No abstract

Flight time is the most accurate and frequently used variable when assessing the height of vertical jumps. The purpose of this study was to analyze the validity and reliability of an alternative method (i.e., the HSC-Kinovea method) for measuring the flight time and height of vertical jumping using a low-cost high-speed Casio Exilim FH-25 camera (HSC). To this end, 25 subjects performed a total of 125 vertical jumps on an infrared (IR) platform while simultaneously being recorded with a HSC at 240 fps. Subsequently, 2 observers with no experience in video analysis analyzed the 125 videos independently using the open-license Kinovea 0.8.15 software. The flight times obtained were then converted into vertical jump heights, and the intraclass correlation coefficient (ICC), Bland-Altman plot, and Pearson correlation coefficient were calculated for those variables. The results showed a perfect correlation agreement (ICC = 1, p < 0.0001) between both observers' measurements of flight time and jump height and a highly reliable agreement (ICC = 0.997, p < 0.0001) between the observers' measurements of flight time and jump height using the HSC-Kinovea method and those obtained using the IR system, thus explaining 99.5% (p < 0.0001) of the differences (shared variance) obtained using the IR platform. As a result, besides requiring no previous experience in the use of this technology, the HSC-Kinovea method can be considered to provide similarly valid and reliable measurements of flight time and vertical jump height as more expensive equipment (i.e., IR). As such, coaches from many sports could use the HSC-Kinovea method to measure the flight time and height of their athlete's vertical jumps.

No abstract

Objectively measured physical activity may influence academic performance during both childhood and adolescence, but this association was negative and very weak. Longitudinal and intervention studies are necessary to further our understanding.

The Assessing Levels of Physical Activity (ALPHA) health-related fitness test battery is a set of reliable, valid, and feasible tests to assess health-related physical fitness in children and in adolescents. The aim of this study was to examine the reliability of this battery in adolescents with Down syndrome (DS). The extended ALPHA health-related fitness test battery was performed twice within 1 month in 17 apparently healthy adolescents, aged 12-18 years, with DS who had an intelligence quotient ≥ 35. Intraclass correlation coefficient (ICC) was used to determinate test-retest reliability, and nonparametric Wilcoxon signed rank test was used to compare mean differences between measurements. With the exception of subscapular skinfold test, which obtained a moderate agreement (ICC = 0.64), all tests had a very high reliability: the 20-m shuttle-run test (ICC = 0.86), the right handgrip strength test (ICC = 0.86), the left handgrip strength test (ICC = 0.86), the standing broad jump test (ICC = 0.85), body mass index (ICC = 0.95), waist circumference (ICC = 0.98), triceps skinfold (ICC = 0.85), and the 4 × 10-m shuttle-run test (ICC = 0.92). There were no significant differences (all p > 0.05) in any of the tests. The ALPHA health-related fitness battery is reliable for measuring health-related components of fitness in adolescents with DS.