Posts Tagged "Exercise"

Women who exercised during their teen years were less likely to die from cancer and all other causes during middle-age and later in life, according to a new study by investigators at Vanderbilt University Medical Center and the Shanghai Cancer Institute in China.

The study was published online July 31 in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association of Cancer Research.

Lead author Sarah Nechuta, Ph.D., MPH, assistant professor of Medicine in the Vanderbilt Epidemiology Center, said understanding the long-term impact of modifiable lifestyle factors such as exercise in adolescence can have important public health implications for disease prevention over the course of a woman’s life.

“Our results support the importance of promoting exercise participation in adolescence to reduce mortality in later life and highlight the critical need for the initiation of disease prevention early in life,” said Nechuta.

The study was designed to ascertain potential associations between adolescent exercise and cancer, cardiovascular disease or other causes of death among women in middle age and later life. The investigators used data from the Shanghai Women’s Health Study, a large ongoing prospective cohort study of 74,941 Chinese women between the ages of 40 and 70. The women enrolled in the study between 1996 and 2000. Each participant was interviewed at enrollment about exercise during adolescence, including participation in team sports, as well as other adolescent lifestyle factors. They were also asked about exercise during adulthood and other adult lifestyle factors and socioeconomic status, and participants were interviewed again every two to three years.

Regular exercise was defined as occurring at least once a week for at least three continuous months. Women who reported regular adolescent exercise were also asked how many hours a week they participated and for how many years they had exercised regularly.

“In women, adolescent exercise participation, regardless of adult exercise, was associated with reduced risk of cancer and all-cause mortality,” explained Nechuta.

Participation in team sports during the teen years was associated with a reduced risk of cancer death later in life.

Source: American Association for the Advancement of Science (AAAS)

Running marathons or completing other ultra-endurance events is not necessarily bad for the heart, although it could be. But first, a clarification: By standard definitions of exercise intensity, running or jogging is moderate or even vigorous exercise. During such exertion, the heart works hard to supply blood to working muscles and over time becomes stronger and somewhat larger.

Research has been unclear on whether these changes can become harmful. Multiple studies have shown that immediately after running a marathon, most racers show increased levels of a protein associated with cardiac damage. But those levels soon return to normal, with no lingering damage.

Years of prolonged and repeated endurance training and racing, however, might have more pronounced, lasting and worrisome effects. A 2011 study of aging former Olympic runners and rowers from Britain, for instance, found that compared with healthy but unathletic men of the same age, the retired Olympians were disproportionately more likely to have scarring within their heart muscles. Similarly, in a 2013 study, people who had competed multiple times in a grueling, 56-mile cross-country ski race in Sweden had a much-higher-than-normal risk of developing heart arrhythmia within five years.

But these studies, although disquieting, “do not mean that it has suddenly become dangerous to exercise,” said Kasper Andersen, a professor at Uppsala University in Sweden who led the study of skiers. In fact, an earlier study from his lab found that, over all, participants in the ski race had a below-average risk of premature death.

Even the Olympians with heart scarring seemed largely unaffected. They were running and competing well into their 60s and 70s, that study found. Conceivably, the researchers wrote, the Olympians’ cardiac changes, which would be undesirable in most people, were normal in lifelong endurance athletes.

At this point, scientists just do not know precisely how years of endurance training might affect the heart.

So the best advice for those who enjoy endurance training is “carry on as usual,” Dr. Andersen said. “But remember to listen to your body and seek a doctor if you experience any symptoms from the heart.”

Source: New York Times

The Presidential Healthcare Center uses cardiac imaging to screen for “Athletic Heart Syndrome”

Investigators working to unravel the impact of genetics versus environment on traits such as obesity may also need to consider a new factor: when individuals were born.

In the current issue of PNAS Early Edition a multi-institutional research team reports finding that the impact of a variant in the FTO gene that previous research has linked to obesity risk largely depends on birth year, with no correlation between gene variant and obesity in study participants born in earlier years and a far stronger correlation than previously reported for those born in later years.

