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Low levels of moderate-to-vigorous physical activity are associated with adverse health consequences.
The intent of the study was to determine the feasibility and efficacy of a 12-week physical activity promotion program targeting children, which was delivered to parents through mobile phones.
Potential participants were recruited through advertisements placed in the newspaper, local hospitals and schools, and an email listserv. Sedentary children aged 6-10 years were randomly assigned to a minimal (MIG) or intensive (IIG) intervention group. Parents in the MIG were given a goal to increase (within 1 month) and maintain their child’s activity at 6000 pedometer steps/day above their baseline levels and to monitor their child’s steps daily. Parents in the IIG were given the same steps/day and monitoring goals, in addition to text messages and articles containing additional behavioral strategies (based on the Social Cognitive Theory) designed to promote their child’s physical activity. The intervention components were delivered via mobile phone. Anthropometrics, body composition, and questionnaires were administered in a clinic. Children wore a New Lifestyles pedometer (NL-1000) each day throughout the intervention and parents were to monitor their child’s step counts daily.
Out of 59 children who screened for the study, a total of 27 children (mean age 8.7, SD 1.4 years; 56%, 15/27 female; 59%, 16/27 African American) were enrolled and completed the study. Overall, 97.90% (2220/2268; 98.20%, 1072/1092 for MIG; 97.60%, 1148/1176 for IIG) of expected step data were successfully entered by the parent or study coordinator. Parents in the MIG and IIG were sent approximately 7 and 13 text messages per week, respectively, averaged over the course of the study. IIG parents accessed an average of 6.1 (SD 4.4) articles over the course of the intervention and accessed a fewer number of articles in the last month compared to the first 2 months of the study (
Parent-targeted mobile phone interventions are feasible, yet more intense interventions may be needed to support parents’ efforts to increase their children’s physical activity to levels that approximate national recommendations.
Clinicaltrials.gov NCT01551108; http://clinicaltrials.gov/show/NCT01551108 (Archived by WebCite at http://www.webcitation.org/6TNEOzXNX).
Low levels of moderate-to-vigorous physical activity are associated with adverse health consequences. Specifically, epidemiological studies demonstrate that low levels of physical activity are positively associated with childhood obesity [
Parents have an important role in teaching and encouraging their children to be physically active. For example, cross-sectional and prospective studies provide evidence that parental support and rules, as well as physical activity modeling and co-participation, are positively associated with objectively measured moderate-to-vigorous physical activity levels in children [
There has been an increase in the use of mobile phones as an intervention delivery strategy. Mobile phones contain several features appealing to researchers. Mobile phones are portable, which provides the opportunity to collect real-time data [
Few family-based interventions have exclusively targeted children’s physical activity [
Children who were 6 to 10 years of age, physically capable of exercise, and sedentary were eligible for the study. A parent or legal guardian of each participating child was eligible if they owned a mobile phone with Internet access and text message capabilities. Children were excluded if they were diagnosed with a serious medical disorder (eg, cancer within the last five years, cardiovascular disease). Families were compensated US $200 for their time, mobile phone data use, and travel costs. All study procedures were approved by the Pennington Biomedical Research Center Institutional Review Board.
Potential participants were recruited through advertisements placed in the newspaper, posted in local hospitals and schools, and delivered through a Pennington Biomedical Research Center email listserv targeting registered individuals interested in participating in research. Once self-identified, one parent completed an initial telephone screen to determine eligibility for themselves and their child. If the parent-child dyad was eligible following the phone screen, they attended a clinic screening visit at the Pennington Biomedical Research Center (Louisiana). The dyad was oriented to the study and then written informed consent was obtained from the parent and written assent was obtained from the targeted child. The baseline assessment (see Measures below) was then conducted. At the end of the clinic visit, the targeted child was fitted with a pedometer (New Lifestyles 1000/NL-1000), the parent was required to use their mobile phone to respond to a text message sent from the study coordinator, and the parent had to access the study website. The dyad was sent home with the following instructions: the child was to engage in their normal level of activity and the parent was instructed to use their mobile phone to access the study website [
Study flowchart.
