Background: Understanding environmental correlates of physical activity can inform

Objective: To examine the reliability of a set of health-related physical fitness tests used in the European Union-funded Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) Study on lifestyle and nutrition among adolescents. Design: A set of physical fitness tests was performed twice in a study sample, 2 weeks apart, by the same researchers. Participants: A total of 123 adolescents (69 males and 54 females, aged 13.6 ± 0.8 years) from 10 European cities participated in the study. Measurements: Flexibility, muscular fitness, speed/agility and aerobic capacity were tested using the back-saver sit and reach, handgrip, standing broad jump, Bosco jumps (squat jump, counter movement jump and Abalakov jump), bent arm hang, 4 Â 10 m shuttle run, and 20-m shuttle run tests. Results: The ANOVA analysis showed that neither systematic bias nor sex differences were found for any of the studied tests, except for the back-saver sit and reach test, in which a borderline significant sex difference was observed (P ¼ 0.044). The Bland-Altman plots graphically showed the reliability patterns, in terms of systematic errors (bias) and random error (95% limits of agreement), of the physical fitness tests studied. The observed systematic error for all the fitness assessment tests was nearly 0. Conclusions: Neither a learning nor a fatigue effect was found for any of the physical fitness tests when repeated. The results also suggest that reliability did not differ between male and female adolescents. Collectively, it can be stated that the reliability of the set of physical fitness tests examined in this study is acceptable. The data provided contribute to a better understanding of physical fitness assessment in young people.

Introduction: The International Physical Activity Questionnaire (IPAQ) was developed to measure health-enhancing physical activity in adult populations. This study explores the concurrent validity of a modified version of the long IPAQ (the IPAQ-A) for the assessment of physical activity among adolescents. Participants and methods: In total, 248 healthy adolescents, divided into one older and one younger age group (aged 15-17 years (N ¼ 188) and 12-14 years (N ¼ 60), respectively) from nine Healthy Lifestyle by Nutrition in Adolescence (HELENA) Study centres across Europe, voluntarily participated in the study. Data on total physical activity, as well as activities in different intensities derived from the IPAQ-A, were compared using Spearman's correlation coefficient and Bland-Altman analysis, with data from an accelerometer. Tertiles of total physical activity for the IPAQ-A and the accelerometer were compared using Kendall's tau-b. Results: For the older age group, significant correlations between the instruments were found for time spent walking, for moderate and vigorous activities as well as for total physical activity (Rs ¼ 0.17-0.30, Po0.05). No significant correlations were found for any of the variables studied in the younger age group. Kendall's tau-b showed low but significant correlations for tertiles of total physical activity (Po0.001). Conclusions: The IPAQ-A has reasonable validity properties for assessing activities in different intensities and for total physical activity in healthy European adolescents aged 15-17 years. For adolescents aged 14 years and younger, the correlations were unsatisfactorily low and objective methodology, such as accelerometry, may be the appropriate alternative.

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Brain-derived neurotrophic factor (BDNF) has a central role in brain plasticity by mediating changes in cortical thickness and synaptic density in response to physical activity and environmental enrichment. Previous studies suggest that physical exercise can augment BDNF levels, both in serum and the brain, but no other study has examined how different types of activities compare with physical exercise in their ability to affect BDNF levels. By using a balanced cross over experimental design, we exposed nineteen healthy older adults to 35-minute sessions of physical exercise, cognitive training, and mindfulness practice, and compared the resulting changes in mature BDNF levels between the three activities. We show that a single bout of physical exercise has significantly larger impact on serum BDNF levels than either cognitive training or mindfulness practice in the same persons. This is the first study on immediate BDNF effects of physical activity in older healthy humans and also the first study to demonstrate an association between serum BDNF responsivity to acute physical exercise and working memory function. We conclude that the BDNF increase we found after physical exercise more probably has a peripheral than a central origin, but that the association between post-intervention BDNF levels and cognitive function could have implications for BDNF responsivity in serum as a potential marker of cognitive health.