A full-factorial test of motivational and volitional intervention strategies for promoting exercise habit formation and exercise maintenance among new users of an online exercise class platform.

Interventions often fail to achieve long-term behavioral maintenance. Utilizing motivational and volitional strategies to promote behavioral maintenance factors may improve this. Using a full-factorial experiment, we tested the effects of three intervention components (focused on intrinsic motivation and identity, exercise preparation habit, and exercise instigation habit) on exercise participation over a year, among new users (N = 751; 91% identifying as female, 54% identifying as White race) of a global, online exercise class platform, run by Les Mills International Ltd, called LM+. We also tested the intervention components' theoretical mechanisms of action-habit formation, intrinsic motivation, identity, and self-efficacy. Multi-level models found some support for a main effect of the exercise preparation habit intervention component in promoting self-reported and objective exercise participation (behavioral outcomes measured via monthly surveys and the LM+ platform; mechanisms measured via monthly surveys)-in particular online exercise class frequency (fixed effect estimate = 0.84, p < 0.05, and = 0.12, p < 0.05, respectively). The preparation habit component also significantly increased preparation habit strength (0.30, p < 0.05) and instigation habit strength (0.33, p < 0.05). Other expected effects were nonsignificant. Helping individuals form an exercise preparation habit may facilitate initiating and maintaining exercise over time, in particular for attending online exercise classes, potentially through promoting greater preparation and exercise instigation habit strength.

Calibration and Validation of the Youth Activity Profile as a Physical Activity and Sedentary Behaviour Surveillance Tool for English Youth.

Self-reported youth physical activity (PA) is typically overestimated. We aimed to calibrate and validate a self-report tool among English youth. Four-hundred-and-two participants (aged 9-16 years; 212 boys) wore SenseWear Armband Mini devices (SWA) for eight days and completed the self-report Youth Activity Profile (YAP) on the eighth day. Calibration algorithms for temporally matched segments were generated from the YAP data using quantile regression. The algorithms were applied in an independent cross-validation sample, and student- and school-level agreement were assessed. The utility of the YAP algorithms to assess compliance to PA guidelines was also examined. The school-level bias for the YAP estimates of in-school, out-of-school, and weekend moderate-to-vigorous PA (MVPA) were 17.2 (34.4), 31.6 (14.0), and -4.9 (3.6) min·week-1, respectively. Out-of-school sedentary behaviour (SB) was over-predicted by 109.2 (11.8) min·week-1. Predicted YAP values were within 15%-20% equivalence of the SWA estimates. The classification accuracy of the YAP MVPA estimates for compliance to 60 min·day-1 and 30 min·school-day-1 MVPA recommendations were 91%/37% and 89%/57% sensitivity/specificity, respectively. The YAP generated robust school-level estimates of MVPA and SB and has potential for surveillance to monitor compliance with PA guidelines. The accuracy of the YAP may be further improved through research with more representative UK samples to enhance the calibration process and to refine the resultant algorithms.

Comparability of children's sedentary time estimates derived from wrist worn GENEActiv and hip worn ActiGraph accelerometer thresholds.

OBJECTIVES: To examine the comparability of children's free-living sedentary time (ST) derived from raw acceleration thresholds for wrist mounted GENEActiv accelerometer data, with ST estimated using the waist mounted ActiGraph 100count·min-1 threshold. DESIGN: Secondary data analysis. METHOD: 108 10-11-year-old children (n=43 boys) from Liverpool, UK wore one ActiGraph GT3X+ and one GENEActiv accelerometer on their right hip and left wrist, respectively for seven days. Signal vector magnitude (SVM; mg) was calculated using the ENMO approach for GENEActiv data. ST was estimated from hip-worn ActiGraph data, applying the widely used 100count·min-1 threshold. ROC analysis using 10-fold hold-out cross-validation was conducted to establish a wrist-worn GENEActiv threshold comparable to the hip ActiGraph 100count·min-1 threshold. GENEActiv data were also classified using three empirical wrist thresholds and equivalence testing was completed. RESULTS: Analysis indicated that a GENEActiv SVM value of 51mg demonstrated fair to moderate agreement (Kappa: 0.32-0.41) with the 100count·min-1 threshold. However, the generated and empirical thresholds for GENEActiv devices were not significantly equivalent to ActiGraph 100count·min-1. GENEActiv data classified using the 35.6mg threshold intended for ActiGraph devices generated significantly equivalent ST estimates as the ActiGraph 100count·min-1. CONCLUSIONS: The newly generated and empirical GENEActiv wrist thresholds do not provide equivalent estimates of ST to the ActiGraph 100count·min-1 approach. More investigation is required to assess the validity of applying ActiGraph cutpoints to GENEActiv data. Future studies are needed to examine the backward compatibility of ST data and to produce a robust method of classifying SVM-derived ST.