This study was a randomized comparative behavioral trial of a minimal versus an intensive intervention delivered to parents via mobile phone with the purpose of increasing physical activity in sedentary children. A block randomization procedure was generated by a study statistician (HH) utilizing SAS software, with a block size of four. The randomization sequence was placed in sealed, numbered envelopes. The clinic coordinator opened the next envelope in the sequence after a participant successfully completed all eligibility criteria. Children in both study groups were instructed to wear a study-provided pedometer every day during the course of the 12-week intervention.
Parents in the MIG were given access to a version of the website (formatted for a mobile phone) in which they could view their child’s daily step goal, monitor their child’s step counts, and receive monthly nutrition tips (
Components of the minimal (MIG) and intensive (IIG) intervention groups.
Intervention component | MIG | IIG |
Access to mobile phone formatted website | X | X |
6000 steps/day goal | X | X |
Daily step monitoring | X | X |
Monthly nutrition tips | X |
|
Weekly behavioral articles |
|
X |
Behavioral text messages |
|
X |
Steps/day graph |
|
X |
Mobile phone screenshot showing pedometer step count entry on P-Mobile website.
Parents in the IIG were given access to a version of the website in which they could view their child’s daily step goal, monitor their child’s step counts, view a steps/day graph, and read weekly behavioral articles, and they also received text messages. The step monitoring and steps/day website components and goals were identical to the MIG. The steps/day graph was color-coded to illustrate how their child’s daily steps compared to the target step goal: red bars represented days in which the child’s step count was below baseline, yellow represented step counts between baseline and the goal, and green represented step counts at or above the goal (
Behavioral articles provided to parents in the intensive intervention group (IIG).
Week | Title | Content |
1 | Self-monitoring | Parental monitoring of child activity, role of parent in child’s activity, increase steps/day by additional 1000. |
2 | Making time for exercise | Goal setting, scheduling time for activity, what is moderate intensity activity, maintain increased step/day of additional 1000. |
3 | Increasing activity outdoors | Benefits of outdoor play, role of the parents in child’s physical activity, increase steps/day by additional 2000. |
4 | Increasing activity indoors | Cues to activity, changing the home environment, increase steps/day by additional 3000 (achieve ≥ 6000 steps/day above baseline). |
5 | Checking-in #1 | Identify barriers to achieving goal. |
6 | Problem solving | 5-step problem-solving process. |
7 | Rewarding your child | Principles of positive reinforcement, rewards for increased activity. |
8 | Reducing sedentary time | Defining and identifying sedentary behavior, ways to reduce sedentary behaviors, substituting physical activity. |
9 | Checking-in #2 | Identify barriers to achieving goal. |
10 | Lifestyle exercise | Incorporating activity that is part of daily living. |
11 | Parental modeling/social support | Parents as a role model for physical activity, obtaining social support from family members. |
12 | Relapse prevention | Defining and anticipating slips and relapses, ways to respond to slips. |
Mobile phone screenshot showing steps/day graph on P-Mobile website.
Mobile phone screenshot showing an article on P-Mobile website.
All measures, with the exception of the pedometers and the Home and Neighborhood Environment Questionnaire, were assessed at baseline and 12-weeks. The assessment staff was not blinded to the participant assignment.
