Sock Doc Training Part I: Aerobic Activity Is the Foundation to Your Health AND Fitness

Aerobic activity will kill you. Aerobic activity will give you a heart attack. Aerobic activity will deplete your sex hormone levels and age you. Aerobic activity will waste away your muscles. Don’t do aerobic activity!

Headlines such as these have been circulating like wildfire lately. I’m not sure exactly why there’s more now – perhaps it’s due to the huge increase in people who are entering and running half or full marathons; I’ll get to them in Part V of this series.  Several CrossFit aficionados and various well known personal trainers are anti-aerobic and they feel that you have to kick your own ass day in, day out, to achieve results (strength, power, and a ripped body). I’ll give you my take based off personal experience, professional experience, research, and knowledge gained from those who know more than me about various subject matters.Whether you’re an endurance athlete, strength athlete, or a little bit of both I hope there’s something you will learn. Even though I come from a deep endurance background I’m not going to say aerobic training is the ideal way to train all the time, (because it isn’t). But aerobic exercise sure isn’t going to wreck your health and strength if done properly. Actually, it’s much the opposite. There’s a time for it all more or less.

What Exactly Do You Mean By Cardio?

To start off with, most people are using the word “cardio” to describe what they think is aerobic conditioning. A”cardio” activity can be either aerobic or anaerobic, depending on the level of effort and exertion required for that individual to do the exercise. Often people train “cardio” anaerobically – they are exercising at a high intensity. These people have neglected to develop a key component of their health and fitness – the aerobic system. Calling anything endurance “cardio” is just as wrong as calling everything you lift, carry, or throw “weight lifting.” It’s a generalized non-specific term. Just as cardio can mean walking 100 meters or running a marathon, weight lifting can mean carrying your laundry from your wash room to your bedroom or it could mean deadlifting three times your body weight. So let’s talk aerobic and anaerobic when it comes to “cardio.” If we don’t do so I might have nightmares of Richard Simmons in his running shorts. Nobody wants that.

Aerobic Capacity: Building a Solid Foundation

Your aerobic system provides a solid foundation for good health. It is the system that predominately moves you efficiently through the day as these muscles support your overall posture. Training your aerobic system will increase mitochondria in your muscle cells to generate energy (ATP) and increase capillary vascularization for increased oxygen utilization. These mitochondria burn fat and glucose (sugar), but they’re much more efficient using fat as energy over glucose – twelve times more. In general, Type I, red, slow twitch muscle fibers are aerobic and burn primarily fat for energy.

Aerobic conditioning is also a necessary foundation of virtually all training. Some exception could possibly be made for sprinting less than 200 meters (one time, no repeats), but most activities or sports will best be performed with a well developed aerobic system. The longer an event, the more your body will rely on the aerobic system. A strong aerobic base will even benefit one’s recovery in-between sets of strength training as well as anaerobic interval training too.

Many people, especially many “athletes” are running long distances with a very poor aerobic system, relying heavily on their anaerobic system to get them through their training. This anaerobic training is their “cardio” and it’s very, very unhealthy, which is part of the reason so many point to “cardio” as harmful to one’s health, especially when it comes to the immune and hormonal systems. So these anti-aerobic “cardio” gurus cite studies such as the one in the Canadian Journal of Applied Physiology in April 2004, “Intensive Swimming Exercise-Induced Oxidative Stress and Reproductive Dysfunction in Male Wistar Rats: Protective Role of Alpha-Tocopherol Succinate” to back up their claims. Well, if you’re making a rat (or a human) swim intensively for three hours a day, five days a week yeah there is going to be oxidative stress and hormonal dysfunction. (As a side note in this study, the researchers noted the free radical damage could be protected with vitamin E.)

But this doesn’t mean aerobic “cardio” is bad. Swimming intensely for three hours (gotta be a long time for a rat) is going to tax the anaerobic system pretty significantly. This is not “aerobic” – it’s chronic anaerobic “cardio.” When you’re constantly using your anaerobic system more than your aerobic system, it puts a major stress to your entire body – your nervous system, cardiovascular system, hormonal system, immune system, and digestive system – pretty much all of it. For example, if you’re out for a long run, say 30-60 minutes, and your aerobic system is very poor, then you might be running at say 70% anaerobic and 30% aerobic. But if you develop your aerobic system, then at that same pace you could flip the energy utilization to 70% aerobic, 30% anaerobic. You’re a much more efficient athlete. This is evident when using a heart rate monitor and seeing your HR lower at a given pace/exertion level than what it once was in weeks or months previously. If you have access to an exercise physiology lab and a gas analyzer you can measure your respiratory quotient – the level of aerobic (fat burning) vs. anaerobic (sugar burning) – occurring during your run or other workout.

