As an anecdote of one, I was doing moderate intensity endurance exercise for a couple years with only modest improvements in basic cardiovascular metrics that kind of flatlined over time.
As an experiment, I switched to high-intensity interval type training for a couple months, which required about half the time to do. All of my cardiovascular metrics immediately changed in a strongly positive way. When I did the old endurance training, performance was much higher than it had been before the high-intensity training.
It is the strongest positive effect I have ever seen from any exercise/gym theory that has been widely promulgated. I never expected to see my cardiovascular metrics change as quickly or as much as they did.
You probably spent all that time training your cardiovascular base, which takes a long time to do. Then, you capped them off with anaerobic gains that were only possible with that prior work.
For optimum gain you should mix moderate exercise with intense exercise, but the time you put in likely made your later success possible.
I had a shitty winter in terms of endurance and was pretty much starting from the gutter in February. Spring and early summer we're stressful so I did mostly Z1/LSD cycling in the form of extended commuting from work to home. Nothing excessive though as stress was plentiful.
The estimated fitness or the Garmin estimate didn't budge much.
Once vacation started I kept this on for few weeks to recover and after that added few harder sessions in a two week period. Few weeks after this I felt the change and Garmin also estimated 6 mil's of added VO2MAX in a week.
Don't care about the metrics, but the added QOL from this and now I hopefully have a structure for the coming winter not to lose as much of this as the previous.
To be competitive in the sport, you need the pyramid method with the high volume base of light effort, middle of volume of sold effort (e.g. lactate threshold work) and a peak of intensity (e.g. interval training).
This is about health.
High volume of exercise is damaging via oxidative stress and other ways. Weekly training volume is the most reliable predictor for injuries.
If health and basic fitness is the goal, rather than bringing home the gold, you can add intensity to just a fairly small volume of moderate exercise, or perhaps even none at all, other than a warmup and cooldown.
That sounds exactly like what one should do for, say, couch to 10k: build a solid base in "zone 2" (low aerobic), which also serves not just as a cardio foundation but also builds the body's ability to withstand effort and impact.
Then once the base is built, to make any progress one needs stronger, more focused stimulus, so you introduce interval training at high aerobic (tempo and threshold paces) as well as anaerobic (400-800 "very hard" sustained and all-out sprints) training, combined with a few zone 2 long runs.
And then the cycle repeats: you have to let the body recover so deload, then start a new cycle.
There's a lot of noise and confusion about what exactly "zone 2" is and why. But definitely longer easier (you're not out of breath) runs build a foundation in more ways than just your cardiovascular system. It's those other components that take a longer time to build. The key is that you are not over-training (watch your sleep and joint pain as an indicator) and can recover and that you are progressively increasing your load by lessay ~10% distance a week. Easy system would be 2 shorter runs and one longer run a week.
There are plenty of online training program generators that are pretty good and will take you from zero to running 10k. I used an online program to run my first 10k somewhere circa 1990.
There a lot of more cutting edge science online (and I follow Nick as well) but if you're not a competitive athlete and are just trying to get in better shape then the answer is mostly just do it. Over some base of running you can throw in some interval training including HIIT.
I was running 10km 3x per week for a few years. When I started swapping some of those runs for HIIT, performance on the remaining 10km runs very noticeably improved in addition to the cardio metrics.
To be clear, performance-maxxing was never the objective. I am in it for the health benefits and conditioning for grueling pursuits. Nonetheless, observable effects of different kinds of training on performance are still interesting to me and helps me optimize the time I spend on it.
Are you able to point out which video explains how to find your current bottleneck? I suspect its something I would find quite useful! Unfortunately most of the videos have quite "clickbaity" titles, which makes it hard to figure out what they are about.
I don't know which video it is either, but what I've found helpful is checking aerobic decoupling. If your heart rate is drifting upward significantly over the course of an hourlong easy run despite not increasing your pace or power, then the bottleneck is probably your aerobic engine. I don't track it daily because it's a noisy metric, but looking at the overall distribution is useful.
After that it's probably determining your LTHR accurately (don't just accept what your Garmin or Apple Watch says it is). This gives a better sense of how hard to push on your hard days, and it's also useful to see what % of HRmax your threshold lands at.
HIIT can have a pretty quick impact on your VO2MAX but that is going to level off. As others have said you will want a more balanced routine in the long run.
It is also possible you were over-training in your "moderate" intensity or conversely not increasing the load/distance enough. Training over years should result in good improvement even without HIIT. You will need to put a lot more time in.