Construct Validity of an Obesity Risk Screening Tool in Two Age Groups.

Home environment influences child health, but the impact varies as children move into adolescence. The Family Nutrition and Physical Activity (FNPA) screening tool has been used to evaluate home environments, but studies have not compared the utility of the tool in different age groups. The purpose of this study was to examine the efficacy of the FNPA tool in first and tenth grade samples. Parents of first grade (n = 250) and tenth grade (n = 99) students completed the FNPA and results were linked to body mass index (BMI) data. FNPA scores were examined by gender, income, race, and school-level socioeconomic status (SES). Correlations examined associations between FNPA scores and several BMI indicators. Logistic and linear regression analyses evaluated the construct validity of the FNPA in both groups. Mean FNPA score differed by age group, by SES in both age groups, and by race in the first grade sample only. Correlations between FNPA score and BMI indicators were higher in the first grade sample, but SES was significantly associated with BMI only in tenth graders. The FNPA has stronger utility in younger children, while school SES is a stronger predictor of adolescent weight status.

Validation of a Noninvasive, Disposable Activity Monitor for Clinical Applications.

BACKGROUND: The study evaluated the concurrent and criterion validity of a new, disposable activity monitor designed to provide objective data on physical activity and energy expenditure in clinical populations. METHODS: A sample of healthy adults (n = 52) wore the disposable Metria IH1 along with the established Sensewear armband (SWA) monitor for a 1-week period. Concurrent validity was examined by evaluating the statistical equivalence of estimates from the Metria and the SWA. Criterion validity was examined by comparing the relative accuracy of the Metria IH1 and the SWA for assessing walking/running. The absolute validity of the 2 monitors was compared by computing correlations and mean absolute percent error (MAPE) relative to criterion data from a portable metabolic analyzer. RESULTS: The output from 2 monitors was highly correlated (correlations > 0.90) and the summary measures yielded nearly identical allocations of time spent in physical activity and energy expenditure. The monitors yielded statistically equivalent estimates and had similar absolute validity relative to the criterion measure (12% to 15% error). CONCLUSIONS: The disposable nature of the adhesive Metria IH1 monitor offers promise for clinical evaluation of physical activity behavior in patients. Additional research is needed to test utility for counseling and behavior applications.

Effects of Enhancing School-Based Body Mass Index Screening Reports with Parent Education on Report Utility and Parental Intent To Modify Obesity Risk Factors.

BACKGROUND: School-based body mass index screenings (SBMIS) have been controversial. We aimed to determine if parents would indicate improved utility with SBMIS when the report included parent education and whether parental intent to modify obesity risk factors would vary with report type or child weight. METHODS: A cluster-controlled trial was conducted with 31 elementary schools randomized to distribute a standard SBMIS report or the standard report plus education (SBMIS+). A random subsample of parents completed a mailed survey (731 SBMIS, 738 SBMIS+). Using a two-stage cluster sampling design, logistic regression models with school-level random effect were used to assess differences between conditions and by weight category. RESULTS: Parents in the SBMIS+ condition vs. the standard condition were more likely to indicate that the report provided useful information (not significant) and an intent to help their child get enough sleep (p < 0.001). Parents of children who were overweight or obese were less likely than parents of children who were not to indicate that the report provided useful information about their child's weight status (p < 0.001) or access to resources (p < 0.05). However, these parents were more likely to plan a visit to healthcare provider (p < 0.001) and to intend to limit sugar-sweetened beverages (p < 0.05). CONCLUSIONS: Parental education can enhance the utility of the SBMIS report and parental intention to modify at least one obesity risk factor. SBMIS reports prompted parents of children with overweight and obesity to seek clinical care and limit sugar-sweetened drinks.

Relationships between County Health Rankings and child overweight and obesity prevalence: a serial cross-sectional analysis.

