CONTEXT: Reducing sedentary behaviors, or time spent sitting, is an important target for health promotion in children. Standing desks in schools may be a feasible, modifiable, and acceptable environmental strategy to this end.
OBJECTIVE: To examine the impact of school-based standing desk interventions on sedentary behavior and physical activity, health-related outcomes, and academic and behavioral outcomes in school-aged children.
DATA SOURCES: Ovid Embase, Medline, PsycINFO, Web of Science, Global Health, and CINAHL.
STUDY SELECTION: Full-text peer-reviewed journal publications written in English; samples of school-aged youth (5–18 years of age); study designs including the same participants at baseline and follow-up; and use of a standing desk as a component of the intervention.
DATA EXTRACTION: Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.
RESULTS: Eight studies satisfied selection criteria and used quasi-experimental (n = 4), randomized controlled trial (n = 3), and pre–post, no control (n = 1) designs. When examined, time spent standing increased in all studies (effect sizes: 0.38–0.71), while sitting time decreased from a range of 59 to 64 minutes (effect sizes: 0.27–0.49). Some studies reported increased physical activity and energy expenditure and improved classroom behavior.
LIMITATIONS: One-half of the studies had nonrandomized designs, and most were pilot or feasibility studies.
CONCLUSIONS: This initial evidence supports integrating standing desks into the classroom environment; this strategy has the potential to reduce sitting time and increase standing time among elementary schoolchildren. Additional research is needed to determine the impact of standing desks on academic performance and precursors of chronic disease risk.
- PRISMA —
- Preferred Reporting Items for Systematic Reviews and Meta-Analyses
- RCT —
- randomized controlled trial
Reducing time in sedentary behaviors (ie, waking time spent sitting or reclining, with energy expenditure <1.5 metabolic equivalents1) is a target for health promotion and obesity prevention efforts in youth.2 Recent evidence from a systematic review of cross-sectional and prospective studies has shown that children’s leisure time sedentary behaviors are associated with unfavorable body composition and other metabolic and cardiovascular disease risk biomarkers, decreased fitness, and lower scores for self-esteem, as well as decreased academic achievement.3 Studies have also shown that sedentary behaviors may be associated with health risks that are in addition to those attributable to not engaging in sufficient levels of physical activity4–6; some findings have been equivocal, however.5
Given the structured environment, the supervision provided by teachers and other school personnel, and the fact that youth spend >50% of the school day sitting, schools present an ideal setting in which to integrate health promotion interventions.7–9 Many interventions have successfully targeted promoting physical activity in schools through physical education, recess, and during lunch breaks and before- and after-school activities.10–13 An activity-permissive curriculum may also yield benefits for academic performance, cognitive functioning, time on task, and other important academic and behavioral outcomes.14–17
The incorporation of “standing desks” or “sit-to-stand desks” which can be raised or lowered in the classroom is a more recent strategy that is being explored to reduce the time children spend sitting in school. This option would be expected to encourage more time spent standing and in light ambulatory movement, improved postural control and function, and increased muscular activity and energy expenditure.18,19 The integration of classroom desks which reduce the time that students spend sitting is a promising target for children’s health promotion initiatives. Indeed, an increasing number of interventions have been tested by using this approach, but the relevant evidence has yet to be synthesized.
In the present systematic review, the effects of school-based standing desk interventions on students’ sedentary behavior and physical activity, health-related outcomes (eg, body composition, caloric expenditure), and academic-related outcomes (eg, academic achievement, classroom behavior) were examined.
The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement was used to identify and collate studies.20 Our systematic review began with a search of the literature to locate articles that used quantitative methodology to assess the effects of standing desk interventions in school grades kindergarten through 12. Standing desk interventions were conceptualized as those which involved changes to the classroom physical environment that supported or encouraged reductions in sitting. Desk designs included both adjustable “sit-to-stand desks,” which permitted use of a stool, and “standing desks,” which did not have a stool.
