Evidence-Based Referral: Effects of the Revised Youth Fit 4 Life Protocol on Physical Activity Outputs

James J Annesi, PhD, FAAHB, FTOS, FAPA; Linda L Vaughn, MS, MBA

Perm J 2015 Summer; 19(3):48-53 [Full Citation]



Background: Lack of physical activity is prevalent in youths. Pediatricians seek referrals to reliably increase outputs, especially in their overweight and underactive patients.
Objective: Within a randomized controlled trial, we contrasted 2 physical activity/nutrition treatments on the basis of social cognitive and self-efficacy theory, and a comparison condition, on time in moderate-to-vigorous physical activity (MVPA) during the 45-min/day physical activity segment of elementary afterschool care.
Methods: In youths ranging in age from 9 to 12 years (9.7 ± 0.8 years, overall), the Original Youth Fit For Life treatment (Original YFFL; n = 49), the Revised Youth Fit 4 Life treatment (Revised YF4L, n = 43), and a comparison condition of typical care (Comparison, n = 46) were contrasted using a 3 (groups) × 2 (sexes) analysis of variance incorporating means of 3 accelerometer measurements over 12 weeks.
Results: There was a significantly greater amount of time in MVPA in the Revised YF4L group than either the Original YFFL or Comparison groups (F2, 132 = 281.20, p < 0.001). Boys completed significantly more time in MVPA than girls (F2, 132 = 16.43, p < 0.001); however, there was not a significant group × sex interaction. Supplementary analyses indicated sedentary time was significantly less by 29% in the Revised YF4L when contrasted with the Comparison group.
Conclusion: The Revised YF4L protocol that sought to maximize participants' cardiovascular physical activity appeared to improve upon the Original YFFL treatment on time in MVPA. Thus, pediatricians might have confidence in referring their patients to such evidence-based approaches. Future research should also evaluate the effects of YF4L on psychosocial predictors of physical activity and change in body mass index.


In the US, more than one-third of youths are presently overweight or obese.1 Comorbidities include increased risk for type 2 diabetes, heart disease, orthopedic injuries, cardiorespiratory problems, and self-esteem issues.2,3 Physical activity among children of all ages has decreased,4 and this decrease is associated with an inappropriately high weight.5 The Centers for Disease Control and Prevention's recommendation for physical activity in children is at least 60 minutes per day of moderate-to-vigorous physical activity (MVPA).6 However, a recent population-based study using accelerometry found that only 42% of US children ages 9-11 years attained this volume.7 Consistent with other research,8 the percentage of boys attaining the recommended amount of physical activity (49%) was considerably greater than that of girls (35%). Notably, the percentages fall to an even more dismal 8% completing the recommended minimum starting at age 12 (3% for girls).7 Because physical activity is the strongest predictor of controlling weight as one ages,9 these patterns of low activity suggest a continuation of the obesity epidemic unless substantial changes occur.

Pediatricians take seriously the need for children to obtain enough physical activity to prevent or improve inappropriately high weight, as well as for promoting cardiovascular fitness. Because pediatricians are not likely to be in a position to directly provide physical activity to patients, they often seek community-based resources as referrals. However, the effectiveness of these resources may vary greatly. For example, although local sports and recreation programs are widely available, overweight, deconditioned, and nonathletic children might feel threatened around more fit and athletic peers. This might lead to even less desire for physical activity for them in the future. Also, many popular sports (eg, baseball, softball, bowling) might not provide much MVPA.

Although physical education (PE) class during the school day provides an obvious venue for physical activity in elementary school students, recent research found that only 27% of a typical class period of 45 minutes (~12 min) is spent in MVPA.10 This is consistent with earlier findings,11-13 and falls significantly short of the Centers for Disease Control and Prevention's recommendations of at least 50% of the PE class period being in MVPA.14 Fewer than 4% of elementary schools provide daily PE, and walking or bicycling to school and recess time have decreased.4 Although physical activity is associated with favorable academic performance,15 school administrators have been unwilling to increase or improve PE. Thus, the highly utilized after-school care setting has been suggested as important for facilitating physical activity.16

