity of genital glands.

produced by the I.A.Kornienko laboratory.

**4.3 Age changes of anaerobic metabolism ferments activity in muscles** 

In 1971 Swedish scientists demonstrated, by means of needle biopsy, that untrained boys at the age of 12 have a sharp (twofold) increase in the activity of phosphofructokinase (Eriksson et al., 1971). That was the first work where age changes in possible human

a considerable increase in presented glycolytic fibers (IIB type).


Table 3. Morphometric indices of skeletal muscles mitochondria in 11-year boy and adult man according to electron microscopy (After Kornienko, 1979; modified)

Such special energetic structure of skeletal muscles for children in prepubescence, as we see it, is caused by the fact that this ontogenesis period is the preparation for the radical reconstructing structural and functional characteristics of somatic muscles, occurring during pubescence under the influence of sex hormones. We used special histochemical tests to prove this (Tambovtseva, 2003).

#### **4.2 Morpho-functional changes of skeletal muscles during postnatal ontogenesis**

Fiber structure of mixed skeletal muscles is usually considered to be determined genetically and not dependent on age and training (Van Praagh & Dore, 2002; Yazvikov et al., 1978). But according to results of histochemical investigations, the ratio of various fiber types in the structure of skeletal muscles is not constant in ontogenesis (Kornienko et al., 2005; Son'kin & Tambovtseva, 2011; Tambovtseva & Kornienko, 1986a,b, 1987).

Research primarily made on laboratory animals – Wistar rats and Guinea pigs – made possible a conclusion that at an early age the most part of mammals is non-differentiated fibers which further acquires features of red oxidative fibers. The share of quick fibers is rapidly increased during pubescence, which become predominant after pubescence (Tambovtseva & Kornienko, 1986а; 1987).

These studies continued on post mortem material of males within the age bracket from birth to adulthood (Tambovtseva & Kornienko, 1986b). On Fig. 6 there are results characterizing

Table 3. Morphometric indices of skeletal muscles mitochondria in 11-year boy and adult

**4.2 Morpho-functional changes of skeletal muscles during postnatal ontogenesis**  Fiber structure of mixed skeletal muscles is usually considered to be determined genetically and not dependent on age and training (Van Praagh & Dore, 2002; Yazvikov et al., 1978). But according to results of histochemical investigations, the ratio of various fiber types in the structure of skeletal muscles is not constant in ontogenesis (Kornienko et al., 2005; Son'kin &

Research primarily made on laboratory animals – Wistar rats and Guinea pigs – made possible a conclusion that at an early age the most part of mammals is non-differentiated fibers which further acquires features of red oxidative fibers. The share of quick fibers is rapidly increased during pubescence, which become predominant after pubescence

These studies continued on post mortem material of males within the age bracket from birth to adulthood (Tambovtseva & Kornienko, 1986b). On Fig. 6 there are results characterizing

Such special energetic structure of skeletal muscles for children in prepubescence, as we see it, is caused by the fact that this ontogenesis period is the preparation for the radical reconstructing structural and functional characteristics of somatic muscles, occurring during pubescence under the influence of sex hormones. We used special histochemical tests to

man according to electron microscopy (After Kornienko, 1979; modified)

Tambovtseva, 2011; Tambovtseva & Kornienko, 1986a,b, 1987).

Electron micro photos of somatic muscle lengthwise cuts (m. Quadriceps Femori)

Mean diameter of mitochondria, micron

Mean thickness of myofibrils, micron

Ratio of mitochondria area to myofibril area

Ratio of mitochondria total area to myofibril total area

prove this (Tambovtseva, 2003).

(Tambovtseva & Kornienko, 1986а; 1987).

Index 11-year old boy 35-year old man Difference, %

236 175 -35

505 590 +14

0,034 0,016 -113

0,153 0,097 -58

the structure of large skeletal muscles in human extremities, achieved by the method of histochemical revelation of ATP myosin activity.

It turns out that all large human skeletal muscles are characterized by the same age tendency: undifferentiated embryo fibers are changed by fibers with a slow actomyosin ATP-ase, by 4-7 years an "aerobic profile" of mixed muscles is formed, which prevails up to 11-12 years. Then, with start of pubescence there is a two-phase transformation of the muscle structural-functional composition, which results in considerable reduction in a share of red oxidizing fibers (I type), some increase in a share of intermediate fibers (IIA type), and a considerable increase in presented glycolytic fibers (IIB type).

Fig. 6. Age changes of muscle fiber composition in men (% of each fiber type). By X-line – age from 4 months intrauterine development up to 70 years. By Y-line –fiber share (%%): MB undifferentiated, MB I type, MB IIA type, MB IIB type. UDF – undifferentiated fibers.

Only by 17-18 years is a definite picture formed, which is characterized by predominance of anaerobic – glycolytic fibers in all large muscles. Such muscle structure is likely to be preserved up to the start of involutive processes at the old age, which might be connected with decreased activity of genital glands.

It should be noted that in the world literature there is no definite view on the age development of somatic muscle structural components. The relatively scarce researches of age features in human skeletal muscles provide conflicting results (Blimkie & Sale, 1998; Van Praagh, 2000). According to some authors, there is a relatively large share of undifferentiated fibers at birth (10-20%). Amount of I-type fibers grows rapidly after birth, and II-type fibers reduces. By the age of one year the structure which is similar to adults is formed (Bell et al., 1980; Colling-Saltin, 1980; Elder & Kakulas, 1993). The ratio of IIA-type and IIB-type fibers is also disputable (Colling-Saltin, 1980; du Plessis et al., 1985; Jansson, 1996). But, according to other authors, children until pubescence are more characterized by I type than adults (Eriksson & Saltin, 1974; Lexell et al., 1992; Lundberg et al., 1979). According to Jansson (1996), development of muscles from birth up to 35 years old for men corresponds to ∩-model: from birth up to 9 years old a substantial increase in percent of Itype fibers is observed, at the age of about 9 there is a maximum, whereupon their share is reduced considerably by 19 years old. It is evident that this model is very close to results produced by the I.A.Kornienko laboratory.

