Background: Accumulating sufficient moderate to vigorous physical activity is recognized as a key determinant of physical, physiological, developmental, mental, cognitive, and social health among children and youth (aged 5–17 y). The Global Matrix 3.0 of Report Card grades on physical activity was developed to achieve a better understanding of the global variation in child and youth physical activity and associated supports. Methods: Work groups from 49 countries followed harmonized procedures to develop their Report Cards by grading 10 common indicators using the best available data. The participating countries were divided into 3 categories using the United Nations’ human development index (HDI) classification (low or medium, high, and very high HDI). Results: A total of 490 grades, including 369 letter grades and 121 incomplete grades, were assigned by the 49 work groups. Overall, an average grade of “C-,” “D+,” and “C-” was obtained for the low and medium HDI countries, high HDI countries, and very high HDI countries, respectively. Conclusions: The present study provides rich new evidence showing that the situation regarding the physical activity of children and youth is a concern worldwide. Strategic public investments to implement effective interventions to increase physical activity opportunities are needed.

The purpose of this study was to examine the influence of the energy cost of swimming, body composition, and technical parameters on swimming performance in young swimmers. Twenty-nine swimmers, 15 prepubertal (11.9 ± 0.3 years; Tanner Stages 1−2) and 14 pubertal (14.3 ± 1.4 years; Tanner Stages 3−4) boys participated in the study. The energy cost of swimming (C_s) and stroking parameters were assessed over maximal 400-m front-crawl swimming in a 25m swimming pool. The backward extrapolation technique was used to evaluate peak oxygen consumption (VO_2peak). A stroke index (SI; m² · s⁻¹ · cycles⁻¹) was calculated by multiplying the swimming speed by the stroke length. VO_2peak results were compared with VO_2peak test in the laboratory (bicycle, 2.86 ± 0.74 L/min, vs. in water, 2.53 ± 0.50 L/min; R² = .713; p = .0001). Stepwise-regression analyses revealed that SI (R² = .898), in-water VO_2peak (R² = .358), and arm span (R² = .454) were the best predictors of swimming performance. The backward-extrapolation method could be used to assess VO_2peak in young swimmers. SI, arm span, and VO_2peak appear to be the major determinants of front-crawl swimming performance in young swimmers.

The aim of the current investigation was to determine the possible relationships of fasting adiponectin level with body composition, bone mineral, insulin sensitivity, leptin, and cardiorespiratory fitness parameters in 153 women. Subjects were classified as premenopausal ( n = 42; 40.8 ± 5.7 yr) if they had regular menstrual periods, early postmenopausal ( n = 49; 56.7 ± 3.6 yr) if they had been postmenopausal for more than >1 yr but 7 yr. All women studied had a body mass index (BMI) <30 kg/m². Adiponectin values were higher ( P < 0.05) in middle-aged (12.0 ± 5.1 μg/ml) and older (15.3 ± 7.3 μg/ml) postmenopausal women compared with middle-aged premenopausal women (8.4 ± 3.2 μg/ml). Mean plasma adiponectin concentration in the total group of women ( n = 153) was 12.2 ± 6.3 μg/ml and was positively related ( P < 0.05) to age, indexes of overall obesity (BMI, body fat mass), and cardiorespiratory fitness (PWC) values. In addition, a negative association ( P < 0.05) between adiponectin with central obesity (waist-to-hip and waist-to-thigh ratio), fat-free mass, bone mineral (bone mineral content, total and lumbar spine bone mineral density), and leptin and insulin resistance (insulin, fasting insulin resistance index) values was observed. However, multivariate regression analysis revealed that only age, fasting insulin resistance index, and leptin were independent predictors of adiponectin concentration. In conclusion, circulating adiponectin concentrations increase with age in normal-weight middle-aged and older women. It appears that adiponectin is independently related to age, leptin, and insulin resistance values in women across the age span and menstrual status.

