PeterLuffman
Level 5 Valued Member
I understand there is growing evidence and research that documents the negative effects of HIIT training?
Does anyone have any links to actual studies?
Does anyone have any links to actual studies?
Other/Mixed Negative health affects of HIIT
- Thread starter PeterLuffman
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Other strength modalities (e.g., Clubs), mixed strength modalities (e.g., combined kettlebell and barbell), other goals (flexibility)
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North Coast Miller
Level 9 Valued Member
I don't think you're going to find any relative to the way HIIT has been developed and studied in a controlled environment.
Anecdotally you'll find all kinds of articles describing rhabdomyolysis and a host of other overtraining symptoms. These tend to be short on specifics or are discussing something more like metabolic conditioning than textbook HIIT.
HIIT done in a manner using short duration repeats over a short training session with only a few sessions/week, is probably the most researched exercise protocol ever studied aside from the DeLorme method. The only negatives I've come across are where it only performed as well as the steady state methods it was compared against. Highly conditioned folk also seem to derive little benefit, meaning folks at the elite level.
Used intelligently (research and anecdotally, many work to rest ratios have been used successfully) it is remarkably consistent in improving all sorts of energy system metrics for most people.
Anecdotally you'll find all kinds of articles describing rhabdomyolysis and a host of other overtraining symptoms. These tend to be short on specifics or are discussing something more like metabolic conditioning than textbook HIIT.
HIIT done in a manner using short duration repeats over a short training session with only a few sessions/week, is probably the most researched exercise protocol ever studied aside from the DeLorme method. The only negatives I've come across are where it only performed as well as the steady state methods it was compared against. Highly conditioned folk also seem to derive little benefit, meaning folks at the elite level.
Used intelligently (research and anecdotally, many work to rest ratios have been used successfully) it is remarkably consistent in improving all sorts of energy system metrics for most people.
PeterLuffman
Level 5 Valued Member
Thanks for the reply.
More specifically, I'm referring to the material for Pavel's Strong Endurance seminar. I was under the impression he goes into this topic. Just wondering if there's any reading material available before I attend next month.
More specifically, I'm referring to the material for Pavel's Strong Endurance seminar. I was under the impression he goes into this topic. Just wondering if there's any reading material available before I attend next month.
North Coast Miller
Level 9 Valued Member
I'm interested in that too, I'd like to see where the cutoff is and how determined.
Sean M
Level 7 Valued Member
@PeterLuffman I believe this article would be of interest to you:
StrongFirst for CrossFit
It goes into some of the “why”. There is also some good stuff on AGT on this blog, from our own @miked:
Why do antiglycolytic training? - Part 1
StrongFirst for CrossFit
It goes into some of the “why”. There is also some good stuff on AGT on this blog, from our own @miked:
Why do antiglycolytic training? - Part 1
PeterLuffman
Level 5 Valued Member
Thank you Sean. That was a good read.
miked
Level 6 Valued Member
Thanks for linking to me! It always feels good to know there are readers out there.
I have a better central list of A+A stuff here - including random rants about why HIIT is bad (the way that most people do it)
Alactic + Aerobic Training (A+A) — Barbell Strategy
Here are some other random HIIT articles I've written - I need to get them indexed better
HIIT works for everyone...until it doesn't
Competitive HIIT Will Kill You
Anti-glycolytic Training Is Like Weight Training For Your Mitochondria
Anti-Glycolytic Training for Endurance Athletes
Mitochondrial mediated cellular apoptosis
Why everyone does Tabata wrong
Antiglycolytic training: invest in your future
Mitochondria Biogensis, Anti-glycolytic Training, and Vegetable Oils - Part 3: Execution
Glycolitic training as a tail event
PeterLuffman
Level 5 Valued Member
Fantastic! Thanks Mike!
Bill Been
Level 5 Valued Member
Despite how often it’s flatly stated ‘round these parts, the actual science on HIIT being harmful in any lasting way (IE beyond temporary over training effects/stalling) doesn’t exist. Articles quoting other people who’ve written articles......are not scientific backing.
