June
2007
A Case Against Cardio (from a former mileage king)
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We all know that we need to exercise to be healthy.
Unfortunately, the popular wisdom of the past 40 years – that we would all be better off doing 45 minutes to an hour a day of intense aerobic activity – has created a generation of overtrained, underfit, immune-compromised exerholics. Hate to say it, but we weren’t meant to aerobicize at the chronic and sustained high intensities that so many people choose to do these days. The results are almost always unimpressive. Ever wonder why years of “Spin” classes, endless treadmill sessions and interminable hours on the “elliptical” have done nothing much to shed those extra pounds and really tone the butt?
Don’t worry. There’s a reason why the current methods fail, and when you understand why, you’ll see that there’s an easier, more effective – and fun - way to burn fat, build or preserve lean muscle and maintain optimal health. The information is all there in the primal DNA blueprint, but in order to get the most from your exercise experience, first you need to understand the way we evolved and then build your exercise program around that blueprint.
Like most people, I used to think that rigorous aerobic activity was one of the main keys to staying healthy – and that the more mileage you could accumulate (at the highest intensity), the better. During my 20+ years as a competitive endurance athlete, I logged tens of thousands of training miles running and on the bike with the assumption that, in addition to becoming fit enough to race successfully at a national class level, I was also doing my cardiovascular system and the rest of my body a big healthy favor.
Being the type A that I am, I read Ken Cooper’s seminal 1968 book Aerobics and celebrated the idea that you got to award yourself “points” for time spent at a high heart rate. The more points, the healthier your cardiovascular system would become. Based on that notion, I should have been one of the healthiest people on the planet.
Unfortunately, I wasn’t - and that same mindset has kept millions of other health-conscious, nirvana-seeking exercisers stuck in a similar rut for almost 40 years. It’s time to get your head out of the sand and take advantage of your true DNA destiny, folks!
The first signal I had that something was wrong was when I developed debilitating osteoarthritis in my ankles…at age 28. This was soon coupled with chronic hip tendonitis and nagging recurrent upper respiratory tract infections. In retrospect, it is clear now that my carbohydrate-fueled high-intensity aerobic lifestyle was promoting a dangerous level of continuous systemic inflammation, was severely suppressing other parts of my immune system and the increased oxidative damage was generally tearing apart my precious muscle and joint tissue.
The stress of high intensity training was also leaving me soaking in my own internal cortisol (stress hormone) bath. It wasn’t so clear to me at the time exactly what was happening – in fact it was quite confusing, since I was doing so much of this so-called “healthy” aerobic exercise – but I had no choice but to give up racing, unable to train at anywhere near the intensity required to stay at an elite level.
To make ends meet…
…I became a “personal trainer” and I refocused my attention on training average “non-athletic” people to achieve reasonable levels of general fitness and health. Of course, we lifted weights as part of the overall plan (and I will go into greater detail on that important aspect of fitness in a later post), but for the aerobic component of their training, I started doing long walks or hikes or easy bike rides with them. My many clients got the benefit of me actually working out right along side them and I got the benefit of 3 to 5 hours a day of very low intensity aerobic work (well, very low for me anyway). It was refreshing and really didn’t take much effort on my part, but I knew I had to be deriving at least some small benefit from those hours.
Since I didn’t have much time left in the week for my own workouts, once or twice a week I would do a very short but very intense workout for my own benefit, usually sprints at the track or “hill repeats” of 2-3 minutes each on the bike. Lo and behold, within a year, my injuries were healing, I was rarely sick and I was even back to occasionally racing – faster than ever. Something “primal” was happening and it made total sense in the context of the DNA blueprint. I was training like my hunter-gatherer ancestors, building my aerobic capacity slowly and steadily without overstressing my adrenals or my immune system, training my body to derive more energy from fats (and not glucose), requiring far fewer carbohydrate calories from my diet, and building muscle with occasional quick bursts of speed and intensity. I was suddenly both fit AND healthy. My Primal Health system was kicking in and it all made perfect sense.
Humans, like all mammals, evolved two primary energy systems that powered the skeletal muscles of our hunter-gatherer ancestors 40,000 years ago and that would keep us all well-powered the same way today, if we weren’t so bent on circumventing them with our ill-fated (literally) lifestyle choices.