The first and second authors identified (with the assistance of a medical librarian to ensure a balance of sensitivity and specificity) relevant sources through searches of the following electronic bibliographic databases: Ovid Embase, Ovid Medline, Ovid PsycINFO, Web of Science, Global Health, and CINAHL. The search included articles published from database inception to September 2014. An updated search was conducted in July 2015 with the use of PubMed and Google Scholar to obtain the most recently published articles. The results were limited to full-article peer-reviewed publications written in English. The search terms included the key words: “student OR pupil” AND “school OR education OR classroom” AND “standing desk OR furniture OR standing OR sitting OR seated OR desk OR sit-stand OR stand biased OR sedentary behavior” (Supplemental Table 3). To identify any articles that may have been missed during the literature search, reference lists of candidate articles were reviewed; this search yielded no additional articles.
Study Selection Criteria
The first and second authors independently reviewed the titles and abstracts of all citations identified by the literature search. Our selection criteria were specified in advance and included the following: (1) published in English in a peer-reviewed journal; (2) available in full text; (3) included youth in grades kindergarten through 12 (∼5–18 years of age, excluding preschool-aged children); (4) intervention designs (ie, randomized controlled trial [RCT], quasi-experimental, pre–post design with no control condition); (5) studies that examined the effects of standing desks on the same students (ie, within-subjects design); and (6) studies that used standing desks as at least 1 component of the intervention. Observational, correlational, and descriptive studies were excluded, as were technical reports, reviews, editorials, unpublished manuscripts, and abstracts. If multiple articles were available from a single study, the most recently published article or the article containing the most comprehensive detail of study characteristics was selected for review and, where appropriate, included data from the other articles.
Article Review and Data Extraction
The PRISMA reporting guideline was adopted for the present article to improve transparency and completeness of reporting.20 The first author conducted the data extraction by using structured summary tables to obtain reliable and consistent data from the primary studies. The fifth author checked data extraction independently, and discrepancies were resolved by discussion. Information was extracted pertaining to study characteristics: author; year; country; study aim; and descriptions of school, sample, study, and intervention.
A second data display matrix was created to extract data related to the study outcomes, including sedentary behavior–related or physical activity–related outcomes (eg, total sedentary, sitting or active time), health-related outcomes (eg, energy expenditure, BMI, musculoskeletal pain), and academic-related outcomes (eg, academic achievement, classroom behavior). Where reported, the results of statistical tests (95% confidence intervals or P values) and effect sizes were extracted. Effect sizes were interpreted as no effect (Cohen’s d ≤ 0.1), small effect (Cohen’s d = 0.2–0.4), intermediate effect (Cohen’s d = 0.5–0.7), and large effect (Cohen’s d ≥ 0.8).21 If available, additional information was extracted pertaining to group characteristics, including the effects of standing desks according to gender, race/ethnicity, and grade level.
Studies were categorized based on their year of publication and geographical location. Where available, outcomes for each study were summarized and compared in terms of the net change in sedentary behavior, health, and academic characteristics. Due to significant variations in study design, participants, and treatment lengths, we were unable to conduct a meta-analysis. Furthermore, many studies did not report confidence intervals for the main outcomes; thus, we would have been unable to construct a forest plot. We did, however, calculate effect sizes for studies that reported sufficient information.
Literature Search Results
The PRISMA flow diagram was used to document the literature search process (Fig 1). A total of 2010 articles were identified and imported into Endnote software. Duplicates were removed and any remaining duplicates were manually removed, leaving a total of 1323 articles. A thorough review of all article titles and abstracts was conducted to identify articles to review in full text (n = 14). The majority of articles excluded after review of their title or abstract were due to a cross-sectional design or because they were unrelated to a standing desk intervention. After full-text review, 8 of the 14 articles were excluded, most often due to not assessing a standing desk intervention or being a position paper or review article. The second search for articles published between October 2014 and July 2015 elicited 2 additional sources. Thus, a final sample of 8 articles was identified for the present review. Two publications that reported findings pertaining to the same intervention22,23 were consolidated in the results of the primary study publication.24
Characteristics of the Relevant Studies Identified
Table 1 summarizes the characteristics of the studies included in our review. All studies examined the implementation of standing desks in school classrooms, and all study settings comprised elementary schools (range: first to sixth grade). No data were reported pertaining to the ownership of the schools (private or public) or the school characteristics other than geographical location and the socioeconomic status of the community. The study sample sizes ranged from 8 to 337 participants, and most were either a feasibility or pilot study, with the exception of 1 large RCT conducted in 3 elementary schools.25 Participants’ mean age varied across studies, from 8.0 to 11.6 years; the sample age was not reported in 1 study.24 Gender was reported in all but 1 study, and the proportions of girls ranged from 37.5% to 58.3%. Race/ethnicity was reported in 3 studies and ranged from 23.0% to 70.3% white.25–27 Anthropometric measurements (weight, height, and waist circumference) were reported in 6 studies. Based on Centers for Disease Control and Prevention BMI-for-age percentiles,28 3 samples had a normal mean BMI (BMI ≥5th and <85th percentiles).25,26,29 Three other samples were overweight/obese (BMI ≥85th percentile),27,30,31 and 2 additional studies did not report BMI or height and weight measures to derive BMI.24,32 Geographically, 4 studies were conducted in the United States, 2 in New Zealand, 1 in Germany, and 1 article reported individual findings from Australia and England.
