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.     

Spatiotemporal characteristics of the heart electrical field in the period of ventricular depolarization in athletes training endurance and strength

As a result of hemodynamic and structural changes occurring in the heart of athletes under the influence of systematic physical loads, the myocardial electrical activity changes, which is reflected on the electric field formed on the body surface. The electrical activity of the heart during ventricular depolarization at rest was studied in the highly skilled athletes training to develop physical characteristics (endurance and strength) by the method of electrocardiotopography. The studied athletes had similar patterns of movement of zones of positive and negative cardiac electrical potentials and location of extrema as well as the total depolarization duration but showed significant distinctions in (1) the amplitude of the maximum negative extremum; (2) the time of the beginning and end of the first inversion; (3) the duration of the second inversion, the initial stage, and the stability period between inversions; and (4) the relative position of positive and negative cardiopotential zones.     

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.     

The effect of labour on somatotype of males during the adolescent growth period

Although the effect of labour and physical stress on the height and weight of growing children is relatively well known, rather limited information concerning the influences of the work environment on the physique of working children and adolescents is available. The purpose of this study was to increase our knowledge of the effects of mechanical stress on the human physique via somatotype during the adolescent growth period. Anthropometric measurements of 509 male apprentices aged 13.50–18.49 years and measurements of 451 nonworking youth (control group) of the same age group were taken. The members of both groups were from the lower socioeconomic strata and had similar living conditions. The apprentices were working an average of 11 h per day in vocations requiring intense physical effort. The subjects were somatotyped using the Heath–Carter anthropometric protocol. The overall mean somatotypes were 2.3–4.4–3.3 for working adolescents, and 2.5–3.9–3.6 for the nonworking controls. A one-way multivariate analysis of variance (MANOVA) indicated significant differences between the groups. Working adolescents were more mesomorphic and less ectomorphic than their nonworking peers. In both groups, endomorphy decreased with age up to age 15; then remained stable for the labourers but increased for the nonworking peers. In both groups, mesomorphy was stable, but decreased with ectomorphy. These results indicate that physical stress not only causes retardation in linear growth, but also produces changes in human physique during the growth period.     

Aerobic power and anthropometric characteristics of Hungarian schoolboys

A sample of 989 male youngsters aged 11–18 years was subdivided into three groups by the type and amount of their physical activity as follows. Group 1 (G1) had a maximum of three curricular PE classes a week, without any additional organized physical activity. With the same number of PE lessons Group 2 (G2) had at most three sessions of sports training per week in addition. Group 3 (G3) had a weekly minimum of five training sessions in addition to the PE lessons at school. The subjects of G3 had significantly higher relative aerobic power, larger relative muscle mass and smaller relative body fat content than the subjects of the other two groups. The effects of sports training on the development of physical working capacity are undeniable, but to explain such differences observed in relative aerobic power between the groups requires also the consideration of inheritance and selection procedure.     

An influence of exercise of increasing intensity on aminotransferase activity and electrolyte level in red blood cells and blood serum in men with average and very high physical working capacity.

Healthy subjects with average and very high physical working capacity were submitted to two 6-min periods of work on a cycloergometer at the work loads 70 and 90 percent VO2max. Changes in the activity of Asp AT and Al AT as well as in the concentrations of NA, K and lactates in erythrocytes and serum were determined. In the subjects with average physical working capacity the serum concentrations of lactate and sodium, as well as the activity of Asp AT were much more increased than in the highly efficient subjects. In both groups similar changes of electrolyte concentrations in erythrocytes occured. The activity of Al AT was increased only in the group of subjects with high physical working capacity after the first period of work and showed a tendency to return to the resting values after the second period.     

Physical working capacity and factors responsible for it after exposure to 120-day antiorthostatic hypokinesia

The effect of 120-day antiorthostatic hypokinesia on human physical working capacity and functional state was studied. The study revealed two adaptation phases: the first phase is characterized by a significant decrease in working capacity and the second by relative readaptation. However, the unfavorable effect of 120-day antiorthostatic hypokinesia was evident as a decrease in the effectiveness of function of the cardiorespiratory system that increased the physiological cost of physical work.     

Diurnal Rhythms of Plasma Ions and Metabolites Levels in Thoroughbred Racehorses

The purposes of this study were to observe the presence of diurnal rhythms in plasma ions and metabolites levels in Thoroughbred racehorses under physical training, and to determine the time of blood sampling in clinical investigations. Plasma calcium, phosphorus, potassium, sodium, chloride, magnesium, iron, glucose, cholesterol, triglycerides, and total proteins levels were studied over a 72-h period. Blood samples were taken every 4 hours from five male and five female Thoroughbred racehorses under physical training. COSINOR analyses (P = 0.05) were done. Plasma potassium and triglycerides showed significant diurnal rhythms, with its acrophases occurring at dark period. No significant diurnal rhythms of other variables were found. It was concluded that, in Thoroughbred racehorses, the optimum time for potassium, and triglycerides sampling seems to be light period. And for other variables, time of diagnosis is not important.     

