Exercise: Is Less Better Than More?

NOTE: Shou-Ching and I will be traveling in Europe next week; she’ll be speaking at this meeting and we’ll take a few days vacation. Blogging will resume on October 2 or so.

A New York Times column, “For Weight Loss, Less Exercise May Be More,” got some attention this week. It was based on a recent study of the effects of exercise on weight loss.

The Danish study [1] found that exercise is helpful for weight loss – but only the first 30 minutes of light exercise per day. Additional exercise had no effect on body weight – in fact it even seemed to diminish weight loss. Those who jogged for 60 minutes a day lost five pounds, those who jogged for 30 minutes lost seven.

The subjects wore activity tracking devices – Actigraph GT1-M devices, which are an older model of these and similar to a Fitbit – which produced a surprising result. Those who exercised 30 minutes a day were seemingly energized by their exercise, as they became more active in their daily lives – more likely to take the stairs, for instance. Those who exercised 60 minutes a day, on the other hand, seemed to be worn down by their exercise, and became less active in daily life.

It seems that 30 minutes of exercise improved health but 60 minutes of exercise may have diminished well-being. When it comes to exercise, perhaps, less is more.

A Well-Supported Result

While the Danish study [1] was novel in looking at how weight loss and non-exercise activity respond to exercise, it is not the first study to show that light activity may be healthier than intense activity.

In the new Scribner edition of our book, we greatly expand the part which discusses how to optimize immunity and heal or prevent disease. The new edition discusses exercise. We found a number of recent studies showing that light daily activity is as good or better than intense activity for health:

  • A study of American runners found that those who ran between 1 and 20 miles per week at a jogger’s pace of 10 or 11 minutes per mile reduced their risk of dying as much as those who ran more than 20 miles a week or who ran faster. [2]
  • Another Danish study reported that Danes who exercised two or three times per week for a total of one to two and a half hours reduced mortality by 44% and extended their lifespans by 6.2 years for men and 5.6 years for women. Those who exercised either more or less had less benefit. [3]
  • A study of 416,175 Taiwanese adults found that an hour and a half of moderate exercise per week (13 minutes per day) reduced mortality by 14% and extended lifespan by 3 years. An additional 15 minutes per day reduced mortality by only another 4%. Benefits peaked at 50 minutes of exercise per day. [4]

These are intriguing results. What’s more intriguing is that it doesn’t seem to matter how fit the exerciser is. People gain substantial health benefits from light exercise, even if the activity never makes them fit.

An Evolutionary Argument for Not Over-Exercising

Thanks to Stephan Guyenet, we’ve been talking a lot about the reward system of the human brain. It evolved in order to make us want to do healthy things, like braving the stings of angry bees to get honey from hives concealed high in trees.

David recently linked to an interesting post suggesting that our Paleolithic ancestors may have done a lot of honey gathering, which reminds me of this movie about the Hadza and their honey seeking:

Why did we develop an attractive taste for sugar, and why does the brain reward us for carb consumption? Presumably because the Paleolithic diet was too low in carbs for optimal health, and evolution wanted to encourage Paleolithic hunter-gatherers to gather more honey.

But, however valuable carbs are, it’s not clear that they are as valuable as the extra six years of life we obtain from light daily exercise. Yet there’s no innate reward for exercise. Many people are quite content to live their whole lives as couch potatoes.

Why didn’t evolution reward exercise, if it is as valuable as carbs? Probably because Paleolithic humans almost invariably got more exercise than they needed. Perhaps our brain evolved to prevent our ancestors from over-exercising, and now our brain unfortunately rewards us for over-resting!

Conclusion

It looks like exercise is healthful, but most or all of the benefits come from a relatively small amount – the first 30 minutes per day.

Doing the research for the new edition of our book has led me to revise my ideas of why exercise is beneficial, and how we should exercise to optimize health. In my next post, I’ll discuss why I think light exercise is most healthful, the tension between healthfulness and fitness, what I think a health-oriented exercise program should look like, and how my personal exercise activity has changed.

References

[1] Rosenkilde M et al. Body fat loss and compensatory mechanisms in response to different doses of aerobic exercise–a randomized controlled trial in overweight sedentary males. Am J Physiol Regul Integr Comp Physiol. 2012 Sep;303(6):R571-9. http://pmid.us/22855277.

