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- Changes in cardiorespiratory fitness predict changes in body composition from childhood to adolescence: findings from the European Youth Heart StudyPublication . Ornelas, Rui T.; Silva, Analiza M.; Minderico, Cláudia S.; Sardinha, Luís B.Background: Several variables, such as waist circumference (WC) and trunk skinfolds (TS), are indicators of body fat. There is interest in evaluating the effect of cardiorespiratory fi tness (CRF) measures on changes in these markers from childhood to adolescence. Purpose: To examine CRF as a potential predictor of changes in body fat over an 8-year follow-up period in a pedi atric population. Methods: A cohort study of 86 children (44 girls, 42 boys) with a mean age of 9.8 ± 0.3 years who participated in the Portuguese arm of the European Youth Heart Study in 2000 completed a follow-up evaluation in 2008 at a mean age of 17.0 ± 0.4 years. Cardio respiratory fi tness, expressed as maximal oxygen consumption (VO2 max) (mL⋅kg−1 ⋅min−1 ), was assessed during an incremental multistage bicycle test to exhaustion. Physical activity (PA) was objectively measured by accelerometry at both periods of evaluation. Fat mass (FM) was assessed using anthropometric models, sum of TS, and WC. Changes were expressed as a percentage of the baseline value. Comparison of means and linear regression analysis were used for data analysis. Results: While CRF signifi cantly increased among boys (P 0.05) and decreased in girls (P 0.01), the percentage of body fat decreased over time in boys (P 0.01) and increased among girls. Alone, CRF explained 39%, 26%, and 25% of the total variance in WC, FM, and TS, respectively (P 0.01). Adjusting for PA, sex, and maturation changes, CRF remained a signifi cant predictor of WC (β = −0.335; P 0.01), FM (β = −2.084; P 0.01), and TS (β = −1.500; P 0.01). Conclusion: Changes in CRF are a signifi cant predictor of changes in body fat percentage from childhood to adolescence. School-based PA interventions are encouraged to maintain or improve CRF from childhood and throughout adolescence to prevent increased percentages of body fat, particularly in the abdominal region.
- Objectively measured time spent sedentary is associated with insulin resistance independent of overall and central body fat in 9-to 10-year-old portuguese childrenPublication . Sardinha, L. B.; Andersen, L. B.; Anderssen, S. A.; Quiterio, A. L.; Ornelas, Rui; Froberg, K.; Riddoch, C. J.; Ekelund, U.OBJECTIVE — We examined the independent relationships between objectively measured physical activity and insulin resistance in Portuguese children. RESEARCH DESIGN AND METHODS — This is a school-based, cross-sectional study in 147 randomly selected girls (aged 9.8 0.3 years; 27.8 9.3% body fat) and 161 boys (aged 9.8 0.3 years; 22.0 9.2% body fat). Physical activity was assessed by the Actigraph accel erometer for 4 days and summarized as time spent sedentary (accelerometer counts 500/min), in light-intensity (accelerometer counts 500–2,000/min), and in moderate- and vigorous intensity activity (accelerometer counts 2,001/min). We measured total and central fat mass by dual-energy X-ray absorptiometry. Insulin resistance was expressed as the homeostasis model assessment score. RESULTS — Time (min/day) spent sedentary was significantly and positively associated with insulin resistance ( -coefficient 0.001 [95% CI 0.0002–0.002]; P 0.013). Time spent in moderate- and vigorous-intensity physical activity ( 0.002 [ 0.003 to 0.001]; P 0.0009) and overall physical activity ( 0.001 [ 0.008 to 0.003]; P 0.0001) were significantly and inversely associated with insulin resistance. All associations remained statistically significant, although they were attenuated after further adjustments for sex, birth weight, sexual maturity, and total or central fat mass (P 0.03). CONCLUSIONS — Physical activity is associated with insulin resistance independent of total and central fat mass in children. Our results emphasize the importance of decreasing sedentary behavior and increasing time spent in moderate- and vigorous-intensity activity in children, which may have beneficial effects on metabolic risk factors regardless of the degree of adiposity.
- Sex specific association of physical activity on proximal femur BMD in 9 to 10 year-old childrenPublication . Cardadeiro, Graça; Baptista, Fátima; Ornelas, Rui; Janz, Kathleen F.; Sardinha, Luís B.The results of physical activity (PA) intervention studies suggest that adaptation to mechanical loading at the femoral neck (FN) is weaker in girls than in boys. Less is known about gender differences associated with non-targeted PA levels at the FN or other clinically relevant regions of the proximal femur. Understanding sex-specific relationships between proximal femur sensitivity and mechanical loading during non-targeted PA is critical to planning appropriate public health interventions. We examined sex-specific associations between non-target PA and bone mineral density (BMD) of three sub-regions of the proximal femur in pre- and early-pubertal boys and girls. BMD at the FN, trochanter (TR) and intertrochanter (IT) regions, and lean mass of the whole body were assessed using dual-energy x-ray absorptiometry in 161 girls (age: 9.760.3 yrs) and 164 boys (age: 9.760.3 yrs). PA was measured using accelerometry. Multiple linear regression analyses (adjusted for body height, total lean mass and pubertal status) revealed that vigorous PA explained 3–5% of the variability in BMD at all three sub regions in boys. In girls, vigorous PA explained 4% of the variability in IT BMD and 6% in TR BMD. PA did not contribute to the variance in FN BMD in girls. An additional 10 minutes per day of vigorous PA would be expected to result in a ,1% higher FN, TR, and IT BMD in boys (p,0.05) and a ,2% higher IT and TR BMD in girls. In conclusion, vigorous PA can be expected to contribute positively to bone health outcomes for boys and girls. However, the association of vigorous PA to sub-regions of the proximal femur varies by sex, such that girls associations are heterogeneous and the lowest at the FN, but stronger at the TR and the IT, when compared to boys.
