Human Limits

Exploring performance and health with Michael J. Joyner, M.D.

Photo of Michael J. Joyner, M.D.

Archive for September, 2012

NFL Referees: The Heart of the Matter?

Anyone who pays attention to sports in the U.S. is aware of the uproar surrounding the “blown calls” by replacement refs during the first three weeks of the National Football League season.  There have even been calls for the resignation of Commissioner Roger Goodell for his failure to settle the strike and look out for the integrity of the game.  As I follow the deep and widespread concerns about the NFL situation (in full disclosure, I am a shareholder of the Green Bay Packers), I am reminded of one of my favorite scientific studies on cardiac events during World Cup soccer matches in Germany.

The figure below shows the number of cardiovascular events evaluated by emergency physicians in Munich during the 2006 World Cup and compares them to non World Cup days in 2003 and 2005.  Days 1-4 in 2006 were for games Germany played in that did not lead to possible elimination.  Days 5 and 6 were elimination games later in the tournament.    Game 7 included Germany but was for third place, and game 8 was the final between Italy and France.  Those at the biggest risk for a game time event were typically middle aged or older men with history of heart disease and elimination game days were especially worrisome.

 The article concludes that:

“Viewing a stressful soccer match more than doubles the risk of an acute cardiovascular event. In view of this excess risk, particularly in men with known coronary heart disease, preventive measures are urgently needed.”

Data like this leads to all sorts of speculation about why anyone would care that much about a game, but the data clearly show that people do care about “their team”.  It also shows that passionate spectators can experience significant emotional stress by simply watching their team.  Substitute the words “NFL game” for soccer match and I wonder if there have been more cardiac events than normal associated with NFL games so far this season as a result of the hullaballoo over the replacement refs.  That having been said, the good news for fan health is that the referees and league settled last night……. before the playoffs.


Obesity and Inactivity: Lessons From The Road

A couple of posts ago I reviewed the “soda ban” in New York City and asked if it would work.  I also reviewed the data on the decline in smoking over the last 30-40 years and highlighted the factors responsible.   Another big public health success over the last 30-40 years is traffic safety.   This link is to an excellent Wiki site with the raw data on traffic fatalities starting in 1899.   Right after WWII (1945) about 10 people died per million miles driven and this has fallen to just over 1 fatality per million miles driven in 2010.    People are driving more and the population has increased over time but the effect is still pretty dramatic.


The traffic safety data was also recently reviewed in an interesting piece that tells us a lot about how regulations and behavioral changes intersect to influence public health.  So drive defensibly campaigns, safer roads, safer cars, seat belts, airbags, seat belt laws, drunken driving laws and speed limits have all made a difference.   The combined effects have also been even more impressive and things are likely to get even better with electronic collision avoidance systems and smart highways.


The need for a comprehensive approach to the twin problems obesity and inactivity was highlighted last week in an entire issue of the Journal of the American Medical Association (JAMA).   Here is a link to an editorial by leaders of the National Institutes of Health that appeared in JAMA on what is needed to figure out what works and what does not work.  The editorial starts by saying.


“The obesity epidemic is not the first major health crisis that the United States has faced. In recent decades, progress has been made against such daunting challenges as tobacco use, infant mortality, and HIV/AIDS. However, obesity may pose the most significant challenge yet because it involves changing approaches to 2 fundamental aspects of daily life: food consumption and physical activity. To have any chance of release from obesity’s ever-tightening grip, the nation will require broad-based efforts in every corner of society: homes, schools, community organizations, all levels of government, urban design, transportation, agriculture, the food industry, the media, medical practice, and, without question, biomedical research.”


That having been said I wonder if 30 years from now a story similar to the one highlighted above for traffic safety and last week for tobacco control will emerge for efforts to get the population to be more active, eat less and ultimately weigh less.  Based on the experience with smoking and traffic safety I am optimistic, but addressing the inactivity/obesity problem is not going to be a simple process.


Live Long and Prosper!

For the last month or so I have been focused on the twin problems of inactivity and obesity.   Today I want to turn the tables on these problems and ask what we know about people who live a long time and remain independent.

