Energy supply of muscular activity of five- to six-year-old children and complex assessment of physical working capacity

A complex study of the physical working capacity of five- to six-year-old children (n = 106) was performed. It was found that the physical working capacity of preschool children at this age is determined by the following five major factors: (I) aerobic capacity, (II) anaerobic glycolytic working capacity, (III) absolute aerobic power, (IV) relative aerobic power, and (V) anaerobic alactic working capacity. Sex-related differences in some parameters reflecting the physical working capacity and fitness, characterizing the anaerobic alactic and anaerobic glycolytic productivity of the body were revealed. These differences are apparently related to an advanced development of anaerobic energy-supply mechanisms of girls compared to age-matched boys. The procedure of a complex assessment of the physical working capacity of five- to six-year-old children has been developed, which includes informative parameters characterizing the power and capacity of energy systems selected on the basis of results of factor analysis and expert assessment. A rapid procedure for a complex assessment of working capacity based on calculating the time during which a physical load (2 W/kg) can be sustained is proposed. The study showed that shifts in the intensity of physical activity within the optimal range resulted in multifold changes in its duration. Importantly, the duration of physical activity’s performance at an intensity of 175–180 bpm in children with a high working capacity is comparable to the maximum work duration at a heart rate of 140–145 bmp in preschool children with a low physical condition. Differences between children with high and low physical working capacity were found to increase with an increase in the physical load aerobicity. The physical working capacity of five- to six-year-old children can be differentiated best of all on the basis of aerobic capacity parameters. The enormous range of changes in the aerobic capacity parameters makes them especially valuable for characterizing the level of somatic health of preschool children. The results of this study were used to construct a nomogram for the determination of the allowable training load depending on its intensity and physical working capacity.     

Assessment of aerobic and anaerobic capacity of athletes in treadmill running tests.

The criteria of max VO2 and max O2D which are traditionally used in studying aerobic and anaerobic work capacity, have the different dimensions. While max VO2 is an index of the power of aerobic energy output, max O2D assesses the capacity of anaerobic sources. For a comprehensive assessment of physical working capacity of athletes, both aerobic and anaerobic capabilities should be represented in three dimensions, i.e. in indexes of power, capacity and efficiency. Experimental procedures have been developed for assessing these three parameters in treadmill running tests. It is proposed to assess anaerobic power by measuring excess CO2, concurrently with determination of max VO2. Maximal aerobic capacity is established as the product of max VO2 by the time of max VO2 maintenance determined in a special test with running at critical speed. The erogmetric criteria derived on the basis of the tests proposed, may be used for systematization of various physical work loads.     

Energy-supply of the muscular activity at boys of 13-14 years in dependence from rates of puberty

In work on the basis of use functional and ergometric working capacity indicators specificity of power supply of muscular activity of healthy boys of 13-14 years (n = 162) with various at puberty stages (PSs). It is established, that the boys, being on II-IV PSs, considerably differ on indicators of power, capacity and efficiency of energy systems. Three groups of the bioenergy systems indicators differing on an orientation of their changes at teenagers depending on rates of puberty stages. The first group includes the physiological variables which most considerable levels are observed at children with high rates of development. All of them concern to anaerobic alactic and anaerobic glycolytic to components of physical working capacity. The second group unites the physiological variables which highest values are marked at teenagers with average rate of development, and the least--at children with the accelerated rate of maturing. These indicators reflect, mainly, set of aerobic possibilities of an organism. The third group includes the indicators which highest levels are marked at teenagers with low rate of development, and the least--at boys with the accelerated rate of maturing. They reflect the maximum aerobic power and endurance to power work. It is revealed, that teenagers of 13-14 years with average rates of development are characterised in comparison with children with the accelerated maturing, higher indicators of power and capacity of aerobic system of energy-supply, and in comparison to teenagers to the slowed down development--lower maximum aerobic power against higher capacity and profitability of functioning of aerobic system. Adolescents with average rates of maturing surpass also schoolboys with the accelerated and slowed down development concerning capacity of work in mixed anaerobic-aerobic a mode. In turn boys of 13-14 years with the accelerated development differ from schoolboys with the average and slowed down rates of maturing, high anaerobic productivity of an organism, rather low aerobic possibilities and increase of a tone of parasympathetic department of autonomic nervous system (AHC). The given circumstance is necessary for considering at realisation of the differentiated approach to rationing of loadings in the course of physical education and sports training of adolescents of 13-14 years.     

