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Catherine R. Marinac, Mirja Quante, Sara Mariani, Jia Weng, Susan Redline, Elizabeth M. Cespedes Feliciano, J. Aaron Hipp, Daniel Wang, Emily R. Kaplan, Peter James and Jonathan A. Mitchell

within an individual. We, therefore, tested if the timing of meals, light exposure, physical activity, and sleep were associated with body mass index (BMI) in a sample of healthy adults who recorded the timing of behaviors over multiple days using a novel smartphone application and actigraphy. We first

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Martin D. Hoffman, Philip S. Clifford, Božo Bota, Michael Mandli and Gregory M. Jones

A theoretical analysis was used to evaluate the effect of body mass on the mechanical power cost of cross-country skiing and roller skiing on flat terrain. The relationships between body mass and the power cost of overcoming friction were found to be different between cross-country skiing on snow and roller skiing. Nevertheless, it was predicted that the heavier skier should have a lower oxygen cost per unit of body mass for roller skiing, as is the case for snow skiing. To determine whether the theoretical analysis was supported by experimental data, oxygen consumption measurements were performed during roller skiing by six male cross-country ski racers who spanned a 17.3-kg range in body mass. The theoretical analysis was supported by the experimental findings of decreases in oxygen consumption for each kg increase in body mass of approximately 1.0% for the double pole technique, 1.8% for the kick double pole technique, and 0.6% for the VI skate technique.

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Ciro José Brito, Aendria Fernanda Castro Martins Roas, Igor Surian Souza Brito, João Carlos Bouzas Marins, Claudio Córdova and Emerson Franchini

The aim of this study was to investigate the methods adopted to reduce body mass (BM) in competitive athletes from the grappling (judo, jujitsu) and striking (karate and tae kwon do) combat sports in the state of Minas Gerais, Brazil. An exploratory methodology was employed through descriptive research, using a standardized questionnaire with objective questions self-administered to 580 athletes (25.0 ± 3.7 yr, 74.5 ± 9.7 kg, and 16.4% ± 5.1% body fat). Regardless of the sport, 60% of the athletes reported using a method of rapid weight loss (RWL) through increased energy expenditure. Strikers tend to begin reducing BM during adolescence. Furthermore, 50% of the sample used saunas and plastic clothing, and only 26.1% received advice from a nutritionist. The authors conclude that a high percentage of athletes uses RWL methods. In addition, a high percentage of athletes uses unapproved or prohibited methods such as diuretics, saunas, and plastic clothing. The age at which combat sport athletes reduce BM for the first time is also worrying, especially among strikers.

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Simone A. Tomaz, Alessandra Prioreschi, Estelle D. Watson, Joanne A. McVeigh, Dale E. Rae, Rachel A. Jones and Catherine E. Draper

, and research on sleep behavior in this age group is lacking from low- and middle-income countries (LMICs), such as South Africa. Furthermore, there has been limited research investigating the relationships between PA, SB, GMS, sleep duration, and body mass index (BMI) in preschool children from LMICs

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Neil Armstrong and Jo Welsman

single best indicator of youth aerobic fitness, but its interpretation in relation to sex, age, body mass, fat-free mass (FFM), and maturity status is controversial ( 4 ). The vast majority of published data are cross-sectional and, on balance, show that boys’ absolute peak V ˙ O 2 (ie, in L·min −1

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Joshua Darrall-Jones, Gregory Roe, Shane Carney, Ryan Clayton, Padraic Phibbs, Dale Read, Jonathon Weakley, Kevin Till and Ben Jones

Purpose:

To evaluate the difference in performance of the 30-15 Intermittent Fitness Test (30–15IFT) across 4 squads in a professional rugby union club in the UK and consider body mass in the interpretation of the end velocity of the 30-15IFT (VIFT).

Methods:

One hundred fourteen rugby union players completed the 30-15IFT midseason.

Results:

VIFT demonstrated small and possibly lower (ES = –0.33; 4/29/67) values in the under 16s compared with the under 21s, with further comparisons unclear. With body mass included as a covariate, all differences were moderate to large and very likely to almost certainly lower in the squads with lower body mass, with the exception of comparisons between senior and under-21 squads.