“Looking at participants in the Framingham Heart Study, we found that the correlation between the best known obesity-associated gene variant and body mass index increased significantly as the year of birth of participants increased,” says Harvard Medical School instructor James Niels Rosenquist of the Massachusetts General Hospital (MGH) Department of Psychiatry, lead author of the report. “These results — to our knowledge the first of their kind — suggest that this and perhaps other correlations between gene variants and physical traits may vary significantly depending on when individuals were born, even for those born into the same families.”

The authors note that most studies of interactions between genes and the environment have looked at differences within specific birth cohorts —groups born during a particular span of years — which would not account for changes in the larger environment that take place over time. To investigate whether different conditions experienced by different age groups might alter the impact of a gene variant, they analyzed data from participants in the Framingham Offspring Study (which follows the children of participants in the original study) gathered between 1971, when participants ranged in age from 27 to 63, and 2008.

Source: Harvard Gazette

*The Presidential Healthcare Center can design a personalized exercise prescription for you.

With chilly weather settling in and darkness arriving before most people’s workdays end, many of us are shifting our workouts indoors, a practice that is much better for us than abandoning exercise for the winter. But a new study of air quality in gyms raises some interesting questions about whether the places in which we work out are as healthy as they should be.

Science and common sense tell us that exercising in polluted air is undesirable. People who frequently run alongside heavily trafficked freeways and breathe great lungfuls of exhaust have been shown to have an increased risk of heart disease, even if they are otherwise in admirably good shape. But few studies systematically have examined the air quality inside gyms.

Therefore, from the journal Building and Environment, researchers at the University of Lisbon in Portugal and the Technical University of Delft in Holland decided that they would place air-quality monitoring equipment in gyms throughout Lisbon. … Their findings were disquieting. In general, the gyms showed high levels of airborne dust, formaldehyde and carbon dioxide. The concentrations of these substances generally exceeded most accepted standards for indoor air quality. (No government agency in the United States formally monitors air quality in gyms.) The levels were especially high during evening aerobics classes, when many people were packed into small studios, stirring up dust and fumes and puffing heavily, producing carbon dioxide with every breath. … In sufficient concentrations, these substances can contribute to asthma and other respiratory problems, she said. Almost all of the gyms in the study had levels of these substances that significantly exceed European standards for healthy indoor air standards.

Source: New York Times

Cardiovascular screenings are a cost-effective way to identify middle-aged athletes who may risk heart attacks or strokes by participating in high-intensity sports, a new study suggests.

“I would suggest that all middle-aged athletes should be screened at least once, particularly men over 40 and women over 50,” said the study’s lead author, Dr. Andrea Menafoglio, a cardiologist at Ospedale San Giovanni in Bellinzona, Switzerland.

While the benefits of regular exercise are well known, vigorous physical exertion can be life-threatening for older athletes who may not realize that they have an underlying heart condition. Guidelines in Europe and the U.S. urge cardiovascular risk evaluations for middle-aged athletes, but researchers say the recommendations aren’t universally followed because widespread implementation hasn’t proved effective or affordable.

To see if widespread screening could detect hidden symptoms and risks for heart disease at a reasonable price, Menafoglio and colleagues at three hospitals in Switzerland evaluated 785 athletes between the ages of 35 and 65.

Each of the athletes reported spending at least two hours a week participating in high-intensity sports such as running, cycling, triathlon, football, swimming, tennis, climbing, or cross-country skiing.

The initial evaluation included a personal and family history, a physical exam, and a resting electrocardiogram, or ECG. For each participant, the researchers also estimated the risk of death from cardiovascular disease within the next 10 years based on gender, age, cholesterol level, blood pressure, and smoking habits.

Overall, the cost of screening averaged $199 per athlete (about 160 euros), because most athletes didn’t need any testing beyond the initial evaluation.

About one in seven athletes needed additional screening. Extra tests found some cases of previously unimagined diabetes, hypertension, high cholesterol, and mild heart valve disease.