Energy supply for muscle activity in 13- to 14-year-old boys depending on the rate of puberty

The energy supply for muscle activity in healthy boys aged 13–14 years (n = 162) at various puberty stages (PSs) has been studied using functional and ergometric working capacity indices. It has been established that boys at PSs II–IV significantly differ in the indices of power, capacity, and efficiency of bioenergy systems. Three groups of bioenergy indices have been distinguished that differ in the direction of variations in adolescents depending on the rate of puberty. The first group includes the physiological variables the highest levels of which are observed in adolescents with high rates of development. All these indices belong to the anaerobic alactic and anaerobic glycolytic components of physical capability. The second group includes the physiological variables the highest levels of which are observed in adolescents with medium rates of development; the lowest levels, in adolescents with accelerated rates of development. These indices mainly reflect the set of aerobic capacities. The third group includes the physiological variables the highest levels of which are observed in adolescents with low rates of development and the lowest levels, in boys with accelerated rates of maturation. These indices reflect the maximal aerobic power and endurance. It was found that adolescents aged 13–14 years with moderate rates of development are characterized by higher indices of power and capacity of the aerobic energy supply system as compared to adolescents with accelerated maturation. This group of adolescents has also been observed to exhibit a lower maximal aerobic power against a background of higher capacity and efficiency of the aerobic system functioning as compared to adolescents with slow maturation. Adolescents with moderate rates of maturation have been shown to surpass schoolboys with accelerated or slow development with respect to the power of mixed aerobic-anaerobic work. Boys aged 13–14 years with accelerated development have been found to differ from schoolboys with moderate or slow maturation by high anaerobic capacity, relatively low aerobic capacities and an increase in the tone of the parasympathetic nervous system. This should be taken into consideration in terms of a differentiated approach to the formation of load during physical education and athletic training of adolescents aged 13–14 years.     

The functional state of children from 9 to 10 years of age under the conditions of intense informational load and physical working capacity

Three-way ANOVA has shown that the functional state (FS) of children from 9 to 10 years of age (n = 91) under intense informational load is significantly influenced by the aerobic and anaerobic components of physical working capacity and their interaction. It has been found that 4 to 21% of the total variation of the studied FS indices are related to the bioenergetic resources of the body. It has been shown that the high levels of development of the aerobic and anaerobic glycolytic capacities are associated with the optimal changes in the FS under the conditions of intense informational load. At the same time, the interaction of the aerobic and anaerobic glycolytic components of physical working capacity exerts the most significant influence on the productivity and “psychophysiological cost” of intellectual activity. The high anaerobic glycolytic and anaerobic alactate capacities proved to have opposite functional effects. The former contribute to a decrease in excessive autonomic reactivity under the conditions of intense work and diminution of trait anxiety; the latter, on the contrary, determine hypermobilization of the system of autonomic support of activity. The results suggest that a combined use of rational proportions of physical loads of the aerobic, anaerobic glycolytic, and anaerobic alactate types will provide efficient control of children’s FS under the conditions of intense intellectual activity.     

Development of the energetics of muscular exercise with age: Summary of a 30-year study. III. Endogenous and exogenous factors influencing the development of the energetics of skeletal muscles

Differences in the age-related changes in the physical working capacity and the structure of the energy supply of muscular exercise of different powers determined by external (physical education conditions) and internal (gender characteristics) factors are described. Periods of synchronous and asynchronous development of the physical working capacity parameters have been revealed that are characterized by predomination of endogenous or exogenous influences on the processes studied.     

Morphofunctional characteristics of enzyme activity of the muscles in ontogenesis and after physical load

By means of histochemical methods using cytospectrophotometer in femoral muscles of white rats 1-, 3- and 12-month-old enzymatic activity of anaerobic and aerobic cycles has been estimated. The greatest changes occur after 20 days of physical load in 1- and 12-month-old animals. The semitendinous muscle (ventral origin), consisting mainly of red muscle fibers, works chiefly in aerobic regime and possesses a more manifested succinate dehydrogenase activity, and the quadriceps muscle (dorsal origin) consists principally of white fibers and its lactate dehydrogenase activity changes more noticeably.     

