Physiologic Responses to Exercise of the Healthy Child

Normative values for heart rate response to exercise in young athletes at 10-18 years old

The assessment of the chronotropic response during acute physical exertion can allow the discovery of many cardiovascular diseases even at a young age. However, the increase in heart rate (HR) depends on the age and sex of the subject and the modality of the graded exercise test. This study aims to provide sex- and age-related normative values for heart rate performance in young athletes aged 10 to 18. A retrospective study was carried out on 7896 young athletes (5356 males and 2540 females) aged between 10 and 18 who underwent pre-participation screening to obtain eligibility for competitive sport. First, anthropometric parameters, performance data, and HR are reported. Thus, each age calculated third, tenth, twenty-fifth, fiftieth, seventy-fifth, ninetieth, and ninety-seventh percentiles for the stage-by-stage HR response, according to sex and graded exercise test modality category. Young female athletes of all ages showed lower performance with fewer stages performed on the cycle ergometer and the treadmill. Young male athletes on treadmill and cycle ergometers show lower HR values at submaximal intensities. The treadmill allows a longer duration than the cycle ergometer for males and females. Sex, age, and the specificity of the movement performed must be considered in assessing the chronotropic response in the young population, particularly for those who carry out a training program. In addition, providing reference values of HR response to acute physical exertion may allow for a better functional assessment of the young athletes.

The effects of soccer training in aerobic capacity between trained and untrained adolescent boys of the same biological age

BACKROUND

The purpose of this study was to examine the effects of soccer training on maximal oxygen uptake and anthropometric characteristics in different ages of soccer players and untrained adolescents of the same biological age.

METHODS

A total of one hundred and twenty-six (N.=126) young soccer players and untrained boys throughout the developmental ages of 12 (soccer players N.=22; untrained boys = 22) 14 (soccer players N.=20; untrained boys = 18) and 16 (soccer players N.=22; untrained boys = 22) volunteered to participate in the study. Sexual maturation was classified according to Tanner's stages. Soccer players participated both in their school's physical education program and in a soccer training program, while the untrained participated only in their school's physical education program. All participants underwent anthropometric measurements and performed a maximal exercise test on a motor driven treadmill to determine maximal oxygen uptake (V̇O2<inf>max</inf>) and cardiorespiratory indices. Blood lactate (BL) concentration was determined in the 5^th minute of recovery using a lactate photometer.

RESULTS

The trained group showed significantly higher V̇O2<inf>max</inf>, in absolute and relative values (P<0.001), BL<inf>max</inf> (P<0.05) and maximal respiratory exchange ratio (RER<inf>max</inf>) (P<0.05) compared to the untrained group. Resting heart rate (HR) and systolic blood pressure were significantly lower (P<0.05) for the trained compared to untrained.

CONCLUSIONS

The results of this study showed that systematic soccer training has a positive effect in the central cardiovascular system expressed as V̇O2<inf>max</inf>, HR and blood pressure.

Musical Instrument Practice Predicts White Matter Microstructure and Cognitive Abilities in Childhood

Musical training has been associated with advantages in cognitive measures of IQ and verbal ability, as well as neural measures including white matter microstructural properties in the corpus callosum (CC) and the superior longitudinal fasciculus (SLF). We hypothesized that children who have musical training will have different microstructural properties in the SLF and CC. One hundred children aged 7.9-9.9 years (mean age 8.7) were surveyed for their musical activities, completed neuropsychological testing for general cognitive abilities, and underwent diffusion tensor imaging (DTI) as part of a larger study. Children who play a musical instrument for more than 0.5 h per week (n = 34) had higher scores on verbal ability and intellectual ability (standardized scores from the Woodcock-Johnson Tests of Cognitive Abilities), as well as higher axial diffusivity (AD) in the left SLF than those who did not play a musical instrument (n = 66). Furthermore, the intensity of musical practice, quantified as the number of hours of music practice per week, was correlated with axial diffusivity (AD) in the left SLF. Results are not explained by age, sex, socio-economic status, or physical fitness of the participants. The results suggest that the relationship between musical practice and intellectual ability is related to the maturation of white matter pathways in the auditory-motor system. The findings suggest that musical training may be a means of improving cognitive and brain health during development.