Overall, the screenings caught previously undetected cardiovascular abnormalities in about 3 percent of participants and a high cardiovascular risk profile in about 4 percent.

Just three athletes had abnormalities that made it too dangerous for them to continue their exercise routines.

Source: Reuters Health

“The Presidential Healthcare Center can design a personalized exercise prescription for you.”

A progressively rising blood pressure trajectory is not an inevitable part of aging in men who remain active and maintain high levels of cardiorespiratory fitness, a prospective, population-based study found.

The study included almost 14,000 men without high blood pressure, cardiovascular disease, or cancer at baseline followed for three and a half decades.

Men in the study who were categorized as having the lowest level of fitness, based on baseline treadmill tests, reached a systolic blood pressure (SBP) of >120 mmHg at approximately 46 years of age, compared with 54 years of age among those whose fitness levels were highest. Age-related diastolic blood pressure differences (DBP) were far more pronounced, with low-fitness men reaching >80 mmHg at approximately 42 years old compared with beyond age 90 in the highest fitness group.

“This suggests that highly fit men are likely to reach abnormal SBP values about a decade later than men in the low fitness category, implying that improving fitness levels may reduce the duration of elevated SBP,” researcher Junxiu Liu, MD, of the University of South Carolina Columbia, and colleagues wrote in the Journal of the American College of Cardiology, published online Sept. 15.

Exercise Keeps Heart Young

The study is one of two published in the issue suggesting that staying physically fit throughout life can keep aging hearts healthy.

In a separate investigation, researchers in Texas examined the impact of long-term exercise on left ventricular (LV) compliance and distensibility in around a hundred older men and women.

The study showed that while low levels of casual, lifelong exercise did not prevent decreased compliance and distensibility, four to five ≥30 minute exercise sessions a week throughout adulthood did prevent most age-related LV stiffness.

“This finding holds important implications for global health, as ventricular stiffening has been implicated in the pathophysiology of many common cardiovascular conditions affecting the elderly,” researcher Paul S. Bhella, MD, of the Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, and colleagues, wrote.

Fit Men Had ‘Younger’ BP

The study by Liu and colleagues included an all male cohort from the Aerobics Center Longitudinal Study, which was a large study that included mostly white, college-educated people with middle to high socioeconomic status.

The men were between the ages of 20 and 90 at study entry, and they completed between three and 28 (mean 3.8) follow-up medical examinations between 1970 and 2006. Fitness was measured by a maximal treadmill exercise test, and longitudinal data were analysed using linear mixed models.

Cardiovascular fitness was assessed using the Balke maximal treadmill exercise test, with total treadmill time (highly correlated with oxygen uptake) used as an index of aerobic power. Participants were classified into low (<33rd percentile), moderate (33rd to 66th percentile), or high fitness categories (>66th percentile), according to the distribution of age-specific treadmill time.

Information on age, smoking status, and alcohol consumption were obtained by self-administered questionnaire. Body fat percentage was assessed using hydrostatic weigh in, skin fold thickness measurements, or both.

Among the key findings from the study:

-DBP tended to increase until nearly 60 years of age, when a decrease was observed, while SBP tended to increase over all age periods.

-Multivariate analysis revealed that average SBP increased by 0.30 mmHg (95% CI 0.29-0.31) with 1-year age increment after adjusting for body fat percent, fitness, resting heart rate, glucose level, triglyceride level, cholesterol level, current smoking, heavy alcohol consumption, and parental history of hypertension.

– had a yearly increase of 0.14 mm Hg (95% CI 0.13-0.15) before age 60 years.

-Overall, abnormal SBP (>120 mm Hg) began to occur at approximately 50 years of age and abnormal DBP (>80 mm Hg) began to occur at 60 years of age.

-Higher fitness levels significantly modified the risk in SBP trajectory across the lifespan, and the age-fitness interaction remained significant after adjusting for known hypertension risk factors.

