Secular change in heights of rural adults in west-central poland between 1986 and 2016: The transition from pre- to post-communism.

Secular change in the heights of adult men and women resident in ten rural communities in west-central Poland in four decennial surveys between 1986 and 2016 is considered. The adults were parents of children attending schools in rural communities in the province of Poznan. During each survey, parents of school children were asked to complete a questionnaire which requested their ages, heights and completed levels of education. Ages were reported in whole years. The self-reported heights were adjusted for the tendency of individuals to overestimate height. Height loss among of individuals 35+ years was estimated with sex-specific equations and was added to the adjusted heights. Secular gains in heights of adult males across the 30 year interval, and across the 1986-1996 and 2006-2016 surveys were, on average, larger than corresponding gains in heights of adult females; the sex difference between 1996 and 2006 surveys was negligible. When heights were regressed on year of birth, heights of males and females born before 1950 (prior to World War II and shortly after) showed minimal and non-significant secular changes, while heights of those born post-1950 showed larger and significant secular gains, more so in males than in females. The results highlight significant secular trends in the heights of rural adults over a 30-year interval. Consistent with other studies in Poland, the positive trends likely reflected political, educational and socio-economic changes and by inference improved nutritional and health conditions across generations.

Weight status of rural school youth in Poland: secular change 1986-2016.

The objective of this study was to evaluate secular changes in the Body Mass Index (BMI) and weight status of rural children and adolescents in west-central Poland across decennial surveys spanning 1986 and 2016. Participants were 8,677 boys and girls 7-15 years attending schools in 10 rural communities in 1986, 1996, 2006, and 2016. Heights and weights were measured; BMIs were calculated. Weight status was classified using International Obesity Task Force (IOTF) criteria. The sample was partitioned into three age groups (7-9, 10-12, 13-15 years) for analysis of secular change in the BMI using sex-specific analysis of covariance (ANCOVA) with age and age2 as covariates, and for comparison of the prevalence of mild, moderate and severe thinness and of overweight and obesity. BMIs increased, on average, across the four surveys, but differences between adjacent surveys varied. Prevalence of severe and moderate thinness was low in both sexes, while mild thinness tended to decline over time, more so among girls. Overweight and obesity increased over time, especially in 2006 and 2016 compared to 1986 and 1996. In conclusion, secular changes in the BMI between 1986 and 2016 were significant. Age-adjusted mean BMIs suggested a gradient, 2016 > 2006 > 1996 > 1986, except in girls 13-15 years. However, changes across the decennial surveys varied. The observed changes in overweight and obesity between 1986 and 2016 were consistent with studies in Poland spanning the past two generations.

Physical Fitness of Rural Polish School Youth: Trends Between 1986 and 2016.

BACKGROUND: The objective of the study was to evaluate secular changes in the physical fitness of rural school youth, 7-15 years, in west-central Poland between 1986 and 2016. METHODS: The fitness of cross-sectional samples of school youth resident in the same 10 communities was evaluated in 4 decennial surveys: 1986-1417 boys/1326 girls; 1996-979 boys/947 girls; 2006-871 boys/843 girls; and 2016-1189 boys/1105 girls. Five tests evaluated speed (5-m run), agility (figure 8 run), explosive power (vertical jump), flexibility (stand and reach), and cardiovascular fitness (modified Harvard step test). Age- and sex-specific descriptive statistics were calculated by survey, while differences among surveys were compared in 3 broad age groups (7-9, 10-12, and 13-15 y) using analysis of variance with age and age squared as covariates. RESULTS: Speed and flexibility declined, while the jump and step test index changed variably across surveys. Although agility improved across surveys, the major improvement occurred between 1986 and 1996. CONCLUSIONS: Performances of rural school youth on 5 tests of physical fitness changed significantly, but, variably, between 1986 and 2016. The results were generally consistent with other studies of Polish school youth that spanned a similar interval.

Secular change in height and weight of rural school children and youth in west-central Poland: 1986 to 2016.

OBJECTIVE: To evaluate secular changes in the heights and weights of rural school youth in west-central Poland across decennial surveys of the same communities spanning 1986 and 2016. METHODS: Heights and weights of school youth 7 to 15 years in 10 rural communities in the vicinity of the city of Poznan were measured in 1986 (1417 boys, 1326 girls), 1996 (979 boys, 947 girls), 2006 (871 boys, 843 girls), and 2016 (1189 boys, 1105 girls). Descriptive statistics for sex-specific single year chronological age groups were calculated by survey, while the sample was partitioned into three age groups (7-9, 10-12, 13-15 years) for detailed analysis of changes across surveys using sex-specific ANCOVA with age and age2 as covariates. Pairwise post hoc comparisons between specific surveys, adjusted for multiple comparisons (Bonferroni), were evaluated. RESULTS: Heights and weights of rural school youth increased significantly between 1986 and 2016, but estimated secular gains between adjacent surveys were variable and not linear over time. CONCLUSION: Significant secular changes occurred in the heights and weights of rural school children in the 10 rural communities between 1986 and 2016, but estimated rates of change across sequential decennial surveys were variable. The results were generally consistent with corresponding studies of Polish youth.

