Category Archives: exercise

Hiking: Eccentric Exercise That's Not That Crazy.

Eccentric Exercise is a hot research topic among exercise physiologists.   Most research has focused on concentric exercise.  As often happens, the eccentric is readily overlooked.  Concentric exercise is exercise that involves muscle fiber shortening.  During eccentric exercise muscles are lengthening under stress.   Hiking is great exercise in part because it involves many different types of stresses.  If you are in mountainous terrain it includes both concentric and eccentric exercise.   Hiking (or running) uphill is concentric exercise, while moving downhill is eccentric.Uphill tends to burn more calories than downhill, but it looks like downhill hiking provides special benefits on its own.

Hiking Eccentric Exercise
A Hiker Prepares Mentally for a bout of Eccentric Exercise

Testing Up Hill (Concentric) and Down Hill (Eccentric Exercise) Hiking.

Researchers in Austria and Lichtenstein have been looking at the benefits of hiking down hill.   The study group has also been looking at ways for people to exercise more easily when they either do not have time or are just not interested in doing it.  The studies used two groups of people.  One group hiked only uphill, and the other hiked only down hill.  Hiking only uphill or only downhill may be problematic for most people.  For the study, a cable car was used to transport hikers in the up group down.  And the down group up.  Blood samples were collected before the start of the hiking procedure and afterward.  Hikers hiked in one direction for two months and then switched to the other directions.

 

Hiking results and findings.

hiking uphill concentric exercise
A hiker rests above 15,000 feet after a little too much concentric exercise and not enough oxygen

Hiking uphill and downhill both improved blood measures of total cholesterol, low-density lippoprotein cholesterole (LDL), apolipproteinB/A1 ratios (by about 11%), insulin resistance and reduced levels of C-reactive protein by ~30%.  Hiking uphill burns more energy.  Hiking uphill requires about 4x as much energy as hiking downhill.

Still, it is nice to know that walking downhill is so healthy.  I find down-hill hiking stresses my knees and toes.  However if you are one of those people who enjoys the downhills don’t worry too much if you hitch rides on cable cars.  Or mules.  Or whatever else is available.  Perhaps this research will result in the development of a new type of fitness equipment: A Stair Descender.

Eccentric exercise is the type of exercise stressor that leads to muscle soreness.  And delayed-onset muscle soreness (DOMS).  But there is increasing evidence that eccentric exercise is more effective for improving muscle strength.

 

If you are looking for traditional hiking or eccentric exercise options and ideas take a look at:

Zeppetzauer M, Drexel H, Vonbank A, Rein P, Aczel S, & Saely CH (2013). Eccentric endurance exercise economically improves metabolic and inflammatory risk factors. European journal of preventive cardiology, 20 (4), 577-84 PMID: 22505055
Drexel H, Saely CH, Langer P, Loruenser G, Marte T, Risch L, Hoefle G, & Aczel S (2008). Metabolic and anti-inflammatory benefits of eccentric endurance exercise – a pilot study. European journal of clinical investigation, 38 (4), 218-26 PMID: 18339002

Exercise and Weight and Gut Microbiota

Exercise and Weight.

Crossfit womens shirt model at Crossfit Seven in Fort Worth
Our crossfit women prefer to lift in WODMASTERS shirts. Designed to protect the sternum from bar abrasions while looking cool and beautiful.

Exercise and weight are closely related. We all know that exercise burns calories and helps maintain body weight. Exercise has a lot of other health benefits. And maintaining a healthy body weight is important too. But ever wonder how gut microbes, exercise and weight interact? If you are like most people you will be thinking about such things as you wander the grocery store aisles, forgetting why you are there in the first place. Or you may wonder about how physical activity changes gene expression. Or how inactivity changes gene expression. You may wonder, as you pass the yogurt section, “what is with this probiotic stuff?” We’ll talk about probiotics another time.

Exercise weight and bacteria.

