Human Limits

I got an e-mail over the weekend from a reader who was a world class runner in his youth and getting ready for an upcoming half marathon.

“Michael: I seem to have hit that mid-60s point where things deflect a little on the difficulty/slower-speed curve. Trying to stay positive…..”

That having been said, I was thinking about doing a post on the lack of discussion in the election about the real problems confronting health care in the United States.  Most of the yapping seems to be about how various insurance programs might be organized and misses the fundamental point that if things don’t change the combination of inactivity, obesity and aging is generating a tidal wave of chronic diseases that will bankrupt anything that is being discussed.    However, the aging and speed curve issue raised by the reader above is more fun and there are some pretty simple ways to address it.

First, what is meant by the “slower-speed curve”?  If you plot records vs. age for almost any distance running event you get a graph like the one below.   I did this one 20 years ago for a scientific review on aging and endurance performance and it plots age vs the US record for 10K road race time.   The times have changed since then but the trends are pretty similar.  (If any enterprising student who might be reading this wants to update the curves let me know and we can set up a guest post on the topic.)

You can see that times are best for competitors from their early 20s until the middle or later 30s.   After the late 30s, things decline at a rate of about 6% per decade and the rate of decline increases somewhere in the 60s for men.   The data for women is similar but a little harder to interpret because we have not seen the full effects of Title IX and increased participation by women on the age group records.   While this data is for record performances by many different runners, many individuals report similar personal experiences and note, as the reader did, that something happens in their 60s.

Second, what happens in your 60s?  There are several possibilities.  From a biological perspective, things like peak heart rate decline as we age, but the rate of decline does not accelerate in your 60s.  That having been said, something called sarcopenia (age related muscle loss) probably starts to accelerate in the 60s.   If you look at people who tend to maintain their performance over time, there is evidence in men that those who decline the least keep their lean muscle mass and training intensity up.   In women it appears to have more to do with training volume (milage) and hormone replacement therapy.   However, I want to point out again that less is known about female master athletes, and there is some evidence that in terms of training intensity, what applies to men applies to women as well.   Here is a link to an article on Kathy Martin who is rewriting the record books for older women.  Note that she does a lot of high intensity training and my understanding is that she has added milage only recently with her move up to the marathon.

The other issue here is that injuries and other health issues catch up with people as they get older and perhaps it is just harder for most folks to train as consistently and consistently hard for these reasons.

Third, can you beat the speed curve?  My personal opinion based on a combination of observations, discussions with others, and a tiny bit of research driven evidence is that training quality is the key.   I would advocate that in your 50s and 60s you might cut your milage back and do most of what we used to call “over-distance” training on the bike or in the pool.  This will let you focus your running on higher quality efforts and provide a lot of bang for the buck with minimal orthopedic risk.   An interesting anecdote is that in the early 1990s the legendary Fred Wilt, a world record holder in the 1940s, told me that when he was in his 50s he came close to breaking 10 minutes for 2-mile.   His training consisted of jogging a few minutes mile to a track near his home and doing two miles of alternating fast and slow 200m runs very hard and then jogging home.  He did this about 4-5 days per week.

Consistent with what Fred Wilt was doing in his 50s, he documented in several books the training used by athletes who ran some pretty incredible times prior to the “modern” ideas about training emerged after World War II.  Much of it seemed to consist of things like 4-5 miles of hard running followed by some all out sprints 4-5 days per week.   I personally try to do something like this 2-3 times per week, and sometimes do the sprints on the bike trainer to keep the risk of injury to a minimum.   The other thing I like to do is 20-30 minutes of hard steady riding on a trainer followed by 20 minutes of 1-minute on/off of fast-slow running.   The advantage of using a treadmill and bike trainer to do this type of training is that it may be a bit easier to push yourself.  I am 54 and following this plan as I prepare for a 5 mile Turkey Trot on Thanksgiving.

Fourth, why will this work?  In an earlier post on distance running and the Olympics this summer I covered the concept of VO₂ max and its role in setting the upper limit for endurance performance.  The type of intense training discussed above and very hard efforts of 3-5 minutes are the keys to keeping your VO₂ max as high as possible while you age.   I also think that biking vs over distance running is a good way to keep your muscle mass up.   I am always impressed at how the best master athlete cyclists and swimmers seem to have maintained their muscle mass in comparison to distance runners who sometimes look a little wasted.

