Research: Physical Activity, Obesity and Health

The Journal of the American Medical Association reported that obesity has doubled among children and quadrupled among adolescents over the past 30 years, and more than one-third of children or adolescents in 2012 were overweight or obese (Ogden et al., 2014). These children are at an increased risk for developing health problems such as heart disease, diabetes, cancer, and hypertension as adults. The Centers for Disease Control and Prevention reported that overweight and obesity are leading cancer risk factors, and that 40 percent of all cancers diagnosed are associated with overweight and obesity (2017).

According to the 2012 National Health and Nutrition Survey, only one-quarter of youth ages 12-15 engage in at least 60 minutes of moderate-to-vigorous physical activity each day, as recommended by the Physical Activity Guidelines for Americans (Fakhouri et al., 2014). Among children, regular physical activity has been strongly associated with improved cardiorespiratory and muscular fitness and metabolic health, better bone health, and weight maintenance and energy balance, with greater benefits for participating in physical activity more often, longer, or at higher intensity (Duncan et al., 2016; Ward et al., 2015; US DHHS, 2008). Only half of American adults achieve recommended levels of physical activity (Ussery et al., 2017). There is a gender gap in physical activity levels, whereby women and girls are less likely than men and boys to attain recommended physical activity levels (Althoff et al., 2017; Ward et al., 2015).

Activity levels for many children have declined, due in part to a built environment that is unsafe for walking and bicycling, reduced physical education in school, and increased popularity of sedentary leisure-time activities. Safe Routes to School can create environmental, policy, and behavioral changes that increase physical activity and promote the health of both children and adults.  Articles summarized in this section address the overall health benefits of physical activity, specifically walking to and from school, as well as the impact that increased physical activity opportunities have on current obesity and health trends in the US.

Research Highlights:

  • Research demonstrates that children who walk or bicycle to school have higher daily levels of physical activity, lower body mass index and waist circumference, and better cardiovascular fitness than do children who do not actively commute to school (Mendoza et al., 2011; Davison, et al., 2008; Østergaard et al., 2012).
  • Two small lifestyle changes – a small increase in physical activity (walking an additional 2000 steps/day) and a small change in diet (eliminating 100 kcal/day) – help address childhood obesity by preventing excess weight gain (Hill, et al., 2007).
  • One study suggests that a 5% increase in neighborhood walkability is associated with 32.1% more minutes devoted to physically active travel and about one-quarter point lower BMI (0.228) (Frank, et al., 2006).
  • Children who walk to school get three times as much moderate to vigorous physical activity during their walk to school than during recess (Cooper et al., 2010). Children walk more when they live on more walkable routes with more open green space and less exposure to road traffic (Gallimore et al., 2011; Rahman, et al., 2011; Lamber et al., 2009).
  • Implementation of Safe Routes to School initiatives like Walking School Buses have demonstrated improved rates of walking to school, increased daily moderate-to-vigorous physical activity, and decreased overweight and obesity (Quarles, 2012; Mendoza et al., 2011; Mori et al., 2012; Kong et al., 2010).
  • Living in a walkable community has been associated with reduced prevalence of adolescent overweight and obesity (Slater et al., 2013).
  • Perceptions of safety and attractiveness impact a neighborhood’s walkability (Project for Public Space, 2016; Ussery et al., 2017).  
  • There are gender, racial, and class disparities in how much people walk. Compared to affluent and mostly white neighborhoods, neighborhoods with residents of low socioeconomic status and minority backgrounds are perceived as less attractive and safe because of crime (Ussery et al., 2017).   
  • Investing in bike lanes is an investment in public health: People bike more when the built environment supports bicycling by including bike lanes, bike racks, and traffic calming (Dill et al., 2013; Hipp et al., 2013; Winters et al., 2016).
  • In addition to more bike infrastructure and road engineering improvements to make bicycling safer, bicycle education is important (Pion et al., 2016).
  • US metro areas with greater multi-modal transportation options (i.e., walking, bicycling, public transit) have better public health outcomes: People make healthier lifestyle choices, have more quality leisure time, exercise more, have lower obesity rates, and live longer (Meehan et al., 2017; Frederick et al., 2017).
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Key takeaway:

  • A significant portion of adult deaths in the United States is attributed to inadequate levels of physical activity. Increasing adults’ physical activity levels to meet current guidelines can help reduce the risk of premature death.
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Key takeaways:

  • Health impact assessment (HIA) has been an entry point for the public health profession to be influential in transportation decisions. The future of HIA practice in transportation could build on HIA’s adaptability to local decision-making contexts and embrace its ways to informally influence policy.
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Key takeaway:

  • People with active commutes experienced better health, confidence, and positive affect. Cycling commuters experienced less security and more distress and fear than walking commuters. 
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Key takeaway:

  • There is “activity inequality” worldwide and high activity inequality is a strong predictor for a nation’s obesity levels.
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Key takeaway:

  • By 2020, California aims to double walking and triple cycling from a 2010 baseline.
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Key takeaway:

  • Overweight and obesity are leading cancer risk factors. There are at least 13 different types of cancer associated with overweight and obesity, which comprise forty percent of all diagnosed cancers. 
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This study shows that among women, the prevalence of self-reported walking significantly increased from 2005 to 2015; meanwhile, among men, the overall prevalence increased but stalled between 2010 and 2015. 

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 A public health law analysis was conducted to review 20 shared used agreements implemented in Los Angeles County during 2010-2014.

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Key takeaway:

  • Latina women spend a lot of time in vehicles and not a lot of time walking, which has health consequences. This is one of the first studies to examine associations of intrapersonal and perceived neighborhood environment factors with objectively measured walking and vehicle time among Latina women. 
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Key takeaway:

  • In this study, interactions with parents and peers and availability of sedentary media activities, after-school programs, and community centers influenced frequency and intensity of physical activity.

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