I have a pretty diverse training load these days. Hiking, mountaineering, running, plus a few sports and some resistance. While I have overtrained in the past on running in particular, it was mostly due to lack of diversity. Nonetheless, none of those things puts the same load on the body as HIIT.
To be clear, I was objectively in good cardiovascular condition before adding HIIT. My resting heart rate has been in the 40s for years. The surprise was that there was so much easy margin left by adding HIIT to my regimen.
If your heart rate has been in the 40s for years your cardiovascular system is at the peak of what’s possible. It’s not “pretty good”. A resting heart rate in the 30s is the kind of thing Olympic distance runners touch on. You are either exaggerating or your assessment of what’s normal is way off. Most very fit people have resting rates in the 50s and 60s.
High-intensity exercise is obviously good, but beware of the trap of doing just high intensity exercise and doing it too frequently - the body does not handle that amount of stress particularly well, and it will be counterproductive to your health.
Low intensity exercise that holds your aerobic base is vital as well - and for a well-rounded exercise week, it should constitute the majority of your exercise time.
That is not to say that you should neglect higher intensities, it's just that you cannot do them as often due to the disproportionate amount of fatigue they generate.
I found that setting a two minute timer and running up and down a stair case with high intensity once per day can resolve a whole host of seemingly unrelated issues.
Same. I found that picking up a 28-kg kettlebell and climbing up a 20-storey building within 6 mins (switching up hands every couple of floors) is an awesome "functional" exercise.
Hits cardio, grip strength and unilateral stability stuff.
I always run stairs when given an opportunity (big proponent of "incidental exercise"), so when I used to live in apartments I would deliberately rent a room in the highest available floor. It's shocking how much HIIT you can get out of running 20+ flights.
I'm not OP, but when I started run-jog-walking one mile, three days a week (which is a bit more than two minute stairs every day, but still asking muscles, joints, and heart to wake up), that my back pain lessened, some niggling knee tightness stopped bothering me, and I noticed an increase in how long I could go doing something moderately strenuous before craving a rest (e.g. moving boxes, or walking with a heavy object, or running after something or someone). It doesn't have to be a massive lifestyle shift -- walking a couple times a week can give similar benefits. But the jump from "basically sedentary" to "loading muscles and joints and heart for ~20 minutes 2-3x a week" is truly ENORMOUS when it comes to our biological systems, and a lot of those systems start running a lot happier with that.
Exercise is not a panacea, and those who say it will fix everything and cure depression and make you perfect are quacks. But, it pains my contrarian ass to say, some light cardio every now and again is much closer to what our bodies are happy with than desk life, such has been my experience.
This right there. No, you're right, it's not a panacea. However, it absolutely fixed the period back problems I've dealt with most of my adult life. Now if I do something to tweak my lower back, I can't wait to get to a treadmill or out onto the sidewalk. It's the one thing I know will make it feel better.
Of course, that's going to be different for everyone. It'll make some people worse. For me, though (and apparently for you, too), it is the right way to treat those issues.
For those with knees not tolerant of running, I've taken to also rucking around with a heavy backpack. It's fantastic for building torso strength, and "your body weight plus 30 pounds" is still far less impact than "your body weight, but running". Walk up some hills steep enough to make you pant and wonder if you can make it to the top and your body may thank you for it, the way mine thanks me.
BTW, doctors have a saying: "motion is lotion". Also, "when you stop moving, you die". We are not evolved to take root on a sofa. Our bodies are meant to move and jostle and bounce and twist. Absent specific reasons not to, it can make a huge difference in physical comfort.
I like sprinting a couple times up our hill, ca 10s each, 4-6 times. It’s full out, and when I‘m untrained (like now), I‘m quite exhausted afterwards.
But the dopamine boost I get from this is immense. It lasts 24-48h. I‘m in a general good mood for this period. Sometimes, a little more competitive than normal - that’s a downside.
Normal jogging or long walks don’t have this effect, at all.
A long race will do it just fine. AKA Runner's High.
I also do hill sprints. I try to do one [HIIT] workout a week and also some longer runs.
Hill sprints tend to be safer then sprinting on flat surfaces. Last time I did my HIIT sprinting on level ground my knee didn't really like that at all. A stationary bike (like the "assault bike") is even safer. Or you can just do burpies. People who don't run and haven't sprinted in a long time shouldn't just jump into sprinting.