Although the provision of dedicated time and space for physical activity during after-school care is common, treatments or protocols have varied widely in terms of their supervision, structure, and physical outputs.16,17 They have ranged from supervised "free play" (participation optional), to highly structured protocols based on accepted theoretical models of health behavior change. Youth Fit For Life (YFFL), first evaluated in 2005,18 was one such structured program; it is based on tenets of social cognitive theory19 and self-efficacy theory20 such as building self-regulatory skills and feelings of ability and mastery, and utilizing social supports. It included components of cardiovascular exercise, resistance exercise, self-regulation skills building (eg, goal setting, controlled self-talk), and nutrition education. Although elementary after-school care treatments have often been atheoretical and lacking in significant health outcomes, numerous studies suggested the positive impact of YFFL on physical activity (both within and outside of structured settings),21-23 body mass index (BMI),24 psychological well-being,25-27 and psychosocial predictors of health behaviors.18,22,23,28 After its validation, YFFL was made available nationally as a program certified by the Research-Tested Intervention Program of the National Institutes of Health and the National Cancer Institute (http://rtips.cancer.gov/rtips/programDetails.do?programId = 293932), usable within a number of community-based venues serving elementary school-age youths. In an effort to better tailor the treatment processes of the Original YFFL to specific age ranges, enhance self-regulatory skills training, improve participants' nutrition behaviors, better address overweight/obesity, and further increase time in MVPA, a revision of the YFFL protocol (entitled Youth Fit 4 Life [YF4L]) was recently developed.

The present preliminary study aimed to contrast the Revised YF4L with typical care and the Original YFFL on time in MVPA during elementary after-school care, while also considering the sex of participants. This is the first investigation on the effects of YF4L, which sought to extend and improve upon YFFL by maximizing participants' time in cardiovascular exercise, making self-regulation skills more palatable, and better supporting consistent nutrition themes. Ages 9-12 were selected for this investigation because there was a somewhat different YF4L curriculum for ages 5-8 and 9-12 (suggesting the need for separate study). It was expected that the Revised YF4L treatment would be associated with a significantly greater duration of time in MVPA, and significantly less time in sedentary and light physical activities, than both the Original YFFL treatment and typical after-school care processes. Boys were expected to demonstrate greater time in MVPA, regardless of group. It was hoped that this initial validation study would inform revisions of the YF4L treatment in regard to its effects on physical activity outputs. Also, results might provide data for pediatricians to assess the usefulness of  YF4L for referral of their patients.



Participants included youths, ages 9-12 years, enrolled in randomly selected elementary after-school care programs operated by YMCA facilities in the greater Atlanta, GA, area. Parents/legal guardians signed written consent forms, and participants provided verbal assent to study staff. Institutional review board approval was received, and processes conformed to the provisions of the Declaration of Helsinki. An inclusion requirement was attendance in at least 2 of the 3 monthly measurement sessions. Data were excluded if a youth arrived late or left early, demonstrated inappropriate behavior, or reported an injury. Thus, the final sample sizes for the 1) typical after-school care processes (Comparison, n = 46), 2) Original YFFL protocol (n = 49), and 3) Revised YF4L protocol (n = 43) reflected those adjustments.

 The sample size adjustments did not significantly differ by group (χ2(df = 2) = 1.09, p = 0.579), with a mean removal of 26.9% of youths, overall, caused by the above conditions. There was also no significant group difference in age (F2, 135 = 0.90, p = 0.410; overall mean ± SD = 9.7 ± 0.8 years), sex (χ2(df = 2) = 2.37, p = 0.305; 51.4% girls, overall), or ethnic grouping (χ2(df = 8) = 14.10, p = 0.079; 31.9% white, 43.5% African American, 14.5% Hispanic, 6.5% Asian, and 3.6% of other ethnicities, overall). On the basis of postal zip codes of participants' residences, almost all were in the middle class.


Physical activity intensity category and time were quantified using the Actigraph GT3X accelerometer (ActiGraph, Pensacola, FL). Consistent with previous research,29 the monitor was attached at the left side of the waist with a belt, over participants' clothing. A 30-s sampling interval (epoch) was used to best capture activity patterns found in youths of ages 9 to 12 years.30 The accelerometer recorded 45 minutes (± 1 min) of physical activity during each of the 3 monthly measurements. No measurements were made in the initial week of after-school care because the learning of new physical activity tasks associated with the present protocols might have affected outputs most during this time. The ActiGraph ActiLife data analysis software, version 5.10.0 (ActiGraph, Pensacola, FL), converted accelerometer counts into time in sedentary, light, moderate, and vigorous physical activity on the basis of cut points established by Evenson,30 which were subsequently determined to be the most accurate estimations available for ages 5 to 15 years.31 MVPA was derived by summing the times in moderate and vigorous physical activity.