Exercise and weight are inter-related. But it looks like there is another player involved. (At least one and probably many.) It looks like exercise has influence over the bacteria that live in your digestive tract. Most of us have been taught that bacteria are bad. But they are not all bad. We need some species to help us digest food, access vitamins, stay healthy and defend us against evil germs. New research shows that the kinds of bacteria in the digestive tract differ depending on level of physical activity.  The study was of mice. Mice may have been chosen for the project because it is more agreeable to pick up their poop and analyze it.  You can scoop them into a flour sifter to remove the litter.  And because you can easily control their diets. And keep them in cages with few complaints.

The researchers wanted to know how exercise, obesity, diabetes and gut microbes interact. The mice were placed in a cage with an exercise wheel. OR placed in a cage with an exercise wheel that didn’t work. After five weeks of exercising or not exercising animals were dosed with a common environmental contaminant. The chemical (PCBs) are known to impair glucose handling. They may also increase risk of diabetes. And a lot of other health problems. After dosing doots were collected. Little rodent poops are often called “doots” by the research community.

Mice who exercised had different kinds of bacteria in their doots. Bacteria from the digestive tracts of sedentary mice had a dramatic loss of proteobacteria and a hugely dramatic loss of Erysipelotrichaceae. The guts of exercising mice had many different kinds of bacteria.

What does this mean for us humans?

This research fits a piece into a larger puzzle. How are exercise and weight and bacteria related? People who are overweight have different gut bacteria profiles. The profiles change when a person loses weight. There are still many other puzzle pieces to fit And many that are missing. But it looks more and more that we need to move to keep our bodies running the way they should. And that things may go badly if we don’t.

Choi JJ, Eum SY, Rampersaud E, Daunert S, Abreu MT, & Toborek M (2013). Exercise Attenuates PCB-Induced Changes in the Mouse Gut Microbiome. Environmental health perspectives, 121 (6), 725-30 PMID: 23632211

CrossFit Training: How fitness protects from chronic disease

CrossFit Training and recent research on links between adaptation to fitness and increased levels of anti-oxidants. Anti-oxidants lower risk of cancer, diabetes and heart disease.There are many benefits in maintaining fitness.  Regular exercise reduces risk of cancer, diabetes and heart disease.  While the association of exercise and disease prevention has been strong, understanding why has been unclear.  But this is changing.

CrossFit Training, Anti-oxidants, free-radicals and fitness.

Uncontrolled free-radicals are major factors in the development of serious diseases.  Diabetes, cancer and cardiovascular disease are all conditions where free-radicals are thought to play major roles.  Free radicals are molecules or atoms that have lost an electron.  These pose problems because they are very reactive and will grab electrons from other molecules.  Free radicals can also interact with other molecules, stress cells and throw wrenches in the works.  This includes wrench throwing into your DNA.    Damaged DNA that is not repaired can result in cancer.  Or birth defects.  Free radicals also  damage tissues and organs by damaging large numbers of cells. They can damage pancreatic beta cells and increase risk of type 2 diabetes.

CrossFit Training and How fitness protects from cancer, heart disease, diabetes.

Of CrossFit Training and General Health.  Anti-oxidants protect us from free-radicals by neutralizing them.  Having enough anti-oxidants reduces risk of diabetes, cancer, or heart disease.  Exercise causes a number of changes beyond weight loss and fitness.  And these changes play into the free-radical games.   These changes are adaptions to the increased stress of exercise.  When people are first getting in shape there is an increase in free-radical production.  And a temporary increase in physical stress.   As a result, your body suffers inflammation, along with aches and pains. This is very much like what happens when you get sick with a fever.  This may be a good part of why getting in shape sucks so much.   When you are getting in shape (or trying to push yourself to a higher level) your body will produce more free-radicals, including more reactive oxygen species, until it adapts to your new level of activity.  Part of that adaptation includes increasing production of its own anti-oxidants.  Once you have adapted you will be producing enough anti-oxidants to protect against other sources of free-radicals.

CrossFit Training, Endurance or Weight Training?

What is CrossFit looking like in terms of increasing anti-oxidants?  Is Endurance Training best?  Or Resistance Training?  So far animal testing indicates that endurance exercise works best for protection against inflammation and production of anti-oxidants (Oliveira et al. 2012).  The animals in the study were subjected to endurance training, resistance training or combination training.   Hopefully more work will be done in this area and we will get a better picture of what is optimal for humans.  Weight training (resistance exercise) remains important.  And CrossFit exercises (and high intensity interval training) show very promising results on other aspects of health and fitness.  It seems likely that adaptation to these forms of exercise (i.e. CrossFit) will produce similar results to endurance training.