North Coast Miller
Level 9 Valued Member
So we don't toss the baby with the bathwater....
Acidosis overrides oxygen deprivation to maintain mitochondrial function and cell survival
Lowered pH in a hypoxic environment protects mitochondria down to a pH of just over 6. A value for fully exhausted muscle is about 6.5-6.4 at the lowest, 6.9 in the surrounding tissues and progressively higher in the bloodstream. If you take mitochondria out of the body and put in a mild acid bath it will immediately begin pumping out ATP, in the absence of any other signalling. The duration of operating with a lowered pH is the important factor, and can actually inhibit immune response (mitochondria have no problem with lowered pH in a physiologic range, but lymphocytes and other white blood cells do).
High-intensity interval training evokes larger serum BDNF levels compared with intense continuous exercise. - PubMed - NCBI
This is really good read on some of the ins and outs of differing exercise strategies on mitochondria biogenesis, although it will be TL/DR for most:
http://gih.diva-portal.org/smash/get/diva2:766681/FULLTEXT01.pdf
This factor also improves insulin sensitivity and increased fat burning from EPOC. Exercise-induced increase in insulin sensitivity and the body's natural antioxidant defenses are dependent on ROS from mitochondrial glycolysis.
Antioxidants prevent health-promoting effects of physical exercise in humans
And another good read that demonstrates any continuous activity above the anaerobic threshhold will lead to reduced performance primarily due to metabolic byproducts from CrP pathway, not lactic acid or lowered pH. Have mentioned this before but didn't link the research.
Challenging the Role of pH in Skeletal Muscle Fatigue
Anyhow, the above has nothing to do with prescribing different loading and recovery strategies for specific outcomes. Results speak for themselves, so pointing out the beneficial aspects of HIIT should not be seen as any sort of criticism or whatnot. Its good for what its good for and a bad idea for everything else.
Folks need to remember that HIIT is primarily a strategy for tuning the metabolism, not for building muscle. Used this way it is a great tool in the box, esp for time challenged individuals. The other take-away is too much glycolytic work in an otherwise healthy individual will predominately impair immune function, not mitochondria, although it has been shown to negatively effect mitochondrial enzymes. Smoke = Fire, maybe so. There is a "J" curve theory that seems to link longer duration/high intensity training or even single competitive events to an increase in upper respiratory infections and several inflammatory markers.
Excessive Exercise and Immunity: The J Shaped Curve | Request PDF
Acidosis overrides oxygen deprivation to maintain mitochondrial function and cell survival
Lowered pH in a hypoxic environment protects mitochondria down to a pH of just over 6. A value for fully exhausted muscle is about 6.5-6.4 at the lowest, 6.9 in the surrounding tissues and progressively higher in the bloodstream. If you take mitochondria out of the body and put in a mild acid bath it will immediately begin pumping out ATP, in the absence of any other signalling. The duration of operating with a lowered pH is the important factor, and can actually inhibit immune response (mitochondria have no problem with lowered pH in a physiologic range, but lymphocytes and other white blood cells do).
High-intensity interval training evokes larger serum BDNF levels compared with intense continuous exercise. - PubMed - NCBI
BDNF important for age-effected cognitive function and memory loss. Any aerobic work helps this, HIIT helps a little bit more.
This is really good read on some of the ins and outs of differing exercise strategies on mitochondria biogenesis, although it will be TL/DR for most:
http://gih.diva-portal.org/smash/get/diva2:766681/FULLTEXT01.pdf
This factor also improves insulin sensitivity and increased fat burning from EPOC. Exercise-induced increase in insulin sensitivity and the body's natural antioxidant defenses are dependent on ROS from mitochondrial glycolysis.
Antioxidants prevent health-promoting effects of physical exercise in humans
And another good read that demonstrates any continuous activity above the anaerobic threshhold will lead to reduced performance primarily due to metabolic byproducts from CrP pathway, not lactic acid or lowered pH. Have mentioned this before but didn't link the research.