半个世纪来南京市儿童体型的长期变化

本文报告了半世纪来南京市儿童体型发展的长期变化,１９３６年至１９８５年,南京市儿童身高、体重、坐高均有显著增加,对１９３６、１９５６、１９７５、１９８５四个年代７－１７岁儿童的坐高指数,克托莱指数,考甫指数,劳累尔指数,利比指数,培利迪西指数六个指数作对比分析,结果表明,半个世纪来,南京市儿童以体重和身高关系所表现的体型趋向瘦长,１９７５、１９８５年资料表明成熟期躯干与下肢比例关系无明显变化。     

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.     

The Use of Normobaric Hypoxic Training to Increase the Physical Working Capacity of Healthy Individuals

The study of the tolerability of a bicycle exercise test before and after normobaric hypoxic training (NHT) in different regimens was conducted to assess the influence of NHT on the state of the physical working capacity of healthy individuals. A biocybernetic approach allowing the assessment of the dynamics of the physiological variables during the performance of the load test was proposed for a detailed determination of the physiological cost of muscle activity. Hypoxic training was shown to significantly increase the tolerance of physical work, especially when more strenuous NHT regimes were used. The high information content of dynamic physiological criteria for assessing the physical working capacity was revealed.     

Diurnal Rhythms of Plasma Ions and Metabolites Levels in Thoroughbred Racehorses

The purposes of this study were to observe the presence of diurnal rhythms in plasma ions and metabolites levels in Thoroughbred racehorses under physical training, and to determine the time of blood sampling in clinical investigations. Plasma calcium, phosphorus, potassium, sodium, chloride, magnesium, iron, glucose, cholesterol, triglycerides, and total proteins levels were studied over a 72-h period. Blood samples were taken every 4 hours from five male and five female Thoroughbred racehorses under physical training. COSINOR analyses (P = 0.05) were done. Plasma potassium and triglycerides showed significant diurnal rhythms, with its acrophases occurring at dark period. No significant diurnal rhythms of other variables were found. It was concluded that, in Thoroughbred racehorses, the optimum time for potassium, and triglycerides sampling seems to be light period. And for other variables, time of diagnosis is not important.     

Seasonal changes in VO2max among Division 1A collegiate women soccer players

Aerobic capacity and body composition were measured at 3 time points over a 1-year period in 26 Division 1A women soccer players from Texas A&M University, in order to determine whether there were seasonal changes in these parameters. Subjects were tested in December, immediately following a 4-month competitive season; in April, following 15 weeks of strength and conditioning; and immediately prior to the start of the regular season in August, following a 12-week summer strength and conditioning program. A periodized strength and conditioning program design was incorporated in order to optimize anaerobic and oxidative capacity immediately prior to the regular competitive season. Significant differences in VO2max were measured between August (49.24 +/- 4.38 ml x kg(-1) x min(-1)) and December (44.87 +/- 4.61 ml x kg(-1) x min(-1)). No significant changes in aerobic capacity were found between April (47.43 +/- 4.01 ml x kg(-1) x min(-1)) and August (49.64 +/- 5.25 ml x kg(-1) x min(-1)). Significant increases in body fat were measured between August (15.71 +/- 2.92%) and December (18.78 +/- 2.79%), before and after the competitive season, respectively. No significant changes in body fat were found between April (16.24 +/- 2.95%) and August (15.71 +/- 2.92%). The results of this study suggest that decreases in muscle mass over the course of a regular competitive season contribute to decreases in aerobic capacity in collegiate women soccer players. Although it is unknown whether this decrease in muscle mass is the result of inadequate training or a normal adaptation to the physiological demands imposed by soccer, the results of the current study suggest that resistance training volume should be maintained during the competitive season, in order to maintain preseason levels of muscle mass.     

Morphological and Functional Changes in Overweight Persons under Combined Normobaric Hypoxia and Physical Training

Functional and morphological changes were studied in overweight persons in tests with various combinations of normobaric hypoxia and physical training. It was shown that normobaric hypoxia combined with training can be used for increasing physical working capacity and aerobic capacity in overweight persons. A combination of physical training and breathing hypoxic gas mixtures was demonstrated to be the most effective method of correcting and increasing the physiological functional potential in overweight persons.     

Effets des marées sur la variation circadienne de la capacité photosynthétique du phytoplancton de l'estuaire du saint-laurent

The photosynthetic capacity of phytoplankton was measured at an anchor station in the Middle Estuary of the St Lawrence, over a period of 120 h. Hourly incubations were made in constant light conditions, under three different colour filters of 3, 4 and 23 W · m^?2. Differences in the oscillations of the photosynthetic capacities were observed in relation to the tidal regime. During spring tide, variations in the photosynthetic capacity are circadian, whereas a tidal pattern was also observed during the neap tide period. Differences in the patterns of photosynthetic capacity were probably due to changes in the gradients of physical factors and to the physiological state of phytoplankton relative to these gradients. The circadian rhythms appeared to be endogenous since they were apparent at non-saturating light intensities and since the photosynthetic potential (U_max) changed during the day.     