[2] Gretchen Reynolds, “Moderation as the Sweet Spot for Exercise,” New York Times, June 6, 2012, http://well.blogs.nytimes.com/2012/06/06/moderation-as-the-sweet-spot-for-exercise/.

[3] European Society of Cardiology (ESC) (2012, May 3). Regular jogging shows dramatic increase in life expectancy. ScienceDaily. http://www.sciencedaily.com/releases/2012/05/120503104327.htm.

[4] Wen CP et al.  Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study. Lancet. 2011 Oct 1;378(9798):1244-53. http://pmid.us/21846575.

Leave a comment ?

59 Comments.

  1. Interesting post. I disagree, however, with your statement that there’s no innate reward for exercise. Exercise releases endorphins and other hormones, and has been found to be more effective in fighting depression than anti-depressant medicines. I think being a couch potato isn’t natural, but happens because people enjoy the quasi-meditative state of watching TV or surfing the web.

    • I guess in light of the study, it may work both ways. The body releases endorphins and gets healthier in response to moderate exercise but discourages more than that.

    • Hi David,

      Well, now that’s an interesting question. Endorphins are one of the circadian immune molecules we want to promote by exercising. Their presence reflects improved health, and cause it.

      It definitely feels better when we become healthier through exercise, and so many people learn from experience that it’s a good idea to exercise, and come to want to do it.

      But for most sedentary people, there’s no desire in advance of exercise to go do it; and there’s no great pleasure in the first day of exercise. As I understand it, it’s prospective wanting (motivating action) and concurrent liking (rewarding it) that the innate reward system of the brain generates. And those cues seem to be lacking.

      Best, Paul

    • I think that exercise is rewarding only while you’re doing it and you have enough energy. For example, I bring the kids to school every weekday on my bicycle, and it sure feels great to speed past the traffic and really pump my legs. It only takes 10-15 minutes in total though.

      However, on weekends I’m quite content to just sit and read. No yearning for a bike ride.

      Finally, doesn’t a runner high (a bunch of opiates your body releases) only happen after running quite a while, perhaps as a pain killer to soothe the apparently necessary task?

  2. Interesting. This has certainly been my experience.

    I used to go through 3-5 months bouts of over-exercising in my attempt to manage my weight. The only other time (before Paleo/PHD) that I successfully lost a substantial amount of weight was a few years ago at which time I severely restricted calories and exercised 1-2 hours most days of the week for a 2-3 month period. T’wasn’t healthy, t’was miserable, it ended quickly, and I gained all the weight back and more.

    Last fall before learning about Paleo/PHD/etc, I spent two months meticulously counting/limiting calories and doing long cardio sessions 5-6 days a week. After two months the scale hadn’t budged.

    Since starting Paleo/PHD in January I have lost 60 lbs and put on a bunch of muscle with ease. I loosely follow Mark Sisson’s fitness rx – I lift heavy things (mostly myself) once or twice a week, I do a full on sprint every week or so, and I do plenty of enjoyable walking, biking, and playing as I am able.

    I definitely prefer smart, manageable, and cheap exercise over what I used to think I needed

  3. If there is no innate reward for exercise, there is still what Nietzsche called the “will to power” which, in its purest form, impels animals to exert themselves in acts that have no survival value and to enjoy themselves.
    Perhaps we didn’t need innate rewards when exercise helped us get food, a mate, status, territory etc. Athletes and other performers still get those rewards.

  4. I suspect that in an individual that is very healthy both mentally and physically, that person enjoys a bit of exercise and as others have mentioned, exercise releases endorphins and is well known to elevate mood. It’s just that now, most of us eat toxic foods from birth (cheerios are typically a baby’s first solid food!!!) and many of us live isolated noncommunal lives far different from what we evolved for.

  5. It may be worth disentangling intensity and volume. Though you say that moderate activity may be better than intense activity, all the evidence cited apart from the words “…or who ran faster” seem to be concerned with volume. It may be that the best sort of exercise is infrequent short bursts at high intensity, rather than longer at moderate intensity.

    • Hi David,

      Yes, that’s an important point. Intensity is a totally different variable than volume and its health effects have to be studied independently.

      Yes, there does seem to be a lot of evidence in favor of HIIT. However, the ability to increase intensity is correlated with health, so we have to be careful in analyzing studies.

  6. I didn’t watch that video the first time through – really fascinating stuff!

  7. I love having you back blogging. Interesting view on the benefits of exercise. You seem to be able look at these things from a new perspective.