Internal and External Loads During Hockey 5's Competitions Among U16 Players.

ABSTRACT: Konarski, JM, Konarska, A, Strzelczyk, R, Skrzypczak, M, and Malina, RM. Internal and external loads during Hockey 5's competitions among U16 players. J Strength Cond Res 35(11): 3199-3206, 2021-The purpose of the study was to characterize the external and internal loads associated with Hockey 5's, the modified small-sided format of competition for U16 field hockey introduced in 2014. Subjects were 10 males, 15.2-16.3 years, who were field players on the U16 Polish National Team. A GPSports Athlete Tracking System was used to estimate external loads (sprints, total distance), and a Polar Team2 unit was used to monitor internal loads (heart rate [HR] and energy expenditure [EE]) during active time of play for 8 field players in 2 international matches. Players covered, on average, a distance of 2,217 ± 178 m during a match including 614 ± 12 m sprinting at 8.1 ± 0.8 km·h-1 with a speedmax of 23.1 ± 1.1 km·h-1. HRmean was 170.5 ± 6.6 b·min-1, whereas HRmax was 184.9 ± 6.4 b·min-1. Speed, sprinting, and distance covered did not differ among periods, whereas HR was greater during the second and third periods. HRmax, %HRmax, and EE varied between forwards and defenders, and among periods. Effort expended by field players during Hockey 5's games can be characterized as heavy. The results highlight the need for preparation in both aerobic and anaerobic activities, which include a major speed component and adequate time for rapid recovery to facilitate the adaptation of youth players to the demands of the modified game. Although not directly comparable, comparison of internal loads during Hockey 5's and 11-a-side matches suggests more intensive activity of field players in the former.

Morphological asymmetry, sex and dominant somatotype among Polish youth.

The aim of the present study was to determine the level of morphological asymmetry among the general population of Polish youth as it correlates to sex and body type. The anthropometric characteristics of a group of 618 Polish youths (354 males aged 19.5 ± 1.2 years and 264 females aged 19.2 ± 1.2 years) were evaluated to assess their somatotypes using the Heath-Carter method. Body composition was calculated using the bioelectrical impedance method, and the absolute asymmetry index was used for comparisons between the right and left sides of the body. Significant differentiation was observed between all morphological characteristics (≤ 0.0001) and two body types (≤ 0.0001) among sexes. Females and males largely exhibited endomorphic and mesomorphic somatotypes, respectively. The findings demonstrated that dominant somatotype and sex both affect the level of fat mass asymmetry in the arms and legs. Furthermore, significant variations in the levels of asymmetry between sexes were observed in fat mass in both the arms and legs, with greater variation observed in the arms. In the case of muscle mass, no great differences were observed between men, women, or body types. This study provides new data on the morphological asymmetry of given body composition according to somatotype and sex. This study has potential medical implications, given that a large degree of inter-limb imbalance could be shown to have a negative effect on health; the findings of the present study would therefore be important for arriving at an understanding of how to prevent such imbalances, or to mitigate their negative effects.

Non-linear relationships between the BMI and physical fitness in Polish adolescents.

BACKGROUND: Comparisons of physical fitness in normal weight and overweight/obese youth generally highlight the negative consequences of an elevated BMI. In contrast, several studies of children and adolescents highlight the importance of variation in indicators of physical fitness across the full spectrum of BMIs from low through high. AIM: The purpose of the study was to evaluate relationships between specific physical fitness items and the BMI among youth. SUBJECTS AND METHODS: Height, weight and six physical fitness tests were measured in 1239 males and 903 females, aged 13-16 years; BMI (kg/m2) was calculated. Fitness tests were compared by weight status using sex-specific MANCOVAs, controlling for age. Sex-specific quadratic regressions of each fitness item on the BMI were also calculated. RESULTS: The sprint, standing long jump and shuttle run indicated better performances in normal than in thin and overweight/obese boys; the latter groups did not differ. Thin and normal weight boys performed better than overweight/obese boys in sit-ups and distance run. Among girls, sit-ups differed as follows: normal > thin > overweight/obese. Thin and normal weight girls performed better than overweight/obese girls in the jump, distance run and shuttle run. Normal weight girls were faster in the sprint than the overweight/obese. The quadratic regressions indicated significant non-linear relationships between the BMI and all fitness items among boys and in four items among girls. CONCLUSION: Performances on fitness tests varied with weight status. Relationships between performances and the BMI were curvilinear except for the distance run and flexibility in girls.