#### **4.3 Age changes of anaerobic metabolism ferments activity in muscles**

In 1971 Swedish scientists demonstrated, by means of needle biopsy, that untrained boys at the age of 12 have a sharp (twofold) increase in the activity of phosphofructokinase (Eriksson et al., 1971). That was the first work where age changes in possible human

Energy Metabolism in Children and Adolescents 135

Boisseau & Delamarche, 2000; Van Praagh & Dore, 2002). Data available in press are

At that same time, dynamics of these indices for various tissues in ontogenesis of rats was studied by Demin in detail (1983, 1985). According to these results, CrK activity in muscles of animal hind extremities in a nest life period makes 2.5 – 2.7 µmol/min/g and it is practically unchanged in the first 2 weeks of life. At the same age CrК activity in cardiac tissue is somehow less than in leg muscles while in neck muscles, which perform the most thermoregulation function – it is 2 times more, than in leg muscles. With start of an active independent motion activity for young rats (3 weeks), CrК in leg muscles grows intensely reaching by pubescence (60 days) the level of 39 µmol/min/g. This is 4.5 times more than in neck and cardiac muscles, 12 times more than in brain tissue and 50 times more than in

For this period CrP content in muscles is approximately increased by 3 times - from 5.4 up to 15.9 µmol/g (in a 60-day rat's heart CrP content – 7.1 µmol/g; in brain – 5.7 µmol/g; in liver

CrP content and CrK activity are increased in skeletal muscles asynchronously with age and it provides age changes in potential duration of CrP expenditure at maximum activity. The most substantial increase in CrK activity is observed at the last stages of pubescence, which provides a considerable acceleration of ATP forming velocity in a creatine kinase reaction, meaning the capacity of an alactacide energy system. As a result, according to Demin (1985), ATP formation velocity in process of a creatine kinase reaction in muscles of rat extremities is increased from 20 µmol/g/min at the age of 12 days up to 80 µmol/g/min at the age of 40-45 days (an active phase of pubescence), and by the end of pubescence changes it grows

The given facts prove that the pubescence period is a "divide" between two qualitative conditions in energetics of somatic muscles. Prior to pubescence changes in muscles, like in other mammal tissues, the predominant role in energy supply is played by mitochondria oxidation. After pubescence changes, muscles acquire that colossal functional range and those specific features of organizing energy metabolism, which differentiates them from other tissues of an adult body, and the role of anaerobic energy sources is rapidly increased (Kornienko et al., 2000). Such reconstruction of energetics in skeletal muscles allows after some time the increase of the realized capacity of outer mechanical production, considerably extending the functional range, as well as promoting repeated growth of efficiency and reliable body function under strenuous muscle activity (Kornienko & Son'kin 1999). However, it should be noted, that the data of Demin, like most other similar results, were obtained for male rats. Sex differences in dynamics of energy facilities for skeletal muscles are studied insufficiently. According to the results of research made by means of up-to-date methods (Boisseau & Delamarche, 2000; Petersen et al., 1999; Treuth et al., 2001; Van Praagh, Dore, 2002 ), for girls at pre- and post-pubescent age such considerable differences in energy

Energy metabolism, presenting the most integral body function, demonstrates logical age changes reflecting qualitative and quantitative redevelopments of a child's organism. The principle of functional economy is likely to be the most vivid of these changes with age development. This principle is implemented in age-related reduction of basal metabolism, in

metabolism structure under muscular load were not revealed.

contradictory.

the liver.

– 2.43 µmol/g).

up to 160 µmol/g/min.

**5. Conclusion** 

anaerobic – glycolytic source at the tissue level were discovered. Next by means of biochemical (Eriksson, 1980; Ferretti et al., 1994; Kornienko et al, 1980; Ratel et al, 2002), histochemical (Tambovtseva, 2003; Kornienko et al, 2000) and physiological (Kornienko et al, 2000; Pyarnat & Viru, 1975; Son'kin, 1988;) methods numerous confirmations of an abrupt activation of anaerobic – glycolytic energy production in the process of pubescence reconstructions were obtained, especially for boys (Boisseau & Delamarche, 2000; Van Praagh & Dore, 2002).

In ontogenesis of rats an activity of glycolysis key ferment – lactate dehydrogenase (LDG) was traced in detail (Musaeva, 1986; Demin et al., 1987). LDG molecule consists of 4 monomers and each of them can have one of two following isoforms: "H" – subunits which are typical for LDG from a cardiac muscle, "M" – subunits which are mainly in skeletal muscles of adult mammals (Lehninger, 1965). These isoferment forms differently participate in a cycle of glycolysis reactions, therefore the ratio of "H" and "M" activities – LDG subunits can be used as a sufficiently informative activity ratio index for aerobic and anaerobic – glycolytic sources.

In these studies it was proven that an age increase in "aerobic" ferment activity in muscles of male rates occurs generally parallel to increasing facilities of the oxidizing source and is complete by the start of pubescence, while total LDG activity rapidly grows in pubescence and even after it. Therefore, in process of pubescence qualitatively reconstructed is organization of energy metabolism in somatic muscle cells: an abrupt extension of facilities for anaerobic – glycolytic energy production in terms of stabilization and even some decrease in a relative capacity of aerobic energy production.

The given facts have proposed an important role of sex hormones in regulation of muscle energetics. Direct evidence of this hypothesis was obtained by Musaeva (1986) in tests on male rates with orchotomy at the age of 3 weeks or artificial androgenization: androgenization accelerates and orchotomy inhibits the formation of ferment systems, which are responsible for anaerobic mechanisms producing energy in somatic muscles, and practically does not have an effect on conditions of mitochondria (aerobic) energy production. Under the influence of exogenous testosterone, the fraction of muscle fibers with a high activity of ATP-ase in the structure of extremities considerably increased, meaning those, which are mainly characterized by anaerobic energy supply. Orchotomy has the opposite results (Musaeva, 1986; Son'kin & Tambovtseva, 2011).