Summary:  The ideas above represent my best guesses about how to maintain a high level of performance especially in your later 50s and 60s.  They are designed to limit the risk of injury.  There is scientific evidence for most of these ideas and there are real world examples showing that these ideas work.   We all eventually lose the battle with aging; the key is to lose it slowly by walking, running, biking, or swimming fast.

In response to the drop Lance Armstrong as fast as you can movement by his sponsors and his resignation as chairman from his foundation one reader sent me a note that went like this:

”He is finished – might as well move to his house in Spain and not come back.”

 I am not sure if Lance has a house in Spain, but I think we all get the point.   At one level perhaps he should try to preserve as much of his reported $125 million fortune as possible, keep a low profile and hope that he does not drown in a tidal wave of lawsuits and settlements.

So, the question is will Lance have a second act?  F. Scott Fitzgerald famously said that there “are no second acts in American lives.”   Lance was trying to forge one in the triathlon, but he was cut off at the pass by USADA in terms of competing at the highest level.  So what is next?  One crazy thought I had is that maybe Lance will “come clean”, write a block buster book, name names, and set the record straight (at least from his perspective).   Who knows he might even find religion?

If something like this does happen, he would not be the first fallen public figure to cash in that way.   To the extent he is driven by the need for fame, celebrity, and cash this might be his best option.  To the extent he needs to be driving the narrative, perhaps it is his only option.   If Lance fades away so be it.  If he opts for the second life I have outlined it will be a nine ring circus.

I mentioned on Monday that I was at the Integrative Biology of Exercise meeting last week.   One of the topics of hallway conversation was the release of the USADA report on Lance Armstrong and the rampant doping in Cycling during the time he won seven Tour de France races in a row.   It turns out that one of the most popular books my colleagues and I were reading on the plane to the meeting was “The Secret Race” by Tyler Hamilton and Daniel Coyle.  Hamilton was one of the world class cyclists who spilled the beans to USADA.

I discussed the ”geopolitics” of Lance situation in detail last summer, but the Hamilton book gives a broader perspective on the problem of doping.   It describes in detail how an earnest and ambitious young athlete gets into the highest level of cycling.   How the super talented find themselves in the middle of the pack.   How a moment or a few moments of truth occur and it is either continue to chase your dreams and dope, or go home and join the real world.   The decision to dope is of course made easier if everyone is doing it,  and who can expect the super competitive to simply unilaterally disarm and simply give up.  The book also describes how it was relatively easy to beat drug testing with a little bit of planning, corrupt doctors, and cash.

As I read to the book I thought back to the time to the late 1970s when I was sometimes running 100 miles per week or more.   Prior to my personal best marathon I ran 522 miles in four weeks before tapering.  Essentially my entire life revolved around training, all my friends and peers were runners, and I was certainly willing to pay a big price to improve.  My only distraction was going to class.   That having been said I wonder if I had been in a corrupt culture with corrupt coaches and big money on the line if I would have doped?    If everyone is doing it, is it really wrong?  I hope I would have said no, but who knows.

As things have emerged over the years it is also pretty obvious that we live in an ergogenic world full of plastic surgery, Botox, Viagra, doping to improve grades, and various anti-aging potions.    Is everyone looking for success in a bottle, a pill, or via a syringe?   Why should elite sport be different than the rest of the world?

That having been said, I recommend two other books for those who want to understand more about doping.   The first is “Game of Shadows” from 2007.  This book details the Barry Bonds case and the BALCO scandal.   In addition to exploring the logistics of sports doping and what motivates athletes to dope, the book raises important questions about what the “authorities” who oversee sports leagues and organizations really want.   Are they concerned with clean competition?   Or, is about brand protection and the appearance of clean competition so that sponsors and general public don’t turn away if things look too overtly corrupt?  Yesterday Lance Armstrong lost most of his major sponsors and stepped down as chairman of his foundation.   Were these acts of organizations interested in doing the right thing or brand protection?

The second book is “Muscle: Confessions of an Unlikely Bodybuilder” by Sam Fussell.  Fussell was essentially a “95 pound” weakling/intellectual with degrees from several top universities who got involved in bodybuilding and went all in.   The book describes how it is possible for an otherwise thoughtful and intelligent person to descend into an athletic subculture and do just about anything to improve.   It is a cult classic, and I highly recommend it.