Children in both groups were asked to wear a NL-1000 pedometer for the duration of the study. The device has a 7-day memory and steps are also digitally displayed on an immediately accessible screen. The NL-1000 contains the same internal mechanism as the NL-2000, which has been previously validated for counting steps in children [
Height and weight were measured with the child dressed in normal street clothes, but without shoes and socks. Height was measured to the nearest 0.1 cm using a wall-mounted stadiometer (Holtain Ltd, Crymych, Dyfed, United Kingdom). Weight was measured to the nearest 0.1 kg using a digital scale (Indiana Scale Company model GSE 450). Waist circumference was measured to the nearest 0.1 cm at the natural waist, with clothing moved out of the way. The circumference was taken twice, with a third measurement taken if the first two were more than 0.5 cm apart. Body mass index (BMI) was calculated by dividing the participant’s average weight in kilograms by the square of their height in meters (kg/m2). BMI was converted to a
The Tanita Body Composition Analyzer (model TBF-240) was used to estimate body fat. The child stood on the scale with bare feet, and impedance data were recorded using a laptop computer. The Tanita has a mean difference of −1.0% with DXA and is considered to be very reliable in children [
Children completed two questionnaires, with the assistance of a study staff member to ensure the child understood all questions. Parents were allowed to be present during the questionnaire administration if the child preferred. The 12-item Physical Activity Enjoyment Questionnaire (PACES) [
Parents completed three questionnaires. The Sedentary Behavior Questionnaire was completed to describe the amount of time their child spent watching TV, playing video games, playing on the computer, and doing other sedentary activities. The Home and Neighborhood Environment Questionnaire, adapted from the Neighborhood Impact on Kids study [
Weekly steps/day means analyzed across all 12 weeks of the study were analyzed using a repeated measures analysis of variance. Change in the secondary outcome data (eg, BMI, body composition, questionnaires, website usage, etc) were analyzed using dependent samples
Characteristics of the participating children are summarized in
Baseline demographic characteristics for all children.
Characteristic | All children |
Minimal intervention |
Intensive intervention |
n (%) or mean (SD) | n (%) or mean (SD) | n (%) or mean (SD) | |
Age (years) | 8.7 (1.4) | 9.1 (1.3) | 8.3 (1.5) |
Gender (% female) | 15/27 (56%) | 7/14 (50%) | 8/13 (62%) |
Ethnicity (% African American) | 16/27 (59%) | 8/14 (57%) | 8/13 (62%) |
Height (cm) | 138.1 (10.7) | 140.0 (8.3) | 135.9 (12.9) |
Weight (kg) | 45.5 (19.7) | 44.5 (18.3) | 46.5 (21.9) |
BMIa (kg/m2) | 23.1 (7.7) | 22.3 (7.4) | 24.1 (8.1) |
BMI |
1.5 (1.0) | 1.3 (0.9) | 1.7 (1.0) |
BMI percentile | 85.6 (20.2) | 83.7 (21.0) | 87.6 (20.1) |
Waist circumference (cm) | 72.4 (18.1) | 70.5 (17.0) | 74.5 (19.7) |
Body fat percent | 31.1 (11.2) | 29.0 (10.3) | 33.4 (12.1) |
CDI-Sa | 47.1 (9.2) | 47.3 (8.9) | 46.8 (9.9) |
Physical activity enjoyment | 66.6 (7.0) | 67.5 (7.9) | 65.6 (6.2) |
Sedentary time (weekday hours) | 5.1 (4.0) | 4.9 (4.1) | 5.4 (3.9) |
Sedentary time (weekend hours) | 8.3 (5.4) | 8.2 (5.0) | 8.4 (5.9) |
TV in room | 16/27 (59%) yes | 5/14 (36%) yes | 11/13 (85%) yes |
Total calorie consumption | 1587.1 (647.5) | 1520.6 (628.7) | 1658.7 (685.1) |
Steps/day | 8621.8 (1955.0) | 9042.5 (1930.5) | 8168.6 (1953.2) |
aBMI: body mass index
bCDI-S: Child Depression Inventory-Short Form
Parents across both groups logged into the website an average of 76.7 (SD 20.1) times over the course of the study (6.3 times/week). Parents were instructed to enter their child’s step counts daily, and parents in the MIG and IIG, respectively, entered 44.20% (520/1176) and 62.80% (686/1092) of their child’s step counts daily as instructed. Parents could also enter step count data for up to 7 days past the date the activity occurred. Another 40.60% (478/1176) and 27.00% (295/1092) of data was entered on a subsequent day for a total of 84.80% (997/1176) and 89.80% (981/1092) of step counts being entered by the parents in the MIG and IIG, respectively. The remaining 13.40% (158/1176; MIG) and 7.80% (85/1092; IIG) of the data were entered by the study coordinator because either the parents sent this information to the coordinator (via text message) or because the study coordinator contacted the parents (via phone) to retrieve missing data when identified. Overall, 97.90% (2220/2268; 98.20%, 1155/1176 for MIG; 97.60%, 1066/1092 for IIG) of expected step data were successfully entered by the parent or study coordinator.