Several previous studies reported strong interinstrument reliability of the ActiGraph accelerometer (r = 0.84-0.92).32-34 There were also significant correspondences between scores derived from the ActiGraph accelerometer and VO2 treadmill testing (r = 0.82-0.87)34 and doubly labeled water measurements (r = 0.39-0.54)35 in children within the age range of this research. It was suggested that the ActiGraph accelerometer had the largest body of research supporting its use.36


YMCA-based after-school care was administered in the same elementary school that participants attended during the school day by the existing after-school care counselors. Regardless of group, the school gymnasium was used for the standard session of 45 min/day reserved for physical activity. Study staff secured the accelerometers to each participant's waist. Although it was obvious that the accelerometer assessed physical activity, there was no coaching given to participants or counselors by study staff to either maximize or minimize intensities. As far as possible, all were kept blind to the purposes of the study. After-school care counselors were generally unfamiliar with PE instruction methods before the training provided on the present protocols. No counselor was involved with more than 1 group. The number of participants per group ranged from 10 to 18, although not all youths present were included in this research (owing mostly to an inability of study staff to secure written consent from parents/guardians).

For the Comparison group, there was no training provided to after-school care counselors beyond information needed for supervision of physical activity in a safe environment. This was provided during the job orientation. For this study, counselors were asked to administer the physical activity component of after-school care in the manner that was typical for them. Some participants ran, some played skill-games in small groupings, and some engaged in primarily sedentary pursuits. It was also an option for participants to use the sport or physical activity equipment (eg, balls and jump ropes) that were stored in the gymnasium.

For the Original YFFL group, after-school care counselors were provided 5 hours of training in the protocol's 4 components: cardiovascular exercise, strength exercise (via rubber resistance bands), behavioral skills, and nutrition. This was supported by an instructor manual and participant workbook that guided program processes37 and the required apparatus (eg, balls, bean bags, resistance bands). In addition to the behavioral skills (eg, short- and long-term goal setting, obtaining progress feedback, thought stopping and use of productive self-talk, recruiting social supports) and nutrition-education components, 30 to 35 minutes was to be dedicated to physical activity via noncompetitive games or tasks that were designated as either high or moderate intensity. Every attempt was to be made to keep participants 1) active, 2) challenging themselves, and 3) fostering feelings of mastery and self-efficacy regarding their fitness and physical abilities. The treatment was intended for ages 5 to 12 years.

For the Revised YF4L group, after-school care counselors were provided a newly designed training of approximately 5 hours, a supporting manual, and apparatus similar to the Original YFFL.38 There was a separate training manual for ages 5 to 8 years; however, only the 9- to 12-year-old version applied here.38 Although application of behavioral skills training and nutrition education remained in the Revised YF4L (in an enhanced form), the separate strength training component was omitted. Rather, participants' own body weight now replaced use of the resistance bands in an effort to minimize time being nearly stationary. Also, both behavior and nutrition topics were reinforced through the use of a new array of cardiovascular activities (ie, "content reinforcement activities"), and new moderate- and high-intensity tasks were incorporated. Competition with oneself, rather than with other participants, was emphasized. On the basis of earlier research on the Original YFFL,21,23 behavioral skills and their associated graphics (eg, posters, hand-outs) were intended to better improve participants' physical self-concept, fitness goal progress, and self-efficacy. As with the Original YFFL, 30 to 35 min/session was to be dedicated to physical activities, and a goal of attaining a mean of 25 to 30 minutes in MVPA was set.

Although the physical activity component of after-school care was five days/week, and the Original YFFL and Revised YF4L protocols met three days/week and four days/week, respectively, analyses were based on single sessions to facilitate statistical contrasts. All personal identifiers were removed before data analyses. Fidelity checks for physical activity programming were completed once every two weeks by YMCA wellness staff using a structured observation form. Any problems were quickly resolved in association with the after-school counselor's supervisor.