 

de Lemos ET, Oliveira J, Pinheiro JP, & Reis F (2012). Regular physical exercise as a strategy to improve antioxidant and anti-inflammatory status: benefits in type 2 diabetes mellitus. Oxidative medicine and cellular longevity, 2012 PMID: 22928086

de Oliveira VN, Bessa A, Jorge ML, Oliveira RJ, de Mello MT, De Agostini GG, Jorge PT, & Espindola FS (2012). The effect of different training programs on antioxidant status, oxidative stress, and metabolic control in type 2 diabetes. Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme, 37 (2), 334-44 PMID: 22458821

Crossfit High Intensity Interval Workouts

Crossfit – High Intensity Interval Training workouts.

crossfit men discuss womens resistence training
Two ugly crossfit men talk about crossfit, high intensity interval training workouts and WODMASTERS WORKOUT SHIRTS.  Why aren’t they weraing them now?  Get to the shop guys.

Endurance exercise is recommended for cardiovascular health.  Years of research have found that about 30 minutes of cardio will reduce risk of stroke and heart attack.  It will also improve insulin sensitivity, reduce risk of diabetes and improve memory and brain function.  Until very recently, there has been little research on the benefits of CrossFit type exercise on health.  These studies focus on High Intensity Interval Training.  High Intensity Interval Training workouts consist of multiple sets of intense exercise that last 1-4 minutes.  These are spaced with short rest periods.  Or periods of light exercise.

High Intensity Interval Training Workouts with gas mark.
There are so many ways to make life harder. High Intensity Interval Training Workouts can make you hurt faster

Research on this approach to exercise indicates that this approach may number of ways.  These include cardio and respiratory fitness.  And also insulin sensitivity and arterial stiffness.  Arterial stiffness is an indicator for risk of cardiovascular disease.  It is also looking like High Intensity Interval Training may be better at controlling or preventing high blood pressure than the traditional 30 minutes of sustained cardio.

CrossFit Training vs. Running?

The question of is CrossFit better than running is not known yet.  And CrossFit is different than the types of High Intensity Interval Training being tested.  In a nutshell, CrossFit is a fitness program that involves high intensity exercise.  Many different muscle groups are targeted in a CrossFit workout (also known as a CrossFit WOD.)  Workouts may last 5-20 minutes and involve springs, weight lifting, pull-ups and other bodyweight exercises.  If you are wondering “what is CrossFit” try this link. CrossFit exercises may or may not include periods of rest between sets.  However, there is a lot of shifting of focus.  Intensity may be sustained, but not sustained on the same muscle groups.  This might be better for vascular health.

CrossFit High Intensity Interval Training.

crossfit shirt rhino crossfit masters
Stiff, Inflexible, Invincible WODMasters shirt for the Masters CrossFit Athlete. And for other people who may also be stiff and inflexible.

Short periods of high intensity interval training type exercise improve capillary growth.  This allows for greater blood flow to tissues.  Including muscle.   It is possible that intense exercise impacting multiple muscle groups would be better than exercise that impacts only legs (as in running). This is an exciting area of research.  It will be interesting to see what comes up next.  Hopefully more research will be done soon that will look at whether or not CrossFit or High Intensity Interval Training does as well with brain health and control of diabetes.  For a look at recent papers take a look at:

Cocks, M., Shaw, C., Shepherd, S., Fisher, J., Ranasinghe, A., Barker, T., Tipton, K., & Wagenmakers, A. (2012). Sprint interval and endurance training are equally effective in increasing muscle microvascular density and eNOS content in sedentary males The Journal of Physiology, 591 (3), 641-656 DOI: 10.1113/jphysiol.2012.239566

Spence AL, Carter HH, Naylor LH, & Green D (2013). A prospective randomised longitudinal study involving 6-months of endurance or resistance exercise on conduit artery adaptation in humans. The Journal of physiology PMID: 23247114

Folate, Cardiovascular disease, migraine, depression and MTHFRs

What is a MTHFR?

