A Case Against Cardio

UpEarly

You know... I don't think he really makes a case against cardio. At the bottom of the article he recommends plenty of low-level cardio with some sprints added in for good measure.

"Knowing what we know about our hunter-gatherer ancestors and the DNA blueprint, we would ideally devise an aerobics plan that would have us walking or hiking several hours a day to maximize our true fat-burning systems and then doing intermittent “life or death” sprints every few days to generate those growth spurts that create stronger, leaner muscle."

Essentially... that pretty much sums up my workout. I hike 4-6 days a week, usually for 70-100 minutes at a time. (occasionally much longer when I can fit it into my busy schedule) Sometimes I get my heart rate way up there for short intervals when I'm climbing an especially steep hill. Sometimes I do this hiking with 20-40 pounds of weight strapped to my back. It's been great conditioning for me. I've lost weight easily, eating 2000 or more calories a day.

I don't personally follow Mark's primal eating plan. It's just not for me. But I do exercise in a manner similar to what he's recommending, and have had great success with it.

UpEarly

Depends on the goal. And don't forget to factor in enjoyment. The best exercise is the type you enjoy.

THIS! Right on! :-)

MikeSEA

I don't know if this is too tangential a question or not, but doesn't it seem like the terms "cardio" and "strength training" are a little inadequate. Maybe they're not.

I ask because I do strength training 3/week, and "cardio" 3/day alternating. My question is really, what constitutes "cardio?" I can only assume on the most basic level it means you're getting your heart rate up, but if we're talking something that gets my heart rate up higher than me sitting or even walking slowly, that leaves a lot room. My cardio days usually involve an hour of me on the elliptical doing fairly low intensity intervals. My heart never really gets up to the more intense cardio zone, but it's usually just out of range of the fat burning zone.

Short story long, I guess my point is that i kind of wish we would speak about topics in specific terms. Instead of generalizing cardio workouts, or even low vs high intensity, it would be nice if ranges were given. Maybe all of that is common knowledge and I just don't have it.

On that point, if anyone knows of a convenient portal for authoritative sources on this topic, please share .

questionablemethods

I think Mark's blog posts are very good at what they are designed for -- getting people on board with a way of living that doesn't revolve around beating yourself up training for marathons if you hate it because you think that is the only way to be healthy. And, of course, creating his brand.

I tend to like what he has to say, but I fully admit that is because it completely jives with how I already LIKE to be active. I don't like running long distances, I hate the elliptical (or the gym, for that matter). I do like walking, so I tend to walk about 15 miles a week (more when I was commuting on foot to work). I like bodyweight exercises and I like doing short, all out sprints, now and then. Well, hot damn! That's exactly what Mark Sisson lays out!

I don't think that it is the only way. I think that people will be far more successful doing whatever it is that they ENJOY doing and will do consistently for the rest of their lives. Period. For me, it is probably not going to be training for long endurance races.

As someone who also likes the science-y side of things, I do think his articles are pretty lacking in citing actual sources (or acknowledging nuances). But I don't think his target audience is made up primarily of researchers, either.

bcattoes

I don't know if this is too tangential a question or not, but doesn't it seem like the terms "cardio" and "strength training" are a little inadequate. Maybe they're not.

I ask because I do strength training 3/week, and "cardio" 3/day alternating. My question is really, what constitutes "cardio?" I can only assume on the most basic level it means you're getting your heart rate up, but if we're talking something that gets my heart rate up higher than me sitting or even walking slowly, that leaves a lot room. My cardio days usually involve an hour of me on the elliptical doing fairly low intensity intervals. My heart never really gets up to the more intense cardio zone, but it's usually just out of range of the fat burning zone.

Short story long, I guess my point is that i kind of wish we would speak about topics in specific terms. Instead of generalizing cardio workouts, or even low vs high intensity, it would be nice if ranges were given. Maybe all of that is common knowledge and I just don't have it.

On that point, if anyone knows of a convenient portal for authoritative sources on this topic, please share .

I don't know about the blog that was referenced, but generally "cardio" refers to aerobic exercise. Here is a description of what aerobic exercise:

http://www.mayoclinic.com/health/aerobic-exercise/EP00002
During aerobic activity, you repeatedly move large muscles in your arms, legs and hips. You'll notice your body's responses quickly.