Anaerobic Conditioning: Are You Ready? Probably Not

Type II, fast twitch muscle fibers are primarily anaerobic, (some are a mix of both fast and slow twitch), – they burn sugar and creatine phosphate and are more for power and speed. They’ll increase your mitochondria too, but the anaerobic system will fatigue much quicker than the aerobic system. High intensity workouts tend to be predominately anaerobic as is much of strength training due to various Type II muscle fibers being utilized and developed rather than Type I aerobic fibers. This however is a generalization, as some forms of strength training can also develop the aerobic system. Anaerobic activity incurs oxygen debt and a build-up of lactic acid; muscle imbalances and fatigue can result if continued. Muscle imbalances can been verified through certain manual muscle testing evaluations, (it’s a very accurate neurological assessment when performed correctly), as well as by visual inspection – one hip higher than the other or one shoulder rotated inwards, for example. Pain, poor performance, and injury often result from chronic muscle imbalances.

Essentially, you’re almost always using both systems, (the exception would be an all out sprint), depending on several factors which will be discussed later – exercise, diet, and lifestyle (overall stress levels). Anaerobic endurance and strength is essential in many circumstances and sports, but it is the aerobic system that will provide you with the endurance to work, play, think, sleep, and go several hours without food. Oh yeah, without a healthy aerobic system you won’t be a star in the sack – impotence & premature ejaculation for men and lack of sex drive as well as the inability to achieve an orgasm for both sexes is partly dependent on a healthy aerobic system (many other factors too).

Training Truly Aerobically

The line between predominantly aerobic and predominantly anaerobic is determined by your lactate threshold (LT).  Below the LT you will be more aerobic than anaerobic, and above you will be more anaerobic than aerobic. True aerobic training is focused around lower-effort training zones 2 and 3, not the typical 3+ zone most are training their chronic “cardio” in. The “180-Age Formula” is also a great way to determine your aerobic training zone. Finding your heart rate zone is discussed more in Part II. Training around your LT too often is not a wise idea. Some call this area the “Red Line” or “Black hole” – it’s a great way to overtrain and should be left for hard days (hard group rides/runs) or racing days. A conditioned athlete may be able to endure this rate of exertion for well over one hour; whereas an unconditioned weekend warrior may be lucky to withstand fifteen minutes. Therefore, anaerobic training is often best performed as shorter, hard interval training above your lactic threshold, well into the anaerobic realm of training. This is where High Intensity Interval Training (HIIT) has its place. This will be discussed next in Part II along with developing your aerobic system regardless of your sport or goals.

Sock Doc Training Part II: Build Your Aerobic System – (Move Your Ass Often, But Not Too Quickly)

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  1. Mark says

    Hi Doc, just a couple of quick querys. I would concider myself reasonably fit so i used the formula 180 – 30 with a resting hr of 48, this give me a threshold of approx 150. Then i used the percentage zones and programmed them into my garmin hrm. My zone 4 is set for 135bpm – 145bpm and ran a 1hr 30mins treadmill session with an average hr of 138bpm, 7.40 min/mile pace which seemed to be the sweet spot for this hr, which was no problem at all for me and i felt as if i could have gone on for another 1 – 2 hrs. My question is, is this a good fat burning workout for me or am i training too close to my LT. I notice you you put zone 4 as chronic cardio, what exactly doe this mean. Lastly once a week i do treadmill interval sessions which consist of 30 seconds at 5min/mile pace then 30 seconds 8min/mile pace all at a 7% incline and ill do this for half an hour, does this sound ok or should i back off.

