Health Medicine Sports Medicine

Is Exercise Bad For You? Shocking News Reports!

Some say a meta-analysis is like a large pile of small, weak, and insignificant studies lumped together into one ugly mess. Sort of like a stew made up of left-overs that might be getting a bit moldy. Others say that by aggregating studies which alone would be too small to amount to anything of significance, the data can gain significance by having a larger number of subjects from different studies put together to be counted.

Couch Potato
Couch Potato

Study Title: Adverse Metabolic Response to Regular Exercise: Is It a Rare or Common Occurrence?

Study Citation: Bouchard, C, Blair, S et. al. (2012) Adverse Metabolic Response to Regular Exercise: Is It a Rare or Common Occurrence?

Study Premise: There is a variability in peoples response to exercise. Some may experience adverse response to exercise. The authors state no study has addressed adverse changes in cardiovascular and diabetes risk factors can occur. The risk factors chosen to be studied include: “Sixty subjects were measured three times over a period of three weeks, and variation in resting systolic blood pressure (SBP) and in fasting plasma HDL-cholesterol (HDL-C), triglycerides (TG), and insulin (FI) was quantified.”

Study Conclusion & Media Announcements: Adverse response to exercise may occur. Some individuals do not respons positively in the measured according to the authors this analysis of 6 previous studies (a meta-analysis) revealed the shocking truth that some overweight people did not have a positive response to exercise and the variables mentioned above worsened. 7% had two variables worsen over the course of an exercise program.

Analysis: Why should one expect 100% positive response to any intervention? The fact that 90% had a positive or non-adverse impact on risk factors is an overwhelming number of individuals for whom exercise is likely quite good. Emphasizing the negative in which case “the minority is the new majority” seems to be the in thing to do in current culture and society. In everything from politics to social policy a majority may be declared at 40% (the U.S. Senate) or at 12-17% as was seen in misused statistics during health care reform debates. The fact that 8% to 12% is neither a majority, nor a vast number, and the “adverse events” were not death, disease or morbidity and mortality should alert those reading this article and the large headlines in the paper that hyperbole is at play.

There is an overwhelming amount of information that says exercise is good for you in many, many ways. In many cases exercise is the missing link to the best health you can have. Exercise is something that almost everyone should be undertaking (to avoid the undertaker). In fact a famous saying goes “where there is no exercise, the people perish”. Well, maybe it was “where there is no vision the people perish”.The reality is that where there is no exercise the people develop sarcopenia (muscle wasting), osteoporosis, obesity, depression, diabetes, high blood pressure, and dementia. So whether or not your high blood pressure goes down and your HDL-C goes up, there are many positive benefits to be achieved by exercising regularly.

Exercise and diet are both vital to overall health. All of the individuals in the studies this meta-analysis selected to include were overweight. Improper diet plays a large role in being overweight or obese.

Successful implementation of a healthy life plan should actually include more than a mere exercise program. It needs life habit modifications that would include good sleep habits, healthy diet, and avoiding the excessive consumption of things that are bad for you (too much alcohol, drugs, etc.). But exercise may be the largest change that is easy to make. Diet is also critical and often needs a tune up. Let’s sum this up in one sentence!

You can exercise and have a great shot at doing as well as you can or you can sit on a couch and take your chances!


  • The study group only included overweight people with a BMI from 25-30
  • Normal variablility in tests – is greater than zero


Bouchard, C, Blair, S et. al. (2012) Adverse Metabolic Response to Regular Exercise: Is It a Rare or Common Occurrence?

Bouchard C, Rankinen T (2001) Individual differences in response to regular physical activity. Med Sci Sports Exerc 33: S446–S451

deMello, V et. al. Insulin Secretion and Its Determinants in the Progression of Impaired Glucose Tolerance to Type 2 Diabetes in Impaired Glucose-Tolerant Individuals
The Finnish Diabetes Prevention Study.
Diabetes Care February 2012 vol. 35 no. 2 211-217. Published online before print December 30, 2011, doi: 10.2337/dc11-1272