Probably, male sex hormones play a role that is not less significant in formation of a morphological–functional status of human skeletal muscles (Boisseau & Delamarche, 2000; Ferretti et al., 1994; Jansson, 1996; Round et al., 1999; Tambovtseva & Kornienko, 1986; Van Praagh & Dore, 2002). It is remarkable that for girls the same effects of pubescence processes on the structure and function of their skeletal muscles are not revealed (Petersen et al., 1999; Tambovtseva, 2003; Treuth et al., 2001), which can be explained by various structural – metabolic consequences of androgen and estrogen effects. For boys testosterone content is increased 4 times at primary stages of pubescence and more than 20 times – at its last stages. For girls the testosterone is only 4 times increased from the primary to the last stages of pubescence (Blimkie & Sale, 1998).

In literature there are no data on creatine phosphokinase (CrК) activity in human muscles with age. In recent years, with development of magnetic resonance research methods (Ross et al., 1992), data on creatine phosphate (CrP) content in muscles in rest as well as under physical load and recreation have been obtained (Zanconato et al., 1993; Ferretti et al., 1994;

anaerobic – glycolytic source at the tissue level were discovered. Next by means of biochemical (Eriksson, 1980; Ferretti et al., 1994; Kornienko et al, 1980; Ratel et al, 2002), histochemical (Tambovtseva, 2003; Kornienko et al, 2000) and physiological (Kornienko et al, 2000; Pyarnat & Viru, 1975; Son'kin, 1988;) methods numerous confirmations of an abrupt activation of anaerobic – glycolytic energy production in the process of pubescence reconstructions were obtained, especially for boys (Boisseau & Delamarche, 2000; Van

In ontogenesis of rats an activity of glycolysis key ferment – lactate dehydrogenase (LDG) was traced in detail (Musaeva, 1986; Demin et al., 1987). LDG molecule consists of 4 monomers and each of them can have one of two following isoforms: "H" – subunits which are typical for LDG from a cardiac muscle, "M" – subunits which are mainly in skeletal muscles of adult mammals (Lehninger, 1965). These isoferment forms differently participate in a cycle of glycolysis reactions, therefore the ratio of "H" and "M" activities – LDG subunits can be used as a sufficiently informative activity ratio index for aerobic and anaerobic –

In these studies it was proven that an age increase in "aerobic" ferment activity in muscles of male rates occurs generally parallel to increasing facilities of the oxidizing source and is complete by the start of pubescence, while total LDG activity rapidly grows in pubescence and even after it. Therefore, in process of pubescence qualitatively reconstructed is organization of energy metabolism in somatic muscle cells: an abrupt extension of facilities for anaerobic – glycolytic energy production in terms of stabilization and even some

The given facts have proposed an important role of sex hormones in regulation of muscle energetics. Direct evidence of this hypothesis was obtained by Musaeva (1986) in tests on male rates with orchotomy at the age of 3 weeks or artificial androgenization: androgenization accelerates and orchotomy inhibits the formation of ferment systems, which are responsible for anaerobic mechanisms producing energy in somatic muscles, and practically does not have an effect on conditions of mitochondria (aerobic) energy production. Under the influence of exogenous testosterone, the fraction of muscle fibers with a high activity of ATP-ase in the structure of extremities considerably increased, meaning those, which are mainly characterized by anaerobic energy supply. Orchotomy has

Probably, male sex hormones play a role that is not less significant in formation of a morphological–functional status of human skeletal muscles (Boisseau & Delamarche, 2000; Ferretti et al., 1994; Jansson, 1996; Round et al., 1999; Tambovtseva & Kornienko, 1986; Van Praagh & Dore, 2002). It is remarkable that for girls the same effects of pubescence processes on the structure and function of their skeletal muscles are not revealed (Petersen et al., 1999; Tambovtseva, 2003; Treuth et al., 2001), which can be explained by various structural – metabolic consequences of androgen and estrogen effects. For boys testosterone content is increased 4 times at primary stages of pubescence and more than 20 times – at its last stages. For girls the testosterone is only 4 times increased from the primary to the last stages of

In literature there are no data on creatine phosphokinase (CrК) activity in human muscles with age. In recent years, with development of magnetic resonance research methods (Ross et al., 1992), data on creatine phosphate (CrP) content in muscles in rest as well as under physical load and recreation have been obtained (Zanconato et al., 1993; Ferretti et al., 1994;

decrease in a relative capacity of aerobic energy production.

the opposite results (Musaeva, 1986; Son'kin & Tambovtseva, 2011).

pubescence (Blimkie & Sale, 1998).

Praagh & Dore, 2002).

glycolytic sources.

Boisseau & Delamarche, 2000; Van Praagh & Dore, 2002). Data available in press are contradictory.

At that same time, dynamics of these indices for various tissues in ontogenesis of rats was studied by Demin in detail (1983, 1985). According to these results, CrK activity in muscles of animal hind extremities in a nest life period makes 2.5 – 2.7 µmol/min/g and it is practically unchanged in the first 2 weeks of life. At the same age CrК activity in cardiac tissue is somehow less than in leg muscles while in neck muscles, which perform the most thermoregulation function – it is 2 times more, than in leg muscles. With start of an active independent motion activity for young rats (3 weeks), CrК in leg muscles grows intensely reaching by pubescence (60 days) the level of 39 µmol/min/g. This is 4.5 times more than in neck and cardiac muscles, 12 times more than in brain tissue and 50 times more than in the liver.

For this period CrP content in muscles is approximately increased by 3 times - from 5.4 up to 15.9 µmol/g (in a 60-day rat's heart CrP content – 7.1 µmol/g; in brain – 5.7 µmol/g; in liver – 2.43 µmol/g).