At first I thought they found something new, however it is known that exercise intensity should be of various types for the best health outcome. In my training regimen I already have a weekly session of high-intensity training, and other session at a lower intensity.
High intensity by far gives you the best gains for the time you put in, but there's only so much you can do without overtraining.
The way to really maximize your potential is to do high intensity 30 mins 3x/wk and then intersperse it with a great deal of low intensity cardio. Like 4x more if you can, per the 80/20 rule.
It works because it's starting to approach the most exercise your body can handle. (Although some athletes definitely fit in more.)
I built this HIIT timer tool www.hiitmeup.fit for exactly this reason as I try to squeeze in a compact exercise during my busy work days. I put this out on show HN a few weeks ago and hope others will find it just as useful as I do.
Same! I used to play Max 300 in heavy mode (on repeat) at my local arcade without hugging the bar - your feet end up moving like Donald Duck from Mathemagic Land.
30 minutes and you are gassed...
Nowadays I switched over to Pump It Up - I feel like the 5-step configuration lends itself towards larger body movements and less river dancing. :)
It's interesting that they characterize a 30-second cycling effort as "all-out" when any cyclist knows it's impossible to go "all-out" for that long. You can go really all-out for a few seconds before your whole metabolic process needs to switch modes. A 30-second effort has to be paced. "All-out" intervals are very effective but for me they mean 4 seconds out of every 30 seconds.
You might need to talk to a doctor if you can only go flat out for 4 seconds before having to slow down. You may put out more power during the first few seconds, but you should be able to go substantially longer than this before falling into the limitations of aerobic capacity.
I assumed this was about uphill cycling, which depending on gradient checks out to me. It's also a function of bike, cargo, and cyclist mass. Lighter cyclists find climbs easier.
Does anyone have a recommendation for a dumb watch (<$100 USD) that has good programmability (flexible alarms) for a HIIT protocol? It would be nice if it had HRM but at that price point, maybe not feasible.
I don't want the fuss or expense of an Android or Apple watch. Garmin makes some nice models but they are still relatively expensive.
2nd hand Garmin or Apple Watch. These things are basically being thrown away and watches like a Gen 6 AW or a Fenix 5 can be found for so little money and they work very well even today if you only care about sports tracking.
I personally cannot stand Apple for sports, which is why I have a AW Ultra 1 AND a Fenix 7 lol. Got both 2nd hand for ~30% of their MSRP.
Personally something like a 2nd hand Garmin Forerunner 55 with a chest based HR monitor is for me the best budget setup. But when shopping second hand you, use what you can find. I often see great deals on things like the Garmin instinct series.
2 years ago I got a Fenix 5 for 180 and it was amazing for me. Just turn off all the "smart" features.
I would look into a used entry model Garmin. Something like a 235 (I have my old one sitting around). It has an HRM though it's not a terribly reliable one.
TL;DR: for some biomarkers, "sprint-interval exercise" (SIE) bursts as short as 5 min can be as effective as much longer periods of "moderate-intensity exercise" (MIE).
Specifically: MIE consisted of 90-min of continuous cycling at 90%–100% of the predetermined first lactate threshold, while SIE consisted of 6 sets of 30-s all-out cycling at a resistance of 0.075 kg·kg−1 body mass, with 4-min rests between the sets (Figure 1A).
The study's sample size was small and the period studied fairly short, but they did measure the levels of several thousand proteins.
"The One-Minute Workout: Science Shows a Way to Get Fit That's Smarter, Faster, Shorter"
EDIT: This book is maybe a bit old but covers a lot of ground on high intensity interval training vs. traditional training. I guess this study adds to the body of evidence that HIIT is effective. My take as a random person interested in this stuff is that ideally you are mixing both high intensity and longer duration workouts for their different benefits. But if you are limited in time it seems high intensity is a winner.
As an anecdote of one, I was doing moderate intensity endurance exercise for a couple years with only modest improvements in basic cardiovascular metrics that kind of flatlined over time.
As an experiment, I switched to high-intensity interval type training for a couple months, which required about half the time to do. All of my cardiovascular metrics immediately changed in a strongly positive way. When I did the old endurance training, performance was much higher than it had been before the high-intensity training.
It is the strongest positive effect I have ever seen from any exercise/gym theory that has been widely promulgated. I never expected to see my cardiovascular metrics change as quickly or as much as they did.
You probably spent all that time training your cardiovascular base, which takes a long time to do. Then, you capped them off with anaerobic gains that were only possible with that prior work.