It turns out a lot is known about who makes it into their later 80s, 90s or 100.   In other words who lives a long time and remains independent and engaged in life   One of the first people to study this topic was Dr. Lester Breslow who died earlier this year at age 97.   His obituary in the Lancet pointed out that he was a pioneer in public health showing that:


“45-year-olds who adopted six healthy habits—exercise, non-smoking, weight control, adequate sleep, moderation in alcohol use, and breakfasting well—lived longer than people with three or fewer healthy habits.”


Midlife fitness is also important because it reduces the burden of chronic disease as people age and limits the slow drift into disability and functional limitations seen in many older people.    So if you want to be a vigorous older person, be a vigorous middle-aged person.

One of the most interesting studies on this topic comes from the Honolulu Heart Project that has followed about 8,000 Japanese American males born in the early 1900s.  The study started in the middle 60s and has found that only a couple of factors explain who lives a long time and who remains healthy.  Recently the more than 2,000 men who are still alive were studied and it was found that:


“Compared with people who died at the age of ≤79 years, centenarians belonged 2.5 times more often to the highest third of grip strength in midlife, were never smokers, had participated in physical activity outside work, and had a long-lived mother (≥80) Associations for nonagenarians (90 year olds) and octogenarians (80 year olds) were parallel, but weaker.  Statistical modeling showed that mother’s longevity and offspring’s grip strength operated through the same or overlapping pathway to longevity. High midlife grip strength and long-lived mother may indicate resilience to aging, which, combined with healthy lifestyle, increases the probability of extreme longevity.”


Clearly we can’t pick our mothers, but we can chose not to smoke and to remain physically active.   Studies of the Seventh Day Adventists in California who have incorporated the ideas outlined above also live long lives and remain independent into old age.  The slide below show that Adventist men live about 7-8 years longer than other men in California, for women it was about 4-5 years.  About 70% of Adventists men make to age 80 but only 40% of the male population as a whole makes it to age 80.


Summary:  Dr. Breslow was right a few simple behaviors can have a big impact on both how long we live and how well we live.


Will The Soda Ban Work?

Last week the New York City Board of Health restricted the sale of sodas larger than 16 ounces in restaurants.  The rationale for the ban is pretty straight forward and based on the ideas I have reviewed in recent posts on the “extra” calories people in the U.S. have been eating over the last 30-40 years.   Since many of the calories are coming from soft drinks, and because soft drink portion sizes have been rising, the idea is to limit portion size.    Here is a link to an article on the action of the board and some of the likely fall out.    That having been said, in this post I do not want to take a deep dive into the specifics of the NYC ban, but want to look at some larger issues about “regulating” behavior and its impact on health.  Here are a few questions to think about.


1)    Will the large drink ban “work” and lower obesity rates?  The short answer is that no one knows but perhaps clues are available from studies on what happens to obesity in schools that ban soda and other sugary drinks.   One of the problems is that if just soda is targeted people will just drink other sugary drinks or more soda other places.  At least some evidence from the schools support these ideas and suggest the ban itself might not do much for NYC as a whole.   However, there is also evidence to support the idea that limiting access to sugary beverages in schools works if it is part of a comprehensive and what might be called “common sense” approach.


“Children who attended schools where soda pop and non-low-fat salty snacks could be purchased were more likely to be obese than those at schools where such items were not sold. Children whose parents rarely or never ensured that their child was avoiding eating too many sweets, avoiding spending too much time watching TV, or engaging in physical activity were more likely to be obese than children whose parents did so always or most of the time.”


2)    Can healthy choices be “legislated’?   If we think about how much smoking has declined over the last 30-40 years (see the figure below) it is pretty clear that healthy choices can be legislated.



The same can be said for the improvements in traffic safety.  The experience with smoking suggests that effective  multi-pronged approaches  include:


  • State and Community interventions – in other words, laws that do things that make tobacco more expensive, less accessible and limit thing like smoking in restaurants.
  • Communication the goal here is to counter advertising and promotion of tobacco and at the same time promote positive behaviors.
  • Cessation – behavior change is key.
  • Surveillance and Evaluation – figuring out what works and does not work and how to counter corporate strategies designed to work around regulations.
  • Administration and management

Eating is clearly different than smoking.  No one needs to smoke, but we all need to eat so the parallels with smoking prevention and cessation and the obesity/physical inactivity epidemic are not absolute.   However, it seems to me that we are going to have to make it harder and perhaps more expensive for people to make unhealthy food and physical activity choices and do a bunch of other things as well to address this problem (or collection of problems) in a comprehensive way.  It is going to take more than just telling people to eat less and exercise more.


