Time spent outdoors was associated with increased moderate-to-vigorous physical activity and cardiorespiratory fitness and decreased sedentary behavior among adolescents, according to study findings in The Journal of Pediatrics.
Lee Schaefer, PhD, of the University of Regina in Saskatchewan, Canada, and colleagues assessed accelerometer and questionnaire data from 306 children aged 9 to 17 years who participated in the 2009 wave of the Healthy Hearts Prospective Cohort Study of Physical Activity and Cardiometabolic Health. Absolute BMI was converted to an age and sex-specific z score using Epi Info.
Overall, 17% of participants reported spending no time outdoors after school; 44% reported spending some time outdoors; and 39% reported spending most/all of their time outdoors.
Children who spent most of their time outdoors were younger (P<.001), more likely to be male (P=.03) and contributed data during warm months (P=.001) compared with children who spent no time outdoors. No differences in BMI z scores were observed between the two groups.
As time spent outdoors increased, moderate-to-vigorous physical activity increased and sedentary time decreased. Children who reported spending no time outdoors had 21 fewer minutes of daily moderate-to-vigorous physical activity and 70 additional minutes of sedentary time per day compared with children who spent most of their time outdoors.
Outdoor time was a significant indicator of moderate-to-vigorous physical activity among children, independent of age, sex, BMI z score, fitness level, sedentary time and season. Sedentary time and cardiorespiratory fitness were significant indicators of moderate-to-vigorous physical activity.
Children who spent most of their time outside were 2.8 times more likely to spend 60 minutes or more doing moderate-to-vigorous physical activity vs. those who spent no time outdoors. However, this relationship was dependent on whether time outdoors occurred during weekdays or the weekend.
When analyzing for after-school hours, defined as 3:30 p.m. to 11:59 p.m., the association between outdoor time and moderate-to-vigorous physical activity and sedentary time was 57% greater among children who spent most of their time outdoors vs. those who spent no time outdoors. This relationship was only 31% greater between these groups during school hours. Sedentary time was 8.2% lower during after-school hours and 2.5% lower during school hours among children who spent most of their time outdoors compared with those who spent no time outdoors.
Children who spent most of their time outdoors accumulated less sedentary time, had greater cardiorespiratory fitness and achieved greater shuttle run scores compared with those who spent no time outdoors. No differences in BMI z scores were observed between these groups.
“The data presented here reinforce the notion that reviving outdoor activities may be an attractive approach for the promotion of higher intensity physical activity as youth who reported spending more time outdoors achieved about 50% more minutes of vigorous intensity physical activity compared with youth who spent no time outdoors,” according to researchers.
“Schools and parents should consider structure time outdoors for children in an effort to boost physical activity levels and enhance fitness,” Schaefer said in a press release.
Disclosure: The researchers report no relevant financial disclosures.