Posted by Me, written by Malik Slosberg, DC, MS.
Move More Eat Less: Deconditioning & Obesity in the United States.
In this sedentary society of ours there has been a progressive decline in physical activity and a concomitant increase in weight gain despite multiple warnings from governmental agencies as well as a very large and ever increasing number of scientific publications recommending much greater amounts of physical activity and exercise along with a reduction of caloric intake.
An increase in obesity, deconditioning, cardiovascular disease, type II diabetes mellitus and an overall increased morbidity are some of the consequences.
Deconditioning and excessive caloric intake have exploded to epidemic proportions and not only impact the general population, but also adversely affect chiropractic patients’ ability to respond as well as possible to spinal adjustments and to comply with and perform effective exercise recommendations.
This column will review some of the recent evidence on deconditioning, obesity, the metabolic syndrome, and the increased risk of cardiovascular disease and type II diabetes mellitus in the United States.
Our Obesogenic Society
Recently, in several research papers, our society has been described as “obesogenic.”
Among adults, Wang et al[1] explain that the prevalence of obesity increased from 13% to 32% between the 1960s and 2004.
Currently, 66% of adults are overweight or obese; 16% of children and adolescents are overweight and 34% are at risk of overweight.
By 2015, the paper estimates that 75% of adults will be overweight or obese, and 41% will be obese. This systematic review concludes that obesity has increased at an alarming rate in the United States over the past three decades.
A 2009 review paper[2] calculates that from the 1970s to 2000s the average weight gain for children and adolescents in the USA was 8.8 lbs and for adults was 18.92 lbs.
According to a comparison of the National Health and Nutrition Examination Survey (NHANES),[3] a nationally representative sample of the US population, comparing data obtained in 2007- 2008 versus 1999 through 2006 concluded that prevalence of obesity in 2007-2008 was 33.8% overall, 32.2% among men, and 35.5% among women.
The corresponding prevalence estimates for overweight and obesity combined were 68.0% overall, 72.3% for men, and 64.1% for women. A major reason for this rapid growth in obesity is the increase in caloric intake in the typical American diet over the past several decades.
Swinburn et al[4] estimate that food energy intake for children was 1690 kcal/day in the 1970s and 2043 kcal/day in the 2000s.
For adults food energy intake was 2398 kcal/day in the 1970s and 2895 kcal/day in the 2000s. That is a more than 17% increase in caloric consumption for both children and adults over this time period.
The authors calculate that this increase in energy intake appears to be more than sufficient to explain weight gain in the US population.
They conclude that in order to reverse the obesity epidemic we need to focus on energy intake by addressing the obesogenic food environment drivers of the current energy overconsumption.
These “drivers” include the marked increase consumptions for universally available cheap calories found in soft drinks, fast foods, snack foods, fried foods, etc.
The Epidemic of Type II Diabetes
According to another recent study[5] the prevalence of type II diabetes mellitus increased from 5.08% of the U.S. adult population in 1976–80 to 8.83% in 1999-2004, a 74% increase.
Of the 3.75 additional cases per hundred that existed in 1999–2004 as compared to 1976–1980, the authors estimate that 8% were among persons of normal or below normal weight (body mass index < 25); 27% were among those who were overweight (body mass index 25 to 30); and 32%, 23%, and 26% among those with class I (body mass index 30 to 35), class II (body mass index 35 to 40), and class III obesity (body mass index > 40), respectively.
Thus, the paper concludes that of the additional prevalent diabetes cases that existed in 1999–2004 as compared to 1976–1980, 81% were obese (i.e. body mass index > 30) and 49% had class II or III obesity (body mass index > 35), a group that increased in prevalence from 4% to 13% of the overall adult population.
Physical Activity and the Deconditioning Syndrome
In addition to this well documented and alarming increase in obesity, recent studies have also documented the startling lack of physical activity in our society.