Parents in the IIG visited the steps/day graph an average of 25.3 (SD 24.5) times over the course of the study (2.1 times/week). There was a clear dichotomy in access, with six participants accessing the graph fewer than 8 times, and seven accessing the graph more than 21 times.
Number of parents in the Intensive Intervention Group (n=13) who accessed each of the 12 articles.
Parents in the MIG were sent 1-2 text messages and parents in the IIG were sent 7-8 text messages per week during the first 6 months of the study. However, daily text message reminders were implemented after the first four participants completed the study in an attempt to increase compliance with parent monitoring of the child’s daily steps. Therefore, parents in the MIG and IIG were sent approximately 7 and 13 text messages per week, respectively, averaged over the course of the study.
Parents in the MIG sent 162 (0.96/week) and parents in the IIG sent 419 (2.7/week) text messages over the course of the study. Approximately half of the text messages sent by parents in both groups were communications with the study coordinator regarding missing step data. The other text messages sent by the parents were related to equipment/resource issues (eg, pedometer, website), requests for further information (eg, spontaneous questions, scheduling), or responses to a text message they had received.
All randomized children attended the Week 12 visit and thus completed the 12-week study.
Average change in child’s steps per week by intervention group.
Change in outcome variables from baseline to 12 weeks.
|
Minimal intervention | Intensive intervention |
|
|
mean (SD) | mean (SD) | |
Height (cm) | 1.5 (1.0) | 1.6 (1.1) | .843 |
Weight (kg) | 0.94 (2.1) | 1.4 (1.7) | .536 |
BMIa (kg/m2) | −0.86 (1.1) | 0.28 (1.0) | .369 |
BMI |
0.016 (0.19) | 0.00 (0.14) | .773 |
BMI percentile | 1.01 (6.1) | 0.27 (1.9) | .455 |
Waist circumference (cm) | 0.85 (4.0) | 1.3 (2.8) | .764 |
Body fat percent | −0.24 (1.9) | 0.69 (2.4) | .275 |
CDI-Sb | −1.1 (4.0) | −3.4 (8.4) | .378 |
Physical activity enjoyment | −0.09 (0.17) | −0.01 (0.29) | .391 |
Sedentary time (weekday hours) | 0.0 (3.2) | −0.59 (3.9) | .617 |
Sedentary time (weekend hours) | −1.2 (4.0) | −1.1 (5.5) | .941 |
Total calorie consumption | 96.2 (682.4) | −310.6 (569.1) | .200 |
% calories from fat | −1.8 (6.7) | −0.06 (7.2) | .483 |
% calories from protein | 0.78 (2.6) | 0.59 (2.3) | .976 |
% calories from carb | 1.0 (5.7) | −0.37 (7.2) | .323 |
Steps/dayc, mean (SE) | 1427.6 (583.0) | 2832.8 (604.9) | .102 |
aBMI: body mass index
bCDI-S: Child Depression Inventory-Short Form
cRepresents the average change in weekly steps/day across 12 weeks
The P-Mobile study demonstrated that it is feasible to deliver a child-targeted physical activity promotion program to parents through their mobile phones. Feasibility was demonstrated by parental utilization of the components of the intervention, including entering their child’s step counts, responding to text messages, and accessing the behavioral articles. The intervention also resulted in increased physical activity in both study groups. Step counts increased significantly in both the MIG and the IIG over the course of the 12-week intervention. These findings suggest that mobile phone-based physical activity promotion interventions delivered to parents have the potential to be utilized and may positively affect physical activity levels in children.
