Large inter-individual variability in force-velocity profile changes in response to acute high-load resistance training.

Background: While the acute effects of high-load resistance training on the force generating capacity of muscles have been widely examined, limited data exist on the relationship with the force-velocity profile (FV). Evidence suggests high sensitivity of the vertical FV profile to monitor changes in the muscle's mechanical properties according to the type of the exercise protocol. However, the interpretation of the findings seems not as straightforward. Therefore, the purpose of this study was to examine the effects of a high-load resistance training protocol on the muscle's mechanical properties during loaded jumps and on the vertical force-velocity profile (FV) in relation to maximal strength. Methods: 29 resistance-trained male (mean age±SD: 35.4 ± 7.8 years) and 29 female athletes (mean age±SD: 32.5 ± 7.0 years) participated in the study. Five-repetition maximum (5RM) in back squat, unloaded countermovement jump (CMJ) and FV profile were assessed. Loaded jumps were performed against 25, 50, 75, and 100 percent of body mass. Participants performed exercise protocols corresponding to their 5RM. Immediately after, unloaded CMJ and FV profile measurements were repeated. Results: A significant decrease in CMJ height (∼5-6%) and in average power (∼4%) was recorded for both men and women. The FV profile did not change after the exercise protocol; however, there was a significant decrease in theoretical maximal power (from 4 to 5%) and in theoretical maximal velocity (∼3%). Maximal strength was not associated with the changes in FV profile. Conclusions: Findings suggest that an acute high-load exercise decreased vertical jump performance and maximal power output, but without a concomitant change in FV profile. The large interindividual variability in FV measures indicates a less straightforward connection of the applied exercise with the acute response in the FV profile, highlighting the complexity of the FV profile to monitor changes in response to an acute training load.

Maturation-dependent vulnerability of emotion regulation as a response to COVID-19 related stress in adolescents.

BACKGROUND: The COVID-19 pandemic created unpredictable circumstances resulting in increased psychological strain. Here we investigate pandemic-related alterations in emotion regulation in adolescents assessed before and during the pandemic. We also take biological age into account in the response to the pandemic. METHODS: Mann-Whitney U tests were conducted to compare baseline data on the Difficulties in Emotion Regulation Scale (DERS) total scores of a pre-pandemic adolescent cohort (n = 241) with those obtained during the second wave of the pandemic (n = 266). We estimated biological age based on an ultrasonic boneage assessment procedure in a subgroup of males, including grammar school and vocational school students in the 9th and 10th grades, and analyzed their data independently. FINDINGS: There is a gender difference in the timing of vulnerability for pandemic-related stress in grammar school students: females are affected a year earlier than males. Vocational school male students mature faster than grammar school male students, and the timing of emotional vulnerability also precedes that of the grammar school students'. DISCUSSION: We interpret our findings within a developmental model suggesting that there might be a window of highest vulnerability in adolescent emotion regulation. The timing of the window is determined by both chronological and biological age, and it is different for females and males. APPLICATION TO PRACTICE: Defining the exact temporal windows of vulnerability for different adolescent cohorts allows for the timely integration of preventive actions into adolescent care to protect mental health during future chronic stressful situations.

Musical training improves fine motor function in adolescents.

BACKGROUND: Adolescence is a sensitive period in motor development but little is known about how long-term learning dependent processes shape hand function in tasks of different complexity. PROCEDURE: We mapped two fundamental aspects of hand function: simple repetitive and complex sequential finger movements, as a function of the length of musical instrumental training. We controlled maturational factors such as chronological and biological age of adolescent female participants (11 to 15 years of age, n = 114). RESULTS: We demonstrated that experience improves performance as a function of task complexity, the more complex task being more susceptible for experience driven performance changes. CONCLUSION: Overall, these results suggest that fine motor skills involving cognitive control and relying on long-range functional brain networks are substantially shaped by experience. On the other hand, performance in a simple repetitive task that explains fine motor speed is primarily determined by white matter development driven by maturational factors.

Ultrasonic bone age fractionates cognitive abilities in adolescence.

Adolescent development is not only shaped by the mere passing of time and accumulating experience, but it also depends on pubertal timing and the cascade of maturational processes orchestrated by gonadal hormones. Although individual variability in puberty onset confounds adolescent studies, it has not been efficiently controlled for. Here we introduce ultrasonic bone age assessment to estimate biological maturity and disentangle the independent effects of chronological and biological age on adolescent cognitive abilities. Comparing cognitive performance of female participants with different skeletal maturity we uncover the impact of biological age on both IQ and specific abilities. We find that biological age has a selective effect on abilities: more mature individuals within the same age group have higher working memory capacity and processing speed, while those with higher chronological age have better verbal abilities, independently of their maturity. Based on our findings, bone age is a promising biomarker of adolescent maturity.

Talent Selection Based on Sport-Specific Tasks Is Affected by the Relative Age Effects among Adolescent Handball Players.