Varied study designs were used, including quasi-experimental (n = 4), RCT (n = 3), and pre–post no control (n = 1). Most studies used a convenience sampling recruitment method (n = 6). The standing desk interventions used 2 variations of standing desks. The first was an adjustable “standing desk” without the use of a stool; this design was used in 3 studies.30–32 The other design was a “sit-to-stand” desk that incorporated both an adjustable standing desk and stool, and some desks included a swinging foot pendulum that permits extra movement and helps to correct posture.24–27,29 There were no marked differences in outcomes between standing desk or sit-to-stand desk designs; henceforth, the term “standing desk” is used to represent both types of desks. Where applicable, the control condition for each study was a traditional seated desk.
In 5 studies, standing desks were configured into workstations as opposed to traditional rows of desks.24,25,27,30,31 In addition to the standing desk intervention, 3 interventions included other nontraditional furniture to induce an activity-permissive and comfortable classroom.27,31,32 In 1 of these studies, the effect of 3 classroom arrangements, including a traditional sitting desk, standing desk, and an activity-permissive classroom, were examined, and results were reported for each condition.31 In the other study, the effects of attending school in a traditional classroom compared with an activity-permissive school environment were examined. In these studies, traditional desks were replaced with standing desks, but floor mats, exercise balls, and beanbags were also available for children to use if tired.27,32 With the exception of 1 study,32 all interventions were <1 year in duration (range: 1–15 months). Sedentary behavior and physical activity data were collected in each study by using at least 1 type of objective measurement (eg, accelerometers, pedometers).
All studies were designed to examine the impact of standing desks on at least 1 of the following outcomes: time spent standing, sitting, and stepping; frequency of step counts and sit-to-stand counts; time spent being physically active in the classroom, walking, dynamic sitting, and sitting on the floor; health (caloric expenditure, BMI, weight/height, and back and neck pain); and academic indicators. The outcomes of the interventions reviewed are displayed in Table 2. A summary of the observed changes in sedentary behavior and physical activity for the intervention group(s) after the integration of standing desks in the classroom is reported in Fig 2.
Effects of Standing Desks on Sedentary Behavior and Physical Activity
Standing Time: The effects of standing desks on standing time were reported in 5 studies, and all indicated improvements in the amount of time children spent standing. In 2 studies, relative to baseline, there was a significant increase, ranging from 26.4% to 30.6%, in the proportion of time children spent standing (P < .05) after the introduction of standing desks in the classroom.26,32 In 2 other studies, children stood for 24 and 40 minutes longer per school day and waking day, respectively, after implementation of the standing desk intervention.27,30 Small and large effect sizes were also found (0.38 and 0.71),26,30 indicating that students stood for the majority of the observation periods. In the 1 study that did not report pre–post data or P values, the mean proportion of time spent standing during the final week of the intervention was 91%.24
Sitting Time and Use of Desks: Sitting time was reported in 4 studies, and each observed a significant decrease in the duration of time children spent sitting after the implementation of the standing desks, ranging from 59 to 64 minutes,27,30 and a 9.4% and 9.8% reduction.26 Small to intermediate effect sizes (ie, 0.27, 0.32, 0.49) were also observed.26,30 In another study, only 2 of 19 students opted for traditional seated desks in the intervention classroom that had both standing and traditional seated desks available.32
Screen time, a proxy often used for sedentary behavior, was examined in 1 study. The investigators found that the intervention classroom reported 71 minutes per day of less television viewing and computer use in the final measurement compared with baseline (t = 2.67; P = .02).27
Physical Activity: The effects of standing desk interventions on step counts and time spent stepping were examined in 6 studies. In 4 studies, the amount of time spent stepping and total step counts improved relative to baseline or control after implementation of the standing desk intervention, but mean differences or effect sizes were either not significant or were small or modest.26,27,29,30 However, after adjustment for sociodemographic characteristics and BMI in 1 large RCT, the classrooms with standing desks had a higher mean step count compared with the control group during the fall semester (1.61 steps/min; P < .001), but the difference decreased to 0.12 step/min (P = .819) in the spring semester.25 In another study that examined differences between 3 intervention exposures (activity-permissive classroom versus traditional desk classroom versus standing desk classroom), significantly more movement for the activity-permissive classroom compared with the 2 other exposures was found (115 m/s2 vs 71 m/s2 vs 71 m/s2; P < .001).31 However, it is worth noting that there may have been an order effect because the same sample experienced all 3 conditions.