For optimum gain you should mix moderate exercise with intense exercise, but the time you put in likely made your later success possible.
Exactly.
I did this on purpose this spring.
I had a shitty winter in terms of endurance and was pretty much starting from the gutter in February. Spring and early summer we're stressful so I did mostly Z1/LSD cycling in the form of extended commuting from work to home. Nothing excessive though as stress was plentiful.
The estimated fitness or the Garmin estimate didn't budge much.
Once vacation started I kept this on for few weeks to recover and after that added few harder sessions in a two week period. Few weeks after this I felt the change and Garmin also estimated 6 mil's of added VO2MAX in a week.
Don't care about the metrics, but the added QOL from this and now I hopefully have a structure for the coming winter not to lose as much of this as the previous.
To be competitive in the sport, you need the pyramid method with the high volume base of light effort, middle of volume of sold effort (e.g. lactate threshold work) and a peak of intensity (e.g. interval training).
This is about health.
High volume of exercise is damaging via oxidative stress and other ways. Weekly training volume is the most reliable predictor for injuries.
If health and basic fitness is the goal, rather than bringing home the gold, you can add intensity to just a fairly small volume of moderate exercise, or perhaps even none at all, other than a warmup and cooldown.
That sounds exactly like what one should do for, say, couch to 10k: build a solid base in "zone 2" (low aerobic), which also serves not just as a cardio foundation but also builds the body's ability to withstand effort and impact.
Then once the base is built, to make any progress one needs stronger, more focused stimulus, so you introduce interval training at high aerobic (tempo and threshold paces) as well as anaerobic (400-800 "very hard" sustained and all-out sprints) training, combined with a few zone 2 long runs.
And then the cycle repeats: you have to let the body recover so deload, then start a new cycle.
Nicklas Rossner has fantastic resources; there's a video there that explains how to find your current bottleneck: https://m.youtube.com/@NicklasRossnerPT
There's a lot of noise and confusion about what exactly "zone 2" is and why. But definitely longer easier (you're not out of breath) runs build a foundation in more ways than just your cardiovascular system. It's those other components that take a longer time to build. The key is that you are not over-training (watch your sleep and joint pain as an indicator) and can recover and that you are progressively increasing your load by lessay ~10% distance a week. Easy system would be 2 shorter runs and one longer run a week.
There are plenty of online training program generators that are pretty good and will take you from zero to running 10k. I used an online program to run my first 10k somewhere circa 1990.
There a lot of more cutting edge science online (and I follow Nick as well) but if you're not a competitive athlete and are just trying to get in better shape then the answer is mostly just do it. Over some base of running you can throw in some interval training including HIIT.
I was running 10km 3x per week for a few years. When I started swapping some of those runs for HIIT, performance on the remaining 10km runs very noticeably improved in addition to the cardio metrics.
To be clear, performance-maxxing was never the objective. I am in it for the health benefits and conditioning for grueling pursuits. Nonetheless, observable effects of different kinds of training on performance are still interesting to me and helps me optimize the time I spend on it.
Are you able to point out which video explains how to find your current bottleneck? I suspect its something I would find quite useful! Unfortunately most of the videos have quite "clickbaity" titles, which makes it hard to figure out what they are about.
I don't know which video it is either, but what I've found helpful is checking aerobic decoupling. If your heart rate is drifting upward significantly over the course of an hourlong easy run despite not increasing your pace or power, then the bottleneck is probably your aerobic engine. I don't track it daily because it's a noisy metric, but looking at the overall distribution is useful.
After that it's probably determining your LTHR accurately (don't just accept what your Garmin or Apple Watch says it is). This gives a better sense of how hard to push on your hard days, and it's also useful to see what % of HRmax your threshold lands at.
On mobile RN. I'll try to find it once I'm on a desktop.
HIIT can have a pretty quick impact on your VO2MAX but that is going to level off. As others have said you will want a more balanced routine in the long run.
It is also possible you were over-training in your "moderate" intensity or conversely not increasing the load/distance enough. Training over years should result in good improvement even without HIIT. You will need to put a lot more time in.
I have a pretty diverse training load these days. Hiking, mountaineering, running, plus a few sports and some resistance. While I have overtrained in the past on running in particular, it was mostly due to lack of diversity. Nonetheless, none of those things puts the same load on the body as HIIT.