    A personal experience:
    The last couple of months I have been doning crossfit style exercise. Lately I have been pondering if I was generally feeling a litle bit better when I was doing more leangains style training.

    What I still really like about crossfit is the community and the focus on learning new movements and improving mobility and not only focusing on gaining muscle.

    Can’t wait for the new book!

  8. Good vacation to you two!

    Exercise: a very complex subject indeed. Based on a recent study, maybe we should not encourage sick people to exercise (at least not more than brisk walks) but try to get healthy first. I think Table 1 is visually very revealing (and disturbing):

    Adverse Metabolic Response to Regular Exercise: Is It a Rare or Common Occurrence?
    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3364277/

    • Hi Mario,

      Yes, I think exercise intensity and volume need to be scaled with health. Exercise should be refreshing, not stressful. For unhealthy people that means a brisk walk may be the most they should do.

  9. This is all very interesting and consistent with my own experience. I definitely feel that for general health and well being a moderate amount of light exercise is the best route. Looking forward to upcoming posts!

  10. Nice post as always.

    This mirrors my experience as well. If I overtrain, my body just doesn’t have time to heal and I end up very tired the rest of the day. I’ve even made myself sick with a cold doing this.

    I think the lack of motivation that occurs after overtraining is the brain’s way of telling us that our muscles need time to repair themselves. This is further compounded with age.

    I find that 24 to 36 hours between cardio and weight lifting workouts works best for me.

    Have a fun and safe trip to Europe!

  11. The issue of more v. less exercise is very provocative and very complex. Isn’t there already research that correlates an over abundance of aerobic exercise with myriad health problems including autoimmune problems?

    I don’t see mention of other forms of exercise such as resistance training or involvement in mildly competitive sports. I wonder if the improvement of one’s physique or running around playing a friendly game of soccer with friends would not provide these rewards.

    I recall while in college really always looking forward to the next intramural basketball game or long bike rides in which we spent time “racing” each other. Too much of modern exercise is of the rat-on-a-turnwheel variety. A boring hour on a stairclimber or a 7 mile jog while inhaling car exhaust are activities I would think a smart person would avoid as much as possible.

    Enjoy your vacation!

    • Hi David,

      The research on exercise is rather difficult to interpret. In general people who exercise are much healthier, but a lot of the association is because healthier people exercise, unhealthy people rest. Trials are generally too short to judge chronic disease risk. Overall I would say most people exercise too little, but of people who do exercise, a significant minority may overtrain.

      I do believe that variety in exercise is helpful. I also agree that fun is important, as is sociability.

      Thanks!

  12. Exercise — moderate at 30 minutes always worked best for me.
    I got the best mood lift and energy from strength conditioning, but I refuse to do that right now. I do walk a lot.
    As for the Hadza honey gatherers, that was an interesting video, and the photos from Tanzania on the blog were great.
    Once in a while (because it is very expensive), I buy a jar of Really Raw Honey. It’s got the wax and propolis on the top layer. Great stuff to chew and spit out, and I do understand how healthy it is, now that I’ve read your post!

  13. A sweet tooth may well have evolved to determine whether pant foods contain toxins or not. The Hadza have access to plenty of starch but dislike their sources (marlowe) both sexes prefer honey to all other foods while men prefer meat next and women berries. Hadza sources of starch are apparently quite nice according to western tastes. Wild starches in my region (NW Europe) are particularly hard to eat in quantity.
    All hunter gatherers dance and play constantly so we can easily say that while they may have to “exercise” more than they might want to they also choose to “exercise” in their free time.

  14. In your view, does this 30 minutes of exercise include walking slowly? (Should I be reconsidering my treadmill desk??)

    • Hi Charlie,

      The exercise in the studies was more intense than walking, like jogging intensity.

      I think it’s healthful to walk for several hours a day. So a treadmill desk should be fine. Stand, sit, and kneel once in a while for variety.

  15. Fitness Wayne | paleo diet and exercise blog

    I am suspicious of this. I know when I spend more time at the gym I lose weight faster. I have a hard time believing that exercising more would decrease your life expectancy.

    The headline is dangerous too. I could see overweight lazy people reading it and deciding that less exercise is better which will lead to no exercise.

    • It is a provocative title but in terms of aerobic exercise at least, there seems to be an optimum around 30 minutes a day. So if you’re doing more than that, less would be more.

