How 'bout this: let's all stop allowing people to develop the impression that glycolysis causes lactic acid and lactic acid necessarily damages myocardial mitochondria, then I'll stop bringing to people's attention that it doesn't.
When we start talking about damaging heart muscle people rightly take that seriously. They shouldn't be encouraged to believe these very short duration excursions into very high heart rates are compromising their health. If a guy makes a conscious decision to really plus up his aerobic capacity, I'm all for him, cheering all the way. If the same guy decided he had to do that because he got the impression his bi-weekly HIIT intervals are damaging his heart, that's a different thing.
It's a testament to your character that you responded appropriately... you're alright, Bill.
I agree with the notion that we should not be scaring folks away from higher intensity training. "Context" is the word of the day, and we all seem to be making blanket assertions. Some of us should not be doing any high intensity training; some of us can tolerate some; other can tolerate more; and others can tolerate a lot... that is, at this point, as we now speak. Things can radically change depending upon a lot of factors. One common scenario that we have seen since the popularization of HIIT, and its bastardization into "all out, all the time", is:
- untrained, or detrained individual begins HIIT
- in the several months that follow, said individual makes fantastic gains, both aerobic and anaerobic
- at some point, too frequent bouts of anaerobic movement collectively begin to turn the individual into a zombie
- as this "disease" progresses, energy plummets, sleep is regularly disturbed, cognitive function falters, health declines... the individual essentially walks around in trance all day, and only conjures up energy to "workout", because it says so in the program
In a less common scenario, we will see a high level athlete succumb to cardiac failure early, as reports began to emerge in the last decade. Now, both of these are rather extreme versions of what a lot of folks are currently doing, the latter more so than the former, but this observation led to investigation, which led to the academic discovery of high exposures to anaerobic by-products (high acidity, specifically) as being degrading to proteins and cells, and from a performance standpoint, mitochondria, specifically.
Along this course of investigation, we have also discovered that there is a tug of war of sorts between aerobic function and anaerobic function. If you hang back and develop your aerobic function, you will be able to tolerate a lot more stress, including a lot of anaerobic function and its by-products... you will be able to buffer a hell of a lot more acids than if you use anaerobic function (re: HITT training) to try and develop both at the time, as we have been duped into believing. For a shorter time, yes, this tactic will work, as I have described above, but in the long run, it will serve most better to tip the scales toward more aerobic training, and less anaerobic training. And guess how long most, if not all of the research studies looking at HITT training last for? Again, context weighs supreme.
A weekly dose of HITT will likely do most of us a lot of good, because of the many reasons that you have pointed out in your many posts. Some of us can do well on more oft dosing. Context, in case I have not mentioned this yet, makes all the difference. That said, I personally recommend building a huge-inated aerobic tank, and run that turbo-charger only when you need it, or, slightly prior to needing it (if you're prepping for an event, e.g.), as 1-3 sessions of glycolytic work on top of lot of aerobic work seems to work rather nicely. Again, context... if someone comes to see me for PT improvement, and they complain of anxiety/panic attacks, "on edge", unexplained injuries/pain, and eating a lot of carbs and crap, I am taking HIIT off the table until they can better buffer they're internal environment.
Final thought: SFGs routinely run group classes organized into circuits. Such circuits are often worked 45/15 for 4 or 5 rounds of 4 or 5 movements, an approach that will obviously lead to significant lactic acid production and a not-inconsiderable degree of build up. If that approach endangers health the impact would be quite widespread. This is all so jarring exactly because it's so at odds with what everybody actually does yet it's being presented as the safe, responsible, healthy option.
Let me create a somewhat hypothetical spectrum of HIIT:
- the all out run (insert choice of tool) for 20min, as fast as you can right out the gate
- the LSD jog/walk (or tool of choice) 15:00/mi pace: 60min
What's in between?
- all out for any work interval followed by a rest interval in any given ratio, and for any given duration
Less intense = more rest less work, less overall duration
More intense = less rest more work, more overall duration
Context. And this describes one session, what about a training block of 8 weeks... 16 weeks ... the annual plan? What's the overall intensity for the year? Context... in the case your point (and well taken) where is each individual? What is the attrition rate, if any? (who reports attrition to Facebook, after all?!?!) What is the success rate? I am not arguing, I am asking these questions, because we have to.
If an SFG is using a little too much intensity, to frequently, those individuals who are at that state of health who make them susceptible to the ill-effects of intense work will drop out; while others might thrive. It is why we can't nail down a blanket prescription for intensity dosing: its a moving target among a group of individuals... context. He/she is not wrong, or incorrectly applying our principles... it is simply the nature of group training + capitalism.
Related... lactate is a buffering system that the cell uses to remove acidity (hydrogen ions [H+]). Lactate is not the devil, and is a natural occurring substrate of metabolism. You have lactate in your blood at rest. When lactate accumulates to a high degree, it is indicative of excess H+, first in the cell, then the tissue, then systemically. High lactate levels are our marker for high H+... it is not damaging in and of itself. Lactate, however, is a weak acid, and will "leak"
out H+ that is bound to it if it lays around in the blood, as in, when it can't be cleared fast enough (too much high intensity work). So, while lactate isn't the issue, a high level of its presence both indicates low pH (high H+), and if not cleared, contributes to more H+.
Aerobic function, the actual process, clears a lot of H+ (read any biochem textbook). Aerobic work: slower, lower HR, more rest... contribute to better aerobic function... more mitochondria is formed throughout muscle tissue, and a higher buffer (the act of clearing H+) rate is achieved. LSD work achieves a lot of this, especially in the slow twitch fibers... "aerobic swings" achieve some of this, especially in the type IIx fibers, and, to a much smaller degree, in the purely fast twitch (type II) fibers.
Trying to do S&S to the time goal every time out is "brief" form of high intensity exercise. You will see both aerobic and anaerobic benefits at first, and maybe for a long while (it is only a 5min "dosing"); then you will see a lack of energy, and some version of the scenario above. High acidity levels will begin to degrade mitochondrial mass and function, decreasing buffering ability, all the while you generate more and more chronic acidity as you continue to train. You will essentially become, more and more dependent on anaerobic metabolism... an unhealthy thing to do. *Note, this is a poor example, as these sessions are only 5min long, but the point is clear... consider what the longer duration high intensity circuits are doing.
Now, if you spend a lot of time reinforcing your aerobic function, AND THEN, hit the accelerator, your superior aerobic function and buffering system will afford two things:
- aerobic function will cover a higher intensity of work... meaning, you will not need to tap into the turbocharger to fuel "higher" intensity work
- when the turbocharger does light up, it's by-products will be efficiently cleared form the blood, maintaining your performance and health
Then, get back to easier aerobic work for most of the year, alternated with shorter blocks of turbocharged work.
What qualifies as staying aerobic with these swings? If you're swinging a 28Kg kettlebell then, if one's including shifts in body mass, your power output is somewhere in the 350W range (This is a rough guesstimate… My kingdom for a force plate). If you're staying completely aerobic with that kind of power output, Then you're in pretty rare company.
Simon, a great question... see directly above. Each set of swings will require anaerobic supplement to your base energy system: aerobic metabolism. To what degree of supplementation required depends upon your current state of training and health. For some, they will remain anaerobic even into the rest periods... for others, they may only tap the turbocharger for a small portion of each set (more so in the latter part of the session, but that's another story).
Context.
Did I miss anything?