The first energy system relied heavily on the slow burning of fats, keeping us fueled while we were at rest or sleeping, yet also allowing for continuous or intermittent low levels of aerobic activity (think of our ancestors walking across the savannah for hours foraging for roots, shoots, berries, grubs, insects and the occasional small animal). It makes sense. Fats are very efficient fuels that are stored easily in the fat cells and burn easily and cleanly when lots of oxygen is present (as when we are breathing normally). Even if there’s no food in the immediate area, a well-trained fat-burning hunter-gatherer could continue walking and foraging for days without compromising his or her health or efficiency.
The second major energy system we developed through evolution was an ATP-fueled system that allowed for intense loads of work to be done in very brief bursts (think of our hunter-gatherer ancestors sprinting to the safety of a tree to avoid being eaten by a lion). ATP is always sitting right there within the muscle cells, available in a split second, and it is the highest octane fuel we have. In fact, it’s ATP and adrenaline that allow the little old lady to lift the front end of the Ford Fairlane off her husband when the jack fails. Unfortunately, the muscles can only store about 20 seconds worth of this precious fuel to complete life-or-death tasks. If our ancestors survived that quick sprint to safety, their ATP reserves were filled again within minutes using the other energy systems.
Furthermore, that brief burst of intense energy sparked a small “growth spurt” in the muscle, making it even stronger for the next encounter with the next lion – a true survival adaptation.
(Note: While our energy systems are actually quite complex, varied and interrelated, I have simplified things here to make it easier to “digest”.)
Bottom line: Fats and ATP were the two primary energy sources for locomotion: we either moved slowly and steadily or “fight or flight” fast, and we became stronger and healthier the more we used only those energy systems.
But here’s the real take-home message for us: We did not evolve to rely heavily on a carbodydrate-fueled energy system, and yet, carbohydrate metabolism seems to rule our lives today. Yes, carbohydrate (in the form of glucose) can play a major role in the production of energy in skeletal muscle, but it turns out that the heart and skeletal muscle prefer fatty acids (fat) as fuel over glucose.
Our hunter-gatherer ancestors didn’t regularly ramp their heart rates up for over an hour a day like so many of us do now. Even when the concept of organized hunting came along, it would appear that our hunter-gatherer ancestors relied more on superior tracking ability (using our highly evolved and exceptionally large brains) and walking (using our superior fat-burning systems), rather than on actually “chasing down” their prey. In fact, squandering valuable energy reserves (and increasing carbohydrate [glucose] metabolism by a factor of ten) by running hard for long periods of time was so counterproductive it would have likely hastened your demise (imagine chasing some game animal for a few hours and – oops - not succeeding in killing it. You’ve spent an incredible amount of energy, yet now you have no food to replace that energy. You have suddenly become some other animals prey because you are physically exhausted).
So, what does all that mean for us in the 21st century seeking to maximize our health and fitness?
Well, we know that this current popular high intensity aerobic pursuit is a dead-end. It requires huge amounts carbohydrate (sugar) to sustain, it promotes hyperinsulinemia (overproduction of insulin), increases oxidative damage (the production of free radicals) by a factor of 10 or 20 times normal, and generates high levels of the stress hormone cortisol in many people, leaving them susceptible to infection, injury, loss of bone density and depletion of lean muscle tissue – while encouraging their bodies to deposit fat. Far from that healthy pursuit we all assumed it was! What, then, is the answer?
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.
However, since allocating a few hours a day to this pursuit is impractical for most people, we can still create a plan that has a fair amount of low level aerobic movement, such as walking briskly, hiking, cycling at a moderate pace, etc a few times a week and keep it at under an hour. Then, we can add a few intense “interval” sessions, where we literally sprint (or cycle or do anything intensely) for 20, 30 or 40 seconds at a time all out, and do this once or twice a week.
If you are willing to try this new approach, but haven’t sprinted for a while, you may want to ease into it. Start with maybe three or four the first time, resting two minutes in between and, after a few weeks of doing this, work your way up to a workout that includes six or eight all-out sprints after a brief warm-up. An easy few minutes of stretching afterwards and you’ve done more in less time than you could ever accomplish in a typical “80-85% Max Heart Rate” cardio” workout. That’s exactly type of the plan I do myself and that I give all of my trainees now.