You'll breathe faster and more deeply. This maximizes the amount of oxygen in your blood. Your heart will beat faster, which increases blood flow to your muscles and back to your lungs. Your small blood vessels (capillaries) will widen to deliver more oxygen to your muscles and carry away waste products, such as carbon dioxide and lactic acid. Your body will even release endorphins, natural painkillers that promote an increased sense of well-being.

questionablemethods

I hope this isn't too off topic, but in trying to add to the discussion I thought I would link to this post: http://www.archevore.com/panu-weblog/2009/11/1/cardio-causes-heart-disease.html

Yeah, it is still by someone who might be under the broad "paleo" umbrella, but it is looking at some specific research and is written by a radiologist. I'm interested in hearing what others have to say.

He wrote a follow-up, too: http://www.archevore.com/panu-weblog/2010/3/21/still-not-born-to-run.html

bcattoes

I hope this isn't too off topic, but in trying to add to the discussion I thought I would link to this post: http://www.archevore.com/panu-weblog/2009/11/1/cardio-causes-heart-disease.html

Yeah, it is still by someone who might be under the broad "paleo" umbrella, but it is looking at some specific research and is written by a radiologist. I'm interested in hearing what others have to say.

He wrote a follow-up, too: http://www.archevore.com/panu-weblog/2010/3/21/still-not-born-to-run.html

I will try to read all of that later, but the thing that turns me off of most paleo writers I've read (and I have not read a lot) is the sarcastic tone, which this article also has. Hopefully when I read the whole article there will be explanation of why marathon runners were chosen for the "cardio" group, when current medical recommendations are for much less aerobic exercise for maximum heart health. Marathon runners often go beyond aerobic levels into anaerobic levels, so it seems an odd choice for the study. Why not use people that do the medically recommended levels of aerobic activity? I also wonder (okay, doubt) that anyone thinks aerobic activity makes them immortal (there's that sarcastick tone I mentioned).

questionablemethods

I will try to read all of that later, but the thing that turns me off of most paleo writers I've read (and I have not read a lot) is the sarcastic tone, which this article also has.

I think Kurt Harris is pretty even-handed in general. He dips into sarcasm once in awhile, but he's not writing a scientific article, he's writing to a blog audience. I could point you to hundreds of non-"paleo" writers with equal amounts of sarcasm (often while lampooning the "caveman diet.") Many of them are also parroting conventional wisdom, without a hint of scientific references anywhere. So, your complaint (and the earlier complaints by many--myself included--about Mark Sisson's post) might be more generalized to "blog writers everywhere" and not just "paleo writers."

Hopefully when I read the whole article there will be explanation of why marathon runners were chosen for the "cardio" group, when current medical recommendations are for much less aerobic exercise for maximum heart health. Marathon runners often go beyond aerobic levels into anaerobic levels, so it seems an odd choice for the study. Why not use people that do the medically recommended levels of aerobic activity? I also wonder (okay, doubt) that anyone thinks aerobic activity makes them immortal (there's that sarcastick tone I mentioned).

I believe the studies where specifically looking at the "too much of a good thing" present in marathoners -- they weren't aiming to say that moderate amounts of aerobic activity are harmful. But, yes, I do think that many people think that if moderate amounts of aerobic activity is good, then more is better. I know people personally who have lost weight and gotten healthier by running some 5Ks who then thought something along the lines of "if 12 miles a week is good, certainly upping that will be even better." Many of these people will drive 3 miles round trip in pleasant weather because they "don't have the time" and certainly don't see the walk as exercise, but they will then go home and pound the pavement/treadmill for a couple hours even if they DON'T REALLY LIKE IT.

Maybe it's just that Americans have a "more is more" mentality, but it's out there. I think that is what Dr. Harris was trying to address. I don't think that he's saying getting out and hiking at a local park or playing some tennis or, hell, running a few miles a few times isn't a good thing.

Hoosiermomma

Interesting stuff here. Bumping to check this later!

aj_rock

I don't think the evidence given by this article leads directly to the conclusion it made. Yeah the guy had problems but he ran A LOT and probably did it on less than ideal surfaces (I still cringe everytime I see someone running on a sidewalk). Fact of the matter is, in order to reach ELITE levels of fitness, you WILL have health problems related to over-exercising in your life. That's exactly why no one preaches that everyone should be elite level athletes.

Essentially, just don't be a nutbar :ohwell:

questionablemethods

Essentially, just don't be a nutbar :ohwell:

Can I get that on a t-shirt?

Statsol

Actually, there was a book in the early 80's called something like "jogging myth" that addressed this very issue. Essentially, movement like walking with a little bit of strength training is supposedly statistically better for you than intense cardio excercise.

aj_rock

Essentially, just don't be a nutbar :ohwell:

Can I get that on a t-shirt?

