Accelerometer Study Suggests Younger People Get Less Physical Activity Than Previously Thought

Younger People Get Less Physical Activity Than Previously Thought

The use of physical activity trackers (accelerometers) has led some researchers to conclude that young people get minimal levels of exercise and that this trend follows them into early adulthood.

The CDC recommends a minimum of 60 minutes of moderate-to-vigorous physical activity (MVPA) each day. Past studies have suggested that these levels can be used as reliable predictors for future health problems like diabetes or obesity. Prior research has also found that about 70% of 15-year-olds do not reach this level of activity.

Most studies of activity habits involve the use of surveys and questionnaires. This study did too, but also employed accelerometers to track the movement of participants. Some 561 10th grade  students were recruited and were asked to wear the trackers on their hip for seven consecutive days for at least ten hours each day. The students were followed throughout high school and for their first year after graduating.

The results were somewhat disheartening. An estimated 91% of the students were not getting at least an hour of MVPA. While those who went on to attend college saw a small increase in their activity, the trend largely continued as the adolescents transitioned into adulthood. The authors do admit, however, that although the difference between college and not-college was statistically significant, the actual difference in number of minutes of activity was small.

Ultimately, the net result of the study is twofold. The first result is the confirmation that young people don’t get enough exercise, which has been repeatedly established. The second, more interesting result is the possibility that accelerometers could be used to help improve accuracy of exercise-related studies. Surveys and self-reporting questionnaires have distinct downsides since people tend to give themselves the benefit of the doubt when filling out information. Accelerometers could be combined with surveys to provide a better idea of what the actual activity levels are and help offer more clarity to future work.

Li, K., et. al., “Changes in Moderate-to-Vigorous Physical Activity Among Older Adolescents,” Pediatrics, 2016; 10.1542/peds.2016-1372.