Parental use of the intervention components varied by the component assessed. Concerning step count data, only half of the parents complied with the study requirement to enter step counts each night. This required the study coordinator to prompt parents for about half of the data and enter 10%-15% of the data. Therefore, the large volume of step data entered was the result of combined efforts by both the parents and the study coordinator, which may be difficult for participants and burdensome on study staff to sustain over a period longer than 12 weeks. Bluetooth capable activity monitors (eg, FitBits, Jawbone, Garmin Vivofit, etc) may lessen this burden and increase compliance. Concerning text messages, on average, parents in the IIG received approximately 13 automated text messages per week. This level appears to be tolerable because only one parent (4%, 1/27) requested a decrease in the frequency of text messages. Parents sent between 1 and 3 text messages per week to the study coordinator, but this was largely related to obtaining missing step data. Text messaging appears to be an acceptable form of communication, but it did not appear to be utilized by parents to increase their child’s physical activity levels. Concerning articles, accessing article content was positively associated with change in steps/day for families in the IIG. However, accessing article content decreased significantly over the course of the study. This finding is consistent with Internet-based studies reporting incrementally reduced usage of websites across the study duration [
The P-Mobile study demonstrated that children in both the MIG and IIG significantly increased steps/day above baseline levels. The intervention where parents received additional behavioral strategies and text messages (IIG) resulted in steps/day increases that were two-fold greater than steps/day levels reported with only daily monitoring and goal setting (MIG). Though this difference was not statistically significant, suggestion of a moderate treatment effect was observed. However, the children in P-Mobile were unable to achieve the study goal (increasing 6000 steps/day above individualized baseline levels) directed to their parents. Children in the MIG were able to reach approximately 24%, while children in the IIG were able to reach approximately 50% of this goal. A 6000 steps/day increase from baseline levels would have amounted to ~13,500 steps/day for girls and ~16,000 steps/day for boys. Surveillance studies of free-living behavior demonstrate that only 25% of girls and 15% of boys aged 6-10 years achieve this level of habitual daily physical activity [
Family-based studies that have used pedometers to increase physical activity in children have typically delivered the intervention through group sessions [
The P-Mobile findings should be interpreted within the context of the study’s limitations. One major limitation was the small sample size. This may have provided insufficient power for detecting statistical significance between the observed group differences. The study had 17% power to detect differences and would have needed a sample size of 105 children/group to detect a 1400 steps/day difference. In addition, the study was limited to only 12 weeks; therefore, the long-term effectiveness of the study is unknown. The mobile phone components utilized in this study were limited to text messages and accessing a website through the mobile phone. Smartphones offer increased functionality, such as specially designed apps that could have fostered automated uploading of step data, thereby reducing participant burden and potentially increasing utilization. Apps also allow for location-based services that can be used to assist participants in identifying nearby facilities conducive for physical activity. Concerning measurement, although we used an objective measure of activity, pedometers do not capture all activity such as biking and swimming, and dietary intake was assessed using the FFQ, which is known to provide biased estimates compared to gold standard techniques, such as doubly labeled water. Finally, P-Mobile did not contain a control group. Our comparison group, the MIG, increased their average steps/day across the study, while control groups in previous studies have not significantly increased steps/day or have resulted in decreased steps/day [
P-Mobile was able to demonstrate that it is both feasible and effective to deliver a physical activity promotion program utilizing mobile phones. The study also showed that parents can be the exclusive targets and thus agents of their children’s behavior change. Our findings add to the literature indicating that pedometers can be used to help increase physical activity in children. Our program relied on text messages, a website, involved few families, and was of a moderate duration. Researchers can build upon this foundation to develop more effective mobile phone-based interventions targeting childhood physical activity.
body mass index
Child Depression Inventory-Short Form
cardiovascular disease
Food Frequency Questionnaire
intensive intervention group
minimal intervention group
New Lifestyles 1000 pedometer
Physical Activity Enjoyment Questionnaire
Parent-Targeted Mobile Phone Intervention to Increase Physical Activity in Sedentary Children
Tanita Body Composition Analyzer
RLNJr was supported by unrestricted funds from the Coca Cola Foundation. RM and WDJ were supported in part by 1 U54 GM104940 from the National Institute of General Medical Sciences of the National Institutes of Health, which funds the Louisiana Clinical and Translational Science Center.
RLNJr conceived and designed the study, interpreted the data, drafted, and critically revised the manuscript. AMM, HRA, and JMSJr acquired and interpreted the data, and critically revised the manuscript. RM, HH, and WDJ conducted the statistical analyses and critically revised the manuscript. STB and CT-L designed the study, interpreted the data, and critically revised the manuscript. TSC conceived the study, interpreted the data, and critically revised the manuscript. All authors provided final approval.
HRA, a co-author, developed the software that was utilized in the study.