Let’s recap:
The benefits of low level aerobic work (walking, hiking, cycling, swimming):
- increases capillary network (blood vessels that supply the muscle cells with fuel and oxygen)
- increases muscle mitochondria
- increases production of fat-burning and fat-transporting enzymes
- more fun, because you can talk with a partner while doing it
The benefits of interval training (sprinting in short intense bursts)
- increases muscle fiber strength
- increases aerobic capacity (work ability)
- increases muscle mitochondria (the main energy production center in muscle)
- increases insulin sensitivity
- increases natural growth hormone production
The costs of chronic (repetitious) mid- and high-level aerobic work
- requires large amounts of dietary carbohydrates (SUGAR)
- decreases efficient fat metabolism
- increases stress hormone cortisol
- increases systemic inflammation
- increases oxidative damage (free radical production)
- boring!
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Technorati Tags: exercise, working out, cardio, toning, strength, DNA
[...] Endurance, Fitness vs Health,and the Great Alberto Salazar Americas Greatest Marathoner(IMO) Suffered a Heart Attack Sunday in Oregon Salazar suffered heart attack; condition upgraded - USATODAY.com and already the powers that be are saying he had a "Family History" of Heart Problems. What a load… Let me say first I wish Alberto a full recovery. He will always be a hero to me. ..that said,What he had(at one Time) was the "heart of a Lion" a strength of will like i’ve never seen. Like many endurance athletes from front runners to back of the packers, he joins a long list of Victims of the "endurance training myth". I hope maybe NOW, people will wake up and see that endurance training is unhealthful and wreaks havoc via inflammation to the arteries and other endoctrine system problems. I was one too and had to stop training due to chronic exhaustion. Then lo and behold, I felt stronger as time went on. I’m very blessed. some arent so lucky. From Jim Fixx to Grete Waitz, and thousands of others, the message is clear: Endurance is not for humans. Humans are built for short intermittant anaerobic stress with longer periods of mild exercise. Mark Sisson, a former world class Triathlete and US Marathon trials top dog has lots to say… Mark’s Daily Apple » Blog Archive » A Case Against Cardio (from a former mileage king) He’s devoted his career to enlightening former Treadmill lab rats like me as does Art Devaney… Art De Vany: Endurance Training: Death, Injury, and Risk Archives please folks, check this stuff out you owe it to yourself Peace. [...]
[...] week, I got a whole slew of questions about my controversial case against cardio, my antipathy towards carbs, what food I eat in a day, and oddly, not one but several emails about [...]
I really enjoyed this article and I found it very informative. It is pretty long and I think it might have been easier to read with better formatting.
My best thoughts,
Bradley Woods
Hi Mark, is there scientific evidence supporting what you’ve found in your experience? If there is could you send me a few links? I would be interested to look into this further.
Thanks,
Sonya
[...] and don’t want to work out for more than 12 seconds. (Admittedly though, sometimes this is the idea. Exercise, like life, is highly nuanced.) Working out at or near your maximum heart rate is [...]
Men’s health magazine is suggesting that you are correct. Keep up the good work!
[...] Mark’s Daily Apple " Blog Archive " A Case Against Cardio (from a former mil… [...]
[...] Mark’s Daily Apple " Blog Archive " A Case Against Cardio (from a former mil… [...]
So would running five miles in 45 minutes three times a week be considered too much?
Cardio Kills?!…
What’s the media trying to tell us now? First it was exercise doesn’t really matter in terms of weight loss and now it’s cardio is a waste of your time.
Folks, where’s the “Cigarette and Coffee Diet?”
Here was a que…
[...] came across this blog entry at Mark’s Daily Apple, and interesting blog about health, diet and fitness, and I think it [...]
By doing cardio 1-2 times per week and no more than 20-30 mins per section, plus total body mass training, you will minimize fat while you get bigger in muscles.
[...] emails from readers asking for more details about my workout routine, especially after publishing a Case Against Cardio and the recent video of my beach sprints. Though I do snowboard and hike and love to try my hand at [...]
Mark,
I’m curious about what you mean by “low level” cardio. I understand that this means reducing our time in aerobic exercise, and thus going shorter distances.
But I am still wondering about relative effort. Do you suggest that we all stay in heart zone 2? Is heart zone 3 ‘low level’? Is heart zone 4 the forbidden zone?
Forgive me for understanding the world through the readout on my Polar monitor! Thanks for your great article,
Mike H.
