Abstract：
PURPOSE:The frequency of interruptions in sedentary time (sedentary breaks) is an aspect of sedentary behaviors that may be associated with metabolic health outcomes. The aim of this study was to describe the change in the frequency of sedentary breaks during a 10-yr period from ages 5 to 15 yr. METHODS:The longitudinal Iowa Bone Development Study has collected accelerometry data at approximately 5, 8, 11, 13, and 15 yr. Data from participants who wore an accelerometer at least 10 h·d(-1) and 3 d per data collection episode were used (423 children at age 5 yr, 550 children at age 8 yr, 520 children at age 11 yr, 454 children at age 13 yr, and 344 children at age 15 yr). The frequency of sedentary breaks was determined based on accelerometry data and compared by weekday/weekend, period during the day, gender, and data collection episode. RESULTS:The frequency of sedentary breaks decreased by >200 times per day during a 10-yr period from ages 5 to 15 yr. Linear regression models estimated a 1.84-times-per-hour decrease per year for boys and a 2.04-times-per-hour decrease per year for girls (P values < 0.0001). Both boys and girls showed significantly fewer breaks on weekdays from morning to 3:00 p.m. than on weekends from morning to 3:00 p.m. (P values < 0.0001). The frequency of sedentary breaks was slightly higher among boys than among girls (gender difference ≤ 2 times per hour; P values < 0.01 at ages 11, 13, and 15 yr). CONCLUSIONS:Breaks in sedentary time notably decrease during childhood and adolescence. During school hours, boys and girls have fewer breaks in sedentary time than during any other period of weekday or weekend day.
journal_name
Med Sci Sports Exercjournal_title
Medicine and science in sports and exerciseauthors
Kwon S,Burns TL,Levy SM,Janz KFdoi
10.1249/MSS.0b013e318245ca20subject
Has Abstractpub_date
2012-06-01 00:00:00pages
1075-80issue
6eissn
0195-9131issn
1530-0315journal_volume
44pub_type
杂志文章abstract：PURPOSE:There is increased interest in developing and disseminating health behavior interventions for cancer survivors. Challenges in these efforts include participant burden in traveling to central intervention sites and sustainability. The purpose of this article is to report various methods used to recruit breast ca...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e31819af871
更新日期：2009-07-01 00:00:00
abstract：PURPOSE:To compare the historical evolution of performance for males and females in anaerobically dominated sprint events in three different sports: running, swimming, and speed skating. METHODS:Times of the top six finishers in a total of 283 men's and women's Olympic and world championship finals held between 1952 a...
journal_title：Medicine and science in sports and exercise
pub_type： 历史文章,杂志文章
doi：10.1249/01.mss.0000247005.17342.2b
更新日期：2007-03-01 00:00:00
abstract：INTRODUCTION:The vascular endothelium plays an important role in the maintenance of vascular health and the modulation of vascular tone and blood pressure. Recently, it has been demonstrated that blood pressure reactivity to physical activity is greater in the morning, and possibly, diurnal variation in vascular functi...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e318195109c
更新日期：2009-06-01 00:00:00
abstract：PURPOSE:This study aimed to examine the effects of footwear and neuromuscular fatigue induced by short distance trail running (TR) on running economy (RE) and biomechanics in well-trained and traditionally shod runners. METHODS:RE, vertical and leg stiffness (Kvert and Kleg), as well as foot strike angle were measured...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0000000000000981
更新日期：2016-10-01 00:00:00
abstract：PURPOSE:The purpose of the study was to investigate the core temperature responses to the induction of electrical exercise and to clarify whether an increase in temperature could be responsible for some of the observed reactions to acute and repeated exposure to electrical muscle stimulation. METHODS:The paralyzed thi...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1097/00005768-200103000-00015
更新日期：2001-03-01 00:00:00
abstract：PURPOSE:Investigate development of specific performance adaptions and hormonal responses every fourth week during a 12-wk high-intensity training (HIT) period in groups with different interval-training prescriptions. METHODS:Sixty-three well-trained cyclists performing a 12-wk intervention consisting of two to three H...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,多中心研究
doi：10.1249/MSS.0000000000001214
更新日期：2017-06-01 00:00:00
abstract：:Two swims (1993 and 1994) are described which led to post-swim orthostatic intolerance and one episode of syncope in a 50/51-yr-old well-trained and experienced marathon swimmer. The swims of 33 km and 38 km took 12 h 30 s and 17 h 35 min, respectively. Water temperature in each swim was above 23 degrees C and rectal ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：
更新日期：1995-09-01 00:00:00