Study Notes

an adverse response was recorded if an increase reached 10 mm Hg or more for SBP, 0.42 mmol/L or more for TG, or 24 pmol/L or more for FI or if a decrease reached 0.12 mmol/L or more for HDL-C. Completers from six exercise studies were used in the present analysis: Whites (N = 473) and Blacks (N = 250) from the HERITAGE Family Study; Whites and Blacks from DREW (N = 326), from INFLAME (N = 70), and from STRRIDE (N = 303); and Whites from a University of Maryland cohort (N = 160) and from a University of Jyvaskyla study (N = 105), for a total of 1,687 men and women. Using the above definitions, 126 subjects (8.4%) had an adverse change in FI. Numbers of adverse responders reached 12.2% for SBP, 10.4% for TG, and 13.3% for HDL-C. About 7% of participants experienced adverse responses in two or more risk factors.

Health Medicine

Parenthetically Speaking: Colons, Math and the New York Times (repost 2008)

Science, Numbers, Journalism and Critical Thinking

I believe it was on a Merlin Mann podcast, where someone jokingly mentioned the concept of an iColon website which in typical Web 2.0 fashion people could share the images and films of their colonoscopy procedures. This week the New York Times managed to demonstrate where their heads were at regarding simple mathematics and statistics. An article by one of their most popular reporters reviewed a new study that showed that colonoscopies were not all they were cracked up to be as far as picking up colon cancer and in their ability to prevent future cancers from developing from detection and removal of polyps.

The American Cancer Society still strongly recommends the colonoscopy as a useful  screening procedure. and the physicians I know who both perform this procedure and recommend it all strongly feel that it is one procedure that can actually save lives. We will however take a quick and simple look at the use of math and see a lack of simple math skills and the failure of editorial checking at the New York Times.

The NY Times reported on a study that demonstrated that colonoscopy missed virtually all polyps on the right side of the colon. The  article stated that 40% of all cancers and polyps originated on this side. Of those on the left side of the colon up to 30% of those were missed. The article then went on to quote and conclude that rather than preventing up to 90% of colon cancer from devleloping it might only be useful in preventing 60% to 70%. Now, this seems to be a fairly simple math problem. And a quick glance by anyone even one with only minimal math skills just looks and sounds wrong on the surface of it all.

If 40% of the lesions occur on the left side but are undetectable, than you have remaining 60% of the lesions to deal with that you can find. If 1/3 of these ones are not found, by splitting them into 3 equal parts of 20% 20% and 20%, and you remove 1/3 you are then left with 40% of the lesions that you would be able to find.
Hence, it is clear that it is not 60%-70% number of lesions that you’ll expect to find, but a number significantly less than 50% and which clearly looks to be 40%. The physician interviewed in the New York Times encourages people to have the colonoscopy as a screening procedure, but to not necessarily expect to be safe for the next 10 years. It is strongly recommnended that you follow the colon cleaning procedures prescribed prior to undergoing the procedure.

There will be more studies in the future and likely ones that will be quite positive on colonoscopy. Techniques will likely be modified that also result in improved detection of right sided lesions. Until then, we now and always will need clear heads to do the math and keep evidence based medicine, based on evidence and not on an easily obtained quote.

Up soon we may dissect an article published within the last few months that looked at the longevity of runners and non-runners. If you know the study, here’s a hint: check out the disparate population groups studied and see if it looked like a well designed and controlled study.

New Math From the New York Times:

“In the new study, the test missed just about every cancer in the right side of the colon, where cancers are harder to detect but about 40 percent arise. And it also missed roughly a third of cancers in the left side of the colon.

Instead of preventing 90 percent of cancers, as some doctors have told patients, colonoscopies might actually prevent more like 60 percent to 70 percent.”

Biology Medicine

Travelling, Running, and Starving – A New Approach To Your Circadian Rhythms (repost 2008)

For many people, long trips disturb the natural rhythms so much that normal functioning on both the physical and intellectual planes is impaired. Clearly, there is a need for some method to improve the travel experience and the race results for those on a tight schedule. First class? Sounds great, but isn’t practical and probably won’t get the job done.

Circadian rhythms may affect racing performance. Most world records have been set in the afternoon or evening rather than in the morning. It may be a matter of when the races are run, but it also may follow along with optimal body rhythms. Workouts seem easier in the afternoon, joints are stiffer in the morning, and some old lecture notes I have indicate that muscles are weakest at 8 AM & 8 PM and strongest at 5 PM. Body temperature reaches a peak around 5PM. (Spiking fevers when you are ill, do not spike in the morning, but late afternoon or evening.) Measured VO2 MAX is greater in the afternoon.



