Here is a problem. You are a middle school principal with a student body that is not very healthy. Your school has high rates of obesity, low levels of physical activity, and because of recent cuts to your physical education department, your students show decreases in motor skill proficiency. This is very concerning to you, because you know that kids tend to form lifelong habits at this age. What will you do to intervene? This exercise (readings plus a structured controversy in class on Wednesday, Nov 14) is designed to help you understand what you can do to effectively intervene.
Public health agencies use many variables to predict future health outcomes. For instance, you can predict a person’s risk for developing type-2 diabetes by age 45 by his BMI at age 16. In this case, “BMI at age 16” is a predictor variable, and “risk of developing type-2 diabetes by age 45” is an outcome variable.
It is very important to understand the relationship between predictors and outcomes. WHY? If we know what predicts an unhealthy outcome later in life, we can intervene to improve a person’s results on a predictor. So, if we know that BMI at age 16 is the strongest predictor of risk of developing type-2 diabetes at age 45, it makes sense that we should intervene to address BMI at age 16, through an obesity prevention program.
The problem is that high BMI at age 16 doesn’t occur in a vacuum. It is also shaped by other predictor variables, such as level of physical activity, motor skill proficiency, and diet (just to name a few). To complicate matters further, if we intervene to improve diet, but not physical activity or motor skill proficiency, our intervention can be compromised.
Fitness vs. Fatness
Predictor variables are typically measures of a person’s fitness or a person’s fatness. It can be difficult to separate “fitness” measures from “fatness” measures, because “fatness” measures, such as BMI or adiposity are often part of comprehensive physical fitness measures. However, for the purposes of this discussion, we are going to separate fitness measures and fatness measures according to the definitions below:
- Fitness measures – general measures of cardiovascular capacity or motor skill proficiency, such as a one-mile walk/run, 20m shuttle run, standing broad jump, chin-ups, push-ups, etc.
- Fatness measures – a measure of body weight in relation to stature, such as caloric intake, body mass index, or adiposity (skin-fold caliper test)
A chin-up test, or bent-arm hang test, could be considered a “fitness” measure.
Using a skin-fold caliper to measure adiposity is a common example of a “fatness” measure.
One critical assumption that gets made frequently is that if you exercise, you will lose weight. However, exercise does not always yield the same weight-loss effects for everyone. This can be problematic, in that if a person is trying to reach a target to lower their score on a predictor variable like BMI by trying to lose weight, and in the process, the person uses unhealthy practices, such as unsafe levels of caloric restriction (not eating enough calories, not getting a balanced diet), the side-effects can be detrimental. Side effects include not having enough energy to exercise, or worse, the development of disordered eating practices.
Goal and purpose of this activity
- Comprehend the differences between:
- “fitness” measures and “fatness” measures
- predictor variables and outcome variables
- Demonstrate how fitness measures and fatness measures could be used in an intervention program for school children who have unhealthy levels of BMI, as well as low levels of physical activity and motor skill proficiency
Assignment – due before class on November 14
- Everyone – Read the background study and then watch the ABC news health minute video linked below.
- Individual reading – there are four ScienceDaily.com briefs outlined below (Sources #1-4). Based on the source assigned to you by your last name, read the summary from Science Daily. You do not need to read the original journal article. You may read the Science Daily summaries for the other three sources if you want.
- Leave a comment – your comment should highlight the most salient point that you took from your assigned reading. It does not have to be more than a few sentences.
Everyone reads this background study
Fitness experts have argued that a focus on obesity and body composition feeds into a stereotype that “skinny = healthy” — which is not always the case, as Nancy Clark, a sports nutritionist, points out in her contribution about the importance of being physically fit:
Data from 650,000 people who were followed for 10 years indicates physically-fit-but-obese people live longer than physically-unfit-but-lean people.
- 3.2 years earlier death for the active-obese
- 4.1 years earlier death for the inactive-lean
- 6.0 years earlier death for inactive-obese
An ABC News Medical Minute provides more background on the fitness vs. fatness question, citing a recent study by the Cooper Institute.
Source #1 – Last names beginning with Bah – Gol
Does compliance with physical education guidelines lead to increased student fitness? Yes, according to this recent study in California. “Researchers found that students in policy-compliant school districts were 29 percent more likely to be physically fit, as measured by performance on a 1-mile run or walk test, than students in noncompliant districts.”
- Emma V. Sanchez-Vaznaugh, Brisa N. Sánchez, Lisa G. Rosas, Jonggyu Baek, Susan Egerter. Physical Education Policy Compliance and Children’s Physical Fitness. American Journal of Preventive Medicine, 2012; 42 (5): 452. DOI: 10.1016/j.amepre.2012.01.008
Source #2 – Last names beginning with Gos – Lam
Techniques ranging from running to push-ups to sit-and-reach tests have been used to measure various aspects of fitness in children and adults.However, evidence is sparse on how well some of these techniques correspond to desired health outcomes in children, fueling debate about the best fitness measures for youth.
Full Report Reference:
- Pate, R., Oria, M., & Pillsbury, L. (eds.). (2012). Fitness measures and health outcomes in youth. Institutional Report: Institute of Medicine of the National Academies. Washington, D. C.: The National Academies Press. http://books.nap.edu/openbook.php?record_id=13483
Source #3 – Last names beginning with McPh – Pier
If you maintain or improve your fitness level — even if your body weight has not changed or increased — you can reduce your risk of death, according to research reported in Circulation: Journal of the American Heart Association.
Summary from Science Daily: Physical fitness trumps body weight in predicting death risks, study finds
- Lee, D. C., Sui, X., Artero, E. G., Lee, I. M., Church, T. S., Mcauley, P. A., Stanford, F. C., Kohl III, H. W., Blair, S. N. (2011). Long-Term Effects of Changes in Cardiorespiratory Fitness and Body Mass Index on All-Cause and Cardiovascular Disease Mortality in Men: The Aerobics Center Longitudinal Study. Circulation, 124, 2483-2490. DOI: 10.1161/CIRCULATIONAHA.111.038422
Source #4 – Last names beginning with Riv – Win
Adults over age 60 who had higher levels of cardiorespiratory fitness lived longer than unfit adults, independent of their levels of body fat, according to a new study.
Summary from Science Daily: Fitness Level, Not Body Fat, May Be Stronger Predictor Of Longevity For Older Adults
- Sui, X., LaMonte, M. J., Laditka, J. N., Hardin, J. W., Chase, N., Hooker, S. P., Blair, S. N. (2007). Cardiorespiratory Fitness and Adiposity as Mortality Predictors in Older Adults. Journal of the American Medical Association, 298(21), 2507-2516.
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