Nearly 90 percent of US high school students fail to meet the bare minimum exercise requirements for healthy living, a new government study revealed.

In all, some 12.2 percent of students met the government standard of three days of “muscle-strengthening” activities and seven days of aerobic activities, according to the research from the Centers for Disease Control. The target requirements were set by the government’s “Healthy People 2020” initiative, which sets decade-long goals for physical fitness.

Researchers said the results, which came from a national survey administered in public and private schools, “justify the need to improve and increase efforts to promote physical activity among youths,” according to a statement

Almost 20 percent of male students reached the target, compared to just over five percent of female students.

Students were less likely to lift weights and exercise as they progressed through high school, with only 10 percent of 12th graders reaching the target, compared to 15 percent of 9th graders.

White, non-Hispanic students were also more active than their black and Hispanic counterparts. Obese students were only half as likely to meet the standards as their underweight, normal or overweight classmates.

Healthy People 2020 (HP 2020), released in December 2010, outlines numerous public health objectives, including objectives for youth physical activity participation (1). HP 2020 includes three objectives for meeting current federal physical activity guidelines for 1) aerobic physical activity (participation in ≥60 minutes of aerobic activity per day, 7 days per week) (PA 3.1); 2) muscle-strengthening activity (muscle-strengthening activities on ≥3 days per week) (PA 3.2); and 3) aerobic physical activity and muscle-strengthening activity combined (PA 3.3) (1,2). The HP 2020 target for PA 3.1 is 20.2 percent; targets for PA 3.2 and PA 3.3 are not set because baseline data are not available. To meet the HP 2020 targets for physical activity, promotion of physical activity among female high school students (3), high school students in upper grades (3), and youths with obesity (4) might be warranted, given that these subpopulations are at risk for low levels of physical activity. To determine the proportion of U.S. youths who meet these HP 2020 objectives, CDC analyzed data from the 2010 National Youth Physical Activity and Nutrition Study (NYPANS), a school-based study conducted by CDC that included height and weight measurements and a survey that measured physical activity and dietary behaviors among a nationally representative sample of students in grades 9–12. This report summarizes the results of that analysis, which indicated that among students nationwide in grades 9–12, 15.3 percent met the aerobic objective, 51.0 percent met the muscle-strengthening objective, and 12.2 percent met the objective for both aerobic and muscle-strengthening activities. To improve youth physical activity participation, efforts are needed among CDC, state and local public health agencies, schools, and other public health partners that promote physical activity.

NYPANS measured the prevalence of behaviors and behavioral determinants related to physical activity and nutrition. The survey used a three-stage cluster sample design to obtain cross-sectional data representative of public- and private-school students in grades 9–12 in all 50 states and the District of Columbia. Students completed an anonymous, self-administered questionnaire in their classrooms during a regular class period in the spring of 2010. Data from 11,429 students were available for analysis. The school response rate was 82 percent, the student response rate was 88 percent, and the overall response rate* was 73 percent. Trained data collectors also measured students height and weight using a standard protocol. A total of 1,728 respondents with missing data on sex, grade, race/ethnicity, height, weight, or physical activity were excluded, resulting in a final sample of 9,701 students.

To assess aerobic physical activity, students were asked, “During the past 7 days, on how many days were you physically active for a total of at least 60 minutes per day? (Add up all the time you spent in any kind of physical activity that increased your heart rate and made you breathe hard some of the time.)” Response choices ranged from 1 to 7 days. To assess muscle-strengthening activity, students were asked, “On how many of the past 7 days did you do exercises to strengthen or tone your muscles, such as push-ups, sit-ups, or weight lifting?” Response choices ranged from 0 to 7 days. Body mass index (BMI) was calculated from measured weight and height (weight [kg] / height [m2]) and classified as under/normal weight, overweight, or obese based on sex-specific and age-specific reference data from the 2000 CDC growth charts.

Students met the HP 2020 physical activity objectives (1) if they met current federal physical activity guidelines for 1) aerobic physical activity (participation in ≥60 minutes of aerobic activity per day, 7 days per week) (PA 3.1), 2) muscle-strengthening activity (muscle-strengthening activities on ≥3 days per week) (PA 3.2), and 3) aerobic physical activity and muscle-strengthening activity (participation in ≥60 minutes of aerobic activity per day, 7 days per week and muscle-strengthening activities on ≥3 days/week) (PA 3.3). Data were weighted to provide national prevalence estimates and were examined by demographic characteristics (sex, grade, and race/ethnicity) and BMI category. Statistical software was used to account for the complex sampling design and calculate prevalence estimates and 95 percent confidence intervals; t tests were conducted for pairwise subgroup comparisons, and linear and quadratic trends in grade and BMI category were tested. Because the numbers of students from other racial/ethnic groups were too small for meaningful analysis, race/ethnicity is reported only for non-Hispanic white, non-Hispanic black, and Hispanic students (who might be of any race). All differences presented in this report are statistically significant (p<0.05).

Nationwide, 15.3 percent of high school students met the HP 2020 objective for aerobic activity. A higher percentage of male (21.9 percent) compared with female (8.4 percent) students; 9th-grade (18.5 percent) compared with 10th-grade (15.3 percent), 11th-grade (13.3 percent), and 12th-grade (13.1 percent) students; white (16.9 percent) compared with Hispanic (11.8 percent) students; and under/normal weight (16.3 percent) and overweight (16.5 percent) students compared with those with obesity (10.7 percent) met the aerobic objective (Table).

Nationwide, 51.0 percent of high school students met the HP 2020 objective for muscle-strengthening activity. A higher percentage of male (65.0 percent) compared with female (36.6 percent) students; 9th-grade (55.6 percent) and 10th-grade (52.2 percent) compared with 12th-grade (46.4 percent) students; and under/normal weight (52.6 percent) and overweight (51.7 percent) students compared with those with obesity (45.2 percent) met the muscle-strengthening objective.

Nationwide, 12.2 percent of high school students met the HP 2020 objective for both aerobic and muscle-strengthening activities. A higher percentage of male (18.5 percent) compared with female (5.8 percent) students; 9th-grade (15.0 percent) compared with 10th-grade (12.3 percent), 11th-grade (10.7 percent), and 12th-grade (10.3 percent) students ; white (14.1 percent) compared with black (9.7 percent) and Hispanic (9.9 percent) students; and under/normal weight (13.3 percent) and overweight (13.6 percent) students compared with those with obesity (7.3 percent) met the objective for both aerobic and muscle-strengthening activities.