Obesity and Physical Fitness in California School Children
The Fitnessgram was performed in 8.4 million students over 6 years (approximately 1.4 million each year in grades 5, 7, and 9) in the State of California, and complete test results were available in 75% (Table I). Between 2003 and 2008, approximately half of the tested students were male (51.13%) and the overall mean age was 12.4 years (mean age 5th grade 10.5 years, 7th grade 12.5 years, 9th grade 14.5 years). Hispanic/Latino (46.8%) was the largest ethnic group followed by whites (30.6%), Asian/Asian American (9.1%), African/African American (7.4%), Filipino/Filipino American (3.1%), American Indian/Alaskan Native (0.8%), and Pacific Islander (0.7%). Ethnicity information was not available from on average 17,323 (1.59%) students each year. Between 2003 and 2008, about 6.5 million students completed participation in the Physical Fitness Test.
The changes in obesity and fitness from 2003 to 2008 can be seen in BMI distributions (Figure 1), HFZ percentage/year/grade (Figure 2), serial changes in HFZ (Figure 3), and HFZ odds ratios (OR) for grade, region, and ethnicity (Figure 4).
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Figure 1.
Body mass index distribution curve. Changes in distribution of BMI in California schoolchildren between 2003 (red/solid) and 2008 (blue/dashed). A small but significant shift in the BMI curve is seen. There was a significant increase in students with BMI >25–36 (P < .0001).
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Figure 2.
Percentage of students in HFZ for each fitness category (A-F). The students in HFZ are shown for 5th, 7th, and 9th grades for each year from 2003 to 2008 in each fitness category (A-F). A significant annual reduction in 5th and 7th grade HFZ is seen for BC, AS, and TES; and an increase is seen in all grades for AC, UBS, and flexibility (P < .001).
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Figure 3.
The serial changes in percentage of students in the HFZ. Students were tracked from 5th to 7th grade (dark gray bars) and students tracked from 7th to 9th grade (light gray bars) for each fitness category (A-F). The 2003 and 2004 students were examined 3 times and tracked from 5th to 7th and from 7th to 9th grade (light/dark gray bars).Although most grade transitions showed serial improvements, these changes were significant only for flexibility in the 2004 students (P < .05).
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Figure 4.
Adjusted odds ratios for students being in the HFZ in California. Adjusted odds ratios for grade, gender, region, and ethnicity with regard to being in the HFZ. Odds ratios above 1 indicate a higher likelihood of the student being in the HFZ.
Although obesity is still increasing, the obesity rate increases may be slowing, with better fitness odds ratios in 9th grades and some ethnic groups (Figure 4), while serial fitness changes show slight improvement within California schools (Figure 3).Additional information can be obtained by examining each of the fitness areas.
The BMI increased between 2003 and 2008 for all students (Figure 1) and for each grade and gender. This increase in individual BMI was most pronounced in the students above the 75th BMI percentile who were overweight or obese.
Using the CDC age-adjusted growth charts, 2% more children were overweight and obese in 2008 than in 2003. In 2003, a total of 33.34% of all children were overweight or obese (17.05% overweight, 16.29% obese); and in 2008, overweight or obesity increased to 35.4% of all children (17.44% overweight, 17.96% obese). The 5th graders (OR 1.92, 95% CI 1.912–1.928) and 7th graders (OR 1.364,95% CI 1.358–1.37) were more likely to be overweight and obese than 9th graders. With regard to obesity alone, the 5th graders (OR 1.519, 95% CI 1.511–1.527) and 7th graders (OR 1.292; 95% CI 1.285–1.299) were more likely to be obese than 9th graders.
As expected, there was a significant decrease of 5th, 7th, and 9th grade students in the HFZ for BC between 2003 and 2008 (P < .001) (Figure 2). However, age-adjusted serial measurements tracking the same student class (entrance classes 2001–2006) revealed improvements in each 7th to 9th transition and late improvements in 5th to 7th grade transitions for changes of body composition (P > .05) (Figure 3A).
Asian and white students showed a slight improvement in BC from 2003 to 2008 and were more likely to be in the HFZ than other ethnicities. Filipinos exhibited no significant change in BC, whereas all other ethnicities demonstrated a decline of students who were in the HFZ between 2003 and 2008 (Figure 4A).
Females, Asians, and whites did better than others in achieving healthy BC (OR 1.799; 95% CI 1.52; 1.286) (Figure 4).
There was a small but significant worsening of AS between 2003 and 2008 (P < .0001) (Figure 2B). However, serial tracking analysis again showed small improvements over time in all 5th to 7th and 7th to 9th grade transitions (P > .05) (Figure 3B).