3)    What about the Nanny State?   The objections to things like regulating soda size frequently bring up concerns about the so-called Nanny State.    This is a complex topic and relates to just how much control “the government” should have over things that can be framed as individual choices.   On the one hand I am sympathetic to this argument, but on the other hand we live in a complex world and all of us pay a price via things like insurance premiums and taxes for the sub-optimal choices of others.  The Nanny State argument has been used to oppose tobacco control and traffic safety initiatives as well, so expect to see it used in the obesity and physical activity debates as well.  The question of course, is where does society draw the line?


In summary, I don’t think the NYC ban will do that much to curb obesity as a stand-alone policy.  However, I do expect this to be the beginning of a long drawn out battle about the regulation of the food industry on issues related to the obesity epidemic.   If the experiences from tobacco control and traffic safety are a guide expect this to go on for the next 30-40 years and expect it to take a long time to see results.    Society did not get fat overnight.


Diet vs Exercise?

Over the last couple of weeks the focus has been on the combined problems of inactivity and obesity that are the dark side of technology and “progress”.    Today’s post is a short one and the question is can a high level of physical activity offset what might be described as a bad diet?

The figure below is from the Aerobics Center Longitudinal Study and shows how fitness and “unhealthy eating” interact in nearly 14,000 adults who were followed for up to 16 years.   People in the moderate and low fitness groups who also scored either moderately high or high on the unhealthy eating index have increased all-cause mortality.   For example, in the moderate fitness group, people who scored high for unhealthy eating had a 1.6 times greater all-cause mortality compared to people in the high fitness group who also ate well.



The authors noted that:

“One primary dietary pattern emerged and was labeled the Unhealthy Eating Index. This pattern was characterized by elevated consumption of processed and red meat, white potato products, non-whole grains, added fat and reduced consumption of non-citrus fruits. The hazard ratio for all-cause mortality in the fifth vs the first quintile of the Unhealthy Eating Index was 1.40 (1.02–1.91). This risk estimate was reduced by 13.5 and 55.0% after controlling for self-reported physical activity and fitness, respectively.”

They went on to conclude that:

“A dietary pattern high in processed meat, red meat, added fats, non-whole grains and white potato products and low in fresh fruit was a risk factor for all-cause mortality. However, the diet-disease relationship was largely confounded by fitness.”


Comment:  I am not advocating that anyone eat what might be called an unhealthy diet, but I think this study is important because it shows that exercise and fitness can limit the negative impact of a sub-optimal diet on mortality.   There may also be times in life (for example while traveling) when it is not possible to eat well and make healthy food choices, but perhaps it is possible to remain active and make sure you get a work out in.


Extra Calories: Where Are They Coming From?

In my September 3rd post, I reviewed the data showing that on average people in the U.S. are eating a lot more now than they did 30-40 years ago.  In this post I want to give you just a little bit of data about where the calories are coming from.   I also hope I can shed some light on comments that both Sheila Ray and Joey Keillor made in response to the September 3rd post.

The graph below gives some clues about the sources of the extra calories.   The left panel is about portion size and you can see that beverage portions have gotten bigger in terms of grams/eating occasion (g/EO).  The right panel is the energy or caloric density per gram of food per eating occasion.  For solid food portion, size is down per eating occasion, but energy density is up so it is a wash.  But clearly we are drinking more calories due to bigger beverage sizes.  Not shown in this slide is that eating occasions have also increased.



The authors of the study that generated this figure conclude that:

 While all three components (eating occasions, energy density, and portion size) have contributed to some extent to 30 year changes in total energy consumption, changes in eating occasions and portion size have accounted for most of the change. These findings suggest a new focus for efforts to reduce energy imbalances in US adults.”


I should note that the authors of the study also estimate that total daily caloric consumption has increased by about 570 calories per day in adults over the last 30-40 years.  This value is in the same ball park as the value shown in the first chart from the USDA in the September 3rd post and on the high side of estimates for increased calorie consumption over time.  Again, whatever the estimates it is pretty clear the population as a whole is eating more calories.


