|Figure 1. Caloric expenditures in different conditions.|
Sunday, November 17, 2013
Project Coach Enhances Activity Levels Beyond what Youth Get When on their Own
Don Siegel and Dennis Nelson
A recent meta-analysis (Metcalf, Henley, and Wilkin, 2012) concluded “physical activity interventions have had only a small effect on children’s overall activity levels.” The authors speculate that one reason for such modest effects may be “… that the intervention specific exercise sessions may simply be replacing periods of equally intense activity. For example, after school activity clubs may simply replace a period of time that children usually spend playing outdoors or replace a time later in the day/week when the child would usually be active.” In our continuing attempt to examine the quantity and quality of Project Coach components, and to determine whether our Fall soccer program was impacting the amount and quality of physical activity enjoyed by our 3rd to 5th graders, we ran our most extensive accelerometer study to date. In essence, one of our goals was to determine whether Project Coach reflected the findings of Metcalf, Henley, and Wilkin, or promoted enhanced activity, beyond what youth get when on their own.
What We Did
After coordinating with teachers and children at Gerena School, 10 youth (7 boys and 3 girls, 10 years of age) volunteered to wear accelerometers (Actigraph GT3X) for 8 days, from when school started at 8:30 a.m. until 5:30 p.m. The strategy was to collect data for 4 days when these participants had Project Coach and 4 days when they did not have Project Coach after school. During this time of the year we run our soccer/dance program on Tuesdays and Wednesdays from 4:30 – 5:30. On Mondays and Thursdays, participants simply wore the accelerometers over the same duration and attended to whatever activities that they normally do after school.
To provide a broader context for the activity levels of our youth, we broke down data hourly so that we could get a sense of how much activity children were getting during the school day, when participating and not participating in Project Coach, and when taking physical education. Using Actilife 6.0 (accelerometer data analysis software), we were able to convert accelerometer activity counts to calories expended, MET rate (a measure of activity intensity), percentages of sedentary to very vigorous activity, and steps taken.
What We Found
Figure 1 shows the calories expended by participants in various conditions. During the school day (8:30 – 3:30) participants burned 23 calories, on average, for each hour that they were in school. In contrast, during the 4:30 – 5:30 period on days that they did not have Project Coach (NonPC KCal) they burned 51 calories. During Project Coach participants expended 126 calories, and during physical education they burned 73 calories (physical education lasted only 40 minutes). Statistical tests run across these conditions (p. < .05) revealed that youth expended more calories during their non Project Coach hour than an average school hour, and that during Project Coach they burned more calories than during the same 4:30 – 5:30 hour when they were not in Project Coach. Tests also revealed no difference between a child’s out of school - non-Project Coach hour and physical education . We did not include dance in the statistical analysis as only 2 children were in dance, but presented data to get a general sense of how it compared to soccer.
As seen in Figure 2, we also report the conversion of accelerometer activity counts to steps. The contrast between the non- Project Coach hour and that in Project Coach is similar and statistically significant, but the average in-school and non-Project Coach hour are statistically not different. Also, the number of steps taken in physical education are greater than during a normal school hour or a non-Project Coach hour, but are statistically less than in Project Coach.
Finally, in Figure 3 we contrast the activity intensity levels across conditions. These data were derived by using Freedson’s (2005) algorithm for converting activity counts to metabolic equivalents with the following cut-offs (Sedentary 0-2.0 METs, Light 2.0 – 2.4 METs, Moderate 2.4 – 6.3 METs, Vigorous 6.3 – 10.3 METs, and Very Vigorous > 10.3 METs). As shown, Project Coach has the lowest amount of sedentary activity (combining PC and Dance), and the highest amounts of moderate activity. It also appears that physical education has a comparable level of vigorous activity to that of Project Coach. When we computed an average for the percentage of moderate and vigorous physical activity (MVPA) for children when they were not in Project Coach and when they were, we found the difference to be dramatically, and significantly different (29.0% vs. 71.9%, p. < .001). Such data, also compare quite favorably with an accelerometer study by Wickel and Eisenmann (2006) who reported that children, when engaged in youth sports had MVPA of between 22% – 27% of the time, and were engaged in sedentary and light activity approximately 52% of the time.
While recommended caloric expenditures for children are not readily available, the American College of Sports Medicine does endorse children taking 12,000 steps/day. If we were to add the number of steps youth in our study took over the hours of 8:30 to 5:30 on a non- Project Coach day and a Project Coach day, we get approximately 6800 and 8400 steps, with Project Coach accounting for about 18% of the total. Again, from a policy perspective, if the 12,000 steps/day goal is to be attained for our youth, more physical activity is needed. This can be achieved by increasing the intensity level of what is done in Project Coach (although over 70% is already at the moderate to vigorous level), increasing the duration of Project Coach activity periods (e.g., going from 60 minutes to 90 minutes), and/or by providing more periods during the school day when children have an opportunity to be active (e.g., increasing the number of days children have physical education from 2 days to 4 or 5 days, and providing daily recess during which children can engage in free play). Our data show that children, on average, spend 77% of their school day engaged in sedentary or light activity).