Conclusions:

The data demonstrate that there appears to be a ceiling to the VIFT attained in rugby union players that does not increase from under-16 to senior level. However, the associated increases in body mass with increased playing level suggest that the ability to perform high-intensity running increases with age, although not translating into greater VIFT due to the detrimental effect of body mass on change of direction. Practitioners should be aware that VIFT is unlikely to improve, but it needs to be monitored during periods where increases in body mass are evident.

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Bo Shen and Chiren Xu

Background:

Researchers have studied exercise determinants primarily from cognitive and social psychology perspectives, which typically give minimal attention to the body as a physical and biological entity. With the belief that tapping into multidimensional variables would potentially help us better understand motivation in exercise, we designed this study to examine the influences of self-efficacy, body mass, and cardiorespiratory fitness level on Chinese college students’ leisure-time exercise motives.

Methods:

208 college students completed measures of self-efficacy and exercise motives during regular physical education classes. Their body mass and cardiorespiratory fitness level data were derived from the latest annual physical training test. Multiple regression analyses were conducted to investigate the effects of self-efficacy, body mass, and cardiorespiratory fitness on exercise motives.

Results:

Cardiorespiratory fitness level and self-efficacy in exercise significantly contributed to both psychological and interpersonal motives. Body mass was the only significant predictor for body-related motives. However, analyses of health and fitness motives did not result in any significant predictors.

Conclusion:

Physical and psychological variables have both independent and specialized functions on exercise motives. Future motivational studies in exercise should pay greater attention to ecological approaches that account for physical, psychological, and social factors.

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Meenakshi Maria Fernandes and Roland Sturm

Background:

Physical activity at school can support obesity prevention among youth. This paper assesses the role of existing school physical activity programs for a national cohort from first grade to fifth grade.

Methods:

We analyzed a cohort from the Early Childhood Longitudinal Survey—Kindergarten Cohort which included 8246 children in 970 schools across the country. Growth curve models estimate the effect of physical education (PE) and recess on individual child body mass trajectories controlling for child and school characteristics. Hierarchical models allow for unobserved school and child effects.

Results:

Among first graders, 7.0% met the National Association of Sport and Physical Education (NASPE) recommended time for PE and 70.7% met the recommended time for recess in the previous week. Boys experienced a greater increase in body mass than girls. Meeting the NASPE recommended time for recess was associated with a 0.74 unit decrease in BMI (body mass index) percentile for children overall. Meeting the NASPE recommendation for physical education was associated with 1.56 unit decrease in BMI percentile among boys but not girls.

Conclusions:

We find evidence that meeting the national recommendations for PE and recess is effective in mitigating body mass increase among children.

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Krista Schroeder, Martha Y. Kubik, Jiwoo Lee, John R. Sirard and Jayne A. Fulkerson

may inform interventions to minimize the decline. 5 – 10 Understanding these associations in preadolescents at risk for poor health outcomes, such as preadolescents with elevated body mass index (BMI), is especially important given the harmful health impact of physical inactivity and prolonged

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Martin Švehlík, Kryštof Slabý, Tomáš Trc̆ and Jir̆í Radvanský

The aim of the study is to investigate whether the net nondimensional oxygen utilization scheme is able to detect postoperative improvement in the energy cost of walking in children with cerebral palsy and to compare it with a body mass normalization scheme. We evaluated 10 children with spastic cerebral palsy before and 9 months after equinus deformity surgery. Participants walked at a given speed of 2 km/hr and 3 km/hr on a treadmill. Oxygen utilization was measured, and mass relative VO2 and net nondimensional VO2 were calculated. Coefficient of variation was used for the description of variability among subjects. Postoperatively, gait kinematics normalized and the mass relative VO2 and net nondimensional VO2 showed significant improvement. Net nondimensional VO2 is able to detect postoperative improvement with smaller variability among subjects than body mass related normalization in children with cerebral palsy.