  • Start sleeping on the schedule of where you will be racing (or working).
  • If you can, train on the schedule of where you will be headed.
  • Get there early if you can, for optimal performance one day for every hour time difference. Otherwise follow all the other suggestions.
  • Melatonin
  • Bright lights for wake up time on new schedule and wake up also.
  • Eat lightly 2 days before travel, then start eating on the arrival schedule

The suggested eating change, of eating on the new arrival schedule comes as a result of a new study on circadian rhythms published in this weeks Science Magazine. The article notes that when food is readily available, circadian rhythms are greatly impacted by the light-dark cycle. If food is only available at night, the animal will shift its circadian rhythms to match the time when food is available. This led to studies of the gene clock Bmal1 and found that the dorsomedial hypothalamic nucleus seemed to impact the role of food and feeding on the circadian timing system (CTS). Light has previously been found to play a role via retinal ganglion cells containing melanopsin which generates signals to the suprachiasmatic nuclei (SCN) of the hypothalamus. The SCN then effects a tuning of the circadian rhythms via synaptic and humoral mechanisms. The studies described here were done on mice.

The authors conclusions were:

Our data indicate that there is an inducible clock in the DMH that can override the SCN and drive circadian rhythms when the animal is faced with limited food availability. Thus, under restricted feeding conditions, the DMH clock can assume an executive role in the temporal regulation of behavioral state. For a small mammal, finding food on a daily basis is a critical mission. Even a few days of starvation, a common threat in natural environments, may result in death. Hence, it is adaptive for animals to have a secondary “master clock” that can allow the animal to switch its behavioral patterns rapidly after a period of starvation to maximize the opportunity of finding food sources at the same time on following days.

The biological clock for mammals, clearly resides in the hypothalamus. In some insects and snails, the clocks seem to be located in the retina. In birds, the pineal gland has been thought to come into play, along with the hypothalamus. Photoreceptors are usually linked into the timing system, to synchronize the clock with the 24 hour day. Old studies showed light to be able to assist in resetting the clock by impacting genes, sleep patterns, alertness, and body temperature.

As we noted above, exercising on the new schedule, can also help. Recent research agrees with this as per the study “Scheduled exposures to a novel environment with a running-wheel differentially accelerate re-entrainment of mice peripheral clocks to new light–dark cycles (Yujiro Yamanaka, Sato Honma and Ken-ichi Honma Genes to Cells (2008) 13, 497-507)

A study from 2001 demonstrated the liver enzyme production could be shifted 10 hours within 2 days by altering feeding. (Science 19 January 2001: Vol. 291. no. 5503, pp. 490 – 493 Entrainment of the Circadian Clock in the Liver by Feeding. Karl-Arne Stokkan, Shin Yamazaki, Hajime Tei, Yoshiyuki Sakaki, Michael Menaker)

Larks and Owls
While we don’t have studies to cite here, others have noted that some people are better at staying up late than others, while others are happy to wake up at 5 or 6am, but can’t stay up to party, play MMORPGs, or text their buddies in the middle of the night.

Some feel that it is easier for Larks to travel west to east and for owls to travel from east to west. The larks have little trouble staying up late, and have probably already shifted in part to the western time zone.

Cardiovascular Changes Medicine Running

Running & Being and Running & Dying (repost 2007)

George Sheehan‘s book “Running & Being” is one that every dedicated runner should read. George, a cardiologist, and one of the early, great running philosophers and gurus has been an inspiration to all old school runners.

Many years back, some people, Jim Fixx included, thought that running marathons would give an immunity to fatal heart disease. While running is certainly excellent for cardiovascular health, this has been found to not be so. The most recent studies seem to demonstrate that long distance running reduces your overall risk from dying from cardiovascular disease but that during running itself your risk is higher than while at rest. I still believe that this is a reason to run and not to avoid running. The overall benefit to reduced risk of cardiovascular disease, high blood pressure, depression, body weight, and many more benefits clearly and strongly outweigh the statistically somewhat increased risk of exercising.