A 2008 paper[6] measuring physical activity among children, adolescents, and adults in the US using objective data obtained with accelerometers from 6329 participants who provided at least 1 day and from another 4867 participants who provided four or more days of accelerometer data found that physical activity declines dramatically across age groups between childhood and adolescence and continues to decline with age.
Among children, 42% obtain the recommended 60 minutes per day of physical activity, only 8% of adolescents achieve this goal. Among adults, adherence to the recommendation to obtain 30 minutes day of physical activity is less than 5%!
This reduced physical activity results in a myriad of deleterious changes commonly referred to as the deconditioning syndrome.[7]Major changes included in this syndrome are:
1. Decreased joint mobilization
2. Wasting of trunk muscles
3. Decreased muscular strength & endurance
4. Reduced cardiovascular fitness
5. Stiffness of ligaments & joints,
6. Reduced metabolic activity
7. Increased susceptibility to sprains, strains, & muscle spasms.
These deleterious effects of muscle and joint disuse provoke symptoms, causing greater avoidance of activity, resulting in a cyclical pattern of pain and avoidance of activity/deconditioning/more painand is considered a defining characteristic of chronic low back patients.
The Dangers of Inactivity
In an excellent 2011 review paper[8] on the dangers of inactivity, the authors describe deconditioning as the physiologic response of the body when there is a reduction in energy use or exercise levels, that is, with bed rest, prolonged sitting or in living a very sedentary life style.
Deconditioning is associated with a host of physiological changes including:
1. Muscle mass decrease
2. Loss of muscle strength
3. Decline in muscle capillary density
4. Decline of mitochondrial enzyme activity & ATP production
5. Loss of muscle oxidative potential
6. Increased fatigability of muscle
7. Reduced cardiac output
8. Decrease in aerobic capacity (VO2 max)
9. Decrease in bone strength as a result of to increased bone resorption & decreased bone formation in response to unloading. Bone loss occurs most at weight-bearing skeletal sites.
10. Disuse decreases the collagen turn-over in tendons & muscles, weakens attachments of ligaments to bone & causes a disorganization of collagenous fibers.
11. Proprioceptive mechanisms within muscle & muscle-tendon junctions degenerate & become less responsive, increasing risk of injury.
12. Metabolic changes lead to increased risk of cardiovascular disease & type II Diabetes.
13. There is a decline in sensitivity to insulin-mediated glucose uptake.
14. There is a shift towards increased reliance on carbohydrate for energy at submaximal & maximal exercise intensities in muscle & a decrease in the contribution from lipid metabolism.
15. Blood lactate concentration with exercise increases at submaximal intensities & the lactate threshold is apparent at a lower percentage of VO2 max so exercise performed at the same intensity after disuse results in a higher heart rate, higher blood lactate accumulation, an increase in muscle glycogen utilization & carbohydrate oxidation,
16. Reduction in exercise time to fatigue
17. Increased dyspnea: Activities demand a higher relative percentage of VO2max & may cause shortness of breath & fatigue.
18. Activities may be reduced or avoided resulting in a vicious cycle wherein activity is reduced, walking speed is lowered, and fitness levels decline.
Inactivity Physiology
Wittink et al[9] review what they describe as “inactivity physiology,” a result of the extended amount of sedentary time in people’s daily routine, such as in prolonged sitting.
Studies published from several different countries show that the majority of adult waking hours (>90%) are spent either in sedentary or in light-intensity activity.[10]
A number of studies, using both subjective and objective measures of physical activity, suggest that prolonged bouts of sitting time are strongly associated with chronic disease including: obesity, abnormal glucose metabolism, diabetes, metabolic syndrome, cardiovascular disease risk and cancer, independent of whether adults meet physical activity guidelines.[11]
This discouraging piece of news indicates that the metabolic changes due to prolonged inactivity cannot be fully reversed or compensated for by one hour of vigorous physical activity.