Mike,
Depends on your level of fitness. The idea is to burn only (90%) fat when you train aerobically. For very fit people, this might be as high as zone 3, but for most it will be walking briskly, hiking, biking at medium pace, etc. Then you reserve the really hard stuff for short anaerobic bursts (intervals) once or twice a week.
Remember, all this is advice for someone wishing to maximize health, energy, longevity etc…If you are deciding to compete, then you might choose some more radical compromises.
[...] A Case Against Cardio [...]
[...] Mark’s Daily Apple » Blog Archive » A Case Against Cardio (from a former mileage k…: “Unfortunately, the popular wisdom of the past 40 years – that we would all be better off doing 45 minutes to an hour a day of intense aerobic activity – has created a generation of overtrained, underfit, immune-compromised exerholics. ” [...]
[...] My Case Against Cardio [...]
[...] and balanced exercise routine that accounts for both of our energy systems (see Mark’s “A Case Against Cardio“). This combined with weight-bearing exercise and periods of intense anaerobic activity [...]
[...] road, making mistakes and harming my body. I wish you luck in all your endeavors. Please read this Mark’s Daily Apple » Blog Archive » A Case Against Cardio (from a former mileage king) Good Luck, [...]
Hi Mark, Have you heard of a product called Isagenix? I have been using it and having great results. I wondered if it is as good for me as it seems to be? I’ve lost weight and have more energy, this product is a health and wellness that cleanses the toxins out of my body. All the ingredients seem to be what I need but I thought with you in the health business you would know if this kind of cleansing is good for the body? It seems to be the new thing to do, but is it the best I can do? Thanks, Roxie
Roxie,
Isagenix has a number of products. Because they are an MLM, I would not rate their products highly. OK ingredients at exhorbitant prices. Also, not a big fan of “cleansers.” That said, if you are getting the results you want, who am I to steer you away?
[...] A Case Against Cardio [...]
It sounds to me like you experienced a classic case of overtraining and overuse injuries, and are now claiming high intensity cardio as the problem.
The problem was not the intensity at which you worked, but rather the frequency by not allowing your body proper rest and recovery. All exercise is beneficial (low intensity aerobic, high intensity aerobic, very high intensity intervals) to overall health. However, you must recognize the intensity and frequency at which you work and allow your body time to recover and grow stronger.
And exercise promoting hyperinsulinemia? That’s news to me! I’d like to see your sources on that one…
Jonathan,
Not sure you got the message here. Of course I overtrained. That’s what many many marathoners and triathletes do. That’s the point. Any exercise IS good provided you do the right amount and allow the proper rest. Most who compete do not allow proper rest.
The necessary high carb diet is what promotes hyperinsulinemia - not the actual training. No sources necessary for that.
[...] Do Not do Excessive Cardio Exercise - More is NOT better. Look at many professional athletes who we think are in great shape, only to die of ageing diseases like heart disease and cancer in their 40s and 50s. Why? Could it be that they are burning 5000 cal a day and need 5000+cal a day to maintain? This is not ideal for long term health. So unless you are a professional athlete who makes a living on this, you have a choice on how to exercise. More is not better and can be shortening our lifespan in the process. Mark from MDA has a great article on the dangers of excess cardio. [...]
Completely agree.
As a trainer myself I rely on diet and weight training to bring about results rather than pointless joint bashing such as running and fixed pivot shitty machines like the cross trainer.
People used to think the earth was flat and now we know better. Its only a matter of time before people feel the same about endless hours on the CV equipment.
http://www.neilmct.com
wwwneilmctcom.blogspot.com
[...] or taking some other type of cortisol suppressing hormone “supplement”. Here’s a good read on danger of the cardio obsession so many people have [...]
[...] cal a day or taking some other type of cortisol suppressing hormone “supplement”. Here’s a good read on danger of the cardio obsession so many people have [...]
Do some kettlebell then think again this whole cardio issue.
David,
I’m not sure I get where you are going with that. What are you saying?
Sorry,I wanted this comment in an another post of an another homepage. This post was in another browser:).
Mark,
I have been reading your site/blog for several weeks and am very impressing by both its content, and your positive attitude.
In terms of fat loss, (assuming that one is eating correctly in terms of macronutrient ratios, adequate protein consumption, caloric leves), what would be your cardio/interval suggestions?
I am assuming low level cardio (i.e. 30 min of steady state interval walking, swimming, etc) and 2 HIIT type worksouts per week?
