Posts Tagged ‘Physical Activity’

Mortality from Bicycle Accidents

September 3rd, 2015

Physical activity is perhaps the most frequently given advice for weight loss. But, as we have reported here, there are rarely-mentioned adverse events from some forms of physical activity. In August, the CDC’s Morbidity and Mortality Weekly Report showed an alarming increase in mortality rates for cyclists aged 35-74 years old. The mortality rate, while down overall, increased nearly three-fold in this age group. Males accounted for 87% of all bicycle deaths in 2012.


How reliable are parent-child surveys?

October 15th, 2012

A study out of Central Michigan University compared parent and child self-reports of diet, physical activity and screen time. What they found was that not one of the 88-dyads of parent-child reports matched up. Not one pairing was congruent on nutritional habits, juices, soft drinks, screen time or physical activity. PubMed: Parent and Child Self Reports of Dietary Behaviors, Physical Activity, Screen time

Life Expectancy and Physical Activity

October 15th, 2012

So how big an effect is physical inactivity? We hear all the time how terrible physical inactivity is but just how bad. Now comes an answer. Some 39 collaborators, part of the Lancet Physical Activity Series Working Group have published an analysis of the burden of physical inactivity on disease and life expectancy.

The researchers calculated population attributable fractions associated with physical inactivity “using conservative assumptions for each of the major non-communicable diseases by country, to estimate how much disease could be averted if physical inactivity were eliminated.”

They estimated that, worldwide, physical inactivity causes, for coronary heart disease, between 3.2% in southeast Asia to 7/8% in the eastern Mediterranean. For type 2 diabetes, physical inactivity contributes 7%, 10% of breast cancer and 10% of colon cancer. “Inactivity,” they calculate, “causes 9% or more of premature mortality or more than 5.3 million of the 57 million deaths that occurred worldwide in 2008. If physical inactivity were eliminated, life expectancy of the world’s population would increase by 0.68 years (range of 0.41-0.95).

That’s it? 8 months?  Well, that’s for both the active and inactive population. If you look at just having the physically inactive reach recommended levels of physical fitness, it is estimated that inactive people would gain 1.3 to 3.7 years from age 50 on in the United States. In East Asia, life expectancy from age 30 increased by 2.6 to 4.2 years. That’s a bit more meaningful. PubMed: Effect of physical inactivity on major non-communicable diseases worldwide


Failure of anti-obesity legislation

August 21st, 2012

Christopher Still and I have a new article out, “Survey of antiobesity legislation: are these laws working?” Unfortunately, the answer is no. This finding is consistent with a paper earlier this year by Dr. Jeffrey Mechanick and last year’s Cochrane Review but contrary to the somewhat rose-tainted view of the Institute of Medicine’s recent report. Here is the abstract:

Obesity is well recognized as a major public health crisis throughout the USA. In recent years,governmental bodies at the federal, state and local levels have enacted policies intended to preventthe transition to obesity. Researchers have had the opportunity to study these policies and evaluate theirimpact on prevention of obesity.

Recent findings Most public policies have been directed principally, but not exclusively, to the prevention of obesity inschool-age children. Interventions have been directed to encouraging breast-feeding, to changing school lunches, limiting access to sugar-sweetened beverages, encouraging physical activity, changing thecomposition of competitive foods and affecting food advertising directed at children as well as collectingBMI information. Efforts more directed at adults include encouraging workplace wellness programs andimproving the nutrition label on packaged foods with front-of-package labels and caloric information on restaurant menus.

Summary  For the most part, evaluations of the interventions reveal weak or modest benefits. The actual picture mightbe less positive due to the poor quality of research and publication bias. Push back by industry and otherswill require higher quality experimental and real world studies. All interventions fail to accommodate themultifactorial aspects of obesity.

See PubMed:

Weight of the Nation: Childhood Obesity – Is Anything Working?

May 4th, 2012

The Surgeon’s General ground-breaking Call to Action on overweight and obesity came out in 2001. Surgeon General: Call to Action: Obesity Since then, millions of dollars have been spent by governmental and non-governmental organizations on steps to prevent obesity, primarily in children. How’s it going? Well, in spite of the best of intentions of hundreds of people, not well.

A paper just out by Dr. Jeffrey Mechanick , a highly respected researcher in the field, and colleagues, looked at three anti-obesity policies: increasing physical activity in children, taxing sugar-sweetened beverages and funding for walking and biking trails. They found, “While numerous studies have established their efficacy when implemented on a local or communal (small-) scale, there is little published evidence demonstrating statistical correlation between BMI (body mass index) and implementation of these policies, or any combination, thereof, on a statewide (large-) scale.” They conclude, “American culture, policy-making, and the obesity epidemic constitute a recursive, complex adaptive system. We have proposed that an emergent property of this system is that implementation of anti-obesity policies may not be reducing the obesity growth rates as early as expected, if at all. This somewhat counter-intuitive finding is, on the surface, discouraging, but with deeper deliberation, offers redirection for an anti-obesity campaign. Since the obesity epidemic remains uncontrolled with vast downstream adverse effects, it is imperative to gain a thorough understanding of this complex system. The focus should be broadened to improve consumer dietary patterns and physical activity. There should be greater supply-side regulation of food content, as well as interventions targeting obesogenic inflammatory mechanisms. PubMed:Lack of Correlation between anti-obesity poliicy and obesity growth rates

This one paper is not alone. The Cochrane Reviews are distinguished for their rigorous study of important health topics. A Cochrane Review was published in 2011 evaluating all randomized clinical trials (RCTs) of interventions for preventing obesity in children. The review included an 55 studies. The majority of studies targeted children aged 6-12 years. The meta-analysis included 27,946 children. According to the authors, overall, the programs were effective, but not all were, reflecting a high degree of heterogeneity. Children in the intervention group had a standard mean difference in adiposity  (measured as BMI or zBMI) of –0.15 kg/m2 The authors urged that the findings be taken cautiously because of the unexplained heterogeneity and the likelihood that studies with negative outcomes were not published. Cochrane Review: Preventing Obesity in Children

A near-universal policy goal is increasing physical activity of children in school. Yet, even here, the evidence is poor to weak.