Study strengths included the large number of participants, the longitudinal measure of SBP, DBP, and other time varying covariates, and the assessment of body fat percentage to measure obesity.

Limitations included the exclusion of women from the study, as well as the inclusion of only a small percentage (5%) of nonwhite and low income men, which limited its generalizability to these populations.

Findings May Not Apply to Women, Nonwhite Men

In an editorial accompanying the study, Stanley S .Franklin, MD, of the University of California Irvine, and Gary L. Pierce, PhD, of the University of Iowa, Iowa City, wrote that the exclusion of women was a major study limitation.

“There is some evidence that men have a steeper rate of increase in aortic stiffening beyond 50 years of age compared with women; therefore, fitness may have a different modifying effect on SBP and DBP trajectory with aging in women than men,” they wrote.

Even with the limitations, Franklin and Pierce wrote that the study suggests “habitual aerobic exercise may counteract the burden of cardiometabolic abnormalities that accelerate artery stiffening- characterized as ‘early vascular aging’ — and therefore slow the onset and severity of isolated systolic hypertension.”

Regular Exercise Preserves LV Function

In the study by Bhella and colleagues, 102 healthy older people (>64 years of age) were recruited and screened for lifelong patterns of exercise. The participants were stratified into four groups: sedentary (<2 ≥30 minute sessions/week), casual (2 to 3 sessions/week) committed (4 to 5 sessions/week) and competitive (6 to 7 sessions/week).

Right heart catheterization and echocardiography were performed while pre-load was manipulated using lower body negative pressure and rapid saline infusion to define LV pressure-volume relationships.

Peak oxygen uptake and LV mass increased with escalating doses of lifelong exercise, with little change in systolic function. At baseline, LV distensibility was greater in committed (21%) and competitive (36%) exercisers than in sedentary participants.

Group LV stiffness constants (sedentary: 0.062±0.039; casual: 0.079±0.052; committed: 0.055±0.033; and competitive: 0.035 ±0.033) revealed increased stiffness in sedentary subjects compared with competitive athletes, whereas lifelong casual exercise had no effect. They also showed greater compliance in committed exercisers than in sedentary or casual exercisers.

The researchers noted that sedentary aging, and the decreases in LV compliance and distensibility that accompany it, may set the stage for the cardiovascular conditions that affect the elderly, such as atrial fibrillation and heart failure with preserved ejection fraction.

In a commentary published with the study, Wilbur Y.W. Lew, MD, of the VA San Diego Healthcare System and the University of California San Diego, wrote that the effects of exercise on the heart are multifactorial and complex and that potential factors that prevent age-related changes in LV compliance include lowering blood pressure and arterial stiffness, decreasing cardiovascular comorbidities, improving endothelial function, and activating metabolic and signaling pathways to reduce chronic inflammation, fibrosis, and LV remodeling.

“A long-term commitment to exercise preserves LV compliance comparable to a young heart,” he wrote. “This may facilitate diastolic filling and preserve diastolic function. We face challenges to establishing causality, identifying mechanisms, and applying these results to an increasingly sedentary population.”

Source: medpagetoday.com

Amyotrophic lateral sclerosis has been all over the news lately because of the ubiquitous A.L.S. ice bucket challenge. That attention has also reinvigorated a long-simmering scientific debate about whether participating in contact sports or even vigorous exercise might somehow contribute to the development of the fatal neurodegenerative disease, an issue that two important new studies attempt to answer.

Ever since the great Yankees first baseman Lou Gehrig died of A.L.S. in 1941 at age 37, many Americans have vaguely connected A.L.S. with athletes and sports. In Europe, the possible linkage has been more overtly discussed. In the past decade, several widely publicized studies indicated that professional Italian soccer players were disproportionately prone to A.L.S., with about a sixfold higher incidence than would have been expected numerically. Players were often diagnosed while in their 30s; the normal onset is after 60.