The female athlete. Before and beyond puberty

As the twentieth century progressed, the female athlete became an accepted participant of sports at all levels. This article reviews various aspects of female sports participation. After an historical perspective, selected comments are provided on psychologic and physiologic aspects. Concepts of adolescent gynecology are reviewed, including breast and menstrual problems and pregnancy. Other areas reviewed include iron deficiency anemia, stress urinary incontinence, and sports injuries in female athletes.

Comparison of yearling, two-year-old and adult Thoroughbreds using a standardised exercise test

The purpose of this study was to compare exercise measurements in yearling, two-year-old and adult Thoroughbreds using a standardised treadmill incremental exercise test. Peak oxygen consumption (VO2 peak: 128.0 +/- 2.1, 140.0 +/- 2.1, 163.7 +/- 3.4; ml/kg/min +/- se, P less than 0.05), peak packed cell volume (PCV peak: 0.50 +/- 0.01, 0.58 +/- 0.01, 0.64 +/- 0.01 litres/litre +/- se, P less than 0.05) and the maximum number of steps completed in the exercise test (STEPmax: 7.7 +/- 0.1, 8.1 +/- 0.1, 8.6 +/- 0.1; steps +/- se, P less than 0.05) increased with age and degree of physical activity. Peak venous lactate concentration (LACpeak: 21.3 +/- 1.5, 19.5 +/- 1.7, 14.4 +/- 1.7; mmol/litre +/- se, P less than 0.05) and peak respiratory exchange ratio (Rpeak) were significantly higher in both groups of younger horses compared to the adult racehorses. Peak heart rate (HRpeak: 230 +/- 2, 231 +/- 3, 229 +/- 3; beats/min +/- se) did not change with age or training. The rate of change of VO2 between steps in the exercise test (VO2trans) was significantly lower in the adult racehorses at the highest exercise intensities. The slopes of the linear approximation between R (LinR bx), the natural log transformation of venous lactate concentration (LogLAC bx), and heart rate (HR bx) with velocity were significantly lower in the trained adult racehorses. The slope of venous lactate concentration normalised to per cent VO2peak (LogLAC per cent bx) was significantly lower and R breakpoint (R brkpt) normalised to per cent VO2peak was significantly higher in the trained adult racehorses. There was a more rapid decrease in venous lactate and a more rapid return to initial R values in the adult horses relative to the younger, untrained horses. No significant age or training effects were found in the remainder of the post exercise measurements. These results indicate that aerobic power and exercise capacity increased with age and training. Anaerobic power was already well developed even at a young age.

Cardiorespiratory response to absolute and relative work intensity in untrained men

Twenty young, untrained men performed two tests on cycle ergometer in order to verify whether the kinetics of the cardiorespiratory reactions exhibit any relation to maximal oxygen uptake (VO2max) in the untrained state. On the 1st day, the subjects exercised at work intensities of 50 and 100 W, the increase as a step function, for periods of 10 min each. The next day, they performed exercise at a relative intensity of 50% VO2max for 10 min. Respiratory frequency, tidal volume, minute ventilation (VE), heart rate (HR), stroke volume (SV), and cardiac output (Q) were measured continuously. The SV was measured by impedance plethysmography. All the cardiorespiratory variables increased rapidly at the onset of both absolute and relative intensity of work, with a faster response for Q than for VE. The increase in absolute intensity of work from 50 to 100 W caused a significantly slower cardiorespiratory reaction than at the beginning of exercise. The SV increased by 20 ml during first 20 s of both absolute and relative intensities of work and then began to decrease after 6 and 4 min of the exercise, respectively. The decrease in SV was associated with an increase in HR and a stable value of Q. Acceleration at the beginning of, and deceleration during recovery from, the relative intensity of work for VE, HR, and Q were well correlated with individual levels of VO2max in the tested men. It is concluded that the kinetics of cardiorespiratory reaction to a constant, relative intensity of work is related to VO2max in untrained men, and that the kinetics probably constitute a physiological feature of an individual.