Sudip,
2 HIITS per week for sure. The rest can be 30 minutes or even 2 hours each, as long as it’s very low level stuff (walking, hiking, etc) Once the Heart Rate gets abover 55-60% max, that’s when you can (and should) reduce the time. When you get to 75-85% max HR, you can get a lot done in as little as 20 minutes. What we DON’T want is 90 minutes or 2 hours of 75-90% Max every day.
Mark,
I think this site is excellent and have been influenced by it to try your 30 day primal challenge. Til now I have been a marathoner and steady state jogger guy.
However I have been more persuaded by your physical condition as evidenced on your videos than by all this conjecture about how primitive humans lived.
The fact is if you look at the San people (Bushmen)of the Kalahari who still lead stone age lives, their method of hunting is to a) dart an animal such as a kudu with a small poison arrow then b) send out one runner to chase it down and literally run it to death. The kudu sprints out of sight but the hunter keeps pressure on it by jogging steadily on its trail. It can take an entire day of steady state jogging before he reaches the exhausted animal and then he will kill it with a spear. So, based on that evidence it would seem that the ability to jog steadily for hours on end has been of great evolutionary advantage to humans. . .
Anyway, thanks for all the great information!
Joe, you must be referring to that Men’s Health article on the San Bushmen. I disagree with the premise. You’ll note that they don’t run hard and long…they “trot” which is actually the kind of low level aerobic activity I’m talking about and saying is OK. Also, they don’t do it every day (once you have a kudu, you don’t go out and get more without a nice freezer to keep the extra in). They don’t train to do this as if it’s a race against the animal. Instead they track it and methodically pace themselves while the wounded, drugged animal sprints and rests. Using their human mental superiority, they “cut the tangents” and slowly move in on the animal. All in all, if I were allowed to do that in the USA, I would consider it a totally Primal activity - one that my other intense training would allow me to do with relative ease once or twice a week. Just because we “can” do it once in a while doesn’t mean we should train for endurance events every day.
Glad you dig the site. Keep watching.
Hi Mark,
I enjoyed your post for the most part. And I agree with 99% of what you said. The main difference is I know that I was designed not evolved. But the mechanics you describe are what we were designed to do.
I am a molecular biologist, personal trainer and former bodybuilder so I have a deep interest in this subject.
I found your post because I have not trained one bit since getting married 5 years ago (new baby, started my own company…etc) and just started training in Brazilian Jujitsu and the cardio intensity when “sparring” (basically wrestling) is intense!
I find myself every two or three days (if I don’t take a day off) getting heart palpitations (with a heart rate of 48-55)… it is really anoying and a little scary. I had a cardiologist friend check me out and my ekg was ok.
Did you ever traing anyone who went from zero cardio for over 5 years to 100% heart rate max training for over an hour? How did they feel?
I know, I know… Do as I say, not as I do.. Hey I’m human.
Kevin, normally you should spend a few weeks or months easing in to an intense training program. Gradually building up from slower aerobic activities to brief intense bursts, etc. As long as your ekg is OK, I guess I can’t add much.
I know you’re right, I just don’t know how to do it with something like Jujitsu where your opponent is going full throttle. I mean if I don’t put at least equal effort, I am going to get tapped out… I’m going to see if I can get some suggestions from the instructor today.
I appreciate your web site and specifically this page, as I have always believed the science behind what you’re saying (less evolution of course)…
To clarify ATP is used all the time independent of what energy system is used to generate it.
you seem to infer ATP is not used during activity that is not sprinting.
I also contend you are unlikely to be able to “trot” a Kudu to the point of exhaustion at a low heart rate.
the fact the runner is not achieving a sub 3 hour marathon pace does not preclude he is making a sustained effort or that the effort is not daily does not invalidate long sustained efforts as a natural activity. The women carrying firewood on her head is most likely making a sustained effort even walking.You don’t see a lot of talking going on while women carry heavy loads for hours a day… stick 20kg on your head and walk for 4 miles
there is millions of women who do substantially more than that 365 days a year. . however how primal is that activity?
I think you primal model is in need of checking not least in that you have odd ideas about hominid evolution. The main problem with a primal model is there probably is and never was a standard regime.
However interval training is highly effective but this is nothing new or absent from endurance training.