Is it all fructose?  Is it all sugar?

One idea that is out there is that all of this weight gain is due to increased consumption of high fructose corn syrup.  This is controversial and a review of key studies on the topic has concluded that:

“Fructose does not seem to cause weight gain when it is substituted for other carbohydrates in diets providing similar calories. Free fructose at high doses that provided excess calories modestly increased body weight, an effect that may be due to the extra calories rather than the fructose.”

 What about fast food?

The information above shows pretty clearly that we are eating more and that sugary drinks are part of the problem.   But it is even worse than that.  Here is a summary from a study of fast food consumption and obesity in teenagers.

More frequent use of fast-food restaurants that primarily served burgers and french fries was associated with higher risk for overweight/obesity; higher intake of total energy, sugar-sweetened beverages, and fat; and with lower intake of healthful foods and key nutrients. For example, those who reported burger-and-fries restaurant use on three or more occasions per week consumed nearly one additional sugar-sweetened beverage per day compared to those who reported burger-and-fries restaurant use on less than one occasion per week.



The data discussed above was used to give a snapshot of key things contributing to the “supply side” of obesity crises:

  • Bigger portions sizes.
  • More eating occasions.
  • More calories are coming from sugary drinks, but high fructose corn syrup is a problem mainly due to the extra calories.
  • Too much fast food consumption as well as the types of fast foods make a difference.


When you see this data you can see why there is a push in places like New York City to limit the portion sizes for sugary drinks.  My personal opinion is that while there may also be subtle differences in metabolism and all calories may not in fact be created equally, these issues are likely “small potatoes” when you consider the magnitude of the overeating problem.  So, the message is eat less per serving, eat less often, and carefully monitor how often and what kind of fast food you eat.  In future posts I will explore why this is so hard to do.




Community Based Fitness – Lawrence, KS

I have been bombarding you with statistics about inactivity and obesity over the last few weeks.  Today we have a guest post from Drs. Carrie Quinn and Sandy Billinger from the University of Kansas about a novel approach to community based fitness in Lawrence, Kansas.   I first heard about this program when I was at the med-school in Kansas City giving a talk at their “Exercise is Medicine” symposia last May.  The presentation on “Red Dog Days” was so impressive  that I thought it would be a good thing to share.   There are lots of messages here, but perhaps the main one is that with a little creativity, community fitness programs can be generated for little or no cost.  They can also be multi-generational and fun. So, I guess the only thing left to say is “Rock Chalk, Jayhawk” and let Sandy and Carrie tell the story.

Dog Days

One Lawrence, Kansas resident has managed to become the envy of exercise professionals everywhere.  Mr. Don “Red Dog” Gardner has done what most thought was impossible: built a free, community-based exercise program that has withstood the test of time.

Nearly thirty years ago Red Dog started using his military training and sports medicine acumen to help six local football players achieve increased fitness.  Year after year the numbers increased.  Students brought siblings, siblings and students brought parents, parents brought friends, and friends brought neighbors until Red Dog’s basic fitness program exploded into a multi-generational, all-are-welcome, free exercise program serving upwards of 500 people per day.



Always ambitious, Red Dog’s desire lead exercise en masse didn’t end with the development of his program, known as Dog Days.  In July of 2009, Red Dog and his loyal group of exercisers made a run at a World Record: the world’s largest workout.  Though Guiness overlooked the accomplishment, Red Dog’s World’s Largest Workout boasted numbers of over 2700 individuals exercising at the same time.  That’s community-based success.



Exercise professionals are in awe of this phenomenon.  We struggle to get our patients and clients to exercise regularly.   We battle the roadblocks of time and location and convenience in an effort to make exercise more accessible.  And here is one individual that makes the development of a community-based exercise program look effortless.   He says, in essence,

Come exercise with us, and bring your friends.  It’s free and built just for you.  No pressure.  No worriesDo what you can, at your own pace, and meet hundreds of others who will support you and every step you take.”