To be clear, I was objectively in good cardiovascular condition before adding HIIT. My resting heart rate has been in the 40s for years. The surprise was that there was so much easy margin left by adding HIIT to my regimen.
If your heart rate has been in the 40s for years your cardiovascular system is at the peak of what’s possible. It’s not “pretty good”. A resting heart rate in the 30s is the kind of thing Olympic distance runners touch on. You are either exaggerating or your assessment of what’s normal is way off. Most very fit people have resting rates in the 50s and 60s.
You’d think more athletes and marathon runners would be living past 100.
It’s always that lady who chilled all day who says laughter is how she lived so long!
Your body gets used to the exercise. You have to constantly change it, otherwise you not gonna get the same thrill.
What metrics were you tracking that moved?
second this
High-intensity exercise is obviously good, but beware of the trap of doing just high intensity exercise and doing it too frequently - the body does not handle that amount of stress particularly well, and it will be counterproductive to your health.
Low intensity exercise that holds your aerobic base is vital as well - and for a well-rounded exercise week, it should constitute the majority of your exercise time.
That is not to say that you should neglect higher intensities, it's just that you cannot do them as often due to the disproportionate amount of fatigue they generate.
I found that setting a two minute timer and running up and down a stair case with high intensity once per day can resolve a whole host of seemingly unrelated issues.
Same. I found that picking up a 28-kg kettlebell and climbing up a 20-storey building within 6 mins (switching up hands every couple of floors) is an awesome "functional" exercise.
Hits cardio, grip strength and unilateral stability stuff.
This has strong vibes of "Do this and you will get rid of back pain" followed by the video of some crazy acrobatic stunt.
Congrats, BTW.
If you can haul a 60 pound lump up 20 stories, this article is not for you.
I always run stairs when given an opportunity (big proponent of "incidental exercise"), so when I used to live in apartments I would deliberately rent a room in the highest available floor. It's shocking how much HIIT you can get out of running 20+ flights.
Issues such as?
I'm not OP, but when I started run-jog-walking one mile, three days a week (which is a bit more than two minute stairs every day, but still asking muscles, joints, and heart to wake up), that my back pain lessened, some niggling knee tightness stopped bothering me, and I noticed an increase in how long I could go doing something moderately strenuous before craving a rest (e.g. moving boxes, or walking with a heavy object, or running after something or someone). It doesn't have to be a massive lifestyle shift -- walking a couple times a week can give similar benefits. But the jump from "basically sedentary" to "loading muscles and joints and heart for ~20 minutes 2-3x a week" is truly ENORMOUS when it comes to our biological systems, and a lot of those systems start running a lot happier with that.
Exercise is not a panacea, and those who say it will fix everything and cure depression and make you perfect are quacks. But, it pains my contrarian ass to say, some light cardio every now and again is much closer to what our bodies are happy with than desk life, such has been my experience.
This right there. No, you're right, it's not a panacea. However, it absolutely fixed the period back problems I've dealt with most of my adult life. Now if I do something to tweak my lower back, I can't wait to get to a treadmill or out onto the sidewalk. It's the one thing I know will make it feel better.
Of course, that's going to be different for everyone. It'll make some people worse. For me, though (and apparently for you, too), it is the right way to treat those issues.
For those with knees not tolerant of running, I've taken to also rucking around with a heavy backpack. It's fantastic for building torso strength, and "your body weight plus 30 pounds" is still far less impact than "your body weight, but running". Walk up some hills steep enough to make you pant and wonder if you can make it to the top and your body may thank you for it, the way mine thanks me.
BTW, doctors have a saying: "motion is lotion". Also, "when you stop moving, you die". We are not evolved to take root on a sofa. Our bodies are meant to move and jostle and bounce and twist. Absent specific reasons not to, it can make a huge difference in physical comfort.
I'd bet money he's talking about... men's issues
The elevator not working
I like sprinting a couple times up our hill, ca 10s each, 4-6 times. It’s full out, and when I‘m untrained (like now), I‘m quite exhausted afterwards.
But the dopamine boost I get from this is immense. It lasts 24-48h. I‘m in a general good mood for this period. Sometimes, a little more competitive than normal - that’s a downside.
Normal jogging or long walks don’t have this effect, at all.
A long race will do it just fine. AKA Runner's High.
I also do hill sprints. I try to do one [HIIT] workout a week and also some longer runs.
