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Lower ambient temperature (Ta) requires greater energy expenditure to sustain body temperature. However, effects of Ta on human energetics may be buffered by environmental modification and behavioral compensation. We used the IAEA DLW database for adults in the USA (n = 3213) to determine the effect of Ta (-10 to +30°C) on TEE, basal (BEE) and activity energy expenditure (AEE) and physical activity level (PAL). There were no significant relationships (p > 0.05) between maximum, minimum and average Ta and TEE, BEE, AEE and PAL. After adjustment for fat-free mass, fat mass and age, statistically significant (p

The aim of the present study was to examine how explosive strength, kicking speed, and body composition are affected by a 12-week plyometric training program in elite female soccer players. The hypothesis was that this program would increase the jumping ability and kicking speed and that these gains could be maintained by means of regular soccer training only. Twenty adult female players were divided into 2 groups: control group (CG, n = 10, age 23.0 [+ or -] 3.2 yr) and plyometric group (PG, n = 10; age 22.8 [+ or -] 2.1 yr). The intervention was carried out during the second part of the competitive season. Both groups performed technical and tactical training exercises and matches together. However, the CG followed the regular soccer physical conditioning program, which was replaced by a plyometric program for PG. Neither CG nor PG performed weight training. Plyometric training took place 3 days a week for 12 weeks including jumps over hurdles, drop jumps (DJ) in stands, or horizontal jumps. Body mass, body composition, countermovement jump height, DJ height, and kicking speed were measured on 4 separate occasions. The PG demonstrated significant increases (p < 0.05) in jumping ability after 6 weeks of training and in kicking speed after 12 weeks. There were no significant time x group interaction effects for body composition. It could be concluded that a 12-week plyometric program can improve explosive strength in female soccer players and that these improvements can be transferred to soccer kick performance in terms of ball speed. However, players need time to transfer these improvements in strength to the specific task. Regular soccer training can maintain the improvements from a plyometric training program for several weeks. KEY WORDS stretch-shortening cycle, jumping ability, kicking performance

ABSTRACT. The authors examined the complex interactions between perception, cognition, and expertise by using a film-based decision-making test. They stratified 40 youth soccer players (aged 13.0-15.8 years) into groups by [...]

This article examines the relationship between adolescent physical fitness and adult activity levels in Flemish males during a twenty-seven year longitudinal study. Findings indicate significant differences in physical activity levels related to sports, work, and leisure activities between adolescence and middle age.

Higher physical activity levels on a regular basis assists physical fitness significantly. Fitness in males first recorded from 13 to 18 and remeasured at 30, 35 and 40 years was the basis for this finding.

This article examines the relationship between physical activity and physical fitness. Research indicates that occupational and leisure-time activity, such as participation in sports, increases overall physical fitness as measured by a series of tests for muscular and cardiorespiratory fitness.

PURPOSE: To model the development of soccer-specific aerobic performance, assessed by the Yo-Yo Intermittent Recovery Test Level 1 in 162 elite pubertal soccer players, age 11-14 y at baseline. METHODS: Longitudinal multilevel modeling analyses comprised predictors related to growth (chronological age, body size [height and weight] and composition [fat mass, fat-free mass]), and motor coordination [3 Körperkoordination Test für Kinder subtests: jumping sideways, moving sideways, backward balancing] and estimated biological-maturation groups (earliest [percentile 66]). RESULTS: The best-fitting model on soccer-specific aerobic performance could be expressed as -3639.76 + 369.86 × age + 21.38 × age2 + 9.12 × height - 29.04 × fat mass + 0.06 × backward balance. Maturity groups had a negligible effect on soccer-specific aerobic performance (-45.32 ± 66.28; P > .05). CONCLUSION: The current study showed that the development of aerobic performance in elite youth soccer is related to growth and muscularity and emphasized the importance of motor coordination in the talent-identification and -development process. Note that biological maturation was excluded from the model, which might endorse the homogeneity in estimated biological-maturation status in the current elite pubertal soccer sample. [ABSTRACT FROM AUTHOR]

The goal of this study was to investigate differences in physical fitness and sports participation over 2 years in children with relatively high, average, and low motor competence. Physical fitness and gross motor coordination of 501 children between 6-10 years were measured at baseline and baseline+2 years. The sample compromised 2 age cohorts: 6.00-7.99 and 8.00-9.99 years. An age and sex-specific motor quotient at baseline testing was used to subdivide these children into low (MQ < P33), average (P33 ≤ MQ < P66) and high (MQ ≥ P66) motor competence groups. Measures of sports participation were obtained through a physical activity questionnaire in 278 of the same children. Repeated Measures MANCOVA and two separate ANOVAs were used to analyze differences in changes in physical fitness and measures of sports participation respectively. Children with high motor competence scored better on physical fitness tests and participated in sports more often. Since physical fitness levels between groups changed similarly over time, low motor competent children might be at risk for being less physically fit throughout their life. Furthermore, since low motor competent children participate less in sports, they have fewer opportunities of developing motor abilities and physical fitness and this may further prevent them from catching up with their peers with an average or high motor competence. [ABSTRACT FROM AUTHOR]