CrP content and CrK activity are increased in skeletal muscles asynchronously with age and it provides age changes in potential duration of CrP expenditure at maximum activity. The most substantial increase in CrK activity is observed at the last stages of pubescence, which provides a considerable acceleration of ATP forming velocity in a creatine kinase reaction, meaning the capacity of an alactacide energy system. As a result, according to Demin (1985), ATP formation velocity in process of a creatine kinase reaction in muscles of rat extremities is increased from 20 µmol/g/min at the age of 12 days up to 80 µmol/g/min at the age of 40-45 days (an active phase of pubescence), and by the end of pubescence changes it grows up to 160 µmol/g/min.

The given facts prove that the pubescence period is a "divide" between two qualitative conditions in energetics of somatic muscles. Prior to pubescence changes in muscles, like in other mammal tissues, the predominant role in energy supply is played by mitochondria oxidation. After pubescence changes, muscles acquire that colossal functional range and those specific features of organizing energy metabolism, which differentiates them from other tissues of an adult body, and the role of anaerobic energy sources is rapidly increased (Kornienko et al., 2000). Such reconstruction of energetics in skeletal muscles allows after some time the increase of the realized capacity of outer mechanical production, considerably extending the functional range, as well as promoting repeated growth of efficiency and reliable body function under strenuous muscle activity (Kornienko & Son'kin 1999). However, it should be noted, that the data of Demin, like most other similar results, were obtained for male rats. Sex differences in dynamics of energy facilities for skeletal muscles are studied insufficiently. According to the results of research made by means of up-to-date methods (Boisseau & Delamarche, 2000; Petersen et al., 1999; Treuth et al., 2001; Van Praagh, Dore, 2002 ), for girls at pre- and post-pubescent age such considerable differences in energy metabolism structure under muscular load were not revealed.

#### **5. Conclusion**

Energy metabolism, presenting the most integral body function, demonstrates logical age changes reflecting qualitative and quantitative redevelopments of a child's organism. The principle of functional economy is likely to be the most vivid of these changes with age development. This principle is implemented in age-related reduction of basal metabolism, in

Energy Metabolism in Children and Adolescents 137

Bell, RD, MacDougall, JD, Billeter, R, et al. (1980) Muscle fiber types and morphometric

Blimkie, C. & Sale, D. (1998). Strength development and trainability during childhood. In:

Boisseau, N, Delamarche, P. (2000) Metabolic and hormonal responses to exercise in

Bosy-Westphal, A., Kossel, E., Goele, K., Later, W., Hitze, B., Settler, U., Heller, M., Glüer,

Bruck, K. (1970). Heat production and temperature regulation. In: *Physiology of perinatal* 

Colling-Saltin, A-S. (1980). Skeletal muscle development in the human fetus and during

Conrad, M. & Miller, A. (1956) Age changes in body size, body composition and basal

Demin, V. (1983). [Indicators of the mitochondrial respiratory chain, anaerobic glycolysis

Demin, V.I. (1985) [Age-related changes of creatine kinase system]. In: *Novye issledovaniya po* 

Demin, V., Kornienko, I., Maslova, G. et al. (1987). [Peculiarities of Energetic Metabolism

du Plessis, M., Smit, P., du Plessis, L., et al. (1985). The composition of muscle fibers in a

W., editors, pp. 323-328, Human Kinetics Publishers, Champaign (IL), USA Elder, G.C. & Kakulas, B.A. (1993) Histochemical and contractile property changes during human development. *Muscle Nerve, Vol.* 16, No.11, pp. 1246-1253, ISSN 0148-639X Eriksson, B.O., Karlsson, J. & Saltin, B. (1971) Muscle metabolites during exercise in pubertal boys. *Acta Paediatr Scand Suppl*; Vol. 217, pp. 154-157, ISSN 0300-8843 Eriksson, B.O. & Saltin, B. (1974) Muscle metabolism during exercise in boys aged 11 to 16 compared to adults. *Acta Paediatr Belg*, Vol. 28 Suppl., pp. 257-65, ISSN 0001-6535 Eriksson, B.O. (1980) Muscle metabolism in children--a review. *Acta Paediatr Scand Suppl.*,

Falk, B. (1998) Effects of thermal stress during rest and exercise in the paediatric population.

Farber, D. & Machinskaya, R. (2009). [Functional organization of the brain in ontogenesis

and its reflection in the electroencephalogram of peace]. In: *Razvitie mozga i formirovanie poznavatel'noi deyatel'nosti rebenka. [The development of brain and cognitive* 

metabolism. *Amer.J.Physiol*., Vol. 186, pp.207-210, ISSN 0002-9513

*schoolchildren],* pp. 77-82, APN SSSR, Moscow, USSR (rus.)

children and adolescents. *Sports Med., Vol.* 30, No.6, pp. 405-22.

*Nutr, Vol.*90, pp.993–1001, ISSN 1938-3207

University Park Press, Baltimore (MD), USA

*period,* pp. 493—557, N. Y., USA

Pedagogika, Moscow, USSR (rus.)

pp. 174-183, Pushino, USSR, (rus)

Vol.283, pp.20-28, ISSN 0300-8843

*Sports Med., Vol.* 25, No.4, pp. 221-40, ISSN 0112-1642

28-31

Champaign (IL), USA

analysis of skeletal muscle in six-year-old children. *Med Sci Sports Exerc, Vol.*12, pp.

*Pediatric anaerobic performance,* Ed. Van Praagh, E., pp. 193-224, Human Kinetics,

C.-Ch., Heymsfield, S.B., & Müller, M. J (2009) Contribution of individual organ mass loss to weight loss–associated decline in resting energy expenditure. *Am J Clin* 

childhood. In: *Children and exercise,* Berg, K., Eriksson, B., editors, pp. 193-207,

and creatine kinase system of skeletal muscles in ontogenesis]. In: *Osobennosti razvitiya fiziologicheskih sistem shkol'nika [On the evolution of physiological systems of* 

*vozrastnoi fiziologii [New research on the physiology of age],* No.1(24), pp. 39-43,

Organization in Different Organs]. In: *Molekulyarnye mehanizmy i regulyaciya energeticheskogo obmena [Molecular Mechanisms and Regulation of Energy Metabolism],* 

group of adolescents. In: *Children and exercise XI,* Binkhorst, R., Kemper, H., & Saris,

slower rate of thermoregulatory reactions, decrease of food thermogenic effect with age, in change of daily energy expenditure structure with age. This is the structure of daily expenditure, where there are most vivid qualitative changes reflecting heterochronic development of most energy-intensive functions. If at an early age the energy metabolism priority is the brain and neural processes associated with it, with growth of the muscular system and formation of its functional facilities energy expenditure on kinesis starts taking a greater share in the daily energy balance.