Last week I had the opportunity to attend the “Integrative Biology of Exercise” conference sponsored by the American Physiological Society.   During an excellent talk on how exercise training can modify the changes in heart function with age, Dr. Ben Levine showed classic data from a study done in the middle 1960s known as the Dallas Bed Rest Study.

In this study 5 healthy young men did nothing but bed rest for three weeks while detailed measurements of their cardiovascular function and exercise capacity were measured.    Not surprisingly, cardiac function declined and exercise capacity fell dramatically with bed rest.   The figure below shows what happened to VO₂ max which is considered the gold standard measurement of exercise capacity after bed rest.

What is even more interesting about this figure is that when the same subjects were studied 30 years after the original bed rest study, their VO₂ max fell more with just three weeks of bed rest than with 30 years of aging.   Below is a video link of Dr. Levine talking about his work on related topics.

 If video does not load, click here.

Another interesting video on the topic of inactivity comes from Dr. Bente Pedersen of the University of Copenhagen.    Her team has conducted an incredible study showing that just two weeks of minimal physical activity can put previously health young men on the path to what might be described as pre-diabetes.    In the video below she discusses these findings and also concepts related to the fit vs. fat topic covered a few posts ago.

If video does not load, click here.

These are terrific talks by scientific leaders who are my friends and colleagues.  One of the great things about the electronic environment is that presentations by such outstanding investigators are available to us all.

There has been a lot of talk recently about the long term health risks associated with U.S. football.  There are two main concerns, the first relates to the long term effects of concussions and cognitive impairment later in life.  The second relates to the long term health risks associated with being “very big”.

It turns out that the neurological consequences of football are more typically seen in so-called speed positions that are associated with high velocity open field “big hits” in comparison to collision positions like the line.   The non-neurological long term health risks of professional football go something like this:

“National Football League players from the 1959 through 1988 seasons had decreased overall mortality but those with a playing-time BMI ≥ 30 had 2 times the risk of CVD mortality compared to other players and African-American players and defensive linemen had higher CVD mortality compared to other players even after adjusting for playing-time BMI.”

Some of these concerns were highlighted in a piece by the columnist George Will who summarized it this way:

“Decades ago, this column lightheartedly called football a mistake because it combines two of the worst features of American life — violence, punctuated by committee meetings, which football calls huddles. Now, however, accumulating evidence about new understandings of the human body — the brain, especially, but not exclusively — compel the conclusion that football is a mistake because the body is not built to absorb, and cannot be adequately modified by training or protected by equipment to absorb, the game’s kinetic energies.”

WHAT TO DO ABOUT IT?

The first thing to remember is that the modern game of football emerged after deaths in college football in the early 1900s led President Theodore Roosevelt to demand that the game be reformed or banned.  So, the safety of football is not a new issue and in that spirit I make the following suggestions:

1. Limit substitutions.   If players had to play both ways my bet is that the premium on very large players (300 pounders) would be replaced by a premium on big but not huge players who had the athletic skills to do more than one thing and also the stamina to play for longer.   When teams go to no huddle offenses frequently their defenses complain about the lack of rest caused by an offense that gets off the field too fast.  So, there would be a new emphasis on conditioning.
2. Shorten the time between plays.  If there were a 20 second clock between plays the game would be more continuous and that would make conditioning even more important and limit the utility of really big players.  It might also limit the likelihood of pre-planned, high speed big hits.
3. Get rid of some of the protective equipment.    It is unclear if the protective equipment is in fact that protective.  Perhaps it gives the players a false sense of security and encourages them engage in high risk, high impact hits.

Some of the ideas above would make U.S. football more like rugby so I bounced them off four outstanding physiologists from rugby loving countries:  Danny Green and Bob Callister from Australia, Tim Noakes from South Africa, and Peter Raven originally from the UK.    All of my colleagues agreed the ideas above had merit.    Dr. Green sent me a fascinating paper about body size in rugby and how it has changed over the last 100 year, and it is unusual for a top class rugby player to be much bigger than 110kg (about 245 lbs).