Socioeconomic status (SES) is often indicated as a factor that influences physical activity and associated health outcomes. This study examined the relationship between SES and sport participation, morphology, fitness and motor coordination in a sample of 1955 Flemish children 6-11 years of age. Gender, age and SES-specific values for morphologic dimensions, amount and type of sport participation and fitness and motor coordination tests were compared. SES was positively and significantly associated with sport participation and sports club membership in both sexes. Although differences were not consistently significant, morphologic dimensions and tests of fitness and motor coordination showed a trend in favor of children from higher SES. The results suggest that public and local authorities should consider providing equal opportunities for children in all social strata and especially those in the lower SES to experience the beneficial effects of sport participation through which they can enhance levels of physical fitness and motor coordination. [ABSTRACT FROM AUTHOR]

Discussions of growth and motor performance of children are often set in the context of physical fitness. Although there is a clear theoretical concept or definition of fitness comprising motor coordination, the latter is not systematically considered. This study determined to what extent the variance in motor coordination might be explained by morphological and fitness characteristics. To postulate understanding of this association during childhood, 613 boys aged 7-11 years completed the morphological measurements, the Körperkoordinationstest für Kinder (KTK) and different fitness tests. The results demonstrated a substantial interrelationship among morphology, fitness and motor coordination in elementary school boys. The magnitude of explained variance and the loadings of the canonical correlation between the several constructs are strongly pronounced during childhood indicating that these constructs should be well considered given their contribution to a child's general development. [ABSTRACT FROM AUTHOR]

We examined differences in visual search behaviors and decision-making skill across different microstates of offensive play in soccer using youth participants (13.0-15.8 years) varying in skill and experience. We used realistic film simulations of offensive play, movement-based response measures, and an eye movement registration technique. Playing experience, skill level, and the unique constraints of the task, expressed by the number of players and relative proportion of offensive and defensive players, determined both the observed search behavior and processing requirements imposed on players in dynamic offensive team simulations. Significant differences in performance were observed between players and nonplayers and across three groups of soccer players who differed in skill level. Implications for talent identification and development are considered. [ABSTRACT FROM AUTHOR]

The reliability and validity of three physical activity questionnaires were studied using 90 Flemish males (30 aged 30 years, 30 aged 35 years, and 30 aged 40 years). Intraclass correlations (R) and kappa values were calculated to verify within judge and between judges reliability (objectivity) and test-retest reliability (stability) of the Tecumseh Community Health Study Questionnaire, the Five City Project Questionnaire, and the Baecke Questionnaire. Results showed high for within judge and between judges reliability. R coefficients for stability varied between 0.47 and 0.95. Kappa values varied between 0.20 and 0.73. Concurrent validity was investigated by comparing three levels of professional status. Workmen had higher indices concerning physical activity during work than clerks and managers. Congruent validity, studied by means of principal-components analysis, confirmed subdivision of habitual physical activity into three entities, physical activity during work, sports activities, and general leisure time. These results indicate that reliable and valid data can be obtained in Flemish males by three interviewer-assisted physical activity questionnaires. Am J Epidemiol 1998; 147: 982–90. [ABSTRACT FROM PUBLISHER]

We investigated the evolution and stability of anthropometric and soccer-specific endurance characteristics of 42 high-level, pubertal soccer players with high, average and low yo-yo intermittent recovery test level 1 (YYIR1) baseline performances over two and four years. The rates of improvement were calculated for each performance group, and intra-class correlations were used to verify short- and long-term stability. The main finding was that after two and four years, the magnitudes of the differences at baseline were reduced, although players with high YYIR1 baseline performance still covered the largest distance (e.g., low from 703 m to 2126 m; high from 1503 m to 2434 m over four years). Furthermore, the YYIR1 showed a high stability over two years (ICC = 0.76) and a moderate stability over four years (ICC = 0.59), due to large intra-individual differences in YYIR1 performances over time. Anthropometric measures showed very high stability (ICCs between 0.94 to 0.97) over a two-year period, in comparison with a moderate stability (ICCs between 0.57 and 0.75) over four years. These results confirm the moderate-to-high stability of high-intensity running performance in young soccer players, and suggest that the longer the follow-up, the lower the ability to predict player's future potential in running performance. They also show that with growth and maturation, poor performers might only partially catch up their fitter counterparts between 12 and 16 years. [ABSTRACT FROM AUTHOR]