  16. I’ve taken to group fitness classes because if I work out on my own I kill myself and it often takes me 4-6 days to recover. I’ve caused all sorts of fascia injuries and also made myself sick by over training. So for some of us, anyway, we aren’t naturally inclined to be lazy.

    My rule of thumb for recovery is that I should be stronger than I was before the workout before I exercise again. It’s often better to do 2-3 moderate workouts per week where I’m not very sore the next day than one hard workout where I basically can’t concentrate the next day.

    • I think the group exercise classes are a prudent move. It’s good to exercise but most days, apart from maybe a few miles of jogging, the exercise should be meditative, refreshing light activity like yoga. I think 2 hard workouts a week is close to optimal for health.

  17. It would seem our bodies are limited by our ability to produce stress hormones which require lots of energy. “Exercise” may have always been built in to our habitats. It’s my opinion that much is not needed and we should seek to surround ourselves with environments that foster creativity, challenge, and play. Modern exercise modalities can be seen as “hacks” and may only provide an hormetic stimulus at most. However, creative, challenging, and playful activities probably go much further than a typical jog or weight training session. This can be elucidated in the fact that resistance training or challenging movement stimulates growth of CNS tissue.., what gets discounted is when these types of undertakings are paired with enjoyment, adventure, or other positive abstractions. Just my rant.

  18. I think it really depends on the person and what type of condition they are in.

  19. I try to do as much low-intensity-activities like standing and walking as I can. Do you believe I have special protein needs? I am also trying to reap all the longevity benefits of a low-protein diet.

  20. Oh man! I guess my 120 minutes of running, 10 minutes of pushups, 45 minutes of bike riding, and 10 minutes of wrestling with kids each day is a little overkill? I would imagine that my 120 minutes of racquetball is totally not paleo either. And my 5 hour trail runs in the mountains every week would definitely make my ancestors cringe. Oh, and that 113 mile fastpacking adventure I had over 3 days and 3 nights this last weekend would have been unthinkable to those monkey people that we share genes with. And here I thought I was being a barbarian… I guess I am just another overstressed, overtraining, obsessive-compulsive american. Oh well.

  21. Here’s an interesting article from the link below that also discusses the point of whether more exercise is better or not.

    http://sweatscience.runnersworld.com/2012/09/is-more-exercise-always-better/

    Still, essentially, I think any exercise is better than none, but as long as you aren’t overtraining, more exercise is likely better for you in the long run – no pun intended. 😉

  22. HI Paul, been lurking for a long time and waiting for a good opportunity to ask for your thoughts on exercise, HIIT in particular:

    – Sprinting seems to have equal or greater effect on aerobic tests and biomarkers than longer sessions of aerobic training, with potentially less negative side effects.

    – Dr. Doug McGuff makes a compelling case in Body by Science that safely performed high intensity strength training may be the safest longterm exercise modality to help maintain overall health, while maintaining the primacy of diet.

    Curious to hear your thoughts, exercise could use some review of the research with the same rationality you have shown to diet.

    Many thanks!

    W

    • Paul, I too would like to know what you see in the growing body of research about HIIT. I to am a follower of a BBS ispired approach to exercise.

      What I am seeing in me and in the research:
      1. HIIT is the only form of exercise that stimulates growth and maintenance of fast twitch muscles.
      2. Steady state exercise does not stimulate fast twitch muscles, on the contrary this practice diminishes fast twitch muscles.
      3. Fast twitch muscles are the ones that help us deal with stress (fight or flight, heart attack).
      4. HIIT more accurately reflects how our ansestors used their bodies.
      5. Studies are showing that steady state exercise over time is harmful to muscles, including the heart muscle.
      6. Studies seem to be showing that in a given week a mixture of brief resistance traning along with some brief HIIT activity is generally the proper approach for most people (Even the Cooper Institute in Dallas [Dr. Cooper invented the term “aerobics,” has gone to this approach]).
      7. Much of the metabolic benefits of HIIT comes after the exercise and during time away from exercise.
      8. Probably the biggest benefit of HIIT is that it is of brief duration and overall takes little time (bang-for-the-buck).
      9. Most of the critisizm of HIIT seems to come from “runners” who are trying to justify their chosen form of exercise.

      As you have pointed out in the PHD, the problem with research is that it tends to point in all directions which requires one to have a theory or approach before diving into it. Otherwise you are digging a hole that never ends. I would like to know the following: A. what your approach is and; B. know what you see in the research generally, but more specifically regarding length of intensity part of HIIT activity followed by how much rest in between (with the understanding that we are talking about ranges and the level of conditioning).