Iron Metabolism in Field Hockey Players During an Annual Training Cycle.

Post-physical training changes in iron metabolism in the human body often occur. To fully describe these processes, fifteen male Polish National Team field hockey players (age 27.7 ± 5.2 years, body mass 72.8 ± 7.6 kg and body height 177.1 ± 5.7 cm) were examined in three phases of an annual training cycle: preparatory (T1), competitive (T2) and transition (T3). To assess aerobic fitness, maximal oxygen uptake (VO2max) was evaluated. Based on the iron concentration, the changes in total iron binding capacity (TIBC), unsaturated iron binding capacity (UIBC) and other selected haematological indicators (haemoglobin, erythrocytes, mean corpuscular haemoglobin - MCH) in iron metabolism were estimated. The average values of maximum oxygen uptake increased from 54.97 ± 3.62 ml·kg(-1)·min(-1) in T1 to 59.93 ± 3.55 ml·kg(-1)·min(-1) in T2 (p<0.05) and then decreased to 56.21 ± 4.56 ml·kg(-1)·min(-1) in T3 (p<0.05). No statistically significant changes in the erythrocyte count were noted. The MCH and haemoglobin concentration decreased between T1 and T2. The maximal exercise test caused a significant (p<0.05) increase in the plasma iron concentration during the competition and transition phases. Progressive but non-significant increases in resting iron concentration, TIBC and UIBC in the analysed annual training cycle were noted. To show global changes in iron metabolism in the human body, it is necessary to determine additional variables, i.e. UIBC, TIBC, haemoglobin, MCH or the erythrocyte count. The direction of changes in iron metabolism depends on both the duration and intensity of the physical activity and the fitness level of the subjects. Dietary intake of iron increases the level of this trace element and prevents anaemia associated with training overloads.

Structure of Physical Fitness Among Young Female Basketball Players (Trends of Changes in 2006-2013).

The aim of this study was to identify trends of changes in the structure and levels of motor effects among young women basketball players in 2006-2013. These changes were examined in the context of comprehensive development of functional, fitness-related, and technical fundamentals with respect to requirements of specific training adopted as typical for targeted sports training stage. The research material was collected in 2006-2013 among young basketball players from the Greater Poland region. The study evaluated 169 girls (mean ± SD: age = 15.5 ± 0.5 years; height = 173.5 ± 5.8 cm; weight = 60.2 ± 7.9 kg). The measurements focused on the structure of motor effects in the athletes studied. For this purpose, the study used the International Physical Fitness Test. The study found that overall physical fitness of young women basketball players has been declining year by year. On the one hand, this might have been caused by the tendency for regression in motor modifications across generations that have been observed among populations. On the other hand, changes in weight-height ratio toward increasing obesity have also been observed. The results may serve as a kind of expertise about the structure of motor development of successive age groups of sports talented young women in light of training objectives at the targeted sports training stage as compared with trends typical for the general population. By describing the results of long-term research, this article offers a way of detecting possible positive or negative tendencies at a relatively early stage.

Analysis of sprinting activities of professional soccer players.

The aim of the study was a detailed analysis of the sprinting activity of professional soccer players. The study involved 147 players who played in 10 matches of the 2008-09 and 2010-11 UEFA Europa League seasons. The number of performed sprints and total sprint distances covered by the players were examined using collected statistical material. Two types of sprints were distinguished based on their duration: S, short-duration sprint (below 5 seconds) and L, long-duration sprint (above 5 seconds). Additionally, sprints were classified according to their distance: 0-10, 10.1-20.0, and >20 m, respectively. The analysis of the sprinting activity of soccer players also involved their respective positions of play. The study was carried out using Amisco Pro (version. 1.0.2), one of the most comprehensive up-to-date computer systems for match analysis. The statistical analysis revealed that the mean total sprint distance covered by players (≥24 km·h) amounted to 237 ± 123 m. With regard to the position of play, the forwards covered the longest sprint distance (345 ± 129 m), that is, 9% longer than midfielders (313 ± 119 m) and over 100% longer than central midfielders (167 ± 87 m). The average number of sprints performed by the soccer players was 11.2 ± 5.3. It should also be emphasized that about 90% of sprints performed by professional soccer players were shorter than 5 seconds, whereas only 10% were longer than 5 seconds. Analysis of physical loads of soccer players during matches can be useful for individualization of training of soccer players' speed capabilities. It is an essential instrument of modern planning and application of training loads.