These findings prompted some small, follow-up epidemiological studies of A.L.S. patients in Europe. To the surprise and likely consternation of the researchers, they found weak but measurable associations between playing contact sports and a heightened risk for A.L.S. The data even showed links between being physically active — meaning exercising regularly — and contracting the disease, raising concerns among scientists that exercise might somehow be inducing A.L.S. in susceptible people, perhaps by affecting brain neurons or increasing bodily stress.

But these studies were extremely small and had methodological problems. So to better determine what role sports and exercise might play in the risk for A.L.S., researchers from across Europe recently combined their efforts into two major new studies.

The more impressive of these, which was published in May in Annals of Neurology, involved almost two dozen researchers from five nations, who developed a deceptively simple but scientifically rigorous research approach. They asked 652 A.L.S. patients if they’d be willing to talk about their lives and activities and did the same with 1,166 people of matching ages, genders and nationalities. They conducted extensive in-person interviews with each volunteer, asking them how active they had been in professional or amateur sports, at their jobs and during leisure time. They also asked about past histories of injuries and accidents, including concussions and other head trauma but also other injuries.

They then compared answers from the people with A.L.S. to those of healthier people.

The results should reassure those of us who exercise. The numbers showed that physical activity — whether at work, in sports or during exercise — did not increase people’s risk of developing A.L.S. Instead, exercise actually appeared to offer some protection against the disease. Even pro athletes showed no heightened risk, although they represented such a tiny subset of the patients with A.L.S. that firm conclusions cannot be drawn, the researchers say.

One aspect of people’s lives did significantly increase their risk of developing A.L.S.: a history of multiple hits to the head. Men and women who had sustained at least two concussions or other serious head injuries were much more likely than other people, including never-concussed athletes, to develop A.L.S.

These results coincide closely with those of the other new study, a review article published in July in the European Journal of Epidemiology, which gathered data from 50 years’ worth of epidemiological studies related to A.L.S. risk (including the other new study) and teased out the effects of physical activity. Most of the studies were limited in scope, but they amplified one another’s validity when combined, the researchers thought.

And their main finding was that “in the general population, physical activity is not a risk factor for A.L.S.,” said Dr. Benoit Marin, a neuroepidemiologist at the French Institute of Health and Medical Research in Paris who oversaw the new review.

But as Dr. Marin also pointed out, the studies involved were all associational, meaning that they cannot establish cause and effect. Exercise and a reduced risk for A.L.S. might be linked to other lifestyle factors, such as a healthy diet, and not to each other.

The new studies also cannot dispel the lingering and troubling questions about the effects of head injuries from contact sports.

“I would not consider this issue settled,” said Ettore Beghi, a neuroscientist at the Mario Negri Institute for Pharmacological Research in Milan and senior author of the study published in May in Annals of Neurology.

In the United States, a few researchers have begun to look at football and A.L.S. risk, a plausible research concern, Dr. Beghi said, given evidence that head trauma sustained playing football might contribute to neurodegenerative diseases. But to date, the football data has been inconclusive.

For now, he and other scientists are continuing to study Italian soccer players, as well as athletes in other sports, including rugby, which, for some reason, confers no increased risk of A.L.S., although it involves considerable contact. Such research may ultimately “shed some light on the underlying mechanisms of the disease, which are still poorly understood,” Dr. Beghi said.

The greatest obstacle to advancing the research, he added, is “the lack of funding,” a situation that could be ameliorated, somewhat, with all of that ice dousing.

Source: New York Times

Postmenopausal women who in the past four years had undertaken regular physical activity equivalent to at least four hours of walking per week had a lower risk for invasive breast cancer compared with women who exercised less during those four years, according to data published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.

But those benefits quickly disappear if regular physical activity stops.

“Twelve MET-h [metabolic equivalent task-hours] per week corresponds to walking four hours per week or cycling or engaging in other sports two hours per week and it is consistent with the World Cancer Research Fund recommendations of walking at least 30 minutes daily,” said Agnès Fournier, PhD, a researcher in the Centre for Research in Epidemiology and Population Health at the Institut Gustave Roussy in Villejuif, France. “So, our study shows that it is not necessary to engage in vigorous or very frequent activities; even walking 30 minutes per day is beneficial.”