This, together with the general tendency to fall in relative heat production, corresponding to the views of progressive functional economy in rising ontogenesis, with growth and development of skeletal muscles the maximum energy production is considerably increased, which is provided by activation of the least economic anaerobic – glycolytic source of energy production. In other words, by the example of age changes in energy metabolism the most important principle of development can be distinctly demonstrated – a principle of biological suitability, which is sometimes implemented due to the breach of other principles with lower value, to implement biosocial objectives of the corresponding ontogenesis stage.

For many decades the researchers of age changes in energy metabolism have been paying attention to reduction in the rate of exchange processes in rest with age. It was attempted to be explained by smaller relative surface of the body (Rubner, 1883), growth of relative muscular mass value (Arshavskii, 1967), lower relative mass of internal organs with a high rate of oxidizing metabolism (Holliday, 1971; Javed et al., 2010; Kornienko, 1979; Wang et al., 2010). But now we think that the most important age redevelopment is the combined reduction of basal and increased maximum energy expenditure (including expenditure pursuant to anaerobic ways to transform energy with realization of the intense muscle activity), which results in the considerable development of a functional range. That is the biological development objectives of energy production mechanisms, as a vast functional range provides implementation of a wide spectrum of social and biological problems facing the adult organism (Son'kin & Tambovtseva, 2011).

Theoretical views of the laws valid for age changes in energy metabolism can considerably effect the formation and implementation of practical methods and means, firstly in such directions as conditioning to the cold, organization of proper nutrition and rational physical activity of children and teenagers.

#### **6. Acknowledgments**

The authors express their sincere gratitude to the colleagues with whom they have for years been investigating age-related changes of energy of the body: Dr. I. Gohblit, Dr. V. Demin, Dr. G. Maslowa and Dr. Z. Musaeva.

We would like to honour the memory of our teacher Professor I.A. Kornienko, whose ideas and experiments formed the basis of this paper.

#### **7. References**

Arshavskii, I. (1967). *Ocherki po vozrastnoi fiziologii [Essays on the physiology of age]*, Medicina, Moscow, USSR (rus.)

Astrand, P.-O. (1952). *Experimental studies of physical working capacity in relation to sex and age*, Munksgaard, Copenhagen, Danmark

slower rate of thermoregulatory reactions, decrease of food thermogenic effect with age, in change of daily energy expenditure structure with age. This is the structure of daily expenditure, where there are most vivid qualitative changes reflecting heterochronic development of most energy-intensive functions. If at an early age the energy metabolism priority is the brain and neural processes associated with it, with growth of the muscular system and formation of its functional facilities energy expenditure on kinesis starts taking a

This, together with the general tendency to fall in relative heat production, corresponding to the views of progressive functional economy in rising ontogenesis, with growth and development of skeletal muscles the maximum energy production is considerably increased, which is provided by activation of the least economic anaerobic – glycolytic source of energy production. In other words, by the example of age changes in energy metabolism the most important principle of development can be distinctly demonstrated – a principle of biological suitability, which is sometimes implemented due to the breach of other principles with lower value, to implement biosocial objectives of the corresponding ontogenesis stage. For many decades the researchers of age changes in energy metabolism have been paying attention to reduction in the rate of exchange processes in rest with age. It was attempted to be explained by smaller relative surface of the body (Rubner, 1883), growth of relative muscular mass value (Arshavskii, 1967), lower relative mass of internal organs with a high rate of oxidizing metabolism (Holliday, 1971; Javed et al., 2010; Kornienko, 1979; Wang et al., 2010). But now we think that the most important age redevelopment is the combined reduction of basal and increased maximum energy expenditure (including expenditure pursuant to anaerobic ways to transform energy with realization of the intense muscle activity), which results in the considerable development of a functional range. That is the biological development objectives of energy production mechanisms, as a vast functional range provides implementation of a wide spectrum of social and biological problems facing

Theoretical views of the laws valid for age changes in energy metabolism can considerably effect the formation and implementation of practical methods and means, firstly in such directions as conditioning to the cold, organization of proper nutrition and rational physical

The authors express their sincere gratitude to the colleagues with whom they have for years been investigating age-related changes of energy of the body: Dr. I. Gohblit, Dr. V. Demin,

We would like to honour the memory of our teacher Professor I.A. Kornienko, whose ideas

Arshavskii, I. (1967). *Ocherki po vozrastnoi fiziologii [Essays on the physiology of age]*, Medicina,

Astrand, P.-O. (1952). *Experimental studies of physical working capacity in relation to sex and age*,

greater share in the daily energy balance.

the adult organism (Son'kin & Tambovtseva, 2011).

activity of children and teenagers.

Dr. G. Maslowa and Dr. Z. Musaeva.

Moscow, USSR (rus.)

and experiments formed the basis of this paper.