BACKGROUND: The County Health Rankings (CHR) system provides health rankings for U.S. counties. These factors may have utility for evaluating and predicting health outcomes. This study examined the association between CHR factors and the prevalence of child overweight/obesity (OWOB) in the state of Pennsylvania over 3 years. METHODS: The prevalence of childhood OWOB was obtained for all Pennsylvania school districts for the 2009-10 through 2011-12 school years. Correlational and inferential statistical analyses were used to examine the associations between the prevalence of OWOB in grades K-6 (OWOB1) and 7-12 (OWOB2) and z-score for the overall CHR Health Factors rank, as well as for individual predictive factors (Health Behaviors, Clinical Care, Social and Economic Factors and Physical Environment). RESULTS: Low to moderate correlations (0.29-0.43) were found between OWOB1 and CHR factors. Weaker and less consistent correlations were found for adolescents. There was a significantly higher prevalence of OWOB in counties with poorer CHR scores. CONCLUSIONS: County-level adult indicators of health are significantly associated with levels of child obesity. Future studies should examine the relationship between CHR and other health outcomes.

Cross-Validation of Aerobic Capacity Prediction Models in Adolescents.

Cardiorespiratory endurance is a component of health-related fitness. FITNESSGRAM recommends the Progressive Aerobic Cardiovascular Endurance Run (PACER) or One mile Run/Walk (1MRW) to assess cardiorespiratory endurance by estimating VO2 Peak. No research has cross-validated prediction models from both PACER and 1MRW, including the New PACER Model and PACER-Mile Equivalent (PACER-MEQ) using current standards. The purpose of this study was to cross-validate prediction models from PACER and 1MRW against measured VO2 Peak in adolescents. Cardiorespiratory endurance data were collected on 90 adolescents aged 13-16 years (Mean = 14.7 ± 1.3 years; 32 girls, 52 boys) who completed the PACER and 1MRW in addition to a laboratory maximal treadmill test to measure VO2 Peak. Multiple correlations among various models with measured VO2 Peak were considered moderately strong (R = .74-0.78), and prediction error (RMSE) ranged from 5.95 ml·kg⁻¹,min⁻¹ to 8.27 ml·kg⁻¹.min⁻¹. Criterion-referenced agreement into FITNESSGRAM's Healthy Fitness Zones was considered fair-to-good among models (Kappa = 0.31-0.62; Agreement = 75.5-89.9%; F = 0.08-0.65). In conclusion, prediction models demonstrated moderately strong linear relationships with measured VO2 Peak, fair prediction error, and fair-to-good criterion referenced agreement with measured VO2 Peak into FITNESSGRAM's Healthy Fitness Zones.

Effects of ready for recess, an environmental intervention, on physical activity in third- through sixth-grade children.

BACKGROUND: The purpose of this study was to determine the effectiveness of Ready for Recess, an elementary school recess intervention targeting staff training (ST) or providing recreational equipment (EQ) separately, and the combination (EQ+ST) on physical activity (PA). METHODS: Participants were children attending 1 of 12 elementary schools (grades 3rd-6th) included in the study. Separate analytical models were used to evaluate the effects of the intervention conditions on children's accelerometry and direct observation derived PA measures. RESULTS: Boys and girls were measured using accelerometry (n = 667). Boys in EQ+ST increased their MVPA by 14.1% while ST decreased their MVPA by -13.5%. Girls in ST decreased their MVPA by -11.4%. Neither boys nor girls in EQ increased their time spent in MVPA. A total of 523 (boys) and 559 (girls) observations were collected. For boys' and girls' sedentary and vigorous activity there were no significant main effects for treatment condition, time, or treatment condition-by-time effects. CONCLUSIONS: Environmental modifications are only as strong as the staff that implements them. Supervision, if not interactive, may be detrimental to PA participation, especially in girls. Research related to staff training for encouragement and promotion of PA coupled with appropriate use of equipment during recess is warranted.

Direct and indirect effects of social support on youth physical activity behavior.

Social support (SS) from parents and peers are key reinforcing factors in the Youth Physical Activity Promotion (YPAP) model. This study aims to identify the relative contribution of parental and peer SS on youth participation in moderate to vigorous physical activity (MVPA). Participants included 203 high school students (n = 125 girls; mean age 14.99 ± 1.55 years). MVPA was assessed by accelerometry. SS influences were evaluated using a well-established scale. Structural equation modeling measured (AMOS, Version 19) the relative fit of the YPAP models using both parental and peer SS. Parental SS had significant associations with both predisposing factors, enjoyment (ß = .62, p < .01), and self-efficacy (ß= .32, p < .01), as well a direct effect on MVPA (ß = .30, p < .01). Peer SS had direct effect on MVPA (ß = .33, p < .05), also significantly influenced levels of enjoyment (ß = .47, p < .01) and self-efficacy (ß = .67, p < .01). In both models self-efficacy mediated the influence on MVPA. The direct effects for parents and peers were similar. This demonstrates that both parental and peer social support exert a strong influence on adolescent MVPA.