Development of the Energetics of Muscular Exercise with Age: Summary of a 30-Year Study: I. Structural and Functional Rearrangements

The series of articles summarizes a 30-year study on the development of skeletal muscles, bioenergetics of muscular exercise, and physical working capacity with age in elementary and secondary school students. Communication I deals with the growth of human skeletal muscles and age-related changes in their fiber composition and the main parameters of aerobic working capacity. The key periods of growth were determined and a substantial rearrangement of skeletal muscle composition and associated age-related changes in aerobic and anaerobic working capacity were found in 7- to 17-year-old boys.__________Translated from Fiziologiya Cheloveka, Vol. 31, No. 4, 2005, pp. 37–42.Original Russian Text Copyright © 2005 by Kornienko, Son’kin, Tambovtseva.     

Ontogenesis of catabolic and energy metabolism capacities during the embryonic development of spotted wolffish (Anarhichas minor)

The catabolic and energy metabolism capacities during spotted wolffish (Anarhichas minor) embryogenesis were investigated. We assessed the embryo's ability to catabolize proteins (trypsin-like proteases) and lipids (triglyceride lipase) and examined the development of metabolic capacities using enzymatic assays: ability to use carbohydrates (pyruvate kinase), amino acids (aspartate aminotransferase) and fatty acids (hydroxyacyl-CoA dehydrogenase) for energy production, and aerobic (citrate synthase) and anaerobic (lactate dehydrogenase) energy production. Functional enzymatic systems were detected from the eyed stage (350 degree-days), except for fatty acids, which was detected from 540 degree-days. To compare the development of 1) aerobic and anaerobic pathways and 2) the capacity to mobilize the different energy substrates, enzymatic ratios were calculated. Anaerobic capacity appeared to increase at a significantly higher rate than the aerobic capacity. Ratios revealing the relative capacity to use specific energy substrates showed a significantly slower increase during development in the capacity to use carbohydrates than amino acids and fatty acids. The end of embryogenesis was characterized by a significant decrease in the use of carbohydrates for aerobic energy production but an increasing capacity to use amino acids. Egg survival as affected by the variability in metabolic parameters is discussed.     

Role of energy systems in two intermittent field tests in women field hockey players

The energetics of 2 field tests that reflect physical performance in intermittent sports (i.e., the Interval Shuttle Sprint Test [ISST] and the Interval Shuttle Run Test [ISRT]) were examined in 21 women field hockey players. The ISST required the players to perform 10 shuttle sprints starting every 20 seconds. During the ISRT, players alternately ran 20-m shuttles for 30 seconds and walked for 15 seconds with increasing speed. Anaerobic and aerobic power tests included Wingate cycle sprints and a .V(O2)max cycle test, respectively. Based on correlation and regression analyses, it was concluded that for the ISST, anaerobic energetic pathways contribute mainly to energy supply for peak sprint time, while aerobic energetic pathways also contribute to energy supply for total sprint time. Energy during the ISRT is supplied mainly by the aerobic energy system. Depending on the aspect of physical performance a coach wants to determine, the ISST or ISRT can be used.     

Physical state of adolescents with high stress reactivity

The characteristics of the physical state were studied in 13- to 14-year-old adolescents with high (n = 97) and low (n = 85) stress reactivities. The data showed that, during the period of sexual maturation, the development of the mechanisms of energy for muscular activity was heterochronic and nonlinear. Hyperreactive boys exhibited relatively high anaerobic nonlactic and low aerobic capacities of the body and enhanced physiological costs of the high-power function. In hyperreactive adolescents, the motor function was specifically characterized by a combination of a high level of movement speed and power and a relatively low level of general endurance. In 13- to 14-year-old adolescents, the differences in muscular working capacities and motor abilities, associated with various stress reactivity, appear during different sexual maturation stages (SMSs). At SMSs II and III, hyper- and hyporeactive adolescents exhibit higher indices of aerobic body capacities and relatively low anaerobic capacities as compared to the children at SMS IV. It is supposed that, in the hyperreactive adolescents, the efficiency of the mechanisms of body protection from hypoxia is lower.     