In closing, I doubt the ideas above will ever be adopted wholesale, but various forms of football have existed for centuries and perhaps the game will evolve in the ways I have outlined above.  If so, I bet we will end up with a safer game to play and watch that is equally exiting.  Watch a clip of the 7 on 7 version of rugby that will be coming to the Olympics in 2016 and see wide open game.   Add the forward pass and imagine what would be possible.

I got an e-mail a couple of days ago from a friend and reader who is world-class engineer/leader for a large company who just returned to the US after several years on an overseas assignment.   Here is an extract from the message:

“I read the blogs for the past month, very interesting.  There was a lot of coverage of obesity…….something I know firsthand, all too well, unfortunately.  You’d think I’d listen to such good advice and make some changes.  But, as you say, it is a complex issue.  I hope that just one poor risk factor out of six, will not be too bad.”

This got me thinking about the whole obesity issue and perhaps it is time to stress some good news.  That having been said, there is pretty convincing evidence that remaining fit and active can trump a lot of the negative health risks associated with obesity.   The graph below shows the relative risk (RR) for all-cause mortality (top panel) and cardiovascular disease (CVD) mortality (bottom panel) in lean, normal and obese subjects.  The dark bars are for unfit people and open bars for fit people.  The study comes from the Cooper Center database and included almost 22,000 men.   The numbers of above the bars are numbers of deaths in each group over a multi-year period of observation.

The dark bars show that obesity puts people at increased risk for both all-cause mortality and cardiovascular disease.   This increased risk is clearly amplified by being unfit.   By contrast, all-cause mortality was lower in the fit people and the amplifying effects of excess body weight were much less.  There are all sorts of reasons why being fit and active can trump other risk factors like obesity; less diabetes, blood vessels that can stay relaxed, and better blood pressure control to name a few.   The other issue here is that people need to avoid getting hung up on losing a set amount of weight to reach an “ideal”.    Losing just 5 or 10 pounds can really make a difference in a number of risk factors and is especially effective if it is accompanied by more physical activity.

So here is an encouraging thought from a recent study for people who worry about their weight:

“Higher fitness should be considered a characteristic of metabolically healthy but obese phenotype. (ii) Once fitness is accounted for, the metabolically healthy but obese phenotype is a benign condition, with a better prognosis for mortality and morbidity than metabolically abnormal obese individuals.”

Or as Dr. Chip Lavie, a noted cardiologist and fitness expert from New Orleans, said recently in the New York Times:

“Maintaining fitness is good and maintaining low weight is good, but if you had to go off one, it looks like it’s more important to maintain your fitness than your leanness……”

So don’t get discouraged, do stay active, and don’t get too hung up on your weight if you are staying active.

Today’s post was stimulated by an e-mail exchange with Amby Burfoot of Runner’s World on reports over the past few months suggesting that lifelong intensive exercise training might be “bad” and actually increase the risk of heart problems.  The idea is that during exercise adrenaline and related hormones cause the heart to beat faster and harder.  Do this day after day for years and the thinking goes that areas of micro damage might occur.  In addition to leading to small areas of heart damage, there might also be a buildup of calcium in the blood vessels that supply the heart.  So what is the evidence to support these ideas?

First, after extremely prolonged and intense exercise like a marathon or ironman triathlon the pumping ability of the heart can be reduced by a few percent for a few days and there can be a rise in blood levels of substances released from the heart.  However, the pumping function of the heart returns to normal within a week and there is no evidence of long term heart damage.   The blood levels of substances released from the heart also return to normal.  The other tricky thing here is that the skeletal muscles of highly trained athletes undergo biochemical changes that make them more like heart muscle.  The wear and tear on skeletal muscles during a competitive event can then cause a rise in the blood levels of so-called cardiac markers that are in fact released from skeletal muscle and set off all kinds of false alarms about heart damage.

Second, no one is sure exactly what finding calcium in the coronary arteries means in asymptomatic people especially older athletes.   Also, case reports in a few people are hard to interpret and in more controlled studies it appears that the coronary arteries of lifelong ultramarathon runners are a bit bigger than those of non-runners and can also dilate more.   The figure below shows this data, and bigger coronary arteries that relax more are almost certainly a very good thing.