      Hope you don’t mind me asking, even if you can’t get to this.

      Hipp

    • That’s a topic for future blog posts but basically I think HIIT is a great exercise to perform once or twice a week on intense days. I don’t think it’s good to do every day. It’s best to concentrate more work in a few hours and have a few rest days afterward.

      • For the record I do 3 HIIT sessions a week as follows:
        1. 15 min resistance session to failure following BBS style approach; followed by 14 min upper body HIIT on either Magnum upper body ergometer or heavy bag (as per Ori Hoffmeckler [sic]);
        2. 20 min lower body HIIT eg eliptical or run walk
        3. 20 bicycle HIIT
        Average Total 70 min a week
        4. Also mixed in once a month wind sprints 15 min; twice every 5 weeks distance activity eg hill climbing 2 to 3 hours or run walk 3 to 5 miles.

        • Hi Jim,

          That’s a great workout schedule if your aim is achieving a high level of fitness. But if you ever start catching mild colds, then I would consider cutting back a bit.

  23. Hi paul,
    Forgive me if this question is off topic, but my wife and i are confused. We have both read PHD and understand the concept of safe starches, and include a moderate amount of white rice in our diet. However, i am currently reading Practical Paleo by Diane Sanfilippo, and on page 76, in a discussion on leaky gut, she includes white rice in her list of food richest in antinutrients. So i am faced with the situation of two authors whom i deeply respect having diametrically opposed views on white rice. My wife and i would appreciate it very much if you could shed some light on this. My understanding was that the antinutrients are in the rice bran and therefore only a problem in brown rice, but how could someone as knowledgable as diane S be wrong about this? I told you i was confused!!

    We are really looking forward to reading the new book!
    Dan

    • Hi Dan,

      I don’t know where she got that. White rice has minimal antinutrients. Phytate is mainly in the bran in brown rice. Even if a bit got into white rice, phytate is not bad in small doses, particularly if it comes with minerals pre-attached so it’s not taking them from food.

  24. Physical Activity: Whence Its Healthfulness? | Perfect Health Diet - pingback on October 11, 2012 at 10:20 pm
  25. One of the reason why longer exercises are not necessarily better could be that the longer one exercises the more probable an injury is. And injuries affect general life expectancy. Virtually all my friends who exercise on a regular basis got injured. Even walking could be dangerous if one has some sort of misalignments. For instance, one my leg is shorter by 1 cm. I learned that just a year ago (I’m 52). Before that I happily did all kind of exercises making my body worse because is was misaligned.

  26. Hi Paul,

    Didn’t know where to leave this.
    Did you read this article in the NYTIMES and what did you think of it?
    They emphasize plant diet for longevity
    http://www.nytimes.com/2012/10/28/magazine/the-island-where-people-forget-to-die.html?pagewanted=6&ref=general&src=me&_r=0#commentsContainer

    • Hi Missbb,

      I don’t think it’s the diet. I think it’s the lifestyle: Bright sun exposure every day, physical activity in the mountain terrain, high levels of social contact during the day, quiet and dim lights at night (dominos, not television) are all strong supporters of circadian rhythms and immune function which are crucial for healthy aging. Many people on this island, including the guy who recovered from cancer, are Greek Orthodox and engage in frequent fasting, another immune and longevity booster. In general their lifestyle sounds low stress.

      I doubt the diet is all that plant based. They had a pig roast for instance, which is a lot of meat. Most Mediterranean diets have a fair amount of meat and fish.

  27. How Much Exercise Do You Need in A Day? | loseweightfasthq - pingback on November 16, 2012 at 9:39 am
  28. Here’s another good article by Alex Hutchinson challenging the recent studies finding that exercise benefits top out at moderate doses:

    http://www.runnersworld.com/health/too-much-running-myth-rises-again

    • Ok so the conclusion still stands: benefits of exercise start to plateau above 30 minutes a day, so the returns are ever diminishing.

      If you exercise more than that without paying attention to stress indicators in your body, you’re probably going to do yourself harm.

      Add to that that endurance athletes tend to eat lots of grains and then the further benefits of exercise may well be eaten up by the problems their diet causes, see e.g http://www.telegraph.co.uk/health/healthnews/9308812/Marathon-running-can-scar-the-heart-researchers-warn..html

      • With that last link I’m just saying that a substancial fraction of marathon runners are not healthy despite lots of exercise, and I’m positing the thought that it may be because of their diet. This is not mentioned in the article.