It is important though to note and keep track of your own personal risks. Be aware of your lipid profile, your total cholesterol, your HDLs, LDLs, Triglycerides, and what you must to do make it as good as can be done for you. Be aware of your personal and family history of cardiovascular illness. Have your blood pressure checked, and as you get older have it checked more often. High blood pressure is a serious and by many an underrated, and undetected but major contributor to severe cardiovascular illness. Do not underestimate it or think you may be immune to it because you did not have it for the first 25, 35 or 40 years of your life.

Jim Fixx, author of one of the early and earth shaking popular books on running, died from heart disease while running. Today, Ryan Shay, a promising American runner died in the U.S. Olympic Marathon trials. At this time the cause of death has not been established. It was a very sad thing to learn. He is believed to be the first american elite runner to die during a running event. Earlier this year Alberto Salazar had a severe heart attack and was without a self-sustaining heartbeat for more than 5 minutes. Amby Burfoot recently wrote a great article about Alberto’s heart attack in Runner’s World, in which his personal risk factors were discussed. One of his grandfather’s died at 52 from a heart attack and the other at age 70. He reported that his father had had more than one heart attack. If I recall correctly Alberto was being treated for high blood pressure and an abnormal lipid profile. His lab tests and blood pressure were considered fine while under treatment. Serious heart disease ran in his family. This was pointed out as a risk factor that you can not alter. A few weeks ago I came across another article about Alberto Salazar in a section of the New York Times written by John Brant, an author who has written a book on the famous Salazar – Beardsley Boston Marathon race. Salazar related to Amby Burfoot that his doctor recommended an echocardiogram which would not have demonstrated cardiovascular disease. In the New York Times article something jumped out at me. Alberto, according to this article, had had significant neck and back pain that made him go to visit his physician. Normally, he endures pain stoically. His doctor did a resting electrocardiogram and some lab tests and it seemed normal. He was then given an appointment for some weeks later to have stress electrocardiogram.

“…in Indianapolis, Salazar was unable to sleep, had little appetite and felt perpetually tired. Stabs of pain rose from his neck and back, which he attributed to sitting awkwardly on the plane. As soon as he returned to Portland, his primary-care physician prescribed some tests, which were inconclusive, and referred Salazar to a cardiologist. An EKG stress test was scheduled for early July.”

Unfortunately, before he had that he had his near fatal heart attack. Or as some called it a fatal one that he survived. (Since he lived, even though his heart stopped, I do not call it fatal.). This is another extremely important item for runner’s to note. Do not ignore chest pain, neck pain, left side of the jaw pain, upper back pain and any other pain that makes you think something could be wrong. If you have risk factors or if a possible coronary atherosclerosis is suspected, you don’t need your stress test and or thallium blood flow study next month, you need it now. You should have that test as soon as possible. Salazar had serious signs of heart disease that were perhaps taken a tad less seriously and attended to a little slower than they should have been. His test should have been the following week and not the following month. Another, not quite as good a runner, David Letterman, did get tested early, and had a quintuple bypass. Salazar, was lucky to only need a stent. Happily, both have recovered and are running again.

The Runner’s World article by Amby was excellently written and gripping. Alberto is thoroughly quoted within the article. In trying to figure out why there was a difference in how he related his symptoms before his heart attack to the two authors I was at a bit of a loss. In a close reading though, Alberto clearly wanted to emphasize his spirtual beliefs in both, and perhaps even more so in the earlier interview with Amby. He viewed his heart attack as part of God’s master plan for him. I don’t know why he didn’t mention the symptoms he had. I’d suggest if you do hear a bit of knocking at the door in the form of unusual discomfort, pain, fatigue or dizziness you pay attention quickly.

Since most of you runners are doing all that you can to be healthy, let’s make sure you don’t ignore signs that you need just a little help to keep that ticker working. And don’t put off the stress test, if you need it.

Biology Medicine Sports Medicine

Viva La Différence: Exercising Sitting Down vs. Standing Up (repost 2007)

The New York Times had an article today which discusses how bicyclists come in all shapes and sizes. Gina Kolata mentions that that many cyclists did not meet her conception of what an in shape cyclist would look like. The reality is that runners come in all shapes, sizes and ages also and this can be seen at many marathon events. The other part of the reality is that elites among both runners and cyclists have different morphological characteristics including a lower body fat content, higher MVO2 and various other items.