I am unhappy with the propagation of the evolution certainties on this site.. but in your defense your training regime appears to be quite beneficial if not enjoyable, there is a large supportive social aspect
did primal man engage in 8 high intensity sprints a day with limited recovery intervals?
great read. I was a bicycle racer for about 7 years and become extremely burnt out, quitting all physical exercise for nearly two years and gaining over 60 lbs. The time investment for cycling is ridiculous, even for a mid level amateur. The accidents are dangerous and people regularly die in races. Cyclists are good at cycling, and not much else. Ask them to do pushups, they cant. One pro(JHK mtb pro) once joked he could not do 10 pushups. The average racer devotes +/- 20 hours per week. Racers now are recognizing they are developing heart conditions, due to the prolonged elevated heart rate. There is also a correlating instance of cancer among endurance athletes. I see it as a fad, and luckily I am locked in at the lower rates for my crossfit gym..
No idea if you’ll get this or not seeing how old this article is, but… Im preparing for a sheriffs academy in February. They used to just run the cadets a lot. But I found out that now theyre making it worse. They are trying to get as many people to quit as possible since they dont have as many spots to fill and want people to quit.
Now, in the current academy, they are running the cadets ~10 miles everyday, sometimes all at once, sometimes accumative throughout the day. I have a feeling it will be the same in Feb. So I have until Feb 9th to get as many miles in as possible to get my body used to the distance.
Its only a few months, then the 6 in the academy, so Im not expecting a lot of long term health problems, but whats the best way to combat the negatives of long, slow distance? I was thinking still throw in sprint days 2 or 3 days a week. Also, keep walking and biking everyday as my main form of in-town transport.
Also, as a former milage-king, what do you think is the best program to increase from an average of 1 mile at a time to 10 at a time?
Brandon, don’t fret. Just do the work necessary to succeed in the training. You won’t do any significant damage at your young testosterone-fueled age. As long as you eat well (cut the grains and simple sugars, but you’ll need to add more starchy carbs like spuds, yams, sweet potatoes, etc)
[...] Read more here: A Case Against Cardio (from a former mileage king) [...]
Hello Mark,
I used to do tempo runs 2-3 miles 2-3 times a week and some strength workouts. Last summer I replaced my tempo-runs with sprints on the grass, which reduced the volume of my running. That brought down my HDL cholesterol from 57 to 44 and I didn’t like it. I thought it would badly effect the health of my arteries (I’m 71 yo). I also checked some other sources and they confirmed that cardio exercise is good for HDL cholesterol.
I am back on my old cardio routine now with tempo-runs. It is moderate fun rather than stressful high intensity training for me. I often include intervals in my runs. I can only hope this cardio routine is harmless for my immune system, and generates not that much oxidative stress. We live and we learn …
Thanks for your blog.
Alex
Alex,
I’m sure your routine is working well - and supporting your immune system. “Moderate fun” rather than stressful is always the key. Don’t know how much your diet had to do with changes in HDL either…it’s often a collection of different variables that causes these changes. Also, cholesterol tests are not always accurate as a snapshot. Cholesterol levels rise and fall under various conditions all day, so you may not have really even had the 7 point drop you were told about.
I say keep doing what you’re doing, Alex.
[...] We’ve talked a lot about the dangers of overtraining before, and now blogger Arthur De Vany gives us the top 10 reasons not to run a marathon. [...]
[...] obrigatoria. São os seguintes: Dear Mark: Chronic Cardio, More Chronic Cardio Talk e A Case Against Cardio (from a former mileage king). Algumas passagens destes [...]
Hi Mark,
I enjoy your site. It seems to me you are an advocate of Covert Bailey’s philosophy. Except, of course he recommends whole grain carbs. It’s hard to give up the bread and pasta! It was his book, Fit or Fat, that finally made sense to me, as to why we should exercise. Thanks for all the good info…
Mark,
Enjoy you perspective. 30 year runner, just started Crossfit and Tabata sprints. Doing 4 sets of 6 sprint of 20/10 splits. Is that too much?
Dave
Dave, depends on your starting fitness levels (regardless of 30 years) and the intensity of the work. If you are doing 24 sprints at 20 secomds each, you are clearly not going all out on most of them. That’s the distance runner mentality - to do more reps at a slightly slower pace and recover quickly. What you are describing puts you in more of a high-end aerobic zone than an anaerobic burst. While your workout might prepare you for a race, if you are looking to boost HGH, increase pure sprint speed and get more bang for your buck, it’s better in this case to go all out for 8 and be “truly knackered” when done.