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Senlin Chen, Yang Liu and Jodee Schaben

Purpose:

The purpose of this study was to examine physical activity (PA)/fitness knowledge and its association with PA and sedentary behavior in youth.

Method:

Eighth grade students from five schools (N = 660) in a midwestern state completed a PE Metrics written test and the Youth Activity Profile to assess PA/fitness knowledge, PA (at school and after school) and sedentary behavior, respectively.

Results:

Participants were clustered into high, medium, and low knowledge groups. Students in the high knowledge group reported higher level of PA after school (p < .05, d = .28) but lower level of sedentary behavior than the low knowledge group (p = .001, d = -.45). The low knowledge group also reported higher PA at school (p < .05, d = .25). PA/Fitness knowledge significantly predicted sedentary behavior, particularly in the low knowledge group (β = -.32, t = -2.46, p < .05, R 2 = .105), after controlling for gender and race/ethnicity.

Conclusion:

Physical education focused on conveying PA/fitness knowledge is warranted to educate youth to move more and sit less.

Open access

Yang Liu, Yan Tang, Zhen-Bo Cao, Pei-Jie Chen, Jia-Lin Zhang, Zheng Zhu, Jie Zhuang, Yang Yang and Yue-Ying Hu

Background:

Internationally comparable evidence is important to advocate for young people’s physical activity. The aim of this article is to present the inaugural Shanghai (China) Report Card on Physical Activity for Children and Youth.

Methods:

Since no national data are available, the working group developed the survey questionnaire and carried out the school surveys for students (n = 71,404), parents (n = 70,346), and school administrators and teachers (n = 1398). The grades of 9 report card indicators were assigned in accordance with the survey results against a defined benchmark: A is 81% to 100%; B is 61% to 80%; C is 41% to 60%, D is 21% to 40%; F is 0% to 20%.

Results:

The 9 indicators were graded as follows: Overall Physical Activity Levels (F), Organized Sport Participation (F), Active Play (D-), Active Transportation (C-), Sedentary Behavior (F), Family and Peers (B), School (B+), Community and the Built Environment (D+), and Government (D).

Conclusions:

Levels of physical activity and sedentary behavior were low and below the respective recommended guidelines. Interventions and policies at the community level should be encouraged to promote physical activity and reduce sedentary behavior. Future national surveys should be encouraged to strengthen Shanghai’s Report Card on Physical Activity for Children and Youth.

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Laurel M. Wentz, Pei-Yang Liu, Jasminka Z. Ilich and Emily M. Haymes

Background:

High rates of vitamin D deficiency have been reported in athletes. The purpose of this study was to evaluate the associations between vitamin D with bone health and parathyroid hormone (PTH) concentrations in female runners who trained at 30.4° degrees north.

Methods:

Serum 25-hydroxyvitamin D (25(OH) D), PTH, body composition, and bone mineral density (BMD) were measured in 59 female runners, aged 18–40 years. Stress fracture history, training duration and frequency were evaluated by questionnaire. As per National Endocrine Society cut-offs, serum vitamin D ranges were: 25(OH)D < 50 nmol/L for deficient; 50–75 nmol/L for insufficient; and ≥ 75 nmol/L for sufficient status.

Results:

Mean serum 25(OH)D concentrations were 122.6 ± 63.9 nmol/L, with 18.6% of subjects in the deficient (5.1%) or insufficient (13.5%) range. No significant differences were observed between sufficient and deficient/insufficient subjects for BMD, PTH, history of stress fractures, or demographic data.

Conclusions:

The majority of distance runners maintained sufficient vitamin D status, suggesting that training outdoors in latitude where vitamin D synthesis occurs year-round reduces the risk for vitamin D deficiency. Data do not support the indiscriminate supplementation of outdoor athletes in southern latitudes without prior screening.

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Laurel Wentz, Pei-Yang Liu, Jasminka Z. Ilich and Emily M. Haymes

Purpose:

To compare female runners with and without a history of stress fractures to determine possible predictors of such fractures.

Methods:

27 female runners (age 18–40 yr) who had had at least 1 stress fracture were matched to a control sample of 32 female runners without a history of stress fractures. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (iDXA). Subjects answered questionnaires on stress-fracture history, training, menstrual status, and diet.

Results:

No significant differences were found in menstrual characteristics, diet and dairy intake, or bone measurements. Weekly servings of milk during middle school significantly predicted BMD at the femur (p = .010), femoral neck (p = .002), Ward’s triangle (p = .014), and femoral shaft (p = .005). Number of menstrual cycles in the previous year predicted femoral-neck BMD (p = .004). Caffeine intake was negatively associated with BMD of the femur (p = .010), femoral neck (p = .003), trochanter (p = .038), and femoral shaft (p = .035). Weekly hours of training were negatively associated with total-body BMD (p = .021), total-body bone mineral content (p = .028), and lumbar-spine BMD (p = .011). Predictors for stress fractures included the number of years running, predominantly running on hard ground, irregular menstrual history, low total-body BMD, and low current dietary calcium intake when controlling for body-mass index (Nagelkerke R 2 = .364).