Munksgaard, Copenhagen, Danmark

**6. Acknowledgments** 

**7. References** 


Energy Metabolism in Children and Adolescents 139

Karlberg, P. (1952) Determination of standard energy metabolism (basal metabolism) in normal infant. *Acta pediat*. (Uppsala), Vol. 41 (suppl.83), pp. 3-151, ISSN 0803-5253 Kassirskii, I. (1934). *Osnovnoi obmen i ego klinicheskoe znachenie. [Basal Metabolism and it's* 

King, J.C., Butte, N.F., Bronstein, M.N., Kopp, L.E. & Lindquist, S.A. (1994) Energy

Kleiber, M. (1961). *The Fire of Life*. John Wiley and Sons, Inc., New York, London, USA, GB Korkushko, O.V. & Orlov, P.A. (1974) [Сalorygenic action of Glucose in Humans of

Kornienko, I.A. (1979). *Vozrastnye izmeneniya energeticheskogo obmena i termoregulyacii. [Age* 

Kornienko, I.A. & Gohblit, I.I. (1983) [Age-related conversion of energy metabolism]. In:

Kornienko, I.A., Son'kin, V.D. & Urakov T.U. (1984). Calorigenic action of glucose in schoolchildren. *Hum Physiol*. Vol. 10, No. 4, pp. 276-82 ISSN 0362-1197 Kornienko, I.A., Demin, V.I., Maslova, G.M. & Son'kin, V.D. (1987) [Development of skeletal

Kornienko, I.A., Gohblit, I.I. & Son'kin, V.D. (1988) [Characterization of energy metabolism]-

Kornienko, I.A. & Son'kin, V.D. (1999) "Biological Reliability," Ontogeny, and Age-Related

Kornienko, I.A., Son'kin, V.D., Tambovtseva, R.V., Bukreeva, D.P. & Vasil'eva, R.M. (2000)

Kornienko, I.A., Son'kin, V.D. & Tambovtseva, R.V. (2005) Development of the Energetics of

Lehninger, A.Z. (1965) *Bioenergetics. The molecular basis of biological energy transformations*.

Lexell, J., Sjoström, M. & Nordlund, A-S. (1992) Growth and development of human muscle:

Lundberg, A., Eriksson, B.O. & Mellgren, G. (1979) Metabolic substrates, muscle fibre

Vol. 59 (2 Suppl), pp. 439-445, ISSN 1938-3207

Vol. 2, P.166, Leningrad, USSR, June 1987 (rus.)

Benjamin, New-York, USA, Amsterdam, Holand

adult age. *Muscle Nerve,* Vol. 15, pp. 404-409, ISSN 0148-639X

Different Age]. *Voprosy pitaniya*, №1, pp. 54-58. (rus)

(rus)

(rus)

Moscow, USSR (rus.)

Moscow, USSR (rus.)

Moscow, Russia (rus.)

130, pp. 79-92, ISSN 1432-1076

0362-1197

0362-1197

*Clinical Significance].* Gosizdat, Sredneaziat. Otdelenie, Moskva-Tashkent, USSR

metabolism during pregnancy: influence of maternal energy status. *Am J Clin Nutr*.,

*Development of Energy Metabolism and Thermoregulation].* Nauka, Moscow, USSR

*Fiziologiya razvitiya rebenka [Physiology of Child Development],* pp. 89-114, Pedagogika,

muscle energetics]. In: *[Proceedings of the XV All-Union Congress of Physiologists],*

*In.*: *Fiziologiya podrostka [Physiology of teenager. Ed. Farber, D.],* pp.71-93, Pedagogika,

Dynamics of Muscular Efficiency. Human Physiology, Vol.25, No.1, pp.83-92, ISSN

[Age-related development of skeletal muscle and exercise performance] In: *Fiziologiya razvitiya rebenka: teoreticheskie i prikladnye aspekty [Physiology of Child Development: Theoretical and Applied Aspects],* pp.209-238, Obrazovanie ot A do Ya,

Muscular Exercise with Age: Summary of a 30-Year Study: I. Structural and Functional Rearrangements. Human Physiology, Vol. 31, No.4, pp. . 402-406, ISSN

a quantitative morphological study of whole vastus lateralis from childhood to

composition and fibre size in late walking and normal children. *Eur J Pediatr,* Vol.

*development of children],* Ed. Farber, D.A. & Bezrukih, M.M., pp. 76-118, Izdatel'stvo moskovskogo psihologo-social'nogo instituta, Moscow, Russia, ISBN 978-5-9770- 0361-2 (rus.)


Ferretti, G., Narici, M.V., Binzoni, T., Gariod, L., Le Bas, J.F., Reutenauer, H. & Cerretelli, P.

Forbes, E. & Swift, R. (1944) Associative dynamic effects of proteins, carbohydrate and fat.

Frankenfield, D., Roth-Yousey, L. & Compher, C. (2005) Comparison of predictive equations

Garrel, D.R., Jobin, N. & de Jonge, L.H. (1996) Should we still use the Harris and Benedict equations? *Nutr Clin Pract*. Vol. 11, No. 3, pp. 99-103, ISSN 0884-5336 Godina, E.Z. (2009) The secular trend: history and prospects. Human Physiology, Vol. 35,

Gohblit, I.I., Bogachev, V.N. & Kornienko, I.A. (1975) [Thermoregulatory responses in

Guminskii, A.A., Tupitsina, L.P. & Feoktistova, S.V. (1985) [Age characteristics of energy

Habas, M.E. & Macdonald, I.A. (1998) Metabolic and cardiovascular responses to liquid and solid test meals. *Br J Nutr,* Vol. 79, No. 3, pp. 241-247, ISSN 0007-1145 Harris, JA.; Benedict, FG. (1919). *A biometric study of basal metabolism in man,* Carnegie

Hayter, J.E. & Henry, C.J. (1994) A re-examination of basal metabolic rate predictive

Himms-Hagen, J. (1989) Role of thermogenesis in the regulation of energy balance in

Holliday, M. (1971) Metabolic rate and organ size during growth from infancy to maturity

Ivanov, K. (1990). *Osnovy energetiki organizma. Teoreticheskie i prakticheskie aspekty. [Basis of* 

*Thermoregulation].* Nauka, Leningrad, USSR, ISBN: 978-5-02-026169-3 (rus) Jansson, E. (1996). Age-related fiber type changes in human skeletal muscle. In: *Biochemistry* 

Javed, F., He, Q., Davidson, L.E., Thornton, J.C., Albu, J., Boxt, L., Krasnow, N., Elia, M.,

review. *J Am Diet Assoc. Vol.*105, No. 5, pp.775-789. ISSN 0002-8223

*Science*, Vol.99, pp.476-478, ISSN 0036-8075

Institute of Washington, Washington, DC, USA

*Clin Nutr.* Vol. 48, No. 10, pp. 702-707, ISSN 0954-3007

No. 6, pp. 770-776, ISSN 0362-1197

548. (rus.) ISSN 0131-1646

(rus.), ISSN 0131-1646

179.ISSN 0031-4005

Champaign (IL), USA

*Nutr, Vol.* 91, pp. 907–912, ISSN 1938-3207

4212

0361-2 (rus.)