Sure; it's on the cheap, but I'm sure Shipping&Handling will be a b***h :P

bcattoes

I will try to read all of that later, but the thing that turns me off of most paleo writers I've read (and I have not read a lot) is the sarcastic tone, which this article also has.

I think Kurt Harris is pretty even-handed in general. He dips into sarcasm once in awhile, but he's not writing a scientific article, he's writing to a blog audience. I could point you to hundreds of non-"paleo" writers with equal amounts of sarcasm (often while lampooning the "caveman diet.") Many of them are also parroting conventional wisdom, without a hint of scientific references anywhere. So, your complaint (and the earlier complaints by many--myself included--about Mark Sisson's post) might be more generalized to "blog writers everywhere" and not just "paleo writers."

Yes, fair enough. I don't read blogs, so that is probably true.

Hopefully when I read the whole article there will be explanation of why marathon runners were chosen for the "cardio" group, when current medical recommendations are for much less aerobic exercise for maximum heart health. Marathon runners often go beyond aerobic levels into anaerobic levels, so it seems an odd choice for the study. Why not use people that do the medically recommended levels of aerobic activity? I also wonder (okay, doubt) that anyone thinks aerobic activity makes them immortal (there's that sarcastick tone I mentioned).

I believe the studies where specifically looking at the "too much of a good thing" present in marathoners -- they weren't aiming to say that moderate amounts of aerobic activity are harmful. But, yes, I do think that many people think that if moderate amounts of aerobic activity is good, then more is better. I know people personally who have lost weight and gotten healthier by running some 5Ks who then thought something along the lines of "if 12 miles a week is good, certainly upping that will be even better." Many of these people will drive 3 miles round trip in pleasant weather because they "don't have the time" and certainly don't see the walk as exercise, but they will then go home and pound the pavement/treadmill for a couple hours even if they DON'T REALLY LIKE IT.

Maybe it's just that Americans have a "more is more" mentality, but it's out there. I think that is what Dr. Harris was trying to address. I don't think that he's saying getting out and hiking at a local park or playing some tennis or, hell, running a few miles a few times isn't a good thing.

I can agree with the fact that people, and maybe Americans more so, believe that more is better. But that' did not seem to be what the article was addressing in the part I read, but again, I did not have time right now to read it all. He seemed to be using a study comparing marathon runners to sedentary people to say "cardio" causes heart disease. Since marathon runners are usually reaching anaerobic levels and sedentary people are doing nothing, I fail to see what the study has to do with "cardio" exercise at all.

questionablemethods

I can agree with the fact that people, and maybe Americans more so, believe that more is better. But that' did not seem to be what the article was addressing in the part I read, but again, I did not have time right now to read it all. He seemed to be using a study comparing marathon runners to sedentary people to say "cardio" causes heart disease. Since marathon runners are usually reaching anaerobic levels and sedentary people are doing nothing, I fail to see what the study has to do with "cardio" exercise at all.

I should also clarify that, in general, I don't really think that "too much exercise" is a problem for the majority of Americans. :happy: But, since I do easily fall into the "all or nothing" mindset, I wonder if images of endurance athletes as models of health and fitness (or those freakin' Biggest Loser beat downs) make people think they can't even begin.

Interesting discussion.

tigeratty

I don't buy into the guru-ness of Mark Sisson because I think that our genome has indeed adapted in the past 10,000 years. But plenty of people love his paleo/primal gig and say it makes them feel great.

That said, I think the no cardio can work for people who are already lean. I know now why only cardio never worked for me all of those years.

For me, just lifting did not help me lose weight. I actually gained because I was so hungry from lifting heavy (once I got to my heaviest weights doing Stronglifts 5X5). I do have thyroid issues which may have contributed to the weight gain.

I also can't help but think one's heart needs some cardio training for general health.

I have added cardio back into my routine. I enjoy running. But I will continue to lift heavy.

sleepytexan

Please, if you, or someone you know participates in sports, stop now, before the cardio kills you.

bcattoes

I don't buy into the guru-ness of Mark Sisson because I think that our genome has indeed adapted in the past 10,000 years. But plenty of people love his paleo/primal gig and say it makes them feel great.

I haven't read much Mark Sisson but basing my opinion solely on what I've read on these boards, which I freely admit is not at all fair to him or his paleo-ness, I think some of it is nonsense. Eating whole foods is great. Giving up grains if you have problems digesting them is just good common sense. But some of the other things I've seen posted ... well, it's a little far fetched.

