Physical Activity and Aerobic Fitness Levels of Middle School Students (Measurement)

The primary purpose of this study was to determine if middle school students differing in aerobic fitness levels also differed in accumulated steps/day. A secondary purpose was to examine the physical activity levels of middle school students using pedometers (grades 7-8). Participants included 223 students from the seventh grade (n=111; 57 males and 54 females) and eighth grades (n=112; 54 males and 58 females). Physical activity was monitored for six weekdays using sealed pedometers and participants performed the FITNESSGRAM Pacer test within two weeks of monitoring. Participants were separated into quintiles based on their estimated VO₂max scores. Low fitness (LOW) was defined as the first quintile of the aerobic fitness distribution, moderate fitness (MOD) was defined as the combination of the second and third quintiles, and high fitness (HIGH) was defined as the combination of the fourth and fifth quintiles. This data treatment is similar to that used in a landmark epidemiological study (Blair et al., 1989). High fit participants accumulated significantly more steps/day (F_2,217=264.9, p<.001) than moderately fit and low fit participants (≈1,491 and ≈2,867 steps/day, respectively). The Pearson correlation between steps/day and aerobic fitness was 0.35 (p<.01). Males accumulated significantly more steps/day than females (11,589 ±3,270 vs. 10,232 ±2,517 steps/day, respectively; F_1,219=16.0, p<.001). There were no differences in steps/day between grades. Participants who participated in sports in addition to physical education (PE) accumulated significantly more steps/day (≈980 steps/day) than those participating in PE only (F_1,219=10.0, p<.002). Several studies have reported a low to moderate relationship between physical activity levels and aerobic fitness levels (see Morrow & Freedson, 1994). The findings from this study are important because they demonstrate that, despite a moderate relationship between physical activity and aerobic fitness levels, students with the highest levels of aerobic fitness accumulated a significantly greater amount of physical activity. This study also adds to the existing research on elementary and high school students to complete a preliminary pedometer-based activity curve for school-aged children. The curve illustrates the consistent pattern of differences between males and females and a decrease in physical activity as youth progress through school.
Keyword(s): exercise/fitness, middle school issues, physical activity