Postmenopausal women who in the previous four years had undertaken 12 or more MET-h of physical activity each week had a 10 percent decreased risk of invasive breast cancer compared with women who were less active. Women who undertook this level of physical activity between five and nine years earlier but were less active in the four years prior to the final data collection did not have a decreased risk for invasive breast cancer.

“Physical activity is thought to decrease a woman’s risk for breast cancer after menopause,” said Fournier. “However, it was not clear how rapidly this association is observed after regular physical activity is begun or for how long it lasts after regular exercise stops.

“Our study answers these questions,” Fournier continued. “We found that recreational physical activity, even of modest intensity, seemed to have a rapid impact on breast cancer risk. However, the decreased breast cancer risk we found associated with physical activity was attenuated when activity stopped. As a result, postmenopausal women who exercise should be encouraged to continue and those who do not exercise should consider starting because their risk of breast cancer may decrease rapidly.”

Fournier and colleagues analyzed data obtained from biennial questionnaires completed by 59,308 postmenopausal women who were enrolled in E3N, the French component of the European Prospective Investigation Into Cancer and Nutrition (EPIC) study. The mean duration of follow-up was 8.5 years, during which time, 2,155 of the women were diagnosed with a first primary invasive breast cancer.

The total amount of self-reported recreational physical activity was calculated in MET-h per week. The breast cancer risk-reducing effects of 12 or more MET-h per week of recreational physical activity were independent of body mass index, weight gain, waist circumference, and the level of activity from five to nine years earlier.

Source: American Association for Cancer Research

Running for only a few minutes a day or at slow speeds may significantly reduce a person’s risk of death from cardiovascular disease compared to someone who does not run, according to a study published today in the Journal of the American College of Cardiology.

Exercise is well-established as way to prevent heart disease and it is component of an overall healthy life, but it is unclear whether there are health benefits below the level of 75 minutes per week of vigorous-intensity activity, such as running, recommended by the U.S. government and World Health Organization.

Researchers studied 55,137 adults between the ages of 18 and 100 over a 15-year period to determine whether there is a relationship between running and longevity. Data was drawn from the Aerobics Center Longitudinal Study, where participants were asked to complete a questionnaire about their running habits. In the study period, 3,413 participants died, including 1,217 whose deaths were related to cardiovascular disease. In this population, 24 percent of the participants reported running as part of their leisure-time exercise.

Compared with non-runners, the runners had a 30 percent lower risk of death from all causes and a 45 percent lower risk of death from heart disease or stroke. Runners on average lived three years longer compared to non-runners. Also, to reduce mortality risk at a population level from a public health perspective, the authors concluded that promoting running is as important as preventing smoking, obesity or hypertension. The benefits were the same no matter how long, far, frequently or fast participants reported running. Benefits were also the same regardless of sex, age, body mass index, health conditions, smoking status or alcohol use.

The study showed that participants who ran less than 51 minutes, fewer than 6 miles, slower than 6 miles per hour, or only one to two times per week had a lower risk of dying compared to those who did not run. DC (Duck-chul) Lee, Ph.D., lead author of the study and an assistant professor in the Iowa State University Kinesiology Department in Ames, Iowa, said they found that runners who ran less than an hour per week have the same mortality benefits compared to runners who ran more than three hours per week. Thus, it is possible that the more may not be the better in relation to running and longevity.

Researchers also looked at running behavior patterns and found that those who persistently ran over a period of six years on average had the most significant benefits, with a 29 percent lower risk of death for any reason and 50 percent lower risk of death from heart disease or stroke.

“Since time is one of the strongest barriers to participate in physical activity, the study may motivate more people to start running and continue to run as an attainable health goal for mortality benefits,” Lee said. “Running may be a better exercise option than more moderate intensity exercises for healthy but sedentary people since it produces similar, if not greater, mortality benefits in five to 10 minutes compared to the 15 to 20 minutes per day of moderate intensity activity that many find too time consuming.”