Males, Asians/Asian Americans (OR 1.204), and whites (OR 1.372) had a higher chance of being in the HFZ, whereas females, African Americans, Native Americans, and Hispanics were less likely to be in the HFZ (Figure 4B).
Although the changes in TES from 2003 to 2008 were statistically significant (P < .001), the actual change in the whole population was small. The 5th and 7th graders showed a decrease of TES between 2003 and 2008, whereas 9th graders significantly improved TES (P < .001) (Figure 2C). Serial tracking showed improvements in all 5th to 7th grade transitions and later 7th to 9th grade transitions (P > .05) (Figure 3C).
Female students were more likely to be in the HFZ than male students (OR 1.268) (Figure 4C). The African/American group showed no significant difference over time, and American Indian/Alaskan Native was the only ethnic group that was able to increase TES (Table I).
Northern Californians, African Americans, Asians, Filipinos, Hispanics, and Pacific Islander groups were less likely to be in the TES HFZ (Figure 4C).
Despite the increases in BMI and obesity, there was a significant improvement in the percentage of students achieving healthy AC (P < .0001) (Figure 2D). Fifth graders and 7th graders were more likely to be in the HFZ for AC than 9th graders (Figure 4D).However, serial tracking showed only late improvements in 5th to 7th grade transitions (P > .05) (Figure 3D). Boys and girls improved AC significantly between 2003 and 2008 (P < .0001, Table I).
All ethnicities, except Pacific Islanders, showed significant improvement in AC between 2003 and 2008. Compared to other ethnicities, more students from the Asian (OR 1.346) and white (OR 1.271) subgroups achieved healthy AC (Figure 3D). Students in both Northern California (NC) and Southern California (SC) improved AC between 2003 and 2008.
There was a significant improvement of UBS from 2003 to 2008 (P < .0001) (Table I). This change was observed in all grades between 2003 and 2008 (P < .001) (Figure 2E). Fifth graders and 7th graders were less likely to be in the HFZ than 9th graders (Figure 4E). Serial analysis of the same student entrance groups showed improvements in all 5th to 7th grade and 7th to 9th grade transitions (Figure 3E).
Boys and girls improved UBS significantly from 2003 to 2008 (P < .0001) (Table I). However, girls were less likely to be in the HFZ for UBS than boys (Figure 4E).
All ethnic groups except Pacific Islanders improved UBS significantly between 2003 and 2008; the Filipino subgroup increased the most with 5.08% (Table I). Students in both NC and SC improved UBS from 2003 to 2008.
Flexibility improved significantly from 2003 to 2008 in all grades (P < .0001) (Table I). However, 5th graders (OR 0.641) and 7th graders (OR 0.9) were less likely to be in the HFZ than 9th graders (Figure 4F).Serial tracking of flexibility showed improvements in most 7th to 9th grade and all 5th to 7thth grade transitions with significant improvements in 2004 students tracked from 5th to 7th and 7th to 9th grade (P = .03) (Figure 3F).
Boys and girls improved flexibility significantly between 2003 and 2008 (P < .0001) (Table I), and girls were more likely to be in the HFZ than boys (OR 1.309) (Figure 4F). Flexibility improved throughout all ethnic groups except Pacific Islanders (Table I).
The percentage of students achieving a perfect fitness score (6/6 fitness categories in HFZ) increased significantly from 28.98% in 2003 to 34.84% in 2008 (P < .0001).
Some grades also showed higher AC, BC, and UBS fitness scores in higher-income counties (median household income ≥$40,000/year). Fifth graders scored significantly higher in body composition and UBS when they were from higher-income counties (BC 72.5% in HFZ vs 67.3% in HFZ, P = .013; UBS 70.1% in HFZ vs 61.5% in HFZ, P = .002). In addition, 7th graders from higher-income counties were more likely to be in the HFZ for aerobic capacity and body composition (AC 71.1% in HFZ vs 60.7% in HFZ, P = .001; BC 71.9% in HFZ vs 66.1% in HFZ, P = .005), and better UBS was seen in counties with low unemployment (<8% unemployment rate; UBS 73.7% in HFZ vs 65.4% in HFZ, P = .035). Aerobic capacity also seemed to be better in 9th grade students from higher-income counties (AC 64.8% in HFZ vs 53.2% in HFZ, P < .0001) and 5th graders from counties with lower unemployment (<8% unemployment rate; AC 65.7% in HFZ vs 54.8% in HFZ, P = .014).
Perfect fitness was seen in more 5th and 9th graders from higher-income counties (5th graders 29.2% in HFZ vs 22.9% in HFZ, P = .045; 9th graders 38.2% in HFZ vs 30.3% in HFZ, P = .022).
