Regular physical activity is associated with a decreased risk of type 2 diabetes mellitus (15
), cardiovascular disease (13
) and some cancers (21
) among adults. Moderate to vigorous intensity physical activity (MVPA) has been associated with improved glycemic status (27
), lipid levels (20
) and lower BMI (17
) among youth. A number of health-related organizations have provided physical activity recommendations for youth. While the recommended amount of activity has varied from between 30 (32
) and 60 min of physical activity per day (5
), recent evidence suggests that many adolescents do not obtain 30 min of moderate to vigorous activity per day (16
). Physical Education (PE) provides a venue and an opportunity, in which all children who attend school may be physically active. Moreover, an accelerometer-based study found that 3rd and 4th grade students were more active in the after-school period on days when they had outdoor recess and PE than when these opportunities were deprived (4
). Although, it is not clear what the exact mechanism for this difference was the findings suggest that activity during school time might encourage students to be more active outside of school. Unfortunately, due to funding limitations and societal pressure to raise the standards in core subjects such as math and English, curriculum time allocated to PE and the enrollment in PE lessons has reduced (7
). While PE has many well established objectives such as the development of sport skills, sport knowledge, teamwork and social skills, it also provides significant opportunities for regular MVPA. PE can therefore help youth meet established physical activity guidelines.
International evidence indicates that the level of activity that is obtained during PE classes is relatively low. Observational data indicate that 3rd grade students in the United States (US) spent only 36% of their PE lessons engaged in moderate to vigorous intensity physical activity (MVPA; 24
) with a similar proportion (35%) reported among Australian students (33
). A recent paper from the US Trial for Activity in Adolescent Girls (TAAG) study group, (which also used the same observational instrument as the studies listed above), reported that 6th grade girls spent an average of 37.9% of PE classes engaged in MVPA (23
). Similarly, heart rate monitoring of activity in PE lessons in the United Kingdom (UK) indicated that 11-14 year old students spent an average of 34% of the lesson engaged in MVPA (11
). It should be noted however, that although the findings are consistent across studies, the definition of MVPA has varied. The observational studies have used the System for Observing Physical Activity Instruction Time (SOFIT) which categorizes walking as moderate intensity physical activity (25
). The UK study employed heart rate monitoring and an estimate of MVPA that was based on the participants resting heart rate. These methods were likely selected to assess different dimensions of physical activity because heart rate monitoring provides a better indication of the cardiovascular load of an activity, while the observational methods provide a more behavioral indication of the type of activity that takes place during the class (10
). Alternative definitions will likely lead to different interpretations of the amount of activity that participants obtain from PE classes.
The data presented above suggest that many children are not meeting the US Department of Health and Human Services (DHHS) Healthy People 2010
target of adolescents spending “at least 50 percent of school PE class time being physically active” (31
). Research conducted in elementary schools indicates that providing new curriculum materials and training can result in increased MVPA during PE classes (33
). However, with the exception of one published intervention (26
) and the TAAG investigation that specifically focused on girls (23
), there has been little research conducted in U.S. middle schools on the value of additional training and supplies.
The data reported here are the results of preliminary work that were conducted by the Studies to Treat or Prevent Pediatric Type 2 Diabetes (STOPP-T2D)—Prevention study group in 2003 and 2004. STOPP-T2D—Prevention is a multisite study funded by the National Institute of Diabetes and Digestive and Kidney Diseases that is designed to reduce the risk factors for type 2 diabetes among middle school children. Two studies were conducted sequentially to address two objectives. The aim of the first study (the activity study) was to examine the upper limit of MVPA that can be obtained during regularly scheduled US middle school PE classes, this would provide an indication of the maximum amount of activity that could be achieved. The aim of the second study (the curriculum study), was to determine the amount of MVPA that can be obtained while meeting state mandated curriculum guidelines. The second study was designed to provide information about the maximum amount of physical activity that could realistically be obtained and maintained over time in US middle schools while also addressing the broader PE objectives of skill development, knowledge teamwork and facilitating lifelong physical activity. A further aim of both studies was to ascertain how the interpretation of the amount of activity obtained from PE classes differs according to the definition of MVPA.