        In my naive view, bouncing around all day while eating PHD and stopping when your body says you have enough is probably mega super healthy.

        I must say I’m getting a lot of benefit from my 30 minutes a weekday vigorously cycling to the train station and back. Stamina, muscle growth+definition and happiness all increased. So n=1 the benefits are certainly there.

    • Hi Todd,

      Alex Hutchinson’s piece is good, and I also agree with Wout.

      The way I read the evidence, the health benefits plateau fairly early, so they aren’t coming primarily from fitness, but from something else, like circadian rhythm entrainment. Harms, on the other hand, are much harder to establish. Fitness is good at preventing exercise from causing harm, so a very fit runner can do a great deal of running before he is harmed, whereas a couch potato would be harmed by a much smaller volume. But people tend to not to exercise beyond their fitness, so it’s not easy to detect the harms in ordinary populations. However, in some competitive athletes, you can see heart damage or other issues, presumably because they are pushing themselves to levels of high stress.

      In general, fitness increases the range of volumes over which running is healthy; there is no one size fits all upper limit.

      My personal goal is to run 3 miles a day, do some light bodyweight exercises and/or yoga/tai chi/qi gong every day, and lift weights intensely once a week. Not sure when I’ll succeed in adopting that routine, but I think that’s a good one.

  29. Thought i would add a couple of Ray Peat quotes.
    I believe Peat was relating to endurance runners, for correct context of these excerpts.

    Source: An Interview With Dr. Raymond Peat
    http://www.thyroid-info.com/articles/ray-peat.htm
    Mary Shomon: “You feel that excessive aerobic exercise can be a cause of hypothyroidism. Can you explain this further? How much is too much?”

    Dr. Ray Peat: “I’m not sure who introduced the term “aerobic” to describe the state of anaerobic metabolism that develops during stressful exercise, but it has had many harmful repercussions. In experiments, T3 production is stopped very quickly by even “sub-aerobic” exercise, probably because of the combination of a decrease of blood glucose and an increase in free fatty acids.
    In a healthy person, rest will tend to restore the normal level of T3, but there is evidence that even very good athletes remain in a hypothyroid state even at rest.
    A chronic increase of lactic acid and cortisol indicates that something is wrong. The “slender muscles” of endurance runners are signs of a catabolic state, that has been demonstrated even in the heart muscle. A slow heart beat very strongly suggests hypothyroidism. Hypothyroid people, who are likely to produce lactic acid even at rest, are especially susceptible to the harmful effects of “aerobic” exercise.
    The good effect some people feel from exercise is probably the result of raising the body temperature; a warm bath will do the same for people with low body temperature.”

    And,
    Source: http://www.equilibrio.com.au/promomail/articles/200706/Hypothyrodism.htm
    According to Peat, exercise accelerates the breakdown of thyroid hormones, resulting in a protective slowing of metabolism. “The slow heart beat of runners is largely the result of this adaptive hypothyroidism.”

  30. something to be aware of,
    have you tested ever tested as anaemic while doing ‘excessive’ exercise?
    when i use to do chronic cardio stuff, i tested as anaemic. since stopping the chronic cardio exercise I no longer test as anaemic.
    This article may have an explanation of why Athletes, especially endurance athletes, test as anaemic (although they are not really anaemic).

    http://www.gssiweb.com/Article_Detail.aspx?articleid=276
    by E. Randy Eichner, M.D.
    Department of Medicine
    University of Oklahoma Health

    Sports Anemia (‘athlete’s anemia’, ‘athlete’s hemolysis’, ‘sports anemia’ etc):
    “Athletes, especially endurance athletes, tend to have slightly low hemoglobin levels as judged by general population norms. Because a low blood hemoglobin concentration defines anemia, this has been called sports anemia.

    But sports anemia is a misnomer because in most such athletes—especially men—the low hemoglobin level is a false anemia. The total volume of red cells in the body is normal, not low. Hemoglobin level is decreased because aerobic exercise expands the baseline plasma volume; this reduces the concentration of red cells, which contain the hemoglobin. In other words, the naturally lower hemoglobin level of an endurance athlete is a dilutional pseudoanemia.