Challenging the Role of pH in Skeletal Muscle Fatigue
Anyhow, the above has nothing to do with prescribing different loading and recovery strategies for specific outcomes. Results speak for themselves, so pointing out the beneficial aspects of HIIT should not be seen as any sort of criticism or whatnot. Its good for what its good for and a bad idea for everything else.
Folks need to remember that HIIT is primarily a strategy for tuning the metabolism, not for building muscle. Used this way it is a great tool in the box, esp for time challenged individuals. The other take-away is too much glycolytic work in an otherwise healthy individual will predominately impair immune function, not mitochondria, although it has been shown to negatively effect mitochondrial enzymes. Smoke = Fire, maybe so. There is a "J" curve theory that seems to link longer duration/high intensity training or even single competitive events to an increase in upper respiratory infections and several inflammatory markers.
Excessive Exercise and Immunity: The J Shaped Curve | Request PDF
PeterLuffman
Level 5 Valued Member
Thank you North Coast! Lots for me to get stuck into here!
North Coast Miller
Level 9 Valued Member
@PeterLuffman,
I am no expert, but in my opinion it is best not to overthink/overanalyze this topic beyond a fairly superficial level, although as stated it has been heavily researched and the links I provided are tip of iceberg. There are good reasons to avoid the rep ranges and TUT that will predominantly be using glycolysis. This to get the specific adaptations that come with training at other load/TUT strategies.
Folks using a ton of metcons or low or zero external resistance HIIT for strength or for longer distance endurance are going the wrong way. Also there is very little evidence to suggest extended duration training at these intensities will prepare you any better than intervals. Although it might confer a certain mental confidence when you have to dig deep it also is liable to leave you flatter or the same physically, and take more of your training time/recovery resources.
Works well for metabolic reasons, works well for time-challenged aerobic improvement (a little is better than a lot), works extremely well for improving recovery doing high intensity work. The other edge of the sword - glycolytic resistance training is proven to induce good size and moderate strength gains going back to DeLorme's seminal work.
For aerobic/metabolic work, more than one or at most two sessions/week are all that is needed as a supplemental, and if you go hard a la Tabata, it can take as little as fifteen minutes including warm up and cool down. I pared my jump rope HIIT back to a single 12 minute/week session and still noticed big gains transferring to resistance recovery over a 6 week period, starting at week 3.
Or you can periodize it into a peaking block for more of a competitive effect as advocated most often here. Good reasons to train either/or, but they are for training adaptations, fret not the metabolic harm aspect. Is more harmful to your training time than anything else if programmed poorly or overused.
I am no expert, but in my opinion it is best not to overthink/overanalyze this topic beyond a fairly superficial level, although as stated it has been heavily researched and the links I provided are tip of iceberg. There are good reasons to avoid the rep ranges and TUT that will predominantly be using glycolysis. This to get the specific adaptations that come with training at other load/TUT strategies.
Folks using a ton of metcons or low or zero external resistance HIIT for strength or for longer distance endurance are going the wrong way. Also there is very little evidence to suggest extended duration training at these intensities will prepare you any better than intervals. Although it might confer a certain mental confidence when you have to dig deep it also is liable to leave you flatter or the same physically, and take more of your training time/recovery resources.
Works well for metabolic reasons, works well for time-challenged aerobic improvement (a little is better than a lot), works extremely well for improving recovery doing high intensity work. The other edge of the sword - glycolytic resistance training is proven to induce good size and moderate strength gains going back to DeLorme's seminal work.
For aerobic/metabolic work, more than one or at most two sessions/week are all that is needed as a supplemental, and if you go hard a la Tabata, it can take as little as fifteen minutes including warm up and cool down. I pared my jump rope HIIT back to a single 12 minute/week session and still noticed big gains transferring to resistance recovery over a 6 week period, starting at week 3.
Or you can periodize it into a peaking block for more of a competitive effect as advocated most often here. Good reasons to train either/or, but they are for training adaptations, fret not the metabolic harm aspect. Is more harmful to your training time than anything else if programmed poorly or overused.
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