MTHFR is a gene.  It is a section of DNA that is responsible for producing an important enzyme.  Enzymes are proteins that drive many biochemical reactions.  Enzyme function is essential for your function as a living entity.  MTHFR is also pronounced (Mother @#$!% by graduate students.  And by younger faculty when they think tenured faculty are not listening.)    The enzyme is called Methylenetetrahydrofolate reductase.  It is key to converting folate (Vitamin B9) to a form that the body can use.

If you had no methylenetetrahydrofolate reductase you would be screwed.  Fortunately this is extremely rare.  Possibly because few would survive long enough to be born.  However, life being complicated . . . there are several different forms of the MTHFR gene.  The different forms produce slightly different kinds of enzyme.  The “normal” form is found in most people.  About 70% of the general population. The other 30% have mutations. Chances are high that someone you know is a mutant.  You may be a mutant too.   And there are different kinds of mutants.  “Normal” has two copies of the gene that makes high function enzyme.  Someone could have one normal and one mutant.  This person would make less high functioning enzyme.  But more than someone with two mutant copies.  About 10% of the population is thought to have two mutant copies.  There are also different types of mutations.  So there is probably a range going on here.  In terms of how much methylenetetrahydrofolate reductase is circulating in people.

What does it mean health-wise for MTHFR mutants?

MTHFR mutants can’t convert folate to its useable form as well as MTHFR normals.  They are more likely to be folate-deficient.  This can lead to greater risk of some birth defects.  For example: spina bifida and anencephaly. (not having a brain).  Mutants are much more likely to get migraine headaches.  The kind of headache with aura.  They are also more likely to get cardiovascular disease.  Even if they do everything else right.  Other bad things are:

  • More severe forms of schizophrenia (not all MTHFR mutants have this! Or so says a very reliable voice)
  • More likely to suffer from depression
  • Greater risk of high blood pressure
  • Greater risk of pre-eclampsia
  • Greater risk of some cancers
  • Greater risk of birth defects including heart defects and spina bifida

Some good things about being a MTHR mutant are:

  • Less risk of colon cancer
  • Less risk of leukemia

What are the chances that I am a MTHFR mutant?

A lot of research is still being done.  So far it looks like there are 24 different polymorphisms.   So far it looks like people of Mediterranean descent and Hispanics are more likely to have a MTHFR mutation.  General Caucasions are next.  MTHFR mutations seem to be least frequent in people of African ancestry.  See this article (page 12 for a chart).  If you look at the chart you will see that MTHFR mutations are not uncommon at all.  So don’t feel bad if you are one.  You will need to be more careful about heart disease.  If you are a young woman of childbearing age you should make sure your diet contains enough folate.  If you are low in folate AND a MTHFR mutant you may be more likely to have health problems.

Is there anything I can do about my mutation (Does CrossFit fix mutations)?

Possibly yes.  Methylenetetrahydrofolate reductase is only one step in the conversion of folate to its useable form.  There are now folate supplements you can take in which the folate is already partly converted.  These are available by prescription.  Some people are taking them to help combat depression.  It will be interesting to see if such supplements will also control migraine headaches.  And cardiovascular disease.  And birth defects.  Very exciting. Oh.  CrossFit will not help with this.

What about diet? Are people on the Paleo diet protected?

People who have the MTHFR mutation may need more folate than others.  Regardless of what diet they follow.  Increasing folate intake may protect them from heart disease.  And other problems.  Beans and whole grains are major sources of folate.  Fruit, vegetables and liver are good sources too.  People who drink alcohol regularly will need more folate than others.  So will young women.  People who follow the Paleo diet (or Paleolithic diet) may also have low folate intake. That is because the paleo diet excludes grains and beans.  High vegetable intake should help.   The paleo diet is popular with CrossFit athletes.

Here are a few citations. For more check pubmed.

