Search

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 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.

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).