However, in another study that used accelerometry to evaluate physical activity, significantly more movement in the standing desk classroom compared with the control classroom was found over a 30-minute period of observation (538 ± 229 vs 134 ± 94 cpm; P < .001).32 In addition, a significantly greater frequency (24.05 vs 2.11 times; P < .001) and duration (10.47% vs 1.75% of time; P < .001) of time spent “walking around” for the intervention classroom compared with the control classroom was shown. In measurements of “being active,” the standing desk classroom had more frequent bouts of activity versus the control classroom (14.00 vs 1.60; P < .001), but there was no significant difference in duration of being active over the 30 minutes of observation (7.79% vs 1.00% of time; P = .225).
Effects of Standing Desks on Health Indicators
Caloric Expenditure and BMI: Caloric expenditure was evaluated in 2 studies by using an armband fitness tracker. In 1 study, children in the standing desk classroom burned 0.182 kcal/min more compared with those in the control classroom of traditional seated desks.24 The difference was most pronounced among children who were overweight/obese. In this subgroup, children exposed to the standing desks burned 1.56 kcal/min versus the control rate of 1.18 kcal/min; however, the authors did not indicate whether this finding was statistically significant. The other study was a large RCT which found, after adjustment for sociodemographic characteristics and BMI, that the classrooms with the standing desks had a higher mean caloric expenditure by 0.16 kcal/min (P < .0001) compared with the control group during the fall semester; this difference decreased to 0.08 kcal/min (P < .01) in the spring semester. In terms of BMI, 1 pre–post study with no control group found no significant or clinical difference in BMI after implementing a 5-month standing desk intervention.29
Neck, Back, and Other Indicators of Pain: The impact of standing desks on neck and back pain was examined in 2 studies. The investigators of 1 study administered a survey during the intervention and found that a greater percentage of children in the intervention group reported neck or back pain than children in the control group (47.4% vs 26.1%), but this finding was not statistically significant (P = .21).32 In another study, neck, shoulder, back, elbow, wrist, hip/thigh, knee, and foot/ankle pain was assessed in the intervention group at baseline and follow-up.27 Although P values were not reported, 4 of the indicators of pain indicated a decline in the percentage of children reporting pain after implementation of the standing desk intervention, most notably foot/ankle (63% to 37%) and elbow (21% to 11%). Two other indicators of pain increased from baseline to follow-up, including hip/thigh (21% to 32%) and knee (26% to 37%), and pain did not change for the shoulder or back.
Effects of Standing Desks on Academic Indicators
Three studies examined the impact of standing desks on classroom behavior and academic indicators.27,29,32 Improvement in classroom behavior, in terms of classroom management, student concentration in academic materials, and student discomfort, reportedly improved in 1 study, but the findings were not statistically significant.29 Similarly, no significant differences between the control and intervention classrooms were reported in terms of frequency (6.78 vs 3.45 times; P = .064) and duration (29.90% vs 26.47%; P = .604) of time spent reading or writing over a 30-minute period of observation.32 Inattention and hyperactivity-impulsivity were examined in another study, and although the intervention group demonstrated a greater reduction in inattention and hyperactivity-impulsivity, there were no significant differences (t = 1.59, P = .16; t = 1.58, P = .13, respectively) between the 2 groups in the final measurement.27
Our review provides initial evidence, derived from examining the findings of intervention trials, that integrating standing desks in schools has the potential to reduce sitting time and increase standing time among elementary schoolchildren. The effects of standing desks on changes in physical activity during the school day were mixed, with some studies reporting no significant change in step counts and stepping time, while others reported increases in classroom physical activity. Although some favorable outcomes were observed in terms of improved classroom behavior and increased energy expenditure, the results were not statistically significant, they had small to intermediate effect sizes, or too few studies were available to make inferences. Nonetheless, the strong, cumulative evidence for reduced sitting time and increased standing time indicates that standing desks have the capacity to reduce sedentary behavior, even when supplementing standing desks with adjustable stools or swinging foot pendulums.