abstract：:Many experimental studies have utilized the activity of dopamine-beta-hydroxylase (DBH) as an index of sympathetic activity, since this enzyme is not submitted to uptake mechanisms or to enzymatic metabolism as are the circulating catecholamines norepinephrine (NE) and epinephrine (E). However, large discrepancies hav...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/00005768-198512000-00011
更新日期：1985-12-01 00:00:00
abstract：:Chronically increased contractile activity by low-frequency stimulation induces a transformation of fast- into slow-twitch muscle fibers in the rabbit. This transformation is progressive with the duration of the stimulation and affects various functional systems of the muscle fiber in an orderly sequence. Early change...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,评审
doi：
更新日期：1984-12-01 00:00:00
abstract：PURPOSE:Unilateral strength training strengthens not only the muscles on the trained side but also the homologous muscles on the untrained side; however, the magnitude of this interlimb cross-education is modest. We tested the hypothesis that heightened sensory feedback by mirror viewing the exercising hand would augme...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,随机对照试验
doi：10.1249/MSS.0000000000000871
更新日期：2016-06-01 00:00:00
abstract：:The degree of parasympathetic control of resting heart rate (PC) was assessed by measurement of variation in heart period (VHP) during cardiopulmonary synchronization of respiration. Respiratory period was arbitrarily preset and standardized at 7 heart beats (3 beats inspiration, 4 beats expiration). The mathematical ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/00005768-198508000-00008
更新日期：1985-08-01 00:00:00
abstract：:The individual anaerobic threshold (IAT) is the highest metabolic rate at which blood lactate (LA) concentrations are maintained at a steady state during prolonged exercise. The purpose of this study was to compare the effects of active and passive recovery on the determination of the IAT before and after an endurance...
journal_title：Medicine and science in sports and exercise
pub_type： 临床试验,杂志文章
doi：
更新日期：1989-10-01 00:00:00
abstract：:The prevalence of the sickle cell trait in a school for elite young athletes in Cameroon, West Africa, was examined in order to evaluate whether the choice of an athletic career was influenced by its presence. The presence of hemoglobin AS was found in 27 of the 145 students attending the school (18.6%). Since the fre...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：
更新日期：1991-03-01 00:00:00
abstract：PURPOSE:We performed two experiments to determine whether cutaneous microvascular adaptations in response to repeated core temperature (Tc) elevation are mediated by increases in skin blood flow (SkBF) and/or skin temperature. METHODS:Healthy subjects participated for 8 wk in thrice-weekly bouts of 30-min lower limb h...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0000000000000349
更新日期：2014-11-01 00:00:00
abstract：INTRODUCTION:Androgen deprivation therapy (ADT) is associated with significant bone loss and an increase in fracture risk among prostate cancer survivors (PCS). We investigated whether impact + resistance training could stop ADT-related declines in bone mineral density (BMD) among PCS on ADT. METHODS:We randomized 51 ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,随机对照试验
doi：10.1249/MSS.0000000000000265
更新日期：2014-08-01 00:00:00
abstract：PURPOSE:The purpose of this study was to examine the impact of exercise-induced metabolic stress on hormonal responses and chronic muscular adaptations. METHODS:We compared the acute and long-term effects of an "NR regimen" (no-rest regimen) and those of a "WR regimen" (regimen with rest period within a set). Twenty-s...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：
更新日期：2005-06-01 00:00:00
abstract：PURPOSE:The purposes of this study were 1) to add layers and features to a previously published fully automated algorithm designed to identify children's nocturnal sleep and to exclude episodes of nighttime nonwear/wakefulness and potentially misclassified daytime sleep episodes and 2) to validate this refined sleep al...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0000000000000486
更新日期：2015-05-01 00:00:00
abstract：:The performance of the Caltrac accelerometer was studied in elementary school-age children under field and laboratory conditions. In Study 1, 35 children (20 boys, 15 girls, mean age = 10.8 yr) wore the accelerometer and a heart rate (HR) monitor for 2 d. Caltrac activity counts per hour were compared to the mean "act...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/00005768-199010000-00023
更新日期：1990-10-01 00:00:00
abstract：INTRODUCTION & PURPOSE:Obesity-related increases of weight on the chest wall are known to decrease lung volume and chest wall compliance, but the effect of this mass loading, independent of other obesity-related complications on the ventilatory response to exercise is unknown. The purpose of this study was to investiga...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/01.mss.0000126386.12402.f5