Liu A, Menon S, Colson NJ, Quinlan S, Cox H, Peterson M, Tiang T, Haupt LM, Lea RA, & Griffiths LR (2010). Analysis of the MTHFR C677T variant with migraine phenotypes. BMC research notes, 3 PMID: 20663228

Gong D, Gu H, Zhang Y, Gong J, Nie Y, Wang J, Zhang H, Liu R, Hu S, & Zhang H (2012). Methylenetetrahydrofolate reductase C677T and reduced folate carrier 80 GA polymorphisms are associated with an increased risk of conotruncal heart defects. Clinical chemistry and laboratory medicine : CCLM / FESCC, 50 (8), 1455-61 PMID: 22868813

Khandanpour N, Willis G, Meyer FJ, Armon MP, Loke YK, Wright AJ, Finglas PM, & Jennings BA (2009). Peripheral arterial disease and methylenetetrahydrofolate reductase (MTHFR) C677T mutations: A case-control study and meta-analysis. Journal of vascular surgery, 49 (3), 711-8 PMID: 19157768

Women should train for pull-ups for more than three months".

A recent New York Times blog post was entitled “why women can’t do pullups.”  Another news article states “even fit women can’t do pull-ups“.  These are interesting headlines, especially to women who can do pullups. The headlines refer to a study at the University of Dayton (can’t find the study itself, sorry) that attempted to train women to do pull-ups over a short period of time.

Women and girls work on pull-ups at CrossFit Seven in Fort Worth, TX.

Yes, women and girls can do pull-ups.  The study mentioned in the Times only looked at women who could not do pull-ups to begin with, and then only trained them for three months.  Three months may not be a long enough training period. Hanging by your fingers and pulling your entire body weight up is not an everyday activity for most people.  It is not only muscles that would need conditioning, but tendons too.  And possibly the neural circuits that would be able to figure out “yes, I can do this action without tearing myself.” and allow the action to proceed.

“Women can’t do pull-ups” vs. “Women should train for pull-ups for more than three months.”

 

Even so, nearly 25% of the women who completed the training were able to do at least one pull-up after three months.  I wish the headline had read “Most women should train for pull-ups for more than three months.”  For me, my ability to hold onto the bar seems to be the limiting factor.  I tend to drop off after 20 or so even though I’m not fatigued muscle-wise.   If you are working on pull-ups keep at it and don’t let words like “women can’t do pull-ups” discourage you.   The most important factor in pull-ups may be lean body mass (Johnson et al. 2009.)  Not gender. Not body fat (although this will matter too.) Women will have less lean body mass (for the most part) than men.  And that takes time and effort to build.  Especially for women. But this doesn’t mean you can’t work up to it.
Be stubborn.  That goes for men too.

As far as the researchers who did the study are concerned, please note that research is often grabbed and misrepresented by well-meaning journalists.  We are glad they are studying women and fitness.  Hope to hear more from them in the future.  If only the headlines had read “many women cannot do pull-ups after training for 12 weeks at the University of Dayton” instead of “women can’t do pull-ups.”

A very tall husband-wife team bend their knees to avoid hitting the ground while doing pull-ups.

Johnson D, Lynch J, Nash K, Cygan J, & Mayhew JL (2009). Relationship of lat-pull repetitions and pull-ups to maximal lat-pull and pull-up strength in men and women. Journal of strength and conditioning research / National Strength & Conditioning Association, 23 (3), 1022-8 PMID: 19387371

Shop Now Rogue Fitness

CrossFit training: Heat dissipation is key to athletic performance

Eye Pood Kettlebell Crossfit shirt
Low T? Feeling awesome increases Testosterone. Wear WODMASTERS and feel it rise.

Work on the effects of heat on athletic performance continues (see earlier post “What are we fighting when we try to push through a challenging workout” for in depth discussion). This is an important area of research for most of us because heat may be the limiting factor in performance. You body will try its best to make you stop exercising when your brain temperature reaches a certain level. Muscle cells will also start to function poorly when they are heat stressed. This is due, in part of in whole, to the sensitivity of enzymes which tend to require a pretty narrow temperature range in order to work. Exercise can raise muscle temperature above this range causing enzyme function to drop and muscle cell resources to plummet. Cooling to normal temperature will allow enzymes to return to optimal function and will allow you to resume activity faster.