Talent selection is often affected by the relative age effects (RAEs), resulting in the overrepresentation of relatively older (vs. relatively younger) players among those selected. The use of sport-specific tasks is suggested to reduce RAEs during talent selection. PURPOSE: To test the hypothesis that talent selection including only sport-specific tasks is not affected by the RAEs and to analyse the body size and biological maturity of the top selection level according to relative age. METHODS: Participants were U14 female (n = 5428) and U15 (n = 4408) male handball players participating in four programs consisting of four selection levels (local, county, regional, and national) grouped in bi-annual age. Handball-specific generic skills, position-specific technical drills and in-game performance were the selection criteria evaluated by experts and coaches. Body dimensions were measured and bone age, as an indicator of maturity, was estimated. The relative age quartile distributions within the bi-annual cohorts were examined using Chi-square and Odds Ratios. RESULTS: In terms of all the registered players no RAEs were evident. However, the RAEs of moderate effect size were evident at the county level; χ2 = 53.2 (girls) and 66.4 (boys), OR = 2.5 and 3.3, respectively. The RAEs of a large effect size were found at the regional level; χ2 = 139.5 (girls) and 144.9 (boys), OR = 8.2 and 5.2, respectively. At national level, RAEs were still present, but with no further increase in the effect size. At the highest selection level, there were no differences in the anthropometric measures between the relatively older and younger players. CONCLUSION: The findings provide support to the hypothesis that the selection process exacerbates RAEs even when using only sport-specific selection criteria. The performance metrics in technical skills, but also coaching assessments are likely involved. In addition, an advanced maturity and/or an above-average body size increases the selection odds for relatively younger players.

How Length Sizes Affect Body Composition Estimation in Adolescent Athletes Using Bioelectrical Impedance.

Bioelectrical impedance analysis (BIA) is a common practice to assess body composition in athletes, however, when measuring athletes with specific body geometry, its accuracy may decrease. In this study we examined how length dimensions affect body composition estimation and we compared BIA and dual-energy X-ray absorptiometry (DXA) assessments in three sports. 738 male adolescent athletes (15.8 ± 1.4 years) from three sports (soccer, basketball, and handball) were measured. Body composition was estimated by BIA (InBody 720) and by DXA (Lunar Prodigy). Differences between the two methods were tested by Bland-Altman analysis and by paired t-test. ANOVA was used for inter-group comparisons. Pearson correlation and multivariate linear regression was used to look for the relationship between segmental lean body mass and length dimensions. BIAInBody 720 consistently underestimated percent body fat (PBF) and overestimated lean body mass (LBM) than DXA. The magnitude of the differences between the two methods varied among the examined sports. Handball (PBF = 8.3 ± 2.4 %; LBM = -5.0 ± 2.1 kg) and basketball players (PBF = 8.8 ± 2.3 %; LBM = -5.3 ± 1.8 kg) had significantly larger differences between the two methods than soccer players (PBF = 6.4 ± 2.2 %; LBM = -3.1 ± 1.4 kg). There was a negative correlation between differences in segmental LBM estimation and length sizes (trunk length, upper extremity length, lower extremity length). The highest correlation was found for lower extremity (r = -0.4). Longer lower extremity resulted in greater difference in LBM estimation. The differences between the sport disciplines are most probably attributed to body height differences. Length dimensions result in overestimation of LBM with BIA, thus body composition assessment with BIAInBody 720 needs to be carefully interpreted in athletes with extreme length sizes, especially, with basketball players.

Vertical Jump Performance in Hungarian Male Elite Junior Soccer Players.

PURPOSE: Vertical jump is a common test to measure impulsive ability in soccer; however, limited normative data have been published on young soccer players from vertical jump measurements on a force platform. The purpose of this study was to provide normative values for three chronological age groups of male junior soccer players (U16, U17 and, U18 years). METHOD: Vertical jump performance of 365 soccer players (16.4 ± 0.8 years) was assessed using a force platform measurement system. Net impulse, force, power, jump height (impulse-momentum), jump height (flight time) were reported for each age group for squat jump (SJ) and countermovement jump (CMJ). RESULTS: Mean values ± SD of jump height were 32.9 ± 4.1, 33.5 ± 4.0, and 33.9 ± 4.2 cm for the three age groups respectively in SJ and 36.3 ± 3.8, 37.5 ± 3.9, and 38.6 ± 4.4 cm in the CMJ. Mean values of all age groups for maximum force and maximum power were 1559 ± 211 N and 3261 ± 492 watt respectively for SJ and 1598 ± 241 N and 3287 ± 502 watt for CMJ. Based on descriptive data, percentiles were reported for all examined variables. CONCLUSIONS: Jump height and relative values were less sensitive discriminator variables between age groups in the studied age range, while maximum impulse, maximum force, and maximum power were more sensitive to changes in maturational status. Normative values can be used by the coaches in the interpretation and evaluation of their athletes' performance and for training and talent identification purposes.