更新日期：2004-05-01 00:00:00
abstract：PURPOSE:To assess physical activity, and its associations with health, clinical, and biochemical factors, in patients with stages 2-4 of chronic kidney disease (CKD). METHODS:Cross-sectional data were collected from 120 patients with CKD enrolled in the Lipid lowering and Onset of Renal Disease (LORD) trial. Patients ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e3181940aef
更新日期：2009-05-01 00:00:00
abstract：:The purpose of this project was to determine whether mild heat stress induced by wearing a wet suit while swimming in relatively warm water (25.4 +/- 0.1 degrees C) increases the risk of heat injury during the cycling and running stages of an International distance triathlon in a hot and humid environment (32 degrees ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1097/00005768-199801000-00014
更新日期：1998-01-01 00:00:00
abstract：:The purpose of the study was to examine the effects of surgical and nonsurgical treatment of previously immobilized ankle fractures on voluntary and evoked contractile properties before and following fatigue. Twelve control and 12 previously immobilized (4-14 wk postfracture) internally fixated and nonfixated ankles w...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1097/00005768-199709000-00001
更新日期：1997-09-01 00:00:00
abstract：:Sprint-trained athletes demonstrate a remarkable ability to perform exercise which results in fatigue quickly. However, the mechanisms for these enhanced performance capabilities have not been fully elucidated. Elevation in glycolytic enzymes and increased fast-twitch fiber compositions which would result in an enhanc...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,评审
doi：
更新日期：1984-08-01 00:00:00
abstract：PURPOSE:To evaluate the effects of physical activity on bone mineral density, bone mineral content, and lean mass in postmenopausal, overweight/obese women. METHODS:We conducted a 12-month randomized controlled aerobic exercise intervention versus control in 173 sedentary, overweight/obese, postmenopausal women, aged ...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,随机对照试验
doi：10.1249/01.mss.0000227308.11278.d7
更新日期：2006-07-01 00:00:00
abstract：INTRODUCTION:Dementia caregivers have an increased risk of cardiovascular disease, and it is possible that metabolic disturbances contribute to this risk. Regular physical exercise reduces cardiometabolic risk, but caregivers may have less opportunity to engage in such activity. We hypothesized that regular physical ac...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e3181e6d478
更新日期：2011-01-01 00:00:00
abstract：PURPOSE:The purpose of this study was to examine the relative association of physical activity, cardiorespiratory fitness (CRF), and adiposity with C-reactive protein (CRP) in prepubescent children. METHODS:Forty-five prepubescent children (age = 9.4 ± 1.6 yr; 26 boys) were assessed for adiposity (percent fat) via dua...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e3181e0355e
更新日期：2010-11-01 00:00:00
abstract：:Natural killer (NK) cells are highly influenced by physical exercise. The possible important mechanisms behind exercise-induced changes in NK cell function are cytokines, hyperthermia, and stress hormones, including catecholamines, growth hormone, cortisol, and beta-endorphins. Infusion studies mimicking stress hormon...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,评审
doi：10.1249/00005768-199402000-00003
更新日期：1994-02-01 00:00:00
abstract：PURPOSE:To examine whether knowledge of the 1995 Centers for Disease Control and Prevention (CDC) and the American College of Sports Medicine (ACSM) national physical activity recommendations varies by sociodemographic, behavioral, and communication-related factors. METHODS:Cross-sectional analyses of 2381 participant...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章
doi：10.1249/MSS.0b013e3181a52100
更新日期：2009-10-01 00:00:00
abstract：:Since many physiological, metabolic, and endocrine changes that occur during pregnancy are evident even at rest, the alterations found during exercise may not necessarily be the same as those found in the normal population. Nonetheless, the exercise-induced cardiopulmonary changes are essentially normal or slightly ex...
journal_title：Medicine and science in sports and exercise
pub_type： 杂志文章,评审
doi：10.1249/00005768-198508000-00001
更新日期：1985-08-01 00:00:00
abstract：:Psychological consequences of exercise deprivation in habitual exercisers. The purpose of this investigation was to evaluate the influence of 3 d of exercise deprivation on selected psychological variables. Ten volunteers (4 female and 6 male) who regularly exercised 6-7 d.wk-1 for at least 45 min at a time participat...
journal_title：Medicine and science in sports and exercise
pub_type： 临床试验,杂志文章
doi：10.1097/00005768-199609000-00018
更新日期：1996-09-01 00:00:00