Functional state of various physiological systems of the human body during respiration of neon-oxygen mixture at depth up to 400 meters]

Hyperbaric neon-oxygen mixture has been studied for the effect of its high density under pressure of 41 ata on basic physiological functions of human organism. Typical changes of the cardiorespiratory system and tissue respiration parameters are revealed. Changes in physical working capacity are shown. Exposure to gaseous medium of high pressure and density is accompanied by the development of some compensatory-adaptive reactions. The possibility to perform mid-hard physical work is attained with overstrain of respiration and circulation function.     

Effects of hibernation on mitochondrial regulation and metabolic capacities in myocardium of painted turtle (Chrysemys picta)

Painted turtles hibernating during winter may endure long-term exposure to low temperature and anoxia. These two conditions may affect the aerobic capacity of a tissue and might be of particular importance to the cardiac muscle normally highly reliant on aerobic energy production. The present study addressed how hibernation affects respiratory characteristics of mitochondria in situ and the metabolic pattern of turtle myocardium. Painted turtles were acclimated to control (25 degrees C), cold (5 degrees C) normoxic and cold anoxic conditions. In saponin-skinned myocardial fibres, cold acclimation increased mitochondrial respiratory capacity and decreased apparent ADP-affinity. Concomitant anoxia did not affect this. Creatine increased the apparent ADP-affinity to similar values in the three acclimation groups, suggesting a functional coupling of creatine kinase to mitochondrial respiration. As to the metabolic pattern, cold acclimation decreased glycolytic capacity in terms of pyruvate kinase activity and increased lactate dehydrogenase (LHD) activity. Concomitant anoxia counteracted the cold-induced decrease in pyruvate kinase activity and increased creatine kinase activity. In conclusion, cold acclimation seems to increase aerobic and decrease anaerobic energy production capacity in painted turtle myocardium. Importantly, anoxia does not affect the mitochondrial functional integrity but seems to increase the capacity for anaerobic energy production and energy buffering.     

The mechanism of nonachlazine on cardiac activity and blood supply]

Nonachlazine (10 mg/kg intravenously) exerted a two-phase influence on the heart activity. The short phase of the weakening of the heart activity gave place to the intensive increase in the cardiac output and the contractility of the myocardium. An increase in the blood supply and heart activity coincided in time with the accumulation of the quantity of noradrenaline and with increase in the phosphorylase "a" activity. Beta-adrenoblockers prevented the development of the effect in question. It is assumed that the efficacy of nonachlazine during ischemic heart disease was connected with its capacity to activate the adrenergic mechanisms of the glycogenolysis regulation leading to the switching of the myocardial metabolism to the anaerobic route of energy release.     

Influence of adipose tissue immune dysfunction on childhood obesity

In recent decades, a dramatic rise has been observed in the prevalence of obesity in childhood and adolescence, along with an increase in fetal microsomia rates. The increased risk of obesity during this key period in development negatively affects the health of the individual later in life. Immune cells residing and recruited to white adipose tissue have been highlighted as important factors contributing to the pathogenesis of childhood obesity. Immune dysfunction in the context of obesity begins early in childhood, which is different from the pathological characteristics and influencing factors of adipose immunity in adults. Here, we explore the current understanding of the roles of childhood and early life events that result in high risks for obesity by influencing adipose tissue immune dysfunction under the pathological condition of obesity. Such knowledge will help in determining the mechanisms of childhood and early life obesity in efforts to ameliorate chronic inflammation-related metabolic diseases.     

Role of fatty acids in the transition from anaerobic to aerobic metabolism in skeletal muscle during exercise