A comparison of skeletal maturity assessed by radiological and ultrasonic methods.

OBJECTIVES: The estimation of skeletal maturity is a useful tool in pediatric practice to determine the degree of delay or advancement in growth disorders and the effectiveness of treatment in conditions that influence linear growth. Skeletal maturity of children is commonly assessed using either Greulich-Pyle (GP) or Tanner-Whitehouse methods (TW2 and TW3). However, a less invasive ultrasonic method, that does not use ionizing radiation, has been suggested for use in epidemiological studies of skeletal maturity. The main purpose of the present study was to determine the accuracy of an ultrasonic method based on the GP maturity indicators compared to the standard GP radiographic method. METHODS: Skeletal maturity of 1502 healthy children, aged from 6 to 18 years, was estimated by quantitative ultrasound and compared to GP bone ages estimated from left hand and wrist radiographs of a subsample of 47 randomly selected participants. RESULTS: The ultrasonic bone age estimation demonstrated very strong correlations with all the radiological age estimations. The correlation coefficients ranged between 0.895 and 0.958, and the strongest correlation of ultrasonic skeletal maturity estimation was found with the Tanner-Whitehouse RUS method. The ultrasonic bone age estimation is suggested for use between the chronological ages of 8.5-16.0 years in boys and 7.5-15.0 years in girls. CONCLUSIONS: The ultrasonic bone age estimation is suggested for use in epidemiological surveys since the sensitivity for screening for not normal bone development is appropriate, at least within the 8-15 years age interval.

Body fatness and endogenous sex hormones in the menopausal transition.

BACKGROUND: Age at the final menstrual period is of clinical and public health interest because the age at which natural menopause occurs may be a marker of ageing and health, and in general the menopausal transition increases the risk of many diseases, e.g. redistribution in the pattern of adiposity during the menopausal transition may increase risk of metabolic disease. The purpose of this research was to study the relationship between the menopausal status and body fatness. SUBJECTS AND METHODS: A random sample of 1932 Hungarian women was studied. Body composition was estimated by body impedance analysis. In a subsample free estradiol and progesterone levels in saliva were quantified. RESULTS: Body fat mass increased until the late 50s and then had a decrease through senescence. Premenopausal women who were much older than the median age at menopause had a higher amount of fat than their postmenopausal age-peers, while postmenopausal women, whose menopause occurred much earlier than the median age at menopause, had less fat than their premenopausal age-peers. The body fat mass in premenopausal women with low levels of sex hormones was always below the age-median value of the menopausal status subgroups, while the body fat mass of postmenopausal women with high levels of sex hormone levels was above the age-median values. CONCLUSIONS: The analysis of body fatness in the menopausal transition revealed that (1) the rate of reproductive ageing and the body fat pattern were significantly related, and (2) body fat mass of women with unexpected levels of sex hormones was related more to their hormonal levels than to their menopausal status or their age. Thus future epidemiological screenings of women exposed to higher levels of menopause-related health risks should be expanded beyond the estimation of menopausal status based only on menstrual history to include sex hormone level assessment, as well as body composition analysis.

THE BIOLOGICAL STATUS OF CHILDREN LIVING IN DISADVANTAGED REGIONS OF HUNGARY.

The aim of this study was to find out whether differences exist in the physical development, nutritional status and psychosomatic status of children living in deprived regions of Hungary compared with the Hungarian national reference values. The Hungarian government's decree No. 24/2003 created a complex indicator of social and economic conditions by which the country's regions were graded into deprived and non-deprived regions. This study examined 3128 children (aged 3-18 years) living in the deprived regions and their biological status was compared with the national reference values (2nd Hungarian National Growth Study). Children's body development was assessed via some absolute body dimensions. Nutritional status was estimated by BMI with children being divided into 'underweight', 'normal', 'overweight' and 'obese' categories. For children aged 7-18 years a standard symptoms list was used to characterize psychosomatic status. The subjects were asked to rate their health status as excellent, good, fair or poor. The body development of children living in these deprived regions was significantly retarded compared with the national references in the age groups 7-9 years and 14-17 years for boys and in the age groups 4-6 and 14-17 for girls. The prevalence of underweight was significantly higher in children and adolescents living in deprived regions (boys: 4.8%; girls: 5.9%) than the national references (boys: 2.9%; girls: 4.0%), while the prevalence of overweight and obese children did not differ between deprived regions (boys: 20.2%; girls: 19.8%) and the national references (boys: 21.5%; girls: 19.1%). Children and adolescents living in the deprived regions rated their health status worse, and experienced more psychosomatic complaints (abdominal discomfort and fear), than the national references. Although the majority of body dimensions of children in deprived regions were close to the 50th centile of the Hungarian national references, a sizeable minority (31%) were 0.20SD or more away from the median value, which has implications as to how social, medical and public welfare policy can be shaped.