But, there is hope for all of us. George Sheehan once said “We are all athletes, some of us are in training and some are not.”

“When I first got into cycling, I would see cyclists and say, ‘O.K., that’s not what I perceive a cyclist to be,’ ” said Michael Berry, an exercise physiologist at Wake Forest University. Dr. Berry had been a competitive runner, and he thought good cyclists would look like good runners — rail-thin and young.

But, Dr. Berry added, “I quickly learned that when I was riding with someone with a 36-inch waist, I could be looking at the back of their waist when they rode away from me.”

He came to realize, he said, that cycling is a lot more forgiving of body type and age than running. The best cyclists going up hills are those with the best weight-to-strength ratio, which generally means being thin and strong. But heavier cyclists go faster downhill. And being light does not help much on flat roads.

But on the other hand, there are differences that make cycling a bit more forgiving:

“In running, when you see someone who is obviously overweight, they will be in trouble,” Dr. Hagberg said. “The more you weigh, the more the center of gravity moves and the more energy it costs. But in cycling, there are different aerodynamics — your center of gravity is not moving up and down.”

The difference between cycling and running is like the difference between moving forward on a pogo stick and rolling along on wheels. And that is why Robert Fitts, an exercise physiologist at Marquette University who was a competitive runner, once said good runners run so smoothly they can almost balance an apple on their heads.

Medicine Sports Medicine

One Sport, One Love (repost)

Over the past several years the concept of well rounded young athletes playing 3 sports over the course of a year has died. Most want to be specialized in one sport. Whether the sport is soccer, baseball or running, we rarely see the child athlete playing football or soccer in the fall, basketball in the winter and baseball or track in the spring.

In fact, school centered sports is no longer the norm. Travel sports rules. Year long focus on one sport is it. This has resulted in more overuse injuries than there should be. It has also resulted in more teens having the “Tommy John” elbow surgery and even for parents to seek it to see if it may make what started as a normal arm, pitch faster. Read Fit Young Pitchers See Elbow Repair as Cure-All in the New York Times for a current journalistic perspective on the surgery aspects of this. The article neglected to mention the year long focus on pitching as the root cause.

…it is becoming more commonplace among teenage pitchers who are injuring their arms through overuse at what surgeons call an alarming rate.

Some parents and young pitchers, hoping for college scholarships or multimillion-dollar professional contracts, misguidedly view the surgery as a performance-enhancement technique instead of a last-resort corrective procedure, said Matt Poe, a speed and strength coach in Nashville.

Often, pitchers who are pushed the hardest and sustain the worst overuse injuries are the most talented, doctors said. In the late 1990s, Dr. Andrews said he performed 5 to 10 Tommy John operations a year on high school pitchers. This year, he said, he may perform 75. Last month, he operated on a 14-year-old.

And for two interesting pages the article goes on.

“I don’t think there’s as deep a talent pool anymore,” Dr. Petty said, because so many kids are coming out of high school with what he called “100,000-mile arms.”

It’s not the talent pool. Pitchers have always been in short supply. High schools have made do with very few pitchers for years. But, not until recently did they only pitch for most all of the year.

Medicine Nutrition Sports Medicine

Quick Carbs: Dark Side of Fructose (repost 2007)

A variety of conflicting studies and articles are coming out regarding high glycemic foods in performance. What impact do they have and what conflicting studies show is a future topic for us. Fructose is not considered an optimal source of carbs and the sports drinks and gels you use should be examined to make sure that fructose is not high on the ingredients list.

It is lower down on the listing of ingredients in Gatorade, but it is number 2, after water on Powerade (Matrix Reloaded). Powerade is said to be the official drink of the US Olympics. Perhaps it is time to revisit that choice.

At the same time this is under discussion Abel Pharmboy at Terrasig has a fine post up entitled “The Questionable Dark Side of Fructose“. He notes that the consumption of fructose has been suggested to be one of the possible causes of obesity and metabolic syndrome. In conjunction with this he links to an article at Medscape which notes the atherogenic profile of fructose vs. glucose.