0301-5548

*development of children],* Ed. Farber, D.A. & Bezrukih, M.M., pp. 76-118, Izdatel'stvo moskovskogo psihologo-social'nogo instituta, Moscow, Russia, ISBN 978-5-9770-

(1994) Determinants of peak muscle power: effects of age and physical conditioning. *Eur J Appl Physiol Occup Physiol.; Vol.* 68, No. 2, pp.111-115, ISSN

for resting metabolic rate in healthy nonobese and obese adults: a systematic

children during the first months of life]. *Fiziologiya cheloveka,* Vol. 1, No.4, pp.541-

metabolism in girls during puberty]. *Fiziologiya cheloveka,* Vol. 11, No.2, pp. 286-292.

equations: the importance of geographic origin of subjects in sample selection. *Eur J* 

relation to obesity. *Can J Physiol Pharmacol, Vol.* 67, No. 4, pp. 394-401, ISSN 0008-

and during late gestation and early infancy. *Pediatrics,* Vol. 47, Pt. 2. pp. 169—

*Organism Energetic. Theoretical and applied aspects] Vol.1. Obshaya energetika, teploobmen i termoregulyaciya [General Energetic, Thermal Turnover and* 

*of exercise IX*. Maughan, RJ, Shirreffs, SM, editors, pp. 297-307, Human Kinetics,

Kang, P., Heshka, S., & Gallagher, D. (2010) Brain and high metabolic rate organ mass: contributions to resting energy expenditure beyond fat-free mass. *Am J Clin* 


Vol. 19, pp. 536-562.

Press, Cambridge, England

5, pp. 599–614, ISSN 0362-1197

Vol. 26, No. 2, pp. 152–155, ISSN 1873-1244

Moscow, USSR (rus.)

Moscow (rus.)

0362-1197

0004-1947

0004-1947

Energy Metabolism in Children and Adolescents 141

Round, J.M., Jones, D.A., Honour, J.W., & Nevill A.M. (1999) Hormonal factors in the

a longitudinal study. *Ann Hum Biol, Vol.* 26, No.1, pp. 49-62, ISSN 0301-4460

Rubner, M. (1883). Über den einfluss der körpergrösse auf stoff- und kraftwechsel. *Z. Biol.*

Schmelzle, H., Schroder, C., Armbrust, S., Unverzagt, S. & Fusch, C. (2004) Resting energy

Schmidt-Nielsen, K. (1984) *Scaling. Why is animal size so important*. Cambridge University

Shmal'gauzen, I.I. (1935) Rost i differencirovka. [Growth and differentiation] - In: *Rost* 

Skinner, J.S. (Ed.) (1993) *Exercise testing and exercise prescription for special cases: theoretical basis* 

Son'kin, V.D., Urakov, T.U., Pavlov, Yu.M. & Deduhova V.I. (1975) [Use of glucose load to

Son'kin, VD. (1988) [Development of energy support for muscle activity in adolescents]

Son'kin, V.D. (2007) Physical working capacity and energy supply of muscle function during

Son'kin, V.D., Kirdin, A.A., Andreev, R.S., Akimov, E.B. (2010) Homeostatic nonshivering

Son'kin, V.D. & Tambovtseva, R.V. (2011) *Razvitie myshechnoi energetiki i rabotosposobnosti v* 

Tambovtseva, R.V. & Kornienko I.A. (1986a) [Development of various types of muscle fibers

Tambovtseva, R.V. & Kornienko, I.A. (1986b) [Development of various types of muscle

Tambovtseva, R.V. & Kornienko, I.A. (1987) [Development of different types of muscle fiber

*Anat Gistol Embriol.* Vol. 91, No. 9, pp. 96-99 (rus.), ISSN 0004-1947

*Fiziol Cheloveka*. Vol. 14, No. 2, pp. 248-255 (rus), ISSN 0131-1646

*Acta Paediatr*. Vol. 93, No. 6, pp. 739-746, ISSN 1651-2227

*and clinical application*. Lea & Febiger, Philadelphia, USA

development of differences in strength between boys and girls during adolescence:

expenditure in obese children aged 4 to 15 years: measured versus predicted data.

*zhivotnyh. [Growth of animals],* Ed. by Mickiewicz, M.S. pp. 74-84, Biomedgiz,

characterize energy metabolism in children of school age]. In: *Novye issledovaniya po vozrastnoi fiziologii,* No. 2 (5), pp.58-60. Academy of Pedagogical Sciences USSR,

postnatal human ontogeny. Human Physiology, Vol. 33, No. 3, pp. 326–341, ISSN

thermogenesis in Humans. Facts and Hypotheses. Human Physiology, Vol. 36, No.

*ontogeneze. [Development of muscle energetics and working capacity during ontogenesis].* Knizhnyi dom «LIBROKOM», Moscow, Russia, ISBN 978-5-397-01708-4 (rus.) St-Onge, M.-P. & Gallagher, D. (2010) Body composition changes with aging: The cause or

the result of alterations in metabolic rate and macronutrient oxidation? *Nutrition*.

in soleus muscle of rat postnatal ontogenesis]. *Arhiv anatomii, gistologii i embriologii. [Archive of Anatomy, Histology and Embryology], V*ol. 90, No. 1, pp. 77-81 (rus.), ISSN

fibers in the quadriceps femori and the soleus during human ontogenesis] *Arkh* 

in the postnatal ontogeny of guinea pig]. *Arhiv anatomii, gistologii i embriologii. [Archive of Anatomy, Histology and Embryology],* Vol. 93, No.7, pp.55-59. (rus.), ISSN