What Do these Data Mean?
While Project Coach continues to work on increasing activity levels in which its participants engage, these data do seem to conflict with the findings of Metcalf, Henley, and Wilkin (2012) in that children participating in Project Coach clearly are getting more physical activity that has greater intensity than they are getting on their own . In relative terms, this amounts to burning 147% more calories and taking 259% more steps during the 4:30 – 5:30 hour. The fact that youth in Project Coach are getting more activity than they do obtain on their own is not accidental in that we have been monitoring activity levels of youth by using accelerometry for several years, and have adapted our coaching practices to minimize sedentary epochs, reduce transition time among drills and games, and instruct coaches on how to lessen “talk time”. We also make it a point to reinforce coaches as they improve on maximizing activity levels of their players. As with most structured physical activity programs, there is nothing magical about increasing a child’s physical activity level. Simple enrollment in a program is not enough. How the program leaders utilize time and engage children determines participants’ physical activity profiles. Normally, when children are having fun, learning new skills, and given opportunities to play games with minimal disruptions, their physical activity levels increase.
While the data also reveal that for the time children are in Project Coach they are getting the dosage of physical activity recommended by the Center for Disease Control and Prevention and the National Association for Sport and Physical Education, we also recognize that youth in this study are most likely not getting at least an hour of physical activity every day, with most of it being at a moderate to vigorous level. Consequently, if such guidelines are to be met, additional programming by Project Coach is needed, or other school and community initiatives should be undertaken to provide more structured opportunities for youth to engage in such programs.
We are also aware that in absolute terms the number of calories expended and steps taken are fairly modest (US Department of Health and Human Services, 2008). However, as conveyed by Freedson, Pober, and Janz (2005) accelerometry counts do not perfectly track physiological indices such as calories expended or metabolic equivalents (METs), since they do not capture “…all movement all the time and thus estimates of total daily energy expenditure from movement counts underestimate actual energy expenditure” (p. S526). Additionally, the data reveal that approximately 28% (about 17 minutes) of the time youth are in Project Coach they are sedentary or engaged in light activity, which would also contribute to these relatively modest values. To place our findings in context, using data from a recent study that computed caloric expenditures in children, aged 10 – 13, for an array of activities, using indirect calorimetry, the 43 minutes of activity in Project Coach was as if youth walked continuously at 3 mph (Graf, et al., 2009). Consequently, it is reasonable to surmise that the actual data represent conservative estimates of physiological values, and that if more direct measures had been taken, it is likely that we would find higher values for calories expended, percentage of MVPA, and steps taken.
While Metcalf, Henley, and Wilkin (2012) have not found compelling evidence for the added value of structured physical activity programs; such data need to be interpreted with regard to the contexts in which youth live and the opportunities that they have to be physically active. For children living in the North End of Springfield, and many other such locals in which parents are apprehensive about allowing their children unstructured and unsupervised free play, it would seem that well conceived programs within schools and during the after school hours should be crafted, supported, and promoted.
Freedson, P., Pober, D., & Janz, K. F. (2005). Calibration of accelerometer output for children. Medicine & Science in Sports & Exercise, 37(11), S523-s530.
Graf, D. L., Pratt, L. V., Hester, C. N., & Short, K. R. (2009). Playing active video games increases energy expenditure in children. Pediatrics, 124(2), 534-540. doi:10.1542/peds2008-2851.
US Department of Health and Human Services. Physical activity guidelines for Americans, 2008. Washington, DC: US Department of Health and Human Services; 2008.
Wickel, E. E., & Eisenmann, J. C. (2007). Contribution of youth sport to total daily physical activity among 6- to 12-yr-old boys. Medicine & Science in Sports & Exercise, 39(9), 1493-1500.
 Children should accumulate at least 60 minutes, and up to several hours, of age-appropriate physical activity on all, or most days of the week. This daily accumulation should include moderate and vigorous physical activity of which the majority of it is intermittent in nature.
 Wickel and Eisenmann (2006) also found that youth were physically more active with regard to both the amount and intensity of activity on days that they were engaged in a structured sports program than on days when they were not so engaged.
 Again, physical education was only 40 minutes in duration, and given the trend, we would expect to find significance if physical education was 20 minutes longer in duration.