Cawley and colleagues examined the impact of state physical activity requirements on youth physical activity and overweight, using data from the Youth Risk Behavior Surveillance System for 1991, 2001, and 2003. They found that high school students with a binding physical education (PE) requirement report an average of 31 additional minutes per week spent physically active in PE classes. Their results indicate that additional PE time raises the number of days per week that girls having exercised vigorously or have engaged in strength-building activity. They found “no evidence” that PE lowers BMI or the probability that a student is overweight. They conclude that “there is not yet the scientific basis to declare raising PE requirements an anti-obesity initiative for either boys or girls. PubMed: Cawley: The Impact of state physical education requirements

A 2011 paper found that adequate PE time was inversely related to recess, and vice versa, suggesting that schools are substituting one form of physical activity for another, rather than providing the recommended amount of both recess and PE.  PubMed: Slater: The Impact of State Laws and District Policies


NIH Disses Physical Activity as Cure of Childhood Obesity

November 23rd, 2011

The National Heart, Lung and Blood Institute has issued guidelines endorsed by the American Academy of Pediatrics. They are directed to all primary pediatric care providers to address the known risk factors of cardiovascular disease, including obesity, blood pressure, cholesterol, tobacco and lipids.

The report notes that longitudinal data on non-white populations are lacking and that “Clinically important differences in prevalence of risk factors exist according to race and gender, particularly with regard to tobacco-use rates, obesity prevalence, hypertension, and dyslipidemia.”

The report notes, “Obesity tracks more strongly than any other risk factor, among many reports from studies that have demonstrated this fact…Tracking data on physical data is more limited.”

Regarding overweight and obesity, the report states,

“The dramatic increases in childhood overweight and obesity in the United States since 1980 are an important public health focus. Despite efforts over the last decade to prevent and control obesity, recent reports from the National Health and Nutrition Examination Survey show sustained high prevalence: 17% of children and adolescents have a BMI at the >95th percentile for age and gender. The presence of obesity in childhood in childhood and adolescence is associated with increased evidence of atherosclerosis at autopsy and of subclinical measures of atherosclerosis on vascular imaging. Because of its strong association with many of the other established risk factors for cardiovascular disease, obesity is even more powerfully correlated with atherosclerosis; this association has been shown for BP, dyslipidemia, and insulin resistance in each of the major pediatric epidemiologic studies. Of all of the risk factors, obesity tracks most strongly from childhood into adult life.”

Given that physical activity is a primary prescription for preventing childhood and adolescent obesity, it is interesting to read what the expert panel has to say about its utility:

“A moderate number of RCTs (randomized controlled clinical trials) have evaluated the effect of interventions that addressed only physical activity and/or sedentary behavior on prevention of overweight and obesity. In a small number of these studies, the intervention was effective. It should be noted that these successful interventions often addressed reduction in sedentary behavior rather than attempts to increase physical activity. In a majority of these studies there was no significant difference in body-size measures. Sample sizes were often small and follow-up was often short (frequently < 6 months). ..Overall, the expert panel concluded that on the basis of the evidence review, increasing activity in isolation is of little benefit in preventing obesity. By contrast, the review suggests that reducing sedentary behavior might be beneficial in preventing the development of obesity.”

The report identifies populations at special risk for obesity: children with a BMI between the 85 and 95th percentiles;children in whom there is a positive family history of obesity in 1 or both parents; early onset of increasing weight; excessive weight gain during adolescence; children who have been very active and become inactive. See Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents- NHLBI, NIH

Normal Weight Persons Heaviest Snackers; Weight loss Mainteners Best on Physical Activity

November 22nd, 2011

Contrary to the assumptions of many, the group that snacks most frequently is the normal weight, followed by weight-loss maintainers and then persons who were overweight. Weight-loss maintainers had the highest level of self-reported physical activity, followed by normal-weight individuals and then overweight participants. Eating Frequency Is Higher in Weight Loss Maintainers and Normal-Weight Individuals than in Overweight Individuals  Earlier research indicated that obese and overweight persons eat the same diet by macro-nutrients as normal weight persons.

Nation’s Obesity Strategy a Failure

October 7th, 2011

The Department of Health and Human Services has issued its 10 year review of the nation’s health care goals, set in 2000. For obesity the picture is not pretty. By direct measurement between 1988-94 and 2005-8, adults over 20 with obesity increased by nearly 47.8%. The target for 2010 was 15%. Children and adolescent rates increased by 63.5% from 11% to 18%. The 2010 target was 5%.  The report also not little to no progress on increasing the proportion of adults or adolescents engaged in regular vigorous physical activity.  Finally, the proportion of adults 20 and over at a healthy weight, directly measured, decreased by 26%; in 2008 only 31% of American adults were at a health weight, the Healthy People goal was 60%. The proportion of persons with healthy eating habits showed no change, still below targets.

CDC – National Center for Health Statistics Homepage

It has to be recognized that during this period millions of dollars have been spent in the public and private sector on educating the public on obesity and the message to ‘eat less and exercise more’ (ELEM).  One would think that this dismal outcome would encourage a critical reappraisal of the nation’s anti-obesity strategy. Alas, I wish it were so. I suspect that we will see merely a call to shout ELEM louder.