Environment and Behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades. Consider that in 1960, nearly 70 percent of adult Americans worked in occupations that required physical labor. Today that number is less than 30 percent. This shift in just the economic environment has resulted in an average daily decrease of 400 to 700 kilocalories of energy expenditure, or the equivalent of walking about 4 to 7 miles (6.5–11 km). It is little wonder that the current guidelines for healthy physical activity levels recommend that we accumulate at least 10,000 steps (about 5 mi, or 8 km) a day to reduce likelihood of chronic disease.
As chapter 12 discusses, simple math suggests that storing only 10 kilocalories a day for a year will result in about a pound of stored fat. This means that the reduction of 400 to 700 kilocalories a day in physical activity would result in weight gains of 40 to 70 pounds (18–32 kg) a year if nutritional intake were constant. Luckily, our physiological systems have some ability to adapt to prevent these great weight shifts. However, too little exercise combined with too much food inevitably results in weight gains.
It is not only our economic environment, but also the built environment that conspires to limit our physical movement. Start to pay attention to the multitude of devices that save you a few kilocalories of effort each time you push a button: your TV remote, automatic car windows, and garage door openers. Consider also the many automatic energy savers that we use without even being aware of it: automatic door openers at many buildings, drive-through windows, escalators, elevators, moving walkways, information obtained by searching the Internet instead of going to the library, and many more. At work, we often use e-mail or the phone to contact colleagues who may be next door or just down the hall rather than walking down to their offices.
The built environment can also be blamed for much more loss of physical activity. Consider how the automobile has replaced walking or biking for many short trips. In 1970, it was estimated that walking and biking accounted for about 52 percent of trips shorter than 2 miles (3 km) for shopping and visiting. That percentage had dropped to under 10 percent in 1995 (Purcher and Leferve 1996), and it is now estimated to be less than 6 percent (CDC 2009). As the next chapter discusses, adding purposeful activity to your daily life is one of the most effective methods to increase your physical activity. Although both are getting older, the authors of this book continue to walk and use their bikes for most activities around town.
Of course, the built environment can be blamed for much of the reliance on the automobile. Many suburbs do not have nearby stores that are easy to walk to. Sidewalks may not exist, or may be inconsistent, making walking difficult or unsafe. People often live far from work, and mass transit may not be available. We all need to evaluate our environment to determine what is possible. You may discover that many opportunities exist. Walking a mile from home to catch a bus that then drops you off a mile from work might be just the purposeful activity to get you going. Walking to a neighborhood store for daily supplies rather than frequently driving to the bigger box store might help you get moving, which will make you feel more energetic. You might consider walking or biking rather than driving to visit friends who live nearby.
The social environment also affects our physical activity. Cultures tend to adapt to social norms. When we see the majority of people driving, sitting, watching television, or using computers, we begin to accept that as normal. As the average waistline gets bigger, our image of normal adapts. Students in our Health and Human Performance class in Missoula conducted a survey, asking other students at the university to view images of people (33% normal weight, 33% overweight, and 33% obese) and rate them as normal, overweight, or obese. The majority of students rated both normal and overweight people as normal and most obese people as either normal or overweight, with few ratings of obese. In our freshman class, where all students complete a body-composition lab, we ask everyone to anonymously self-rate themselves prior to both underwater and skinfold measurement and then, again anonymously, to report their percentage of body fat. Eighty percent of overweight students believed they were normal weight, while 24 percent and 43 percent of obese students rated themselves as normal or overweight, respectively. We obviously have a skewed image of a healthy body composition.
The social environment goes much further than just image. Someone who associates with sedentary friends is likely to be sedentary. Youth emulate their peers and their parents. In a project to measure physical activity in Missoula schools, we used accelerometers for a week to measure physical activity of more than 800 2nd- through 12th-grade students. Physical activity decreased dramatically from elementary school to middle school. Seniors in high school were doing almost no vigorous physical activity. Only one-third were meeting health guidelines for adult physical activity, and fewer than 15 percent were meeting youth guidelines. They had adopted the American culture by the time they finished high school. Of course, this should be no surprise, since they are only doing what they see their peers and role models doing. In order to break this cycle, it is necessary to understand the stages of behavior change.
Sallis studied the most common reasons that adults cite for not adopting more physically active lifestyles (Sallis and Hovell 1990, Sallis et al. 1992). His lists include the following:
- Not enough time to exercise
- Find exercise inconvenient
- Lack self-motivation
- Do not find exercise enjoyable
- Find exercise boring
- Lack confidence in ability to be physically active (low self-efficacy)
- Fear of being injured of have been injured recently
- Lack self-management skills such as goal setting, progress monitoring, or a reward process
- Lack encouragement, support, or companionship from family and friends
- Do not have parks, sidewalks, bicycle trails, or safe pleasant paths convenient to the home or office
Each of us can come up with additional reasons as to why we might not be physically active. Understanding the common barriers to physical activity and your personal beliefs and barriers will help you to develop strategies to become more active. You can start by taking the barriers to being physically active quiz (form 5.1). Once you identify your personal barriers, you can use the strategies provided to begin your personal plan toward an active life. What keeps you from being more active?