The purpose of the study was to evaluate the developmental changes in performance in a repeated-sprint ability (RSA) test in young soccer players of contrasting maturity status. A total of 83 regional level Portuguese youth soccer players, aged 11-13 years at baseline was assessed annually. Stature, body mass, 7x34.2-m sprint protocol (25-s active recovery), 20-m multi-stage continuous shuttle endurance run and counter-movement jump (CMJ) without the use of the arms were measured. Fat-free mass (FFM) was determined by age and gender-specific formulas. Developmental changes in total sprint time across ages were predicted using multilevel modeling. Corresponding measurements were performed on an independent cross-sectional subsample of 52 youth soccer players 11-17 years to evaluate the predictive model. CA, CA2, maturational status (SA-CA), body size (mass and stature), FFM, aerobic endurance, lower limb explosive strength and annual volume training significantly improved the statistical fit of the RSA multilevel model. In 'late' maturing athletes, the best model for predicting change in RSA was expressed by the following equation: 86.54 - 2.87 x CA + 0.05 x CA2 - 0.25 x FFM + 0.15 x body mass + 0.05 x stature - 0.05 x aerobic endurance - 0.09 x lower limb explosive strength - 0.01 x annual volume training. The best fitting models for players who were 'on time' and 'early' maturing were identical to the best model for late maturing players, less 0.64 seconds and 1.74 seconds, respectively. Multilevel modeling provided performance curves that permitted the prediction of individual RSA performance across adolescent years in regional level soccer players. [ABSTRACT FROM AUTHOR]

Motor coordination and physical fitness are multidimensional concepts which cannot be reduced to a single variable. This study evaluated multivariate relationships among morphology, physical fitness and motor coordination in 74 pre-pubertal girls 8.0-8.9 years of age. Data included body dimensions, eight fitness items and four motor coordination tasks (KTK battery). Maturity status was estimated as percentage of predicted mature stature attained at the time of observation. Canonical correlation analysis was used to examine the relationships between multivariate domains. Significant pairs of linear functions between indicators of morphology and fitness (r c = 0.778, Wilks' Lambda = 0.175), and between fitness and motor coordination (r c = 0.765, Wilks' Lambda = 0.289) were identified. Girls who were lighter and had a lower waist-to-stature ratio and % fat mass attained better scores in the endurance run, sit-ups and standing long jump tests, but poorer performances in hand grip strength and 2-kg ball throw. Better fitness test scores were also associated with better motor coordination scores. Relationships between body size and estimated fatness with motor fitness suggested an inverse relationship that was particularly evident in performance items that required the displacement of the body through space, while motor coordination was more closely related with fitness than with somatic variables.

Purpose: To model the development of soccer-specific aerobic performance, assessed by the Yo-Yo Intermittent Recovery Test Level 1 in 162 elite pubertal soccer players, age 11-14 y at baseline., Methods: Longitudinal multilevel modeling analyses comprised predictors related to growth (chronological age, body size [height and weight] and composition [fat mass, fat-free mass]), and motor coordination [3 KÖrperkoordination Test für Kinder subtests: jumping sideways, moving sideways, backward balancing] and estimated biological-maturation groups (earliest [percentile 66])., Results: The best-fitting model on soccer-specific aerobic performance could be expressed as -3639.76 + 369.86 × age + 21.38 × age² + 9.12 × height - 29.04 × fat mass + 0.06 × backward balance. Maturity groups had a negligible effect on soccer-specific aerobic performance (-45.32 ± 66.28; P > .05)., Conclusion: The current study showed that the development of aerobic performance in elite youth soccer is related to growth and muscularity and emphasized the importance of motor coordination in the talent-identification and -development process. Note that biological maturation was excluded from the model, which might endorse the homogeneity in estimated biological-maturation status in the current elite pubertal soccer sample.

Background: The reproducibility of day-to-day testing of isokinetic concentric and eccentric muscular actions among adolescent basketball players aged 14 to 16 years and relationships of mean within-subject variation in two isokinetic testing sessions with chronological age, biological maturation (estimated age at peak height velocity), training experience, body size, lower-body morphology, and initial strength performance were evaluated., Material and Methods: The sample included 27 basketball players who completed replicate test sessions of 5 repetitions of reciprocal concentric and eccentric knee extensions and flexions at 60º s(-1). A randomly selected subsample of 8 players completed a third testing session to confirm reliability estimates., Results: Coefficients of variation (CV) between sessions 1 and 2 ranged from 8.1% to 17.4%, and intraclass coefficients (ICCs) ranged from 0.72 to 0.89. For sessions 1 and 3, CVs ranged from 3.9% to 6.0%, and ICCs ranged from 0.95 to 0.99. The initial level of strength of eccentric knee flexion (r=-0.43) and eccentric knee extension (r=-0.42) were correlated (P<0.05) with eccentric knee extension within-variation between two sessions. Training experience (r=-0.37, P<0.05) and initial values of concentric knee flexion (r=-0.62, P<0.01) were correlated with concentric knee flexion within-subject differences. Within-subject variation of eccentric knee extension was correlated (P<0.05) with chronologic age (r=0.41), estimated age at peak height velocity (r=-0.38), body size (r=0.41 to 0.47), and leg volume (r=0.39)., Conclusions: Familiarization sessions may improve the reliability of concentric and eccentric knee isokinetic strength testing at 60º s(-1) in adolescent basketball players. Age, maturity status, and training experience of young athletes should be considered when testing knee isokinetic strength at 60º s(-1).