Third, there is some data in animal models that areas of micro damage caused by prolonged intense exercise make the heart more susceptible to dangerous irregular heartbeats.  However, in these studies aversive stimuli (tail shock) were used to get the animals to run so there is the added issue of “mental stress” in addition to exercise.   Also, the animals were doing a training regimen that was truly heroic in terms of both daily duration and intensity and how this translates to what even the most fanatical human might do over 10 or 20 years is unclear.   In other animal models, exercise training tends to protect the heart from irregular beats.

Fourth, when detailed research and data collection is done on who dies during exercise a couple of patterns emerge.  Young people who die suddenly typically have congenital problems with the electrical system in their hearts or defective coronary arteries.   Middle aged and older people typically have evidence of heart disease that in many cases probably started before they became fit or started to train.   There are also cases of heart problems in athletes likely related to acute inflammation of the heart perhaps associated with a viral illness.   However, marathon running as a whole appears to be very safe.

Fifth, all the news is not positive.  There is some evidence that lifelong training is associated with a condition known as lone atrial fibrillation.   However, the data are only suggestive and much bigger and better controlled studies are required on this topic.   This condition while bothersome is typically not life threatening and can be treated.

Perspective:  Over the last few months I have been making the case that one of the biggest public health and ultimately medical problems out there is inactivity.   Is there a cardiac risk associated with being super fit and training a whole lot?  To the extent there is comprehensive and well controlled data the answer appears to be no.  It does appear that in terms of health there are diminishing returns and that people who train “a whole lot” (say more than an hour almost every day) are not  better off than people who just do “a lot” (30-60 minutes most days).  However, people who do a whole lot of training are probably doing it for reasons other than health that include things like a need to compete, a need for time alone, or the need for some sort of big challenge in life.  Not exercising enough is extremely common and dangerous.  By contrast, a life time of exercising “too much” is extremely rare and the evidence to suggest it does long term harm to the heart is pretty speculative.

Last week in the Opinion section of the New York Times, the food writer Mark Bittman made the case in layman’s terms that Alzheimer’s disease might be considered “type 3” diabetes.   There are two main lines of evidence in support of this idea.  The first is that glucose and insulin in large amounts do bad things to the brain.   In type 2 diabetes blood levels of both glucose and insulin can be high.   The second is that diabetes is a risk factor for Alzheimer’s disease, and the increased rates of diabetes and Alzheimer’s in the population tend track each other.  However, the story is a bit more complex than simple “type 3” diabetes.

The current thinking is that Alzheimer’s is caused by the buildup of one or more proteins (one of the major ones is called beta-amyloid) in the brain that damage nerve cells and ultimately cause brain function to decline.  However, there are holes in the protein theories and drug therapies designed to lower the levels of amyloid have not improved brain function in clinical trials.   It is also interesting to note that in addition to diabetes, several behavioral risk factors seem to put people at increased risk for Alzheimer’s disease.

When I look at these risk factors I am struck by how similar they are to traditional risk factors for heart disease.   For both heart disease and Alzheimer’s, diabetes, hypertension, obesity, inactivity, and smoking all damage blood vessels and their negative effects tend to multiply in people with more than one risk factor.   Also, the only genetic risk factor with a big effect in Alzheimer’s some something called ApoE4 which affects cholesterol metabolism and can also damage blood vessels.  To me this suggests that there is an interaction between the buildup of “bad” proteins in the brain and poor blood flow to the brain.   There is also some evidence that exercise causes an increase in the levels of something called BDNF (brain derived neurotrophic factor), which promotes the growth of new brain cells even in middle aged and older people.

If you take the evidence outlined above a step further and ask what effect improvements in “life style” might have on Alzheimer’s the data is pretty startling.  Here is a quote from the summary of the key paper on behavioral risk factors mentioned above.

“At present, about 33.9 million people worldwide have Alzheimer’s disease (AD), and the prevalence is expected to triple over the next 40 years. The aim of this Review was to summarize the evidence regarding seven potentially modifiable risk factors for AD: diabetes, midlife hypertension, midlife obesity, smoking, depression, cognitive inactivity or low educational attainment, and physical inactivity…….Together, up to half of AD cases worldwide (17.2 million) and in the USA (2.9 million) are potentially attributable to these factors. “

Who knows if there will ever be a simple explanation for Alzheimer’s disease that will lead to effective drug therapy.  However, it is pretty clear that what is good for your heart is good for your brain.