Despite the heterogeneity of outcomes that each study reported and the somewhat equivocal or limited findings, all of the studies identified either a reduction in sedentary time or an increase in standing time. Although heterogeneity in terms of study design, intervention methodology, and sample size did not permit a meta-analysis on overall reduction in sedentary time, 1 study did report an overall reduction in sedentary time of 59 minutes during waking hours30 and another reported a reduction of 64 minutes during the school day.27 Indeed, similar observations have been noted among the adult population, in whom a recent systematic review and meta-analysis confirmed that activity-permissive workstations effectively and feasibly reduced sedentary time by 77 minutes per 8-hour workday.33 Evidence-based guidelines have recently been developed for employers to promote the avoidance of prolonged periods of sedentary work, indicating a gradual increase of 2 to 4 hours of standing or light activity per workday.34
One of the studies included in the present review illustrates the potential health benefits of reducing sedentary time. This study evaluated the impact of stand-biased desks with height-appropriate stools used by students in fourth grade classrooms.24 After 6 weeks, 70% of the students never used their stools to sit and the other 30% stood for the majority of the time that they were at their desks. Furthermore, accelerometer data established that students burned 32 calories more per hour than before implementation of the intervention. During a typical school day, this change would translate into 225 additional calories burned, the equivalent of walking, skateboarding, or roller-skating for 1 hour after school.35 Over the course of a school year, students who stand most of the day could be expected to expend 40 000 calories more than they would have had they been seated all day. Theoretically, this intervention could thus result in a net reduction of ∼12 pounds (5.4 kg) per year in weight gain.
However, standing for long periods without moving also has the potential to increase neck and back pain and result in a reduction in blood pressure.36 The frequency of sit-to-stand transitions, how to stand (eg, shifting weight from 1 foot to the other), and having a resting bar or pendulum for the foot may all be important considerations for future studies and for policy and practice. Furthermore, the design and cost-effectiveness of standing desks versus traditional classroom desks need to be considered. Some estimates suggest sit-to-stand desks cost ∼20% more than traditional seated desks,24 whereas others found standing workstations to cost 40% less than standard desks.26 One study examined the effect of sit-to-stand desks in 1 classroom equipped with such desks for all students and another classroom that rotated the use of sit-to-stand desks among students; interestingly, the investigators noted similar reductions in sitting time relative to control conditions, despite the differences in desk provision.25 Thus, creative and less costly approaches to integrating standing desks in schools may be considered.
Collectively, this evidence suggests that standing desk interventions may reduce sedentary behavior and could therefore have implications for health promotion initiatives in the school setting. Indeed, the efficacy and effectiveness of other health promotion interventions in the school setting have been established; these interventions include those that aim to increase physical activity and improve dietary behavior through health education, curriculum-based behavior change, parental education and support, environmental modification, use of other activity-permissive equipment (ie, exercise balls), and/or policy change,.37–40 Results of most school-based health promotion programs demonstrate significant improvements in knowledge, self-efficacy, and health behavior for physical activity and healthy eating.41
These observations provide support for ecological models that identify those modifiable individual (student and parent), interpersonal (peers and teachers), and community/environmental (school neighborhoods, grounds, building design, facilities, and equipment) determinants of sedentary behavior and physical inactivity that may interact to drive long-term behavior change, improve metabolic functioning, and potentially help to prevent weight gain.42–44 Because of the ubiquitous opportunities for students to be sedentary during the school day, such as during transportation, class, and at lunch, a multipronged approach to promoting the avoidance of prolonged periods of sedentary behavior is warranted.