Results
The Fitnessgram was performed in 8.4 million students over 6 years (approximately 1.4 million each year in grades 5, 7, and 9) in the State of California, and complete test results were available in 75% (Table I). Between 2003 and 2008, approximately half of the tested students were male (51.13%) and the overall mean age was 12.4 years (mean age 5th grade 10.5 years, 7th grade 12.5 years, 9th grade 14.5 years). Hispanic/Latino (46.8%) was the largest ethnic group followed by whites (30.6%), Asian/Asian American (9.1%), African/African American (7.4%), Filipino/Filipino American (3.1%), American Indian/Alaskan Native (0.8%), and Pacific Islander (0.7%). Ethnicity information was not available from on average 17,323 (1.59%) students each year. Between 2003 and 2008, about 6.5 million students completed participation in the Physical Fitness Test.
The changes in obesity and fitness from 2003 to 2008 can be seen in BMI distributions (Figure 1), HFZ percentage/year/grade (Figure 2), serial changes in HFZ (Figure 3), and HFZ odds ratios (OR) for grade, region, and ethnicity (Figure 4).
(Enlarge Image)
Figure 1.
Body mass index distribution curve. Changes in distribution of BMI in California schoolchildren between 2003 (red/solid) and 2008 (blue/dashed). A small but significant shift in the BMI curve is seen. There was a significant increase in students with BMI >25–36 (P < .0001).
(Enlarge Image)
Figure 2.
Percentage of students in HFZ for each fitness category (A-F). The students in HFZ are shown for 5th, 7th, and 9th grades for each year from 2003 to 2008 in each fitness category (A-F). A significant annual reduction in 5th and 7th grade HFZ is seen for BC, AS, and TES; and an increase is seen in all grades for AC, UBS, and flexibility (P < .001).
(Enlarge Image)
Figure 3.
The serial changes in percentage of students in the HFZ. Students were tracked from 5th to 7th grade (dark gray bars) and students tracked from 7th to 9th grade (light gray bars) for each fitness category (A-F). The 2003 and 2004 students were examined 3 times and tracked from 5th to 7th and from 7th to 9th grade (light/dark gray bars).Although most grade transitions showed serial improvements, these changes were significant only for flexibility in the 2004 students (P < .05).
(Enlarge Image)
Figure 4.
Adjusted odds ratios for students being in the HFZ in California. Adjusted odds ratios for grade, gender, region, and ethnicity with regard to being in the HFZ. Odds ratios above 1 indicate a higher likelihood of the student being in the HFZ.
Although obesity is still increasing, the obesity rate increases may be slowing, with better fitness odds ratios in 9th grades and some ethnic groups (Figure 4), while serial fitness changes show slight improvement within California schools (Figure 3).Additional information can be obtained by examining each of the fitness areas.
Body Composition
The BMI increased between 2003 and 2008 for all students (Figure 1) and for each grade and gender. This increase in individual BMI was most pronounced in the students above the 75th BMI percentile who were overweight or obese.
Using the CDC age-adjusted growth charts, 2% more children were overweight and obese in 2008 than in 2003. In 2003, a total of 33.34% of all children were overweight or obese (17.05% overweight, 16.29% obese); and in 2008, overweight or obesity increased to 35.4% of all children (17.44% overweight, 17.96% obese). The 5th graders (OR 1.92, 95% CI 1.912–1.928) and 7th graders (OR 1.364,95% CI 1.358–1.37) were more likely to be overweight and obese than 9th graders. With regard to obesity alone, the 5th graders (OR 1.519, 95% CI 1.511–1.527) and 7th graders (OR 1.292; 95% CI 1.285–1.299) were more likely to be obese than 9th graders.
As expected, there was a significant decrease of 5th, 7th, and 9th grade students in the HFZ for BC between 2003 and 2008 (P < .001) (Figure 2). However, age-adjusted serial measurements tracking the same student class (entrance classes 2001–2006) revealed improvements in each 7th to 9th transition and late improvements in 5th to 7th grade transitions for changes of body composition (P > .05) (Figure 3A).
Asian and white students showed a slight improvement in BC from 2003 to 2008 and were more likely to be in the HFZ than other ethnicities. Filipinos exhibited no significant change in BC, whereas all other ethnicities demonstrated a decline of students who were in the HFZ between 2003 and 2008 (Figure 4A).
Females, Asians, and whites did better than others in achieving healthy BC (OR 1.799; 95% CI 1.52; 1.286) (Figure 4).
Abdominal Strength
There was a small but significant worsening of AS between 2003 and 2008 (P < .0001) (Figure 2B). However, serial tracking analysis again showed small improvements over time in all 5th to 7th and 7th to 9th grade transitions (P > .05) (Figure 3B).