Cooling speeds recovery “better than steroids.”  At CrossFit Seven in Fort Worth, TX.

Many animals, including humans, have heat transfer mechanisms. Excess body heat can be directed outwards by directing blood flow to the surface of highly perfused regions. Dog tongues are examples here, as are the ears of jack rabbits. In people facial tissue and tissue in the palms of the hands and soles of the feet serve as heat dissipators. This is probably why some people get so red in the face during runs and workouts. It may also be why some people swear by barefoot running. They may enjoy the feel of it, but they may just plain be able to go longer, harder and faster because their feet are uninsulated by thick layers of synthetic cushioning.

Researchers at Stanford University are working on a glove (not a pair of gloves; apparently one works just fine) that is effective at rapid cooling. It involves circulating cool water around the hand while applying gentle suction. It looks a lot like having a hand encased in an ironing board: not quite ready for in-play use. Let us know you devise something lower tech and tell us how it worked for you.

Grahn DA, Cao VH, & Heller HC (2005). Heat extraction through the palm of one hand improves aerobic exercise endurance in a hot environment. Journal of applied physiology (Bethesda, Md. : 1985), 99 (3), 972-8 PMID: 15879169

Research Shows CrossFit Diet/Exercise Reduces Risk of Heart Disease." Cool.

“Research Shows CrossFit Diet/Exercise Reduces Risk of Heart Disease”.  An article in Google News had this headline. Could that be true? Probably. A diet low in refined carbohydrates and high in vegetables and fruit, as well as an active lifestyle has long been associated with reduced risk of death and disease. However, no scientific research as been published on relationships between CrossFit training and cardiovascular disease. If one were to do a search today on Web of Knowledge using the search term “Crossfit” you would get a single hit:

Jansen, J., van Dam, N., Hoefsloot, H., & Smilde, A. (2009). Crossfit analysis: a novel method to characterize the dynamics of induced plant responses BMC Bioinformatics, 10 (1) DOI: 10.1186/1471-2105-10-425.

Summer Rogers of CrossFit Seven in Fort Worth is encouraged by a Master CrossFit-ter

I’m sure the intentions of whoever wrote the article (which turned out to be a press release by a box in California. Not sure why they paid to do this but to each his/her own) were good . . . but . . . their interpretation of the research is quite a stretch. Stretching and far-fetchedness probably hurt the cause as much as they help. Still, interesting that it made it into Google News. The research the author discusses has nothing to do with CrossFit. The press release does, however, attempt to associate a high-fat diet with lower incidence of cardiovascular disease by comparing incidence of disease between residents of Switzerland and Australian aboriginals living in modern Australia.

The claim was that a high-fat dining Swiss have less cardiovascular disease than the presumed low-fat dining Australian Aboriginals and that, therefore, high-fat diets are healthier than low-fat diets. There are also obviously many other differences between the Swiss and the Aboriginals (differences in poverty levels, availability of lederhosen and differences in other possibly important variables like intake of strong coffee and chocolate).

I have not looked up the statistics for the Swiss, but Australian Aboriginals have been suffering increasing rates of cardiovascular disease over at least the last 30 years. They are also suffering from increasing obesity and diabetes just like so much of the rest of the world. However, few modern Aboriginals are likely to be following a traditional Aboriginal diet. It is extremely unlikely that the increasing rate of heart disease observed in Australian Aboriginals has been caused by low intake of dietary fat. The increased incidence of cardiovascular disease in Aboriginals may be due to genetic vulnerability and a change to a Western-type diet but extremely unlikely to be caused by a low-fat diet (especially since they are not eating this way anymore anyway).   An Australian aboriginal is still less likely to die from heart disease than an Australian of European ancestry, but that may be in part because Aboriginals are more likely to fall to a violent or accidental death.

The Press release did not provide a reference.  I think this is the original article but I’m not sure.  In any case it has some very interesting things to say if you are interested in learning more about relationships between cholesterol and risk of cardiovascular disease.