140 Bioenergetics

Lusk, G. (1919) Calorigenic cosporet de l'ingestion de viande decide lacticue et datanine chez l'anisal. *Compt. Rend. Acad. D.sc*., Paris, Vol. XVIII, pp.1012-1015. Macler, В., Grace, R. & Duncan, H. (1971) Studies of mitochondrial development during

Mader, A. & Heck, H. (1986) A theory of the metabolic origin of "Anaerobic threshold". *Int.* 

Mahin'ko, V.I. & Nikitin, V.N. (1975) Obmen veshestv i energii v ontogeneze. [Substrate and

Margaria, R. (1963) Biochemistry of muscular contraction and recovery. *J.Sports Med .and* 

McDuffie, J.R., Adler-Wailes, D.C., Elberg, J., Steinberg, E.N., Fallon, E.M., Tershakovec,

Musaeva, Z.T. (1986) [Changes in the activity of lactate dehydrogenase and creatine kinase

Nagornyi, A.V., Nikitin, V.N. & Bulankin, I.N. (1963) *Problema stareniya i dolgoletiya [The* 

Nedergaard, J. & Cannon, B. (2010) The changed metabolic world with human brown

Nedergaard, J., Bengtsson, T. & Cannon, B. (2007) Unexpected evidence for active brown

Petersen, S.R., Gaul, C.A., Stanton, M.M. & Hanstock, C.C. (1999) Skeletal muscle

Pyarnat, Ya.P. & Viru, A.A. (1975) [Age peculiarities of physical (aerobic and anaerobic) capacity]. *Fiziologiya cheloveka,* Vol. 1, No. 4, pp.692-696 (rus.) ISSN 0131-1646 Ratel, S., Bedu, M., Hennegrave, A., Dore, E. & Duche, P. (2002) Effects of age and recovery

Robinson, S. (1938) Experimental studies of physical fitness in relation to age. *Arbeitsphysiol*.

Ross, B., Kreis, R. & Ernst, T. (1992) Clinical tools for the 90s: magnetic resonance

girls. *J Appl Physiol.* Vol. 87, No. 6, pp. 2151-2156, ISSN 1522-1601

Vol. 23, No. 6, pp. 397-402, ISSN 1439-3964

*J. Sports Med*, Vol. 7, Suppl., pp. 45-65, ISSN 1439-3964

*Physical Fitness,* Vol*.* 168, No. 3, pp. 145-156, ISSN 0022-4707

*problem of aging and longevity],* Nauka, Moscow, USSR (rus.)

0003-9861.

(rus.)

(rus.)

1932-7420

1872-7727

E452, ISSN 1522-1555

Vol. 10, No. 3, pp.251-323

pp. 117-130, ISSN 0308-4329

embryogenesis in the rat. *Arch. Biochem. and Biophysics,* Vol. 144, pp.603-610, ISSN

energy metabolism in ontogeny] In: *Rukovodstvo po fiziologii. Vozrastnaya fiziologiya [Guide to Physiology. Developmental physiology],* pp. 249-266, Nauka, Moscow, URSS

A.M., Arslanian, S.A., Delany, J.P., Bray, G.A., & Yanovski, J.A. (2004) Prediction equations for resting energy expenditure in overweight and normal-weight black and white children. *Am J Clin Nutr*. Vol. 80, No. 2, pp.365–373, ISSN 1938-3207 Morgan, J. (1980) The pre-school child: diet, growth and obesity. *J Hum Nutr*, Vol. 34, No. 2,

in skeletal muscle during puberty]. In: *Novye issledovaniya po vozrastnoi fiziologii [New research on the physiology of age]*, N 2, pp. 14-17, Pedagogika, Moscow, USSR

adipose tissue: therapeutic visions. *Cell Metab, Vol.* 11, No. 4, pp. 268-272, ISSN

adipose tissue in adult humans. *Am J Physiol Endocrinol Metab*, Vol. 293, pp. E444–

metabolism during short-term, high-intensity exercise in prepubertal and pubertal

duration on peak power output during repeated cycling sprints. *Int J Sports Med.*

spectroscopy and metabolite imaging. *Eur J Radiol.* Vol. 14, No. 2, pp. 128-40, ISSN


*Brazil* 

**Role of Inorganic Polyphosphate** 

Eldo Campos1,4, Arnoldo R. Façanha2,4, Jorge Moraes1,4 and Carlos Logullo3,4 *1Universidade Federal do Rio de Janeiro - Macaé 2Universidade Estadual do Norte Fluminense 3Universidade Estadual do Norte Fluminense* 

 **in the Energy Metabolism of Ticks** 

*4Instituto Nacional de Ciência e Tecnologia - Entomologia Molecular* 

Inorganic polyphosphates are long chains of a few to several hundred phosphate residues linked by phosphoanhydride bonds (Figure 1). Polyphosphates have been found in all cell types examined to date and have been demonstrated to play diverse roles depending on the cell type and circumstances (Kornberg et al., 1999; Kulaev & Kulakovskaya, 2000). The biological roles played by polyphosphates have been most extensively studied in prokaryotes and unicellular eukaryotes, where they have been shown to regulate many biochemical processes including the metabolism and transport of inorganic phosphate, cation sequestration and storage (Kornberg et al., 1999), and membrane channel formation (Reusch, 1989; Jones et al., 2003), and they have also been found to be involved in cell envelope formation and bacterial pathogenesis (Rashid et al., 2000; Kim et al., 2002), the regulation of gene and enzyme activities (McInerney et al., 2006), the activation of Lon

proteases (Kuroda et al., 2001), and KcsA channel regulation (Negoda et al., 2009).

Conversely, polyphosphate functions have not been extensively investigated in higher eukaryotes; however, there is a good deal of interest in polyphosphates in mitochondria regarding two circumstances: polyphosphate as a macroenergetic compound with the same energy hydrolysis of the phosphoanhydride bond as an ATP and, according to the endosymbiotic theory, mitochondria originated from ancient prokaryotic cells (Clements et

**1. Introduction** 

Fig. 1. Inorganic Polyphosphate

