Related Experiment Video
Updated: Jul 3, 2026
Visualization of Intensity Levels to Reduce the Gap Between Self-Reported and Directly Measured Physical Activity
Published on: March 7, 2019
Moderate-to-vigorous physical activity from ages 9 to 15 years
Philip R Nader1, Robert H Bradley, Renate M Houts
1Department of Pediatrics, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093-0927, USA. pnader@ucsd.edu
Context:
Decreased physical activity plays a critical role in the increase in childhood obesity. Although at least 60 minutes per day of moderate-to-vigorous physical activity (MVPA) is recommended, few longitudinal studies have determined the recent patterns of physical activity of youth.
Objective:
To determine the patterns and determinants of MVPA of youth followed from ages 9 to 15 years.
Design, Setting, And Participants:
Longitudinal descriptive analyses of the 1032 participants in the 1991-2007 National Institute of Child Health and Human Development Study of Early Child Care and Youth Development birth cohort from 10 study sites who had accelerometer-determined minutes of MVPA at ages 9 (year 2000), 11 (2002), 12 (2003), and 15 (2006) years. Participants included boys (517 [50.1%]) and girls (515 [49.9%]); 76.6% white (n = 791); and 24.5% (n = 231) lived in low-income families.
Main Outcome Measure:
Mean MVPA minutes per day, determined by 4 to 7 days of monitored activity.
Results:
At age 9 years, children engaged in MVPA approximately 3 hours per day on both weekends and weekdays. Weekday MVPA decreased by 37 minutes per year [corrected], while weekend MVPA decreased by 39 minutes per year [corrected]. By age 15 years, adolescents were only engaging in MVPA for 50 minutes per weekday [corrected] and 36 minutes per weekend day [corrected]. Boys were more active than girls, spending 18 and 14 more minutes per day [corrected] in MVPA on the weekdays and weekends, respectively. The rate of decrease in MVPA was the same for boys and girls. The estimated age at which girls crossed below the recommended 60 minutes of MVPA per day was approximately 13.2 years for weekday [corrected] activity compared with boys at 14.9 years [corrected], and for weekend activity, girls crossed below the recommended 60 minutes of MVPA at 12.7 years [corrected] compared with boys at 13.6 years [corrected].
Conclusion:
In this study cohort, measured physical activity decreased significantly between ages 9 and 15 years.
Related Concept Videos
01:17Exercise and Cardiac Output
Sustained exercise increases the muscles' oxygen demand, which can be met...
01:20Exercise and Cardiovascular Response
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...
01:27Exercise and Muscle Performance
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
01:09Changes in the Appendicular Skeleton with Age
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
01:27Signs of Puberty
01:20Lifestyle Factors and Health
Benefits of Physical Activity
Physical activity, whether through structured exercise or casual activities like walking, biking, or dancing, is a cornerstone of a...