Rowley K, Walker KZ, Cohen J, Jenkins AJ, O’Neal D, Su Q, Best JD, & O’Dea K (2003). Inflammation and vascular endothelial activation in an Aboriginal population: relationships to coronary disease risk factors and nutritional markers. The Medical journal of Australia, 178 (10), 495-500 PMID: 12741936

O’Dea K (1991). Westernisation, insulin resistance and diabetes in Australian aborigines. The Medical journal of Australia, 155 (4), 258-64 PMID: 1875844 Petursson H, Sigurdsson JA, Bengtsson C, Nilsen TI, & Getz L (2012). Is the use of cholesterol in mortality risk algorithms in clinical guidelines valid? Ten years prospective data from the Norwegian HUNT 2 study. Journal of evaluation in clinical practice, 18 (4), 927-928 PMID: 22639974

 

The very basics of Insulin: what Masters Crossfit and people in general should know.

This post is in response to stuff we overhear, or see repeated on CrossFit affiliate websites, or are told by well-meaning individuals:  The message we keep encountering is that insulin is bad.  A quote that seems to have been copied and pasted to a number of different sites is “insulin makes people sedentary” and it has been attributed to Dr. Robert Lustig.  If he wrote this, it was probably taken out of context and then confused.  That sort of thing happens all the time.  Or there might have been a typo at some point.  (The statement does bring up some thoughts as to how you could test to see if insulin makes people sedentary.  Inject them and see if they decided they’d rather stay home and watch TV or go for a walk?  You might cause their blood sugar to plunge, which might pull the floor out from under them and send them into a coma, but that’s not the same thing as becoming sedentary.  At least not in the context of exercise and fitness.)
Future CrossFit Dude and EMT with his Dad.

Insulin gets sugar out of your blood stream, and keeps it from damaging your blood vessels.  This is important.  If your fat cells are full, or otherwise stressed, they may stop responding to insulin.  They are protecting themselves (Hoehn et al. 2009) possibly at the expense of other types of cells.  The result is that sugar stays in your blood stream. This is what is bad, especially since this can easily become a chronic condition.

Insulin is part of a system that keeps your blood sugar stable.  You want just enough.  Not too much sugar which will cause damage.  Not so little sugar that there will not be enough energy available to keep you walking around.  You need the entire system to function well.  Its system health that matters. Trying to stop one part from doing its job is not going to help.  What you can do to help your body regulate itself, and keep things from spiraling out of control, is to eat well, keep stress at manageable levels, and exercise.   Avoid long periods of sitting too.  You can be a high performer at the gym, but its hard to be active all day long if you have a desk job.  Get up and move around a little, especially after meals (Dunstan et al. 2012).  Even this little bit of effort will help lower blood glucose after a meal, and reduce your body’s need to put out more insulin response (at least in Masters).  You will be keeping your body from having to deal with chronic overloads, which will wear it out (Ceriello et al. 2008), and allow it to keep running the system efficiently.  Again, its the system that matters, not insulin by itself.

Ceriello, A., Esposito, K., Piconi, L., Ihnat, M., Thorpe, J., Testa, R., Boemi, M., & Giugliano, D. (2008). Oscillating Glucose Is More Deleterious to Endothelial Function and Oxidative Stress Than Mean Glucose in Normal and Type 2 Diabetic Patients Diabetes, 57 (5), 1349-1354 DOI: 10.2337/db08-0063

Dunstan, D., Kingwell, B., Larsen, R., Healy, G., Cerin, E., Hamilton, M., Shaw, J., Bertovic, D., Zimmet, P., Salmon, J., & Owen, N. (2012). Breaking Up Prolonged Sitting Reduces Postprandial Glucose and Insulin Responses Diabetes Care, 35 (5), 976-983 DOI: 10.2337/dc11-1931  

Hoehn KL, Salmon AB, Hohnen-Behrens C, Turner N, Hoy AJ, Maghzal GJ, Stocker R, Van Remmen H, Kraegen EW, Cooney GJ, Richardson AR, & James DE (2009). Insulin resistance is a cellular antioxidant defense mechanism. Proceedings of the National Academy of Sciences of the United States of America, 106 (42), 17787-92 PMID: 19805130 ResearchBlogging.org