Data Analyses

To detect the moderate effect size found in related analyses and pilot research39 at the statistical power of 0.80, an overall minimum sample size of 117 was required.40 The significance level was set at α = 0.05 (2-tailed). It was previously suggested that 3 accelerometer measurements foster accuracy in assessing physical activity outputs in youth.41 Thus, after using the expectation-maximization algorithm for imputation of missing data of no more than 1 of the 3 monthly measurements,42 the mean number of minutes in each physical activity category (ie, sedentary, light, moderate, and vigorous) was calculated. There was no significant difference in scores based on date of measurement for any of the physical activity categories.

For the primary analysis, a 2-way between-subjects analysis of variance of 3 (groups) × 2 (sexes) was used to contrast the Comparison, Original YFFL, and Revised YF4L groups; boys and girls; and their interaction on mean number of minutes in MVPA. Post hoc follow-up tests using the Least Significant Difference method were incorporated for pairwise contrasts. Supplementary analyses were also completed on each of the 4 separately measured physical activity intensity categories (ie, sedentary, light, moderate, and vigorous) in the same manner. Effect sizes were expressed as partial eta-square (η2p) where 0.01, 0.06, and 0.14 denote small, moderate, and large effects, respectively.


Primary Analysis

For MVPA, the main effect for treatment group was significant (F2, 132 = 281.20, p < 0.001, η2p = 0.17). The main effect for sex was also significant (F2, 132 = 16.43, p < 0.001, η2p = 0.11). There was not a significant group × sex interaction (F2, 132 = 0.54, p = 0.582, η2p = 0.01). Descriptive statistics and results of all pairwise post hoc analyses are given in Table 1.

Supplementary Analyses

For sedentary time, the main effect for treatment group was significant (F2, 132 = 5.57, p = 0.005, η2p = 0.08). The main effect for sex was not significant (F2, 132 = 1.91, p = 0.169, η2p = 0.01). There was not a significant group × sex interaction (F2, 132 = 0.21, p = 0.813, η2p = 0.003).

For light physical activity, the main effect for treatment group was not significant (F2, 132 = 2.08, p = 0.130, η2p = 0.03). The main effect for sex was significant (F2, 132 = 4.81, p = 0.030, η2p = 0.04). There was not a significant group × sex interaction (F2, 132 = 0.29, p = 0.748, η2p = 0.004).

For moderate physical activity, the main effect for treatment group was not significant (F2, 132 = 2.52, p = 0.085, η2p = 0.04). The main effect for sex was significant (F2, 132 = 12.01, p = 0.001, η2p = 0.08). There was not a significant group × sex interaction (F2, 132 = 1.05, p = 0.354, η2p = 0.02).

For vigorous physical activity, the main effect for treatment group was significant (F2, 132 = 24.13, p < 0.001, η2p = 0.27). The main effect for sex was also significant (F2, 132 = 10.04, p = 0.002, η2p = 0.07). There was not a significant group × sex interaction (F2, 132 = 0.37, p = 0.692, η2p = 0.01).



The Revised YF4L treatment was associated with a significantly greater duration of time in accelerometer-measured MVPA when contrasted with typical after-school care and the Original YFFL protocol. This is an important finding because numerous studies suggested the positive effects of the original theory-based protocol on various health behaviors and their psychosocial predictors.18,22-28 For the Revised YF4L, sedentary time was also significantly less than with typical after-school care processes. Consistent with other research,7 boys were more active than girls. Although there was no treatment × sex interaction found, future research should integrate and evaluate intervention components that might increase MVPA specifically for girls (possibly by incorporating modes of activity that might be especially appealing to them).

Although it was above the typical proportion of MVPA/overall time in PE class previously reported for elementary school ages,10-13 the goal of 25 to 30 minutes/day in MVPA was not attained. Approximately one-third of the treatment time presently spent in light physical activity and sedentary time (~9 min/day) would need to be converted to moderate and/or vigorous activity to attain that goal. Although an attempt was made to reinforce the learning of behavioral skills and nutrition information through physical activities, such activities might also be extended to the time during the learning process itself to increase total time in MVPA in the future.