    Pseudoanemia is an adaptation to hemoconcentration that occurs during workouts. Vigorous exercise acutely reduces plasma volume by 10-20% in three ways. One, a rise in blood pressure and muscular compression of venules boost the fluid pressure inside the capillaries of the active muscles. Two, generation of lactic acid and other metabolites in muscle increases tissue osmotic pressure. These forces drive plasma fluid, but not red cells, from blood to tissues. Three, some plasma water is lost in sweat.

    In response comes the release of renin, aldosterone, and vasopressin to conserve water and salt. Also, albumin is added to the blood (Nagashima et al., 2000). As a result, baseline plasma volume expands. Even a single bout of intense exercise can expand the plasma volume by 10% within 24 h (Gillen et al., 1991).

    So it is common for an endurance athlete to have a hemoglobin concentration 1 g/dL or even 1.5 g/dL below “normal”. Recognizing this as pseudoanemia depends on knowing the setting (aerobic training at sea level) and excluding other anemias. Plasma volume waxes and wanes quickly in concert with level of exercise, so athletes who train the most have the lowest hemoglobin levels and when daily workouts are stopped, hemoglobin level soon rises.

    Pseudoanemia is key to aerobic fitness. The rise in plasma volume—plus the adaptations of “athlete’s heart”—increases cardiac stroke volume. This more than compensates for the fall in hemoglobin concentration per unit of blood, so more oxygen is delivered to muscles. Result: A better athlete.”

  31. Very interesting and useful blog post. Thanks for sharing. This topic is apt to the latest lifestyle and must be read about. It would be great if you write more about the benefits of exercise focused for specific age-groups.

  32. Hi Paul
    Interesting article, summary here http://www.newyorker.com/reporting/2013/05/20/130520fa_fact_orlean
    by Susan Orlean in this weeks’s New Yorker about the dangers to health of more than 3 hours of sitting per day (even if one still gets some exercise…yikes!) and treadmill desks, where one walks at slow speed while working, using the computer, etc. as a solution. The nice thing is that this solution takes no time away from one’s normal daily activities..desk or computer time, although not aerobic exercise time which is still needed, no longer counts as dangerous sedentary time either. One can cobble the parts together oneself, too. Seems like an excellent idea.

    • I agree, Jack. Earlier this year a colleague purchased, for $90, a very nice wooden stand to go on top of her desk so that she can now stand at her computer. I wanted to do the same thing, but not for $90. So, toward the back of my desk, I placed a small folding stool I had at home and put the monitor on it. Then, I took three plastic paper trays and stacked them upside down and I rest my keyboard on top. It works great. The trays provide small shelves for immediate things that I don’t want to leave until the next day. This would not work for a standard keyboard that comes with the computer, but I type a TypeMatrix keyboard (with the Dvorak key arrangement) and it is small enough to just fit on the paper tray. http://www.typematrix.com/ Needed a place for my mouse, so to the right of the stack of paper trays I stacked the Robber Knights box on top of the Killer Bunnies box and the mouse height is now perfect. Love, love, love not having to sit so much and not having to drop $90 for the modification. Within a few weeks, I did notice a small divot on the front of my thigh and realized that I had taken to leaning on the edge of my desk. Very soon after getting comfortable with my new arrangement, I caught this article of Chris Kresser’s: http://chriskresser.com/how-to-walk-10000-steps-a-day-if-youre-a-desk-jockey
      So, now I’m on the hunt for ways to bargain basement this arrangement.
      Anyone curious about typing Dvorak or Colemak might want to look into it. On my Dvorak I can type 5000 words on my home row. If you’re using a qwerty, you can type only 150 words on your home row. Much improvement in my repetitive stress pain a dozen years ago when I switched. Took me a summer. Not hard at all. An experience of “strangeness” for my brain. 😎

  33. The Massive Benefits of Daily Cardio | Michael Cocchiola - pingback on July 12, 2015 at 6:00 pm
  34. hi paul. i would like you to try and watch some videos of Scott Sonnen, Ido Portal, Alvaro Romano, MovNat, Emilio Troiano etc. its an area broadly called Movement, as far as I can tell. Its mostly dynamic work on the floor without any equipment. It looks like a child playing around! It covers resistance, flexibility, and what I would call functional integration. It is developing and has many aspects/versions. Many of the UFC fighters are using it for warmup, explosiveness, nervous system, and recovery. Listen to Ido Portal philosophising about what he does – quite interesting 🙂 – YouTube: “THE MOVEMENT! Ido Portal”

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