But I don't live like a Paleo man (or woman) so I see no reason try and eat like one. I prefer to live in the now and listen medical research done on people that have similar lives to me.

bcattoes

Please, if you, or someone you know participates in sports, stop now, before the cardio kills you.

I can't wait to get home and kill myself with some Zumba. What a fun way to go!!

And then I think I'll eat some whole grains.

sleepytexan

Please, if you, or someone you know participates in sports, stop now, before the cardio kills you.

I can't wait to get home and kill myself with some Zumba. What a fun way to go!!

And then I think I'll eat some whole grains.

excellent! I'm with you

ninerbuff

I despise cardio, but do it daily for a minimum of 30 minutes for calorie usage and for my heart. I rely on my eating habits and my weight training (to retain what muscle I have now) to keep me lean.

Drunkadelic

He really isn't bashing all cardio here, just "cronic cardio" which he defines in his book as over 30 mins of working at 70-85% of your maximum heart rate. That's pulled straight from memory so don't quote me on that but I think I'm close. The reasoning behind it (from what I understand) is that working out longer than that CAN cause stress on the body, which produces cortisol, which "helps" you store belly fat.

He suggests moving slowly for long periods of time, sprinting occasionally, and lifting heavy things.

I'm not trying to start an argument, just wanted to get that out there. I personally follow a similar plan because it seems to work great for people, I'm already starting to see improvement for the first time in MONTHS, and because I enjoy it. The only type of exercise I hate is extended cardio at that level. I love to walk, hike, ride my bike, lift weights and do HIIT workouts so this is perfect for me. Plus it really helps my stress level. Feeling like I HAD to burn at least 600 calories a day or whatever was really weighing heavy on me. I finally don't feel overwhelmed with guilt if I miss a workout and I definitely don't miss the dread of knowing I had to do my high intensity cardio session.

If it's something that seems interesting to you, then try it out. If it doesn't and you want to keep running your 10 miles a day, then keep running. As long as you can enjoy it, that's all that matters.

sleepytexan

I don't know what the point of doing ANY sport at less than maximum effort, or for less than 30 minutes would be. Why would you just get started and then stop? Barring time constraints of some kind, I guess this might be all you could tolerate while staring at a TV on some mindless cardio machine at the gym, but if that is the case, why are you on a boring machine at the gym?

Whatever works for this guy is great, but frankly, he sounds really boring to me. I'd much rather hang with dancers, cyclists, surfers and SUPers -- people who enjoy what life has to offer, people who work their bodies because they are creative, enjoy nature, love pushing limits and improving their skills.

How could you stand this guy -- ooh, sorry guys I can't catch any more waves -- those last 2 sets caused my heart rate to be up for 20 minutes and I still have to carry my board to the car. WHAT?! Time to go pump the iron at the smelly gym. Hmmmmm.

questionablemethods

I don't know what the point of doing ANY sport at less than maximum effort, or for less than 30 minutes would be.

Please point me to one serious athlete who trains every SINGLE session at absolute maximum effort for more than 30 minutes. The point he's trying to make is that we can't and shouldn't always be beating ourselves to a pulp. It is counter productive and even if you love the sport, if you are going all out every single time you step on the field (or strap on the shoes, or whatever) you will do more damage than good and likely not be able to enjoy the sport (or just life) to your fullest potential.

Whatever works for this guy is great, but frankly, he sounds really boring to me. I'd much rather hang with dancers, cyclists, surfers and SUPers -- people who enjoy what life has to offer, people who work their bodies because they are creative, enjoy nature, love pushing limits and improving their skills.

That's pretty much what Mark Sisson is all about. Getting outside, having fun, enjoying your body, etc. He's just not about the gerbil wheel of "chronic" cardio if it isn't something that you LOVE.

Time to go pump the iron at the smelly gym.

And he definitely doesn't lift at a gym. He promotes some simple bodyweight movements and encourages doing them outside, using natural tools, from what I have seen.

He goes into a lot of detail in his free ebook, which you can sign up for on his site (and then unsubscribe from his mailing lists if you aren't interested). I'm not going to quote it all here but I'll add this bit where he talks about an important element -- play -- which has been overlooked in much of this discussion:

I have learned to focus my training on one major goal: so I can play—hard! I hope you can get into that same mindset. Why else do we want to be strong and fit and able to run and jump? In order to enjoy our existence. Being unable to walk up those stairs or lift that box of books equals just another thing to worry about and stress over. When you don’t have to worry about the physical stuff anymore, or the aches and pains, you can start enjoying life again. Stress dissipates, melts away. Life is good when you’re able to play.