Further research is needed to determine the efficacy, effectiveness, and feasibility of implementing standing desks on a larger scale with longer term follow-up. Although the studies included in this review provide evidence of the potential for standing desks to improve standing time and reduce sedentary behavior in elementary schools, most were relatively small-scale studies and were therefore limited by a small sample size, low statistical power, nonrandomized study design, lack of intention-to-treat analyses, order effect of intervention delivery, and long-term follow-up, or they lacked valid and reliable measures of sedentary behavior. Furthermore, few of the studies examined the same outcomes in terms of health indicators (ie, energy expenditure, BMI) or academic parameters (ie, test scores) to comment on those outcomes.
Further studies are needed with adequately powered RCT designs, the use of objective measures that allow quantitative estimates of energy expenditure (ie, accelerometry or inclinometers) and that examine the impact of standing desks according to gender, race/ethnicity, and age group (including adolescents in middle and high school). Assessment of strategies that may be used to successfully implement standing desks in the classroom is also needed, such as the degree of teacher instruction and development of educational curricula to teach students about the benefits of standing and reducing time spent sedentary. Qualitative research is also needed to assess the perceptions of educators, administrators, students, and parents on integrating standing desks into the school setting.
In addition to the methodologic limitations of the studies included in this review, our findings must be interpreted in the context of the following limitations. First, although exhaustive search methods were used to eliminate any potential bias, it is possible that not all quantitative studies were identified. In addition, the exclusion of unpublished and gray literature may have contributed an element of publication bias, with potential implications for the robustness of the findings; however, such studies may have lower methodologic quality45 and likely did not evaluate the effects of the intervention on the same students. Second, the sample characteristics of race/ethnicity and school characteristics were omitted from several of the reviewed studies, potentially influencing the generalizability of the findings to other contexts. Third, some of the studies reviewed did not report tests of statistical significance or pre–post data; when complete data were available, however, effect sizes were calculated. It is also worth noting that our findings must be interpreted with caution as few studies have been published in this area and most studies included in this review lacked long-term follow-up.
The early evidence found that standing desk interventions in the school setting have the potential to reduce sitting time and increase standing time in elementary grade children. In essence, it can be hypothesized that students could effectively learn while simultaneously reducing the high volumes of sedentary time accumulated through passive and static sitting in the classroom. However, additional research is needed to examine the impact of standing desks on academic performance, precursors of chronic disease risk, and other outcomes. The implementation of standing desks in schools may be a feasible, acceptable, and beneficial environmental strategy to reduce sedentary behavior in the school setting, but further and more rigorous research studies are needed to determine the efficacy and effectiveness of this approach.
- Accepted November 16, 2015.
- Address correspondence to Karl E. Minges, MPH, Yale School of Nursing, 400 West Campus Dr, Orange, CT 06477. E-mail:
FINANCIAL DISCLOSURE: The authors have indicated they have no financial relationships relevant to this article to disclose.
FUNDING: Mr Minges was funded by a predoctoral fellowship from the National Institute of Diabetes and Digestive and Kidney Disease/National Institutes of Health (T32-DK07718). Dr Chao was funded by a predoctoral fellowship from the National Institute of Nursing Research/National Institutes of Health (F31-NR014375). Dr Owen was funded by a National Health and Medical Research Council Program Grant (no. 569940), a Senior Principal Research Fellowship (National Health and Medical Research Council #1003960), and the Victorian Government’s Operational Infrastructure Support Program. Dr Salmon was funded by a Principal Research Fellowship, National Health and Medical Research Council (APP1026216). Funded by the National Institutes of Health (NIH).
POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose.
- Owen N,
- Healy GN,
- Matthews CE,
- Dunstan DW
- Peterson KE,
- Fox MK
- Minges KE,
- Chao A,
- Nam S,
- Grey M,
- Whittemore R
- Murray R,
- Ramstetter C; Council on School Health; American Academy of Pediatrics
- Hamilton MT,
- Hamilton DG,
- Zderic TW
- Cohen A
- Benden M,
- Pickens A,
- Shipp E,
- Perry J,
- Schneider D
- Clemes SA,
- Barber SE,
- Bingham DD, et al
- Kuczmarski RJ,
- Ogden CL,
- Guo SS, et al.
- Koepp GA,
- Snedden BJ,
- Flynn L,
- Puccinelli D,
- Huntsman B,
- Levine JA
- Buckley JP,
- Hedge A,
- Yates T, et al
- Council on Sports Medicine and Fitness; Council on School Health
- Copyright © 2016 by the American Academy of Pediatrics