Hill sprints tend to be safer then sprinting on flat surfaces. Last time I did my HIIT sprinting on level ground my knee didn't really like that at all. A stationary bike (like the "assault bike") is even safer. Or you can just do burpies. People who don't run and haven't sprinted in a long time shouldn't just jump into sprinting.
What about adapting the core principle of "Greasing the groove" to cardiovascular workouts?
At first I thought they found something new, however it is known that exercise intensity should be of various types for the best health outcome. In my training regimen I already have a weekly session of high-intensity training, and other session at a lower intensity.
High intensity by far gives you the best gains for the time you put in, but there's only so much you can do without overtraining.
The way to really maximize your potential is to do high intensity 30 mins 3x/wk and then intersperse it with a great deal of low intensity cardio. Like 4x more if you can, per the 80/20 rule.
It works because it's starting to approach the most exercise your body can handle. (Although some athletes definitely fit in more.)
I built this HIIT timer tool www.hiitmeup.fit for exactly this reason as I try to squeeze in a compact exercise during my busy work days. I put this out on show HN a few weeks ago and hope others will find it just as useful as I do.
I know the most physically fit I have ever been was when I was able to do every video of the Insanity workout.
I play Dance Dance Revolution. Doing hard songs in that game is basically the definition of high intensity interval training. And it's fun!
Same! I used to play Max 300 in heavy mode (on repeat) at my local arcade without hugging the bar - your feet end up moving like Donald Duck from Mathemagic Land.
30 minutes and you are gassed...
Nowadays I switched over to Pump It Up - I feel like the 5-step configuration lends itself towards larger body movements and less river dancing. :)
It's interesting that they characterize a 30-second cycling effort as "all-out" when any cyclist knows it's impossible to go "all-out" for that long. You can go really all-out for a few seconds before your whole metabolic process needs to switch modes. A 30-second effort has to be paced. "All-out" intervals are very effective but for me they mean 4 seconds out of every 30 seconds.
You might need to talk to a doctor if you can only go flat out for 4 seconds before having to slow down. You may put out more power during the first few seconds, but you should be able to go substantially longer than this before falling into the limitations of aerobic capacity.
I assumed this was about uphill cycling, which depending on gradient checks out to me. It's also a function of bike, cargo, and cyclist mass. Lighter cyclists find climbs easier.
Does anyone have a recommendation for a dumb watch (<$100 USD) that has good programmability (flexible alarms) for a HIIT protocol? It would be nice if it had HRM but at that price point, maybe not feasible.
I don't want the fuss or expense of an Android or Apple watch. Garmin makes some nice models but they are still relatively expensive.
2nd hand Garmin or Apple Watch. These things are basically being thrown away and watches like a Gen 6 AW or a Fenix 5 can be found for so little money and they work very well even today if you only care about sports tracking.
I personally cannot stand Apple for sports, which is why I have a AW Ultra 1 AND a Fenix 7 lol. Got both 2nd hand for ~30% of their MSRP.
Personally something like a 2nd hand Garmin Forerunner 55 with a chest based HR monitor is for me the best budget setup. But when shopping second hand you, use what you can find. I often see great deals on things like the Garmin instinct series.
2 years ago I got a Fenix 5 for 180 and it was amazing for me. Just turn off all the "smart" features.
I would look into a used entry model Garmin. Something like a 235 (I have my old one sitting around). It has an HRM though it's not a terribly reliable one.
You could just make a playlist of your intervals and use earbuds, or exercising in the town square under a large clock
The sky is blue.
Cows eat grass.
Film at 11^
^more research needed
TL;DR: for some biomarkers, "sprint-interval exercise" (SIE) bursts as short as 5 min can be as effective as much longer periods of "moderate-intensity exercise" (MIE).
Specifically: MIE consisted of 90-min of continuous cycling at 90%–100% of the predetermined first lactate threshold, while SIE consisted of 6 sets of 30-s all-out cycling at a resistance of 0.075 kg·kg−1 body mass, with 4-min rests between the sets (Figure 1A).
The study's sample size was small and the period studied fairly short, but they did measure the levels of several thousand proteins.
"The One-Minute Workout: Science Shows a Way to Get Fit That's Smarter, Faster, Shorter"
EDIT: This book is maybe a bit old but covers a lot of ground on high intensity interval training vs. traditional training. I guess this study adds to the body of evidence that HIIT is effective. My take as a random person interested in this stuff is that ideally you are mixing both high intensity and longer duration workouts for their different benefits. But if you are limited in time it seems high intensity is a winner.