The way I see it, the ability to play (Primal Blueprint Lifestyle Law # 7)—to engage in unscripted, random bouts of youthful exuberance with loved ones, friends, and family—is the ultimate goal of Primal Blueprint Fitness. I’ve already stated that enjoyment of life is what being fit is all about. I maintain my fitness in order to enjoy life, rather than hobble around from waiting room to waiting room. What better way to muster some real happiness than to play like a kid again? This is an ab- solutely integral aspect of the Primal Blueprint Fitness program. When playing, you’re often getting exercise without even knowing it. Plus, play has been a vital part of our lives for many thousands of years, used as a way to unwind, connect with community, or—quite simply—enjoy life.

Yeah, he sounds like a total drag. :laugh:

sleepytexan

Please point me to one serious athlete who trains every SINGLE session at maximum effort. The point he's trying to make is that we can't and shouldn't always be beating ourselves to a pulp. It is counter productive and even if you love the sport, if you are going ALL OUT every single time you step on the field (or strap on the shoes, or whatever) you will do more damage than good and likely not be able to enjoy the sport (or just life) to your fullest potential.

This would assume that people only train in one sport. Lots of well-rounded people I know, myself included, train in multiple sports every day. I teach spin for 45 minutes in the morning on Tuesdays, and then later have a 3 -hour dance rehearsal--of course not all 3 hours is maximum effort, however there is always more than 30 minutes at max effort; otherwise, why are you there? I might SUP 90 min. in the morning and do a dance performance the same evening. I also cycle for a minimum of 2 hours at a time -- usually more like 4 -- because . . . I'm going somewhere. Around here there are a lot of hills -- they will push you to maximum effort, but then you go down hill -- minimum effort. It balances out, but there is usually a lot more than 30 minutes of 75% heartrate -- this is common among cyclists. Finally, when you're in the ocean, SUPing or surfing you'd better be putting out maximum effort while swimming or paddling over waves the entire time, or . . . you will never catch one to ride in. By the time you haul your board to the beach, no one's gonna quit in 30 minutes.

questionablemethods

Please point me to one serious athlete who trains every SINGLE session at maximum effort. The point he's trying to make is that we can't and shouldn't always be beating ourselves to a pulp. It is counter productive and even if you love the sport, if you are going ALL OUT every single time you step on the field (or strap on the shoes, or whatever) you will do more damage than good and likely not be able to enjoy the sport (or just life) to your fullest potential.

This would assume that people only train in one sport. Lots of well-rounded people I know, myself included, train in multiple sports every day. I teach spin for 45 minutes in the morning on Tuesdays, and then later have a 3 -hour dance rehearsal--of course not all 3 hours is maximum effort, however there is always more than 30 minutes at max effort; otherwise, why are you there? I also cycle for a minimum of 2 hours at a time -- usually more like 4 -- because . . . I'm going somewhere. Around here there are a lot of hills -- they will push you to maximum effort, but then you go down hill -- minimum effort. It balances out, but there is usually a lot more than 30 minutes of 75% heartrate -- this is common among cyclists. Finally, when you're in the ocean, SUPing or surfing you'd better be putting out maximum effort while swimming or paddling over waves the entire time, or . . . you will never catch one to ride in. By the time you haul your board to the beach, no one's gonna quit in 30 minutes.

All of that sounds very much in line with his philosophy. Maybe more than his general heart rate guidelines or whatever, and maybe it doesn't get across very well in his one post, but I think he's trying to reign people in from the idea that they need to constantly be at max effort for hours and hours every week in order to achieve a level of fitness that will allow them to just enjoy their freaking LIVES. I think there's a big difference between someone like you (and, I would argue, me), who is active and enjoy many different physical activities, and someone who feels like they "have to" chug away on the stair master for a certain number of minutes or until some certain number of calories have been burned or they will not lose/maintain their weight. I think he is aiming that post (and his Primal Fitness ebook) at the latter.

manjingirl

Wow, what a great discussion. Seems to me we've got abit hung up on the definitions and values of different types of exercise. But some things are well researched.

In my days in medical research (left to become a winemaker in 2000) I remember teaching about the inverted J curve of exercise intensity duration and the immune system response. If you exercise or do some activity at 85% or more exertion/heart rate for more than 45 minutes per day you measureably compromise your immune system. Also after a bout of high intensity exercise there is a 'window' of approximately 2 hours when you immune system is measurably depleted or less active and you may be more susceptible to developing an infection, especially respiratory tract infection IF there are sufficient germs around, either loitering in your upper airways or arriving from other individuals.