Conclusions:

Servings of milk during middle-school years were positively correlated with hip BMD, although current calcium intake, low BMD, irregular menstrual history, hard training surface, and long history of training duration were the most important predictors of stress fractures.

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Aaron P. Crombie, Pei-Yang Liu, Michael J. Ormsbee and Jasminka Z. Ilich

Purpose:

To examine relationships between changes in body weight, body composition, and fitness level in male students of the general population and those in the Army Reserve Officer Training Corps (ROTC) program during the freshman year of college.

Methods:

Thirty-seven (18.4 ± 0.7 yr) healthy, nonsmoking, first-semesterresident male students were divided into 3 groups: low active (LA), high active (HA), and ROTC. Baseline (beginning of freshman year) and 6-month follow-up measurements included anthropometry, body composition (by DXA), 3-day food records, and physical activity (PA) assessment.

Results:

Weight and body-mass index did not change significantly within or among groups. HA participants compared with LA and ROTC had a significant decrease in body fat (–1.6% ± 2.5% vs. 1.9% ± 1.2% and 0.8% ± 2.2%, respectively). They also had a significant increase in lean mass compared with LA and ROTC (1.8 ± 1.1 kg vs. –0.2 ± 2.0 kg and 0.2 ± 1.7 kg, respectively). All p values were <.05. ROTC and LA participants were similar in all measures of body composition and PA and had significantly lower PA levels than the HA group. No significant relationships were observed between dietary variables and body-composition changes.

Conclusions:

These results suggest that higher PA was the most powerful determinant in achieving favorable body-composition outcomes. In addition, current physical training conducted by ROTC at Florida State University (which seems to be a practice nationwide) might not be sufficient to offset gains in body fat.

Open access

Yang Liu, Yan Tang, Zhen-Bo Cao, Jie Zhuang, Zheng Zhu, Xue-Ping Wu, Li-Juan Wang, Yu-Jun Cai, Jia-Lin Zhang and Pei-Jie Chen

Open access

Silvia A. González, Joel D. Barnes, Patrick Abi Nader, Dolores Susana Andrade Tenesaca, Javier Brazo-Sayavera, Karla I. Galaviz, Marianella Herrera-Cuenca, Piyawat Katewongsa, Juan López-Taylor, Yang Liu, Bilyana Mileva, Angélica María Ochoa Avilés, Diego Augusto Santos Silva, Pairoj Saonuam and Mark S. Tremblay

Background: The Global Matrix 3.0 brings together the Report Card grades for 10 physical activity indicators for children and youth from 49 countries. This study describes and compares the Global Matrix 3.0 findings among 10 countries with high Human Development Index. Methods: Report Cards on physical activity indicators were developed by each country following a harmonized process. Countries informed their Report Cards with the best and most recent evidence available. Indicators were graded using a common grading rubric and benchmarks established by the Active Healthy Kids Global Alliance. A database of grades from the countries was compiled, and letter grades were converted to numerical equivalents. Descriptive statistics and scores for groups of indicators were calculated, and correlation analyses were conducted. Results: Grades for the 10 countries clustered around “D” ranging from “F” to “B+.” Active Transportation had the highest average grade (“C”), whereas Overall Physical Activity had the lowest average grade (“D-”). Low grades were observed for both behavioral and sources of influence indicators. Conclusions: In the context of social and economical changes of high- Human Development Index countries, urgent actions to increase physical activity among children and youth are required. Surveillance and monitoring efforts are required to fill research gaps.

Open access

Salomé Aubert, Joel D. Barnes, Chalchisa Abdeta, Patrick Abi Nader, Ade F. Adeniyi, Nicolas Aguilar-Farias, Dolores S. Andrade Tenesaca, Jasmin Bhawra, Javier Brazo-Sayavera, Greet Cardon, Chen-Kang Chang, Christine Delisle Nyström, Yolanda Demetriou, Catherine E. Draper, Lowri Edwards, Arunas Emeljanovas, Aleš Gába, Karla I. Galaviz, Silvia A. González, Marianella Herrera-Cuenca, Wendy Y. Huang, Izzeldin A.E. Ibrahim, Jaak Jürimäe, Katariina Kämppi, Tarun R. Katapally, Piyawat Katewongsa, Peter T. Katzmarzyk, Asaduzzaman Khan, Agata Korcz, Yeon Soo Kim, Estelle Lambert, Eun-Young Lee, Marie Löf, Tom Loney, Juan López-Taylor, Yang Liu, Daga Makaza, Taru Manyanga, Bilyana Mileva, Shawnda A. Morrison, Jorge Mota, Vida K. Nyawornota, Reginald Ocansey, John J. Reilly, Blanca Roman-Viñas, Diego Augusto Santos Silva, Pairoj Saonuam, John Scriven, Jan Seghers, Natasha Schranz, Thomas Skovgaard, Melody Smith, Martyn Standage, Gregor Starc, Gareth Stratton, Narayan Subedi, Tim Takken, Tuija Tammelin, Chiaki Tanaka, David Thivel, Dawn Tladi, Richard Tyler, Riaz Uddin, Alun Williams, Stephen H.S. Wong, Ching-Lin Wu, Paweł Zembura and Mark S. Tremblay

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.