Physical Activity, Sedentary Time, and Obesity in Adolescents: Differences by School Grade.
Doyoung Gwak, Younghwan Choi, Yunmin Han and 1 others
PMID 41904787WHAT IT FOUND
Korean adolescents meeting both physical activity and sedentary time guidelines had the lowest odds of obesity (OR 0.54).
Sedentary time over 8 hours was associated with higher obesity odds (OR 1.69). Meeting only one guideline was weaker.
Key findings
01Adolescents meeting physical activity guidelines had lower odds of obesity than those not meeting them (OR 0.73, 95% CI 0.70–0.77).
02Sedentary time above 8 hours per day was associated with higher odds of obesity than 2 hours or less (OR 1.69, 95% CI 1.61–1.77).
03Adolescents meeting both physical activity and sedentary time guidelines had the lowest odds of obesity (OR 0.54, 95% CI 0.50–0.59).
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was cross-sectional, so it cannot show that physical activity or sedentary time caused obesity. Physical activity, sedentary time, height, and weight were self-reported, so recall and social desirability bias could affect the estimates. Diet, sleep, and academic sedentary time were not included. BMI can misclassify muscular adolescents. Complex survey weights were not applied. Data from 2013 to 2023 were pooled, so changes over time were not separated.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not read the lower odds as proof that adding exercise prevents obesity. The study measured existing behavior at one time point and used self-reported activity and sedentary time, so cause and effect cannot be separated. The result is an association, not a tested intervention.