In moderate physical exercise, the transition from predominantly anaerobic towards predominantly aerobic metabolism is a key step to improve performance. Increase in the supply of oxygen and nutrients, such as free fatty acids (FFA) and glucose, which accompanies high blood flow, is required for this transition. The mechanisms involved in the vasodilation in skeletal muscle during physical activity are not completely known yet. In this article, we postulate a role of FFA and heat production in this process. The presence of uncoupling protein-2 and -3 (UCP-2 and -3) in skeletal muscle, whose activity is dependent on FFA, suggests that these metabolites can act as mitochondrial uncouplers in this tissue. Evidence indicates however that UCPs act as uncouplers only when coenzyme Q is predominantly in the reduced state (i.e. under nonphosphorylation conditions or state 4 respiration) as is observed in resting muscles and in the beginning of physical activity (predominantly anaerobic metabolism). The increase in the lipolytic activity in adipose tissue in the beginning of physical activity results in elevated plasma FFA levels. The FFA can then act on the UCPs, increasing the local heat production. We propose that this calorigenic effect of FFA is important to activate nitric oxide synthase, resulting in nitric oxide production and consequent vasodilation. Therefore, FFA would be important mediators for the changes that occur in muscle metabolism during prolonged physical activity, ensuring the appropriate supply of oxygen and nutrients by increasing blood flow at the beginning of exercise in the contracting skeletal muscles.     

Serum hormones and physical performance capacity in young boy athletes during a 1-year training period

Serum hormones and physical performance capacity in boy athletes (AG; n = 19) were investigated during a 1-year training period (between the ages of 11.6 and 12.6 years). Six young untrained boys served as the control group (CG). The mean serum testosterone concentration increased significantly in AG (P less than 0.05) following the training period from 2.92 nmol.l-1, SD 1.04 to 5.81 nmol.l-1, SD 1.33. Significant differences were not observed in the cortisol, sex hormone binding globulin and growth hormone levels during the follow-up period. The AG clearly increased speed (P less than 0.001), speed-strength (P less than 0.01-P less than 0.001) and anaerobic capacity (P less than 0.001) whereas CG had only slight increases (NS) in physical performance capacity during a 1-year period. During the last 6-month training period significant positive correlations (r = 0.49-0.58; P less than 0.05-P less than 0.01) were observed in AG between the relative changes in testosterone, testosterone:cortisol ratio and growth hormone and the relative performance change in speed, maximal isometric force and endurance, respectively. At the end of the period significant positive correlations were observed in all subjects between the level of testosterone and speed-strength (r = 0.52-0.64; P less than 0.01-P less than 0.001) and anaerobic capacity (r = 0.49; P less than 0.05). It was concluded that an increase in anabolic activity with the synchronous training already has positive effects on trainability and physical performance capacity at an early stage in puberty.     

Ergometric Criteria of Anaerobic Working Capacity in Athletes of Different Age and Gender

The ergometric assessment of anaerobic working capacity in athletes of different age (11–32 years) and gender was carried out. The results showed a well-defined interrelationship between the level of the anaerobic working capacity, the total body sizes, and such a physical (motive) quality as quickness. Athletes with more pronounced signs of an athletic heart and a more perfect reaction of the circulatory system under conditions of submaximum physical loads performed short-term muscular work of maximal intensity with greater power, which evidenced their higher level of anaerobic working capacity.     

Effects of 20 days bed rest on mechanical efficiency during upright cycling and leg muscle mass in young males

Delta efficiency defined as increase in work over the corresponding increase in energy liberation (delta work/delta energy) may be used to express the efficiency of working muscles under standard conditions where work is performed with similar changes in muscle length, identical pedal revolution frequencies, and contraction-to-relaxation ratios. The Delta efficiency is probably the most valid measure of the efficiency of muscular work, so it may be influenced by the difference in distribution and/or density of muscle fiber types in exercising muscles. It has been reported that after bed rest of 7-14 days, not only maximum oxygen uptake (VO2 max) but also oxygen uptake (VO2) at 3-min submaximal upright exercise decreased. However, the decrease might be apparent, and the mechanical efficiency might be unchanged. On the other hand, muscle mass of bicycling legs was decreased after continuous horizontal bed rest of 10 days and 20 days. Because the decreased muscle mass is probably related to decrease in the density of the slow twitch muscle fibers (ST-fiber), the decrease in submaximal VO2 during bicycle exercises after bed rest may result from a decrease in ST-fiber mass. Therefore, it could be hypothesized that the mechanical efficiency should increase during upright exercise because of the relative increase in amount of more efficient fast twitch muscle fibers (FT-fiber) than ST fibers in exercising muscles. The purpose of the present study was to investigate whether delta efficiency in working muscle is influenced by the decrease in muscle mass after 20 days horizontal bed rest in young males.