- Promoting health-related cardiorespiratory fitness in physical education: a systematic reviewPublication . Peralta, Miguel; Henriques-Neto, Duarte; Gouveia, Élvio Rúbio; Sardinha, Luís B.; Marques, AdilsonThis article aimed to systematically review the contribution of physical education (PE) clas ses to improve cardiorespiratory fitness (CRF) in children and adolescents; and to define potentially relevant factors for promoting CRF in PE classes. Methods Studies were identified from searches in ERIC, PubMed, SPORTDiscus, and Web of Science databases. Primary source articles, relating PE classes and CRF, published up to July 2019 in peer-reviewed journals were eligible for inclusion. Specific inclusion criteria were: (a) having cross-sectional or longitudinal and observational or interventional study designs; (b) targeting school-aged children or adolescents; (c) measuring CRF, heart rate or CRF test results as an outcome; (d) having statistical analyses of the CRF, heart rate or CRF test results outcomes reported; (e) focusing on PE classes or PE interventions that did not extended time or fre quency of the classes; and (f) published in English, French, Portuguese, or Spanish. Results A total of 24 studies met the inclusion criteria. Overall, 10 studies have found a neutral effect of PE classes in students’ CRF, eight studies found that PE indeed contributed to the improvement of CRF and six studies revealed mixed findings, when PE classes where con trolled for others variables (e.g. body mass index, intensity). Higher intensity PE classes consistently demonstrated contributions to improving students’ CRF. Conclusion Review findings suggest that PE classes can contribute to the improvement of students’ CRF. Intensity, age and weight status were identified as potentially relevant factors for pro moting CRF in PE classes. To improve CRF, higher intensity classes should be provided.
- Pulse pressure tracking from adolescence to young adulthood: contributions to vascular healthPublication . Melo, Xavier; Santos, Diana A.; Ornelas, Rui; Fernhall, Bo; Santa-Clara, Helena; Sardinha, Luís B.Purpose: We examined whether exposure to high PP in adolescence predicts carotid artery intima-media thickness (IMT) and stiffness indices at young adulthood. Methods: Seventy-nine participants had their brachial systolic (SBP) and diastolic blood (DBP) pressures taken at the age of 15–16 years and later at young adulthood (29–31 years). Carotid IMT, distensibility and stiffness index b were measured at young adulthood. Linear and logistical regression analysis were performed. Results: PP at adolescence and at young adulthood predicted vascular health independently of sex, body mass index, and mean arterial pressure, explaining up to 37% of the variance. When analyzing its single constituents, at adolescence DBP was more predictive of vascular health, whereas DBP and SBP were equally important at young adulthood. Adolescents with high PP were at risk for increased carotid IMT (OR: 4.04–4.09), even if PP decreased at young adulthood. Young adults with high PP were at risk for increased stiffness regardless of adolescence PP (OR: 4.64–7.35). Conclusion: PP at adolescence and young adulthood may be a better predictor of early pathological changes in carotid artery structure and stiffness. Whereas carotid IMT in young adults appears to be influenced by PP at adolescence, carotid stiffness depends primarily on current PP.
- Presidential elections and secretary appointment: an event study for us biotechnology and drugsPublication . Martins, António Miguel; Albuquerque, Bruno; Sardinha, Luís; Moutinho, Nuno; Martins, António; Albuquerque, Bruno; Sardinha, LuisThe aim of this study is to analyse the effect of the 2024 US presidential election and the appointment of the US health secretary to the largest US listed biotechnology and drug firms. Using an event study methodology, we find that President Donald Trump’s election had no sig nificant impact on the industry. On the contrary, the results show statistically significant negative stock price reactions around the US health secretary appointment. The negative industry reaction to the US health secretary appointment is largely explained by his scepticism about vaccination and criticism about the high prices of drug prescriptions and margins in the industry. These re sults highlight the importance of top government position appointments, especially when such appointments eliminate much of the uncertainty regarding future government action in the in dustry and political uncertainty hypothesis. Finally, cross-section analysis reveals that the firms most penalized by the 2024 US presidential election and the appointment of the US health sec retary are those with the highest investments in R&D and capital expenditures. This could mean lower future investments in new vaccines or drugs, seriously harming society.
- 2024 U.S. presidential elections: an event study for U.S. and non-U.S. fossil fuel and renewable listed firmsPublication . Martins, António Miguel; Albuquerque, Bruno; Sardinha, Luís; Moutinho, Nuno; Martins, António; Albuquerque, Bruno; Sardinha, LuisThis study examines the short-term market effect of Donald Trump’ victory in the 2024 US presidential election on largest US and non-US listed worldwide fuel fossil and renewable firms. Employing an event study meth odology, we observe a negative and statistically significant stock price reaction for worldwide renewable listed firms. An analysis by economic zones reveals the existence of negative abnormal returns for renewable energy firms in the US, Europe, India and in the rest of the world. In the case of China, abnormal returns are not sta tistically significant. With respect to worldwide fossil fuel listed firms, abnormal returns are generally not sta tistically significant. However, regarding US firms, we observe positive and statistically significant abnormal returns. These abnormal returns are explained by the change of US energy policy (pro-oil and gas policy) and the expected cut in subsidies and lower profitability of investments in green energies. Finally, our study provide insight into which firm-specific characteristics emerge as value drives around US presidential elections. The results show that despite the change in environmental policy in the US, favourable to fossil energy, the stock markets reward firms with high environmental ratings. Overall, our results indicate that 2024 US presidential election, for implying a change in US energy policy, has relevant policy implications for energy listed firms.