    Kind Regards


  2. Wendy Liu says

    Dear Dr. Doc,

    My 14 years old daughter is a competitive figure skater.
    Her training is quite intensive, 12-14 hours per week (including on ice and off ice).
    Everything was normal until about three weeks ago; she started to complaint that she couldn’t sleep the whole night on every single day. We didn’t pay too much attention. Until recently, she said she is extremely tired because of no sleep for almost three weeks. We discussed with her about school and training. It sounds like nothing really bothers her that much. I have slept with her since last weekend try to see how she sleeps. From what I observed and what she described, her sleep is only at stage 1 and/stage 2 (of the sleep cycle) for the whole night, which makes her exhausted during day time.
    I did a lot of research, until I saw your article; I realized something could be wrong in her daily life too. In cooperating with the training, she need to keep her body in good shape, she eat just a little bit in the evening, plus the hard training. I am not sure if these will cause the sleep disorder.
    Since last week, she has worked on a reduced schedule, only 2-3 hours training/week; I am thinking to stop training until she is recovered.
    Do I need to ask our family doctor to get blood test for her blood cortisol and epinephrine?
    Do you have any suggestion in terms of treatment and exercise?

    Thanks a lot,

    • says

      I wouldn’t have any personal advice w/o seeing her – best I can offer you is what’s on this site.

      The epi and cort blood tests are useless. They won’t show functional problems. If she’s having a cortisol problem you can often find it through a saliva test. See link here and check out the first one (Diagnos-Techs):

  3. Dzung Ng says

    Dear Dr. Doc
    I am 44, recreational distant runner from Vietnam. I have followed your posts with great interest.
    I started running since 2010 to lose weight (and got it down to 60kg from 80kg in one year). After completing 10K and 20K races (best time 52’ and 1h53h respectively) I have trained for about 6 months and ran my first marathon in Sep 2013. However, I got cramps from the 18th km and basically walked to the finish line (average speed 7,5km/h). Although that day was very hot and humid, which could partly explain the early cramps (I never experienced serious cramps before, only once when I ran 32km the first time), after reading your posts on aerobic base training, I think that one of the main reasons could be my weak aerobic base. When I trained for 10K and 20K, my speed was around 10-11km/h and my heart rate was in the 150-170bpm zone. During the training for the marathon, I reduced the speed to 9,5-10km/h but the heart rate was still somewhere btw 150-160bpm.
    Now, my next marathon in April 13 2014. I am following your advice, to improve the aerobic base first, before doing some marathon specific training. I plan to run 4-6 miles a day, 5 days a week, till end of December 2013, trying to keep the HR under 141 (180-44 (my age) + 5). However, my speed is now very slow, running with good form becomes difficult and basically I was forced to walk half of the distance just to keep the HR under the 141 mark. I am wondering whether it is OK to go on like this, and in your experience how long it might reasonably take until I could run the whole distance.
    Another question is whether the (180 –Age) formula needs some modification for Asian?
    Thank you for your post and your time
    Dzung Ng

  4. Kris says

    Sock Doc,

    This question may be a matter of semantics, but I become confused when you are discussing aerobic v. anaerobic training. You mention that LT may be a good division between the two, but you also refer to the 180 – age formula as a division as well. There is a big difference between my LT running pace (a pace I could hold for approx 1 hour) and the pace dictated by the 180 – age HR. When it comes to metabolic energy pathways, are you referring to the anaerobic (glycolytic) system v. the aerobic (oxidative) system? Or are you referring to the oxidative system and its preferentiality for glucose(anaerobic) v. fat (aerobic). My guess is the latter, but the LT threw me off…

    I think the semantics of aerobic v. anaerobic can be confusing because, for example, I will often read about long distance races and their energy contribution, i.e. the marathon is 99% aerobic. But generally when racing, marathon pace is above the 180-age HR, which would mean at an anaerobic HR. (My aerobic threshold is 145 bpm, but my race pace HR is approx 160-165) How do you make sense of this?


    • says

      If you’re aerobic threshold is 145 then most likely you’re burning up a substantial amount of glucose/glycogen racing a marathon in the 160 range. So it’s not 99% aerobic. That’s only when someone is truly utilizing their oxidative system, and most people don’t do that.

  5. anas lampard says

    hello doc. im a student and i wanna ask. is aerobically fit person also anaerobically fit? what do you think

  6. Conor says

    Would playing a lot of golf, around 12+ hours a week lead to a healthy aerobic system? If so would it be sufficient to train anaerobically for all other training?

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