Though, to the exercisers, the program organization looks effortless, but Red Dog knows the success is due to a very precise combination of ingredients.  It starts with a commitment, not only his own commitment to planning and organizing daily events for 500 exercisers, but commitment from his all-volunteer staff.  A staff that is absolutely essential to the success of the program.   Red Dog’s formula for a successful community-exercise program are:

  1. A charismatic leader
  2. A behind the scenes organizer
  3. Volunteers, volunteers, volunteers
  4. Strong set of rules and values
  5. Facilities
  6. Donor support
  7. Social opportunities

And what’s the payoff for the exerciser?  A coveted t-shirt.   Not sold in stores and never simply given away.  Worn proudly as a badge of honor, those who earn a Dog Day’s t-shirt know the meaning of accomplishment.   They’ve gutted out the workouts and earned their place in line.  Remember, too, Dog Day’s is free.  That means, the design, purchase and distribution of these t-shirts is due to the diligent fundraising of Red Dog and his team.  And this is where community involvement really gels and comes full circle.  Asking the local businesses to support the community effort makes everyone accountable for this exercise movement that started with 6 football players back in 1984.


If you find yourself in Lawrence, Kansas, even if just passing through, look up Red Dog, spend some time at his Dog Days, and you’ll see that getting people to exercise really isn’t that hard after all.


What About Diet?

My recent focus on physical activity and obesity leads to an important question.  How much of the big increase in obesity rates seen in the U.S. over the last 30 or so years is due to what we eat?  Like some of my earlier posts on physical activity and obesity this one is going to be data intensive.


We are eating more!

The U.S. Department of Agriculture (USDA) reports interesting statistics on what people are eating in the U.S.  The figure below shows trends in calories per person.  The top line is total food supply.  The bottom line is an estimate of what people might actually be eating.  As the title of slide indicates there has been about a 19% increase sine the early 1980s.  This is equal to about 400 calories per day!

Clearly these are average statistics and there is all sorts of individual variability related to what people eat.  However, the story for society as a whole is pretty alarming.  If these changes in consumption are not offset by at least some increased energy expenditure this would work out to a pound of weight gain every 9 days or about 40 pounds (18kg) per year based on the idea that a pound of fat is 3500 calories of excess energy consumption.



The USDA statistics about increased calorie consumption have been challenged and better estimates are shown below for all adults (ALL), normal weight (NW), overweight (OW), and obese (OB) adults in the U.S.  These data compare estimates made in the early 1970s to data from 2005-2006.




So, if we use these data, about 200 calories per day, then we would expect people to gain about 20 lbs (9kg) per year.  Also remember from my earlier posts only about 5% of people are meeting the guidelines for physical activity and there has been an average loss of about 100-150 calories a day of physical activity at work for many people.

When you see statistics like this the question isn’t why is the population getting fatter, the question is why isn’t the population getting even fatter!


We are less fat than predicted!

The figure below shows the average adult is “only” about 10kg heavier now then in the early 70s when caloric consumption starts to rise.  This figure comes from an excellent paper with a lot mathematical modeling on how and why our energy expenditure goes up when we eat too much and why it goes down when we diet.


1975                                                                                                          2010


Here is a link to a simulator you can use to project changes in your body weight with dieting using the computer models that generated the simulated changes in body weight noted above.

So the good news is that it is actually pretty hard to gain weight and that  the combination of a lot of extra calories and a lot less activity is required to pack the pounds on.  The bad news is that these same principles apply in reverse and make it hard to lose weight.   The figure below from the modeling paper is an example or what happens to most people when they try to lose weight.

The bottom panel shows a baseline energy consumption of 10 Mega Joules or about 2500 calories per day.  Dieting starts and people reduce their caloric consumption by 30-35% but unless they really start to exercise the energy consumption also goes down.  After a couple of months their eating begins to pick back up, but energy expenditure is still down and weight begins to creep back up over the next couple of year.   This pattern of weight gain is shown in the top panel.  The other interesting thing is just how much inter individual variation there is both total weight loss, energy expenditure and how they interact over time.



The concepts outlined in this figure explains why the National Weight Control Registry data on successful long term “losers” shows that a combination of a low calorie diet and high levels of physical activity are required to take and keep weight off over time.  In coming posts I will try to figure out where the extra calories are coming from over the last 30-40 years and why there is not a linear relationship between eating less (or becoming more active) and losing weight.