Each one hour increase in sitting time watching television increased the prevalence of the metabolic syndrome in women by 26%, independently of the amount of moderate to vigorous physical exercise performed. This is approximately the same quantity of decreased risk (28%) of the metabolic syndrome caused by 30 minutes of extra physical exercise.
Even activities as minimal as standing, rather than sitting, which is associated with muscle inactivity, a lack of muscular contraction, and minimal metabolic demand, were shown to result in substantial increases in total daily energy expenditure and resistance to fat gain.
In people who do not exercise, it is important to reduce their sitting time and attempt to maintain a high level of daily low intensity activity (such as standing, walking and walking stairs) to reduce their metabolic risk.
The Metabolic Syndrome
The metabolic syndrome or insulin resistance syndrome is characterized by 3 out of the 5 following metabolic derangements:
1. High serum levels of triglycerides,
2. Low high-density lipoprotein (HDL) or ”good” cholesterol,
3. Hypertension,
4. Elevated fasting blood glucose
5. Increased waist circumference (>102 cm for men and >88 cm for women).
These insulin-resistant individuals commonly have an abnormal fat distribution characterized by predominantly upper-body fat.
Waist circumference, a measure of visceral fat, actively contributes to an adverse inflammatory response and to disordered insulin signalling and endothelial dysfunction.
Endothelial dysfunction contributes to the initiation and progression of atherosclerotic disease and is an independent vascular risk factor. The metabolic syndrome is associated with a marked risk of CVD and DM II, myocardial infarction and stroke.
Mortality from any cause is increased 2.26 fold in men and 2.78 fold in women with metabolic syndrome, independent of age, body mass index, cholesterol levels and smoking.
A 2009 retrospective study[12] performed a 40 year followed up of 5 men who at the age of 20 voluntarily consented to 3 weeks of strict bed rest in 1966 to measure the impact of deconditioning.
The men then went through 8 wks of heavy endurance training to help them recover from bed rest’s deconditioning effect. In 2009 the now 60 year subjects were re-evaluated to compare the decline from 40 years of aging with that as a result of the 3 weeks of strict bed rest.
Over those 40 years, the subjects had a major decline in cardiovascular fitness and endurance – about 27% reduction of aerobic capacity attributed a loss of fitness due to aging and comorbid conditions. The net loss of fitness with 40 yrs of aging among the 5 men was, amazingly, roughly the same loss of fitness – 27% vs 26% they suffered with just 3 weeks of bed rest at age 20!
Move More, Eat Less
So, the take home message can be concisely expressed as, “Move more, eat less.” This is clearly the basic formula for a healthy, long and functional life.
This essential advice can also be integrated into our patient care, education and management as a primary directive for our patients. It is important for them to understand that as patients, they cannot simply be passive and compliant, but must learn to accept responsibility for their health and function.
They need to understand that a lot of their symptoms and dysfunction are within their control and not the doctor’s.[13] As chiropractors, we can adjust our patients, educate them, prescribe exercises for them, but they need to be active partners in the recovery and maintenance of their health.
References below….
other related articles:
Is Junk Food Really Cheaper-New York Times Sept 2011
Back to School: How to Raise Healthier, Smarter, Fitter Children-Mark Hyman, M.D.
Blood Sugar Control Improved by Weight Training
Diabetics Diet-Paleolithic diet is better-Cardiovasc Diabetol. 2009
Exercise Makes Us Feel Good-NY Times 2011
Inflammation-13 Tips To Fight Inflammation
Sitting-Can sitting too much kill you? Scientific American Jan 2011
Sugar-Is Sugar Toxic? Gary Taubes New York Times April 2011
Walking is Good “medicine” and it’s FREE! Journal of Exercise Phys 2011
Your Office Chair Is Killing You
viewing time with cardiometabolic risk biomarkers: Australian Diabetes, Obesity
and Lifestyle (AusDiab) study 2004e2005. Diabetes Care 2010;33(2):327e34.
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