Sedentary lifestyle and not caloric intake may be to blame for increased obesity in the US, according to a new analysis of data from the National Health and Nutrition Examination Survey (NHANES). A study published in the American Journal of Medicine reveals that in the past 20 years there has been a sharp decrease in physical exercise and an increase in average body mass index (BMI), while caloric intake has remained steady. Investigators theorized that a nationwide drop in leisure-time physical activity, especially among young women, may be responsible for the upward trend in obesity rates.

By analyzing NHANES data from the last 20 years, researchers from Stanford University discovered that the number of US adult women who reported no physical activity jumped from 19.1% in 1994 to 51.7% in 2010. For men, the number increased from 11.4% in 1994 to 43.5% in 2010. During the period, average BMI has increased across the board, with the most dramatic rise found among young women ages 18-39.

“These changes have occurred in the context of substantial increases in the proportion of adults reporting no leisure-time physical activity, but in the absence of any significant population-level changes in average daily caloric intake,” explains lead investigator Uri Ladabaum, MD, MS, Associate Professor of Medicine (Gastroenterology and Hepatology), Stanford University School of Medicine. “At the population level, we found a significant association between the level of leisure-time physical activity, but not daily caloric intake, and the increases in both BMI and waist circumference.”

The study looked at the escalation of obesity in terms of both exercise and caloric intake. While investigators did not examine what types of foods were consumed, they did observe that total daily calorie, fat, carbohydrate, and protein consumption have not changed significantly over the last 20 years, yet the obesity rate among Americans is continuing to rise.

Researchers also tracked the rise in abdominal obesity, which is an independent indicator of mortality even among people with normal BMIs. Abdominal obesity is defined by waist circumference of 88 cm (34.65 in) or greater for women and 102 cm (40.16 in) or greater for men. Data showed that average waist circumference increased by 0.37% per year for women and 0.27% per year for men. Just like the rise in average BMIs, the group most affected by increased rates of abdominal obesity was women.

“The prevalence of abdominal obesity has increased among normal-weight women and overweight women and men,” observes Dr. Ladabaum. “It remains controversial whether overweight alone increases mortality risk, but the trends in abdominal obesity among the overweight are concerning in light of the risks associated with increased waist circumference independent of BMI.”

When Ladabaum et al grouped respondents to the most recent NHANES survey by race/ethnicity and age, they found that more than 50% of the workforce-aged adults in eight demographic subgroups reported no leisure-time physical activity. The following chart displays the results and highlights the differences between the 1994 survey results and those collected in 2010 (albeit, with slightly different survey methods). According to this data, women, and black and Mexican-American women in particular, showed the greatest decreases in reported exercise.

While increased caloric intake is often blamed for rising rates of obesity, no association between these was found in this study; in contrast, an association was found between the trends over time for lack of physical activity and high BMI numbers. “Our findings do not support the popular notion that the increase of obesity in the United States can be attributed primarily to sustained increase over time in the average daily caloric intake of Americans,” concludes Dr. Ladabaum. “Although the overall trends in obesity in the United States are well appreciated and obesity prevalence may be stabilizing, our analyses highlight troublesome trends in younger adults, in women, and in abdominal obesity prevalence, as well as persistent racial/ethnic disparities.”

There is no easy answer in our ongoing battle against obesity, but identifying the link between the drop in physical activity and increased BMIs, as well as the groups particularly affected, can assist public health officials to develop targeted, effective interventions. In an accompanying commentary Pamela Powers Hannley, MPH, Managing Editor, the American Journal of Medicine, notes, “If we as a country truly want to take control of our health and our health care costs, the Ladabaum et al paper should be our clarion call. From encouraging communities to provide safe places for physical activity to ensuring ample supply of healthy food to empowering Americans to take control of their health, we must launch a concerted comprehensive effort to control obesity.”