Evaluating the youth physical activity promotion model among Portuguese elementary schoolchildren.

BACKGROUND: The Youth Physical Activity Promotion (YPAP) model provides an integrated approach to understanding the predisposing, enabling, and reinforcing factors influencing physical activity (PA) behavior. The purpose of this study was to evaluate an adapted version of the YPAP model for explaining PA among Portuguese schoolchildren. METHODS: A random cross-sectional sample of 683 children (8-10 years of age) attending elementary public schools in the north of Portugal completed a detailed survey assessing attraction to PA, perceived physical competence, parental influences and leisure time PA. Structural equation modeling techniques were conducted (EQS6.1). RESULTS: Attraction to PA was directly associated with children's PA participation (ß = 0.271, P < .05). Perceived physical competence imposed an indirect effect on children's PA through children's attraction to PA (ß = 0.253, P < .05). Parental influence had an indirect effect on children's PA through perceived physical competence and attraction to PA (ß = 0.318 and 0.662, respectively, P < .05). Perceived physical competence and parental influence were not directly associated with children's PA (ß = 0.069 and 0.180, respectively, P > .05). CONCLUSIONS: The adapted version of YPAP model was useful in explaining PA participation in elementary Portuguese schoolchildren. Intervention programs intended to enhance attraction to PA, perceived physical competence and favorable parental influence should be developed to promote children's PA participation.

Parenting styles and home obesogenic environments.

Parenting behaviors are known to have a major impact on childhood obesity but it has proven difficult to isolate the specific mechanism of influence. The present study uses Baumrind's parenting typologies (authoritative, authoritarian, and permissive) to examine associations between parenting styles and parenting practices associated with childhood obesity. Data were collected from a diverse sample of children (n = 182, ages 7-10) in an urban school district in the United States. Parenting behaviors were assessed with the Parenting Styles and Dimension Questionnaire (PSDQ), a 58-item survey that categorizes parenting practices into three styles: authoritative, authoritarian, and permissive. Parent perceptions of the home obesogenic environment were assessed with the Family Nutrition and Physical Activity (FNPA) instrument, a simple 10 item instrument that has been shown in previous research to predict risk for overweight. Cluster analyses were used to identify patterns in the PSDQ data and these clusters were related to FNPA scores and measured BMI values in children (using ANCOVA analyses that controlled for parent income and education) to examine the impact of parenting styles on risk of overweight/obesity. The FNPA score was positively (and significantly) associated with scores on the authoritative parenting scale (r = 0.29) but negatively (and significantly) associated with scores on the authoritarian scale (r = -0.22) and permissive scale (r = -0.20). Permissive parenting was significantly associated with BMIz score but this is the only dimension that exhibited a relationship with BMI. A three-cluster solution explained 40.5% of the total variance and clusters were distinguishable by low and high z-scores on different PSDQ sub-dimensions. A cluster characterized as Permissive/Authoritarian (Cluster 2) had significantly lower FNPA scores (more obesogenic) than clusters characterized as Authoritative (Cluster 1) or Authoritarian/Authoritative (Cluster 3) after controlling for family income and parent education. No direct effects of cluster were evident on the BMI outcomes but the patterns were consistent with the FNPA outcomes. The results suggest that a permissive parenting style is associated with more obesogenic environments while an authoritative parenting style is associated with less obesogenic environments.

Validation of the SOPLAY direct observation tool with an accelerometry-based physical activity monitor.

BACKGROUND: The System for Observing Play and Leisure Activities (SOPLAY) is a direct observation instrument designed to assess group physical activity and environmental contexts. The purpose of this study was to test the convergent validity of the SOPLAY using temporally matched data from an accelerometry-based activity monitor. METHODS: Accelerometry-based physical activity data were obtained from 160 elementary school children from 9 after-school activity programs. SOPLAY coding was used to directly observe physical activity during these sessions. Analyses evaluated agreement between the monitored and observed physical activity behavior by comparing the percent of youth engaging in physical activity with the 2 assessments. RESULTS: Agreement varied widely depending on the way the SOPLAY codes were interpreted. Estimates from SOPLAY were significantly higher than accelerometer PA levels when codes of walking and vigorous were used (in combination) to reflect participation in moderate to vigorous PA (MVPA). Estimates were similar when only SOPLAY codes of vigorous were used to define MVPA (Difference = 1.33 ± 22.06%). CONCLUSIONS: SOPLAY codes of walking corresponded well with estimates of Light intensity PA. Observations provide valid indicators of MVPA if coding is based on the percentage of youth classified as "vigorous."

