Study Suggests Causal Relationship Between Phys. Ed., Child's Weight
Increasing the amount of physical education time for 5th graders appears to reduce the likelihood of childhood obesity, according to a study published online Monday in the Journal of Health Economics.
The authors set out to investigate whether changes in the amount of time spent in physical education could affect the weight of elementary school students, using data from the Early-Childhood Longitudinal Study, Kindergarten Class of 1998-99 (ECLS-K). Overall, across grades K-5, students participated in an average of 87.35 minutes of physical education per week, the ECLS-K data shows.
In states with no physical education mandate, K-5 students only participated in an average 77.27 minutes of weekly P.E., while students in states that mandated a specific amount of physical education participated in an average of 101.20 minutes of gym class each week. Researchers discovered, however, that only 34 percent of the K-5 students in states with mandated amounts of physical education time actually participated in P.E. for the required number of minutes.
Adding an additional 60 minutes of physical education time per week for 5th graders reduced the probability of obesity by 4.8 percentage points, according to the study.
The relationship between extra physical education time and weight appeared to be affected by gender, however. For boys, an additional 60 minutes of P.E. time reduced the probability of being overweight and the likelihood of obesity by 7.2 percentage points, the study found. For girls, the additional time in gym only reduced the probability of being overweight by 0.6 percentage points and the probability of obesity by 1.8 percentage points.
The authors dug further into the gender differences by looking at whether the relationship between additional P.E. time and other types of physical activity varied for boys and girls. They discovered that additional P.E. time decreases the probability that girls will participate in individual sports and playground activities, while additional P.E. time increased structured activities (including sports), free-time physical activity, and aerobic exercise for boys.
"These results suggest that P.E. time and other types of physical activity may be complements for boys, but substitutes for girls, which is one explanation for the gender difference in how P.E. affects weight," the authors write.
The study also took a look at whether additional P.E. time had any effect (either positive or negative) on other academic subjects. The authors discovered that the only class to experience a decrease in class time with increased amounts of time for P.E. was music; an additional one minute of P.E. was associated with a 0.2-minute decrease in music class. Schools that added extra P.E. time tended to also extend the school day, with a one-minute increase in P.E. linked to a 1.6-minute increase in the length of the school day.
The study, "The Impact of Physical Education on Obesity Among Elementary School Children," will be published in the June print edition of the Journal of Health Economics.
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