The aim of the current investigation was to investigate any potential effect of fasting plasma adiponectin concentration on bone tissue, and to find possible relationships of fasting plasma adiponectin level with different body composition, insulin sensitivity and physical performance parameters in a group of healthy perimenopausal women. Twenty-one premenopausal and 17 early postmenopausal women participated in this study. The women were matched for body mass index (BMI) and level of mean daily energy expenditure. Women had similar adiponectin (8.4 ± 3.9 vs. 9.9 ± 5.4 µg/ml) and leptin values (12.0 ± 7.7 vs. 14.0 ± 8.2 ng/ml) before and after menopause. Significant relationships were observed between plasma adiponectin and bone mineral content, total bone mineral density (BMD) and lumbar spine BMD values (r > - 0.36; p < 0.05). Furthermore, adiponectin had a significant negative association with total BMD (β = - 1.228; p = 0.004) and lumbar spine BMD (β = - 0.312; p = 0.005) independent of the influence that other measured body compositional, hormonal or physical performance factors may exert on BMD. Adiponectin was also significantly related to waist-to-hip ratio (WHR) (β = - 2.300; p = 0.002) and fasting insulin resistance index (FIRI) (β = - 0.006; p = 0.007) in separate regression models. No relationship was observed between leptin and measured bone, physical performance and insulin resistance values. Leptin significantly correlated to BMI (β = 0.018; p = 0.034), lean body mass (β = 0.025; p = 0.024) and fat mass (β = 0.019; p = 0.001) in separate regression models. In conclusion, the results of present study show that circulating adiponectin appears to exert an independent effect on BMD in perimenopausal women and may represent a link between adipose tissue and bone mineral density.

In aerobic exercise testing are influenced by menstrual cycle phases and use of oral contraceptive (OC) in female rowers. Twenty-four eumenorrheic female rowers distinguished on the basis of both menstrual status and athleticism participated in this study and were divided into competitive cyclic athletes (n = 8), recreationally trained cyclic athletes (n = 7), and recreationally trained athletes taking OC pills (ROC; n = 9). Rowers performed 2 incremental tests to voluntary exhaustion on a rowing ergometer during 2 different phases of the menstrual cycle: the follicular phase (FP) and the luteal phase (LP). The study variables were power output (Pa), heart rate (HR), oxygen consumption (JOURNAL/jscr/04.03/00124278-201106000-00013/OV0312_8/v/2021-02-09T093803Z/r/image-pngO2), carbon dioxide production (JOURNAL/jscr/04.03/00124278-201106000-00013/OV0312_8/v/2021-02-09T093803Z/r/image-pngCO2), minute ventilation (JOURNAL/jscr/04.03/00124278-201106000-00013/OV0312_8/v/2021-02-09T093803Z/r/image-pngE), the mean respiratory exchange ratio, and ventilatory equivalents of O2 (JOURNAL/jscr/04.03/00124278-201106000-00013/OV0312_8/v/2021-02-09T093803Z/r/image-pngE/JOURNAL/jscr/04.03/00124278-201106000-00013/OV0312_8/v/2021-02-09T093803Z/r/image-pngO2) and CO2 (JOURNAL/jscr/04.03/00124278-201106000-00013/OV0312_8/v/2021-02-09T093803Z/r/image-pngE/JOURNAL/jscr/04.03/00124278-201106000-00013/OV0312_8/v/2021-02-09T093803Z/r/image-pngco2), which were measured at maximal and at the aerobic-anaerobic transition intensities. In addition, maximal blood lactate (La) values after the test were obtained. When comparing Pa, JOURNAL/jscr/04.03/00124278-201106000-00013/OV0312_8/v/2021-02-09T093803Z/r/image-pngo2, HR, and La values, no significant differences (p > 0.05) between FP and LP at maximal load and at threshold intensity were found in all 3 groups of the rowers studied. However, we observed higher values (p < 0.05) for JOURNAL/jscr/04.03/00124278-201106000-00013/OV0312_8/v/2021-02-09T093803Z/r/image-pngE/JOURNAL/jscr/04.03/00124278-201106000-00013/OV0312_8/v/2021-02-09T093803Z/r/image-pngCO2 at both intensities in LP compared with FP in the ROC group. In conclusion, sport-specific endurance performance was not influenced by the phase of the normal menstrual cycle and the synthetic menstrual cycle of the OC users in the rowers studied. Therefore, normally menstruating female rowers and female rowers taking OC pills should not be concerned about the timing of their menstrual cycle with regard to optimized sport-specific endurance performance....