Environmental correlates of objectively measured physical activity and sedentary behavior in after-school recreation sessions.

BACKGROUND: Active recreation sessions taking place within after-school programs (ASP) present an opportunity for attending children to attain part of the recommended 60 minutes of daily moderate-to-vigorous physical activity (MVPA). This cross-sectional study's purpose was to assess relationships between microlevel ASP environmental characteristics and physical activity and sedentary behavior (SED). METHODS: During 161 ASP active recreation sessions, 240 children from 7 schools wore Actigraph GT1M accelerometers and were observed up to 6 times per year, over 3 years. To provide microlevel environmental data, trained observers recorded session times, location, duration, organization, equipment, and number of children and staff. Unadjusted bivariate correlations and multivariable regression analyses were used to assess the influence of microlevel environmental variables on MVPA and SED, with regression models controlling for relevant covariates. RESULTS: Across all ASP active recreation sessions, children spent 39 ± 15% in MVPA and 16 ± 11% in SED. Session location, boy-to-girl ratio, and duration were significantly related to MVPA in the regression model. For SED, location and duration were significant influences in the model. CONCLUSIONS: Both location and duration appear to be modifiable correlates of group physical activity level, which may serve to inform intervention efforts to promote physical activity in ASP.

Environmental modifications to increase physical activity during recess: preliminary findings from ready for recess.

BACKGROUND: The purpose of this study was to determine the effectiveness of Ready for Recess: an elementary school recess intervention targeting staff training (ST) and providing recreational equipment (EQ). METHODS: Ready for Recess had 4 intervention schools: 1) EQ+ST, 2) EQ, 3) ST, and 4) control. Moderate-to-vigorous physical activity (MVPA) was assessed with accelerometers at the four schools in 257 3rd- to 6th-grade children. Random intercept models for overweight/obese (OWOB) and healthy weight (HW) for boys and girls separately, examined change in percentage of time spent in MVPA during recess across EQ+ST, EQ, and ST compared with the control from baseline to postintervention. RESULTS: HW boys receiving EQ+ST increased MVPA by 19.4%, OWOB boys receiving ST increased MVPA by 4.5%, OWOB girls receiving EQ-ST increased MVPA by 6.0%, while HW girls receiving EQ decreased MVPA by 13.6% in comparison with the control. CONCLUSIONS: Ready for Recess represents a possible means to increase MVPA in OWOB girls/boys, populations least likely to meet MVPA recommendations. However, the effect of the intervention was not uniform across all subgroups.

Ready for recess: a pilot study to increase physical activity in elementary school children.

BACKGROUND: Creating an optimal environment at recess may be necessary to maximize physical activity (PA) participation in youth. The purpose of this study was to determine the initial effectiveness of an elementary school recess intervention on the amount of moderate PA (MPA) and vigorous PA (VPA) during recess and the school day. METHODS: This school-based intervention included staff training, activity zones, and playground equipment. The PA levels of third, fourth, and fifth grade students (n = 93) at two schools were measured at baseline and post-intervention using ActiGraph accelerometers. Paired t tests were used to compare percentage of time spent during recess in MPA and VPA. Multiple regressions were utilized to model the effect of intervention, age, sex, race, body mass index, and school on minutes spent in MPA and VPA. RESULTS: The multiple regression results demonstrated increases of 2.5 minutes of MPA (p < .001) and 2.2 minutes of VPA (p < .001) at recess and an increase of 18.7 minutes of MPA (p < .001) and 4.7 minutes of VPA (p < .001) during the school day. These represent respective increases of 51.2% and 112.2% in the adjusted means of MPA and VPA during recess and respective increases of 92.2% and 71.6% in the adjusted mean of MPA and VPA during school day. CONCLUSION: Staff training, recreational equipment, and playground markings are inexpensive, simple ways to increase PA during recess so that children can accumulate minutes of PA to meet the recommended guidelines of 60 minutes per day.

Equating accelerometer estimates of moderate-to-vigorous physical activity: in search of the Rosetta Stone.