As you drop back on the intensity this effect goes away and you can exercise all day long (just like Mark Sisson found). In ELITE athletes there is an observable increase in the incidence of upper repiratory tract infections, and in females, urinary tract infections immediately prior to, during and immediately after major competitions. There may also be an increase in skin infections though this was less clear. And there is an observable increase in injuries of the muscles and joints.

BUT - the other bit of the inverted J curve is very important. As you increase your exercise/activity levels your health by many measures improve in an almost direct fashion. This includes heart health, improved mobility of joints, mood, appetite regulation, insulin/sugar regulation and immune responsiveness.

What does this mean for us average folk who just want to get fit and have fun? Cardio is really good for you.
Don't overdo it, but do do it. Long bouts of sub-maximal exercise like walking, working, biking is really good and you can go all day if you want. Weight training has measurable benefits as listed above but don't over do it. Don't do the high intensity stuff for too long at a time. The fitness nuts who do long sessions of tabata and extreme spin are fit but not necessarily as healthy as they could be.

Just my 2 cents worth.

carrie1128

Personally, I believe both cardio and strength training have a place in my workout regime. Along with yoga. What I have trouble swallowing is the 5,000,000 conflicting opinions on the "best" exercise for weight loss. The fact of the matter is, whatever exercise you're going to do and enjoy is the best for you, whether that's long endurance cardio, intense HIIT, Pilates, yoga, strength training, Zumba, spinning, or any combination of these and the many types of exercise you can do.

I completely agree.

Edithrenee

I prefer endurance training, over cardio.

what is difference between endurance and cardio? I though cardio was doing somehting to keep your heart rate up fo r aperiod of time so that is endurance..Right? Wha tdo you mean? im interested maybe I can do somthing else in addition to cardio lol

Azdak

Wow, what a great discussion. Seems to me we've got abit hung up on the definitions and values of different types of exercise. But some things are well researched.

In my days in medical research (left to become a winemaker in 2000) I remember teaching about the inverted J curve of exercise intensity duration and the immune system response. If you exercise or do some activity at 85% or more exertion/heart rate for more than 45 minutes per day you measureably compromise your immune system. Also after a bout of high intensity exercise there is a 'window' of approximately 2 hours when you immune system is measurably depleted or less active and you may be more susceptible to developing an infection, especially respiratory tract infection IF there are sufficient germs around, either loitering in your upper airways or arriving from other individuals.

As you drop back on the intensity this effect goes away and you can exercise all day long (just like Mark Sisson found). In ELITE athletes there is an observable increase in the incidence of upper repiratory tract infections, and in females, urinary tract infections immediately prior to, during and immediately after major competitions. There may also be an increase in skin infections though this was less clear. And there is an observable increase in injuries of the muscles and joints.

BUT - the other bit of the inverted J curve is very important. As you increase your exercise/activity levels your health by many measures improve in an almost direct fashion. This includes heart health, improved mobility of joints, mood, appetite regulation, insulin/sugar regulation and immune responsiveness.

What does this mean for us average folk who just want to get fit and have fun? Cardio is really good for you.
Don't overdo it, but do do it. Long bouts of sub-maximal exercise like walking, working, biking is really good and you can go all day if you want. Weight training has measurable benefits as listed above but don't over do it. Don't do the high intensity stuff for too long at a time. The fitness nuts who do long sessions of tabata and extreme spin are fit but not necessarily as healthy as they could be.

Just my 2 cents worth.

I just think it's a big mistake to take data from elite athletic performers and try to extrapolate that to the general population. Elite athletes DO NOT EXERCISE FOR HEALTH--they train to compete. The two do not always coincide. Part of "peaking" for athletic performance means taking your body as close to the edge as possible -- in Daniel Coyle's book about Lance Armstrong he writes that professional cyclists call it "going out on the razor". In preparation for something like the Tour de France, the top candidates for overall victory bring their body fat down to dangerous levels. As stated, their immune systems are compromised. They avoid physical contact, will only open doors and push elevator buttons with their elbows, get winded walking up a flight of stairs (in fact avoid walking altogether whenever possible). They focus on one thing only -- being able to ride a bike fast, 4-7 hours a day for 20 of the next 22 days.

You cannot take that data/experience and use it as a basis for denigrating cardio exercise in the general population. Not if you want any credibility, that is.