Males, Asians/Asian Americans (OR 1.204), and whites (OR 1.372) had a higher chance of being in the HFZ, whereas females, African Americans, Native Americans, and Hispanics were less likely to be in the HFZ (Figure 4B).
Trunk Extensor Strength
Although the changes in TES from 2003 to 2008 were statistically significant (P < .001), the actual change in the whole population was small. The 5th and 7th graders showed a decrease of TES between 2003 and 2008, whereas 9th graders significantly improved TES (P < .001) (Figure 2C). Serial tracking showed improvements in all 5th to 7th grade transitions and later 7th to 9th grade transitions (P > .05) (Figure 3C).
Female students were more likely to be in the HFZ than male students (OR 1.268) (Figure 4C). The African/American group showed no significant difference over time, and American Indian/Alaskan Native was the only ethnic group that was able to increase TES (Table I).
Northern Californians, African Americans, Asians, Filipinos, Hispanics, and Pacific Islander groups were less likely to be in the TES HFZ (Figure 4C).
Aerobic Capacity
Despite the increases in BMI and obesity, there was a significant improvement in the percentage of students achieving healthy AC (P < .0001) (Figure 2D). Fifth graders and 7th graders were more likely to be in the HFZ for AC than 9th graders (Figure 4D).However, serial tracking showed only late improvements in 5th to 7th grade transitions (P > .05) (Figure 3D). Boys and girls improved AC significantly between 2003 and 2008 (P < .0001, Table I).
All ethnicities, except Pacific Islanders, showed significant improvement in AC between 2003 and 2008. Compared to other ethnicities, more students from the Asian (OR 1.346) and white (OR 1.271) subgroups achieved healthy AC (Figure 3D). Students in both Northern California (NC) and Southern California (SC) improved AC between 2003 and 2008.
Upper Body Strength
There was a significant improvement of UBS from 2003 to 2008 (P < .0001) (Table I). This change was observed in all grades between 2003 and 2008 (P < .001) (Figure 2E). Fifth graders and 7th graders were less likely to be in the HFZ than 9th graders (Figure 4E). Serial analysis of the same student entrance groups showed improvements in all 5th to 7th grade and 7th to 9th grade transitions (Figure 3E).
Boys and girls improved UBS significantly from 2003 to 2008 (P < .0001) (Table I). However, girls were less likely to be in the HFZ for UBS than boys (Figure 4E).
All ethnic groups except Pacific Islanders improved UBS significantly between 2003 and 2008; the Filipino subgroup increased the most with 5.08% (Table I). Students in both NC and SC improved UBS from 2003 to 2008.
Flexibility
Flexibility improved significantly from 2003 to 2008 in all grades (P < .0001) (Table I). However, 5th graders (OR 0.641) and 7th graders (OR 0.9) were less likely to be in the HFZ than 9th graders (Figure 4F).Serial tracking of flexibility showed improvements in most 7th to 9th grade and all 5th to 7thth grade transitions with significant improvements in 2004 students tracked from 5th to 7th and 7th to 9th grade (P = .03) (Figure 3F).
Boys and girls improved flexibility significantly between 2003 and 2008 (P < .0001) (Table I), and girls were more likely to be in the HFZ than boys (OR 1.309) (Figure 4F). Flexibility improved throughout all ethnic groups except Pacific Islanders (Table I).
Composite Fitness Score
The percentage of students achieving a perfect fitness score (6/6 fitness categories in HFZ) increased significantly from 28.98% in 2003 to 34.84% in 2008 (P < .0001).
Socioeconomic Status
Some grades also showed higher AC, BC, and UBS fitness scores in higher-income counties (median household income ≥$40,000/year). Fifth graders scored significantly higher in body composition and UBS when they were from higher-income counties (BC 72.5% in HFZ vs 67.3% in HFZ, P = .013; UBS 70.1% in HFZ vs 61.5% in HFZ, P = .002). In addition, 7th graders from higher-income counties were more likely to be in the HFZ for aerobic capacity and body composition (AC 71.1% in HFZ vs 60.7% in HFZ, P = .001; BC 71.9% in HFZ vs 66.1% in HFZ, P = .005), and better UBS was seen in counties with low unemployment (<8% unemployment rate; UBS 73.7% in HFZ vs 65.4% in HFZ, P = .035). Aerobic capacity also seemed to be better in 9th grade students from higher-income counties (AC 64.8% in HFZ vs 53.2% in HFZ, P < .0001) and 5th graders from counties with lower unemployment (<8% unemployment rate; AC 65.7% in HFZ vs 54.8% in HFZ, P = .014).
Perfect fitness was seen in more 5th and 9th graders from higher-income counties (5th graders 29.2% in HFZ vs 22.9% in HFZ, P = .045; 9th graders 38.2% in HFZ vs 30.3% in HFZ, P = .022).