Although various ethnicities were represented, future research should evaluate the benefit of YF4L specifically in underrepresented and minority groups, who also tend to have the greatest health risks.1 Replication should also be completed on the YF4L version for ages 5 to 8 years. Although limitations included a lack of data on 1) psychosocial mediators of MVPA; 2) effects on BMI, nutrition, and changes in MVPA outside of the programs, and 3) expectation effects (eg, Hawthorne effect; Rosenthal effect),43 these initial findings on the Revised YF4L protocol in elementary after-school care were informative. Additional validation research is now required to evaluate effects of YF4L on BMI and psychosocial factors. Also, because resistance training was omitted in the new YF4L curriculum (except for some body weight resistance incorporated within the increased cardiovascular exercise time), favorable benefits related to muscle mass and muscular strength gains might have been reduced.


It is hoped that, ultimately, widespread dissemination of evidence- and theory-based protocols such as YF4L will allow pediatricians to have confidence in referring patients in need of programs for increasing their MVPA and, possibly, normalizing their BMI. Involvement from physicians in matters of health behavior change is increasingly warranted and could have immense pay-offs for the future health of the nation.

Disclosure Statement

The author(s) have no conflicts of interest to disclose.


We acknowledge Sarah Samter and Brittney Greenwood for their expertise provided in the data collection phase of this study. We also acknowledge contributions provided on protocol development by the staff of Children's Healthcare of Atlanta.

Mary Corrado, ELS, provided editorial assistance.

 1.    Ogden CL, Carroll MD, Kit BK, Flegal KM. Prevalence of childhood and adult obesity in the United States, 2011-2012. JAMA 2014 Feb 26;311(8):806-14. DOI: https://doi.org/10.1001/jama.2014.732.
    2.    Daniels SR, Arnett DK, Eckel RH, et al. Overweight in children and adolescents: pathophysiology, consequences, prevention, and treatment. Circulation 2005 Apr 19;111(15):1999-2012. DOI: https://doi.org/10.1161/01.CIR.0000161369.71722.10.
    3.    Dietz WH. Overweight in childhood and adolescence. N Engl J Med 2004 Feb 26;350(9):855-7. DOI: https://doi.org/10.1056/NEJMp048008.
    4.    Building evidence to prevent childhood obesity [Internet]. Minneapolis, MN: Healthy Eating Research; [cited 2015 Apr 22]. Available from: http://healthyeatingresearch.org/who-we-are/the-childhood-obesity-epidemic/.
    5.    Must A, Tybor DJ. Physical activity and sedentary behavior: a review of longitudinal studies of weight and adiposity in youth. Int J Obes (Lond) 2005 Sep;29 Suppl 2:S84-96. DOI: https://doi.org/10.1038/sj.ijo.0803064.
    6.    Childhood obesity facts [Internet]. Atlanta, GA: Centers for Disease Control and Prevention; [updated 2014 Dec 11; cited 2015 Mar 18]. Available from: www.cdc.gov/healthyyouth/obesity/facts.htm.
    7.    Troiano RP, Berrigan D, Dodd KW, Mâsse LC,

Tilert T, McDowell M. Physical activity in the United States measured by accelerometer.

Med Sci Sports Exerc 2008 Jan;40(1):181-8.

DOI: https://doi.org/10.1249/mss.0b013e31815a51b3.
    8.    Lenhart CM, Hanlon A, Kang Y, Daly BP, Brown MD, Patterson F. Gender disparity in structured physical activity and overall activity level in adolescence: evaluation of youth risk behavior surveillance data. ISRN Public Health [Internet] 2012 [cited 2015 Mar 12];2012:[8 p]. DOI: https://doi.org/10.5402/2012/674936. Available from: www.hindawi.com/journals/isrn/2012/674936/cta/.
    9.    Svetkey LP, Stevens VJ, Brantley PJ, et al;

Weight Loss Maintenance Collaborative Research Group. Comparison of strategies for sustaining weight loss: the weight loss maintenance randomized controlled trial. JAMA 2008 Mar 12;299(10):1139-48. DOI: https://doi.org/10.1001/jama.299.10.1139.
    10.    Matthews-Ewald MR, Moore LC, Harris CV, Bradlyn AS, Frost SS. Assessing moderate to vigorous physical activity in rural West Virginia elementary school physical education classes.