No universally accepted ActiGraph accelerometer cutpoints for quantifying moderate-to-vigorous physical activity (MVPA) exist. Estimates of MVPA from one set of cutpoints cannot be directly compared to MVPA estimates using different cutpoints, even when the same outcome units are reported (MVPA mind(-1)). The purpose of this study was to illustrate the utility of an equating system that translates reported MVPA estimates from one set of cutpoints into another, to better inform public health policy. Secondary data analysis. ActiGraph data from a large preschool project (N=419, 3-6-yr-olds, CHAMPS) was used to conduct the analyses. Conversions were made among five different published MVPA cutpoints for children: Pate (PT), Sirard (SR), Puyau (PY), Van Cauwengerghe (VC), and Freedson Equation (FR). A 10-fold cross-validation procedure was used to develop prediction equations using MVPA estimated from each of the five sets of cutpoints as the dependent variable, with estimated MVPA from one of the other four sets of cutpoints (e.g., PT MVPA predicted from FR MVPA). The mean levels of MVPA for the total sample ranged from 22.5 (PY) to 269.0 (FR) mind(-1). Across the prediction models (5 total), the median proportion of variance explained (R(2)) was 0.76 (range 0.48-0.97). The median absolute percent error was 17.2% (range 6.3-38.4%). The prediction equations developed here allow for direct comparisons between studies employing different ActiGraph cutpoints in preschool-age children. These prediction equations give public health researchers and policy makers a more concise picture of physical activity levels of preschool-aged children.

Joint association of fatness and physical activity on resting blood pressure in 5- to 9-year-old children.

The purpose of this study was to determine the joint association of fatness and physical activity on resting blood pressure in children. Subjects included 157 children (age 5.5-9.5 years). Moderate-to-vigorous physical activity (MVPA, min/day), body fatness, and resting blood pressure were measured. Four categories were created by cross tabulation of high/normal levels of fatness and high/low levels of MVPA. There were significant differences in systolic blood pressure and mean arterial pressure across the fat/MVPA groups (p < .05). Regardless of participating in an acceptable level of MVPA, overfat children had higher resting systolic blood pressure than normal fat children. MVPA did not significantly attenuate blood pressure within a fat category.

Lifespan snapshot of physical activity assessed by accelerometry in Porto.

BACKGROUND: The purpose of the study is to evaluate age and gender differences in objectively measured levels of physical activity (PA) in a large and diverse sample of residents from an urban area in Porto, Portugal. METHODS: Participants included 822 residents, 334 males (41%), and 488 females (59%), aged 6 to 90 years. GT1M accelerometer was used to assess daily PA over 7 consecutive days, and the measurement was from October (2007) to June (2008). RESULTS: Males were more active than females. This difference was attenuated in the 2 oldest age groups (40-59 and 60+ yrs). An accentuated declined in all PA variables occurred between the youngster group (6-11 yrs) and adolescents group (12-19 yrs). Surprisingly, young adults (20-39 yrs) engaged in more moderate-to-vigorous PA (MVPA) than adolescents. Further, females also had higher MVPA in the fourth group (40-59 yrs) compared with the second group (12-19 yrs). Males had higher compliance rates of PA guidelines than females regardless the age group considered. Adolescents had very low compliance rates (females = 18.18%; males = 33.50%). CONCLUSIONS: Porto metropolitan area residents had low rates of compliance with current PA guidelines. A low level of PA in Porto adolescents is a matter of concern and suggests that interventions are needed.

Estimating minutes of physical activity from the previous day physical activity recall: validation of a prediction equation.

BACKGROUND: This study was designed to develop a prediction algorithm that would allow the Previous Day Physical Activity Recall (PDPAR) to be equated with temporally matched data from an accelerometer. METHODS: Participants (n = 121) from a large, school-based intervention wore a validated accelerometer and completed the PDPAR for 3 consecutive days. Physical activity estimates were obtained from PDPAR by totaling 30-minute bouts of activity coded as ≥4 METS. A regression equation was developed in a calibration sample (n = 91) to predict accelerometer minutes of moderate to vigorous physical activity (MVPA) from PDPAR bouts. The regression equation was then applied to a separate, holdout sample (n = 30) to evaluate the utility of the prediction algorithm. RESULTS: Gender and PDPAR bouts accounted for 36.6% of the variance in accelerometer MVPA. The regression model showed that on average boys obtain 9.0 min of MVPA for each reported PDPAR bout, while girls obtain 4.8 min of MVPA per bout. When applied to the holdout sample, predicted minutes of MVPA from the models showed good agreement with accelerometer minutes (r = .81). CONCLUSIONS: The prediction equation provides a valid and useful metric to aid in the interpretation of PDPAR results.