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.     

A randomized clinical trial to assess the influence of a three months training program (Gym-based individualized vs. Calisthenics-based non-invidualized) in COPD-patients

Introduction

Pulmonary rehabilitation has been demonstrated to improve exercise capacity, dyspnoea, quality of life and to reduce the adverse effects of acute exacerbations. Current guidelines recommend exercise training in patients with mild to very severe disease. However, there is insufficient data comparing the efficacy of different training approaches and intensities.

Methods

Between January 2009 and December 2012, 105 COPD patients were screened to participate in the study. 61 patients were randomly assigned into an individualized training group or into a non-individualized training group. Both groups exercised once a week for 60 minutes over a time period of three months. At the beginning and after three months, the following measurements were performed: 6-minute walking test (6-MWT), health-related quality of life (St. Georges Respiratory Questionnaire; SGRQ and COPD-Assessment-Test; CAT), M. rectus femoris cross-sectional area, and inflammatory markers in peripheral blood.

Results

Only in the individualized training group we observed a significant change of the 6-MWT (increase of 32.47 m; p = 0.012) and the cross-sectional area of the M. rectus fermoris (increase of 0.57 cm²; p = 0.049), while no significant changes occurred in the non-individualized training group. Peroxisome-proliferator-activated receptor-γ coactivator 1α increased in the individualized training only after the three months training period (increase of 0.43 relative copies; p = 0.017), all other myokines and inflammatory markers were not influenced by either of the programs. The total drop-out-rate was 44.3%.

Conclusion

A low frequency outpatient training program may induce modest improvements in exercise capacity and muscle mass only if it is performed on an individualized basis.     

Visual working memory capacity and proactive interference

Background

Visual working memory capacity is extremely limited and appears to be relatively immune to practice effects or the use of explicit strategies. The recent discovery that visual working memory tasks, like verbal working memory tasks, are subject to proactive interference, coupled with the fact that typical visual working memory tasks are particularly conducive to proactive interference, suggests that visual working memory capacity may be systematically under-estimated.

Methodology/Principal Findings

Working memory capacity was probed behaviorally in adult humans both in laboratory settings and via the Internet. Several experiments show that although the effect of proactive interference on visual working memory is significant and can last over several trials, it only changes the capacity estimate by about 15%.

Conclusions/Significance

This study further confirms the sharp limitations on visual working memory capacity, both in absolute terms and relative to verbal working memory. It is suggested that future research take these limitations into account in understanding differences across a variety of tasks between human adults, prelinguistic infants and nonlinguistic animals.     

Physical working capacity and energy supply of muscle function during postnatal human ontogeny

On the basis of the results of our studies and literature data, an analysis of the physiological mechanisms responsible for the multifold increase in the physical working capacity during human development has been performed. Physiological and biochemical studies have shown that the aerobic energy system already has a high capacity during the second period of childhood, and the further increase in working capacity is mainly provided by the development of anaerobic mechanisms of energy supply. The maturation of mechanisms of energy production is related to considerable changes in the activity of tissue enzymes and radical rearrangement of the composition of muscular fibers. Puberty considerably influences the development of anaerobic muscle energetics in boys due to stimulation of the growth of type II fibers by testosterone. It has been shown that widespread tests for assessment of physical working capacity mainly reflect changes in the power of energy systems and only in rare cases may be used to characterize changes in their capacity. However, the capacity parameters, which depend to a greater extent on the quality of regulation at the cellular, tissue, and body levels, show multifold growth during ontogeny, which corresponds to the actual increase in the working capacity in the period from childhood to youth. A classification of tests of physical working capacity is proposed. The use and development of this classification may facilitate the development of new tests and an increased efficiency of testing involved in solving various applied and fundamental problems.     

Kinetic analysis of folding and unfolding the 56 amino acid IgG-binding domain of streptococcal protein G.

The 56 amino acid B domain of protein G (GB) is a stable globular folding unit with no disulfide cross-links. The physical properties of GB offer extraordinary flexibility for evaluating the energetics of the folding reaction. The protein is monomeric and very soluble in both folded and unfolded forms. The folding reaction has been previously examined by differential scanning calorimetry (Alexander et al., 1992) and found to exhibit two-state unfolding behavior over a wide pH range with an unfolding transition near 90 degrees C (GB1) at neutral pH. Here, the kinetics of folding and unfolding two naturally occurring versions of GB have been measured using stopped-flow mixing methods and analyzed according to transition-state theory. GB contains no prolines, and the kinetics of folding and unfolding can be fit to a single, first-order rate constant over the temperature range of 5-35 degrees C. The major thermodynamic changes going from the unfolded state to the transition state are (1) a large decrease in heat capacity (delta Cp), indicating that the transition state is compact and solvent inaccessible relative to the unfolded state; (2) a large loss of entropy; and (3) a small increase in enthalpy. The most surprising feature of the folding of GB compared to that of previously studied proteins is that its folding approximates a rapid diffusion controlled process with little increase in enthalpy going from the unfolded to the transition state.