W V Med J 2013 Jul-Aug;109(4):12-6.
    11.    McKenzie TL, Feldman H, Woods SE, et al. Student activity levels and lesson context during third-grade physical education. Res Q Exerc Sport 1995 Sep;66(3):184-93. DOI: https://doi.org/10.1080/02701367.1995.10608832.
    12.    Simons-Morton BG, Taylor WC, Snider SA, Huang IW. The physical activity of fifth-grade students during physical education classes. Am J Public Health 1993 Feb;83(2):262-4. DOI: https://doi.org/10.2105/AJPH.83.2.262.
    13.    UCLA Center to Eliminate Health Disparities; Samuels & Associates. Failing fitness: physical activity and physical education in schools [Internet]. Los Angeles, CA: The California Endowment; 2007 Jan [cited 2014 Oct 15]. Available from: www.calendow.org/uploadedFiles/failing_fitness.pdf.
    14.    Guidelines for school and community programs to promote lifelong physical activity among young people [Internet]. Atlanta, GA: Centers for Disease Control and Prevention; 1997 Mar 7 [cited 2014 Oct 15]. Available from: http://wonder.cdc.gov/wonder/Prevguid/m0046823/m0046823.asp.
    15.    Rasberry CN, Lee SM, Robins L, et al. The association between school-based physical activity, including physical education, and academic performance: a systematic review of the literature. Prev Med 2011 Jun;52 Suppl 1:S10-20. DOI: https://doi.org/10.1016/j.ypmed.2011.01.027.
    16.    Atkin AJ, Gorely T, Biddle SJ, Cavill N, Foster C.

Interventions to promote physical activity in young people conducted in the hours immediately after school: a systematic review. Int J Behav Med 2011 Sep;18(3):176-87. DOI: https://doi.org/10.1007/s12529-010-9111-z.
    17.    Beets MW, Huberty J, Beighle A; Healthy Afterschool Program Network. Physical activity of children attending afterschool programs: research- and practice-based implications. Am J Prev Med 2012 Feb;42(2):180-4. DOI: https://doi.org/10.1016/j.amepre.2011.10.007.
    18.    Annesi JJ, Westcott WL, Faigenbaum AD,

Unruh JL. Effects of a 12-week physical activity protocol delivered by YMCA after-school counselors (Youth Fit For Life) on fitness and self-efficacy changes in 5-12-year-old boys and girls. Res Q Exerc Sport 2005 Dec;76(4):468-76. DOI: https://doi.org/10.1080/02701367.2005.10599320.
    19.    Bandura A. Health promotion by social cognitive means. Health Educ Behav 2004 Apr;31(2):143-64. DOI: https://doi.org/10.1177/1090198104263660.
    20.    Bandura A. Self-efficacy: the exercise of control. New York, NY: WH Freeman Publishers; 1997.
    21.    Annesi JJ. Relations of physical self-concept and self-efficacy with frequency of voluntary physical activity in preadolescents: implications for after-school care programming. J Psychosom Res 2006 Oct;61(4):515-20. DOI: https://doi.org/10.1016/j.jpsychores.2006.04.009.
    22.    Annesi JJ, Moore JC, Dixon GM. Correlates of changes in voluntary physical activity associated with the Youth Fit For Life intervention during after-school care. Psychol Rep 2008 Jun;102(3):911-9. DOI: https://doi.org/10.2466/pr0.102.3.911-919.
    23.    Annesi JJ, Faigenbaum AD, Westcott WL, Smith AE. Relations of self-appraisal and mood changes with voluntary physical activity changes in African American preadolescents in an after-school care intervention. J Sports Sci Med 2008 Jun 1;7(2):260-8.
    24.    Annesi JJ, Marti CN, Stice E. A meta-analytic review of the Youth Fit For Life intervention for effects on body mass index in 5- to 12-year-old children. Health Psychol Rev 2010;4(1):6-21. DOI: https://doi.org/10.1080/17437190903168561.
    25.    Annesi JJ. Relations of age with changes in self-efficacy and physical self-concept in preadolescents participating in a physical activity intervention during afterschool care. Percept Mot Skills 2007 Aug;105(1):221-6. DOI: https://doi.org/10.2466/pms.105.1.221-226.
    26.    Annesi JJ. Improvements in self-concept associated with reductions in negative mood in preadolescents enrolled in an after-school physical activity program. Psychol Rep 2005 Oct;97(2):400-4. DOI: https://doi.org/10.2466/pr0.97.2.400-404.
    27.    Annesi JJ. Correlations of depression and total mood disturbance with physical activity and self-concept in preadolescents enrolled in an after-school exercise program. Psychol Rep 2005 Jun;96(3 Pt 2):891-8. DOI: https://doi.org/10.2466/pr0.96.3c.891-898.
    28.    Annesi JJ, Faigenbaum AD, Westcott WL. Relations of transtheoretical model stage, self-efficacy, and voluntary physical activity in African American preadolescents. Res Q Exerc Sport 2010 Jun;81(2):239-44. DOI: https://doi.org/10.1080/02701367.2010.10599671.
    29.    Pate RR, Almeida MJ, McIver KL, Pfeiffer KA, Dowda M. Validation and calibration of an accelerometer in preschool children. Obesity (Silver Spring) 2006 Nov;14(11):2000-6. DOI: https://doi.org/10.1038/oby.2006.234.
    30.    Evenson KR, Catellier DJ, Gill K, Ondrak KS, McMurray RG. Calibration of two objective measures of physical activity for children.

J Sports Sci 2008 Dec;26(14):1557-65. DOI: https://doi.org/10.1080/02640410802334196.
    31.    Trost SG, Loprinzi PD, Moore R, Pfeiffer KA. Comparison of accelerometer cut points for predicting activity intensity in youth. Med Sci Sports Exerc 2011 Jul;43(7):1360-8. DOI: https://doi.org/10.1249/MSS.0b013e318206476e.
    32.    Metcalf BS, Curnow JS, Evans C, Voss LD, Wilkin TJ. Technical reliability of the CSA activity monitor: The EarlyBird Study. Med Sci Sports Exerc 2002 Sep;34(9):1533-7.
    33.    Puyau MR, Adolph AL, Vohra FA, Butte NF. Validation and calibration of physical activity monitors in children. Obes Res 2002 Mar;10(3):150-7. DOI: https://doi.org/10.1038/oby.2002.24.
    34.    Trost SG, Ward DS, Moorehead SM, Watson PD,

Riner W, Burke JR. Validity of the computer science and applications (CSA) activity monitor in children. Med Sci Sports Exerc 1998 Apr;30(4):629-33. DOI: https://doi.org/10.1097/00005768-199804000-00023.
    35.    Ekelund U, Sjöström M, Yngve A, et al. Physical activity assessed by activity monitor and doubly labeled water in children. Med Sci Sports Exerc 2001 Feb;33(2):275-81. DOI: https://doi.org/10.1097/00005768-200102000-00017.
    36.    de Vries SI, Bakker I, Hopman-Rock M, Hirasing RA, van Mechelen W. Clinimetric review of motion sensors in children and adolescents.

J Clin Epidemiol 2006 Jul;59(7):670-80. DOI: https://doi.org/10.1016/j.jclinepi.2005.11.020.
    37.    Annesi J, Westcott W, Faigenbaum A. Youth Fit For Life training manual. Atlanta, GA: YMCA of Metropolitan Atlanta; 2005.
    38.    Annesi JJ, Walsh SM, Smith AE, et al. Youth Fit 4 Life program training manual, ages 9-12. Atlanta, GA: Children's Healthcare of Atlanta; 2014.
    39.    Annesi JJ, Faigenbaum AD, Westcott WL,

Smith AE, Unruh JL, Hamilton FG. Effects of the Youth Fit For Life protocol on physiological, mood, self-appraisal, and voluntary physical activity changes in African American preadolescents: contrasting after-school care and physical education formats. Int J Clin Health Psychol 2007;7(3):641-59.
    40.    Cohen J. Statistical power analysis for the behavioral sciences. 2nd ed. Mahwah, NJ: Lawrence Erlbaum Associates; 1988.
    41.    Pate RR, Pfeiffer KA, Trost SG, Ziegler P,

Dowda M. Physical activity among children attending preschools. Pediatrics 2004 Nov;114(5):1258-63. DOI: https://doi.org/10.1542/peds.2003-1088-L.
    42.    Schafer JL, Graham JW. Missing data: our view of the state of the art. Psychol Methods 2002 Jun;7(2):147-77. DOI: https://doi.org/10.1037//1082-989X.7.2.147.
    43.    Morgan WP. Methodological considerations. In: Morgan WP, editor. Physical activity and mental health. Washington, DC: Taylor & Francis; 1997. p 3-32.


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