The art of intervals?
 

I've been reading articles about interval training for years, have done plenty of intervals, but I think there are still a lot of things left unexplained about how to actually approach them and what a specific interval accomplishes. This has, likewise, left me with some questions that come about as I do my sessions.

1. The intent is to "ride as hard as you bloody can", but can you actually do intervals too hard? I've found that if I push beyond the red zone, especially on the first interval when I'm most fresh, I'm unable to recover well enough to finish the rest of the session strong (or even at all). Is the goal in actuality to ride hard but also modulate your effort so you can finish the session, even if you feel like you had more left in the first few intervals? Your goal, really, is to ride beyond FTP, so a whole session at even 101% is going to be more more valuable than cranking one out at 125% and then burning yourself down to below FTP by the end, correct?

2. Is the longer the interval duration, the longer you train your body to ride at that effort? Obviously, the longer the effort, the less power you can produce since you have to sustain it, so is riding a 20 minute interval where you're close to FTP going to produce the same gains as a 3 minute interval where you're well in excess of FTP?

3. Do short, more or less VO2max intervals (30s-1min) improve overall speed, or only your ability to produce short, extremely powerful surges? Likewise, does doing short hill repeats at all-out effort really only produce short-burst power/speed?

4. One of the key points of intervals is to limit the rest period between each effort. Is there benefit to decreasing the rest time, even if it inhibits your ability to produce the necessary power on each subsequent effort? Or is it better to give yourself the time needed to recover for the next one to give 100% the entire session?

5. If your goal is simply to get stronger and faster in general, are the longer intervals more valuable than the short 1-2 minute intervals? Or is a combination of a short and a long interval day each week a better overall compliment? Is an 8-10 minute long (say 3x8) session a mix of both worlds, or is that not a suitable replacement for, say, a 2x20 day and a 15x2 day? Is there not really a one silver bullet that produces the best all-around results?

In general you should be riding the intervals at an intensity that allows you to complete the set. If you're doing 6 intervals with limited rest in between the first couple should feel relatively easy and the final one should be a struggle.

One of the most effective interval sets for raising FTP is 6x5x1 (6 - 5min intervals with 1 min rest) @ 106-108%FTP so you don't have to do long intervals to improve your ability to ride longer durations.

1 min isn't long enough for a VO2Max interval which is typically in the 4-6 min range. Short 30-60S intervals are useful for improving your anaerobic work capacity. Can be useful for longer term energy systems if you keep the rest interval short, i.e. 30S on 30S off.

Shorter rest is fine for aerobic systems but if you're looking to improve your sprint you should generally be fully recovered in between efforts.

Why do you want to get 'stronger and faster in general'? Are you racing? Any training plan will involve an assessment of your strengths and weaknesses and consideration for the requirements of the events or type of riding you're training for.

An important criteria for interval sessions is to pick something you can do consistently for a period of time. VO2Max intervals 5 times a week are fantastic for raising your VO2Max but you'll want to blow your brains out after a few weeks and would be unlikely to keep doing them.

Perhaps I've gained a misguided understanding of what a VO2max interval is. Is this 4-6 min. at a specific target % over FTP? I should point out that I don't have a power meter to actually know where I'm at, so my interval work is all by feel (other than HR, which isn't a great indicator).

1. Ideally, you want to do the whole set, with each interval at the same power, finishing while feeling like maybe you could do one more, maybe not. That takes practice with each interval protocol, to get the feel for what the first one should feel like. I like to do them as hill repeats. Then I can judge my relative power easily by how far I get up the hill when the time runs out. If I'm supposed to do a set of 6 X 6' f.i. and on #5 don't get as far up the hill as on the first 4, then I did them a hair too hard and my power has thus dropped off. So I stop with that one, because the training effect of doing them at a lower power is less and I'm better off saving my energy for another day.

2. Each interval protocol targets energy systems is a slightly different way. Some protocols increase endurance at a specific power level, some increase maximum power output, some increase anaerobic capacity, etc. My goals have always been for endurance rides. I'm not interested in anything shorter than a metric century because I'm older so my VO2max is squat but my endurance isn't bad. I don't race formally, but every long event ride is really a race for me. Anyway, the training regimen that has worked best for me is to periodize my workouts. I start with base work. Next is tempo work, especially low cadence tempo work. Then long sweet spot (Z4) intervals, 15'-30'. Then long VO2max of 6'-8'. Then shorter 3' VO2max. Then speed work with 30"-2' efforts. Then full sprints every 5'. Then event taper. Each interval protocol builds on strengths developed by the previous protocol. And of course I mix them together, not usually doing only one protocol/week.

3. Short efforts are called speed work. They are designed to increase your average speed on the flat. They are done at very high power and high cadence. No, they don't just increase your momentary power. Short bursts on hills increase leg strength and ability to put more power on the pavement. Hopefully you'll be able to translate that to greater sustainable power on steep hills. Maybe your legs won't pack it in on 20% grades anymore.

4. Decreasing the rest time is designed to increase the protocol's stress on clearing (burning) lactate. The more lactate you accumulate, the better you get at burning it. That can be a key improvement, i.e medicine one can take as necessary. Longer rest time increases the power one can put down, which has a slightly different effect.

5. "Traditional" periodized interval training uses a variety of protocols, which I talked about in #2. However there is very good evidence that all you really need to do is one set of 4 X 8' X 8 anaerobic intervals once a week. That seems to produce a very good result. Some studies show it producing a higher FTP than the usual long Z4 FTP intervals.

Joe Friel's blog has good info on intervals:
Joe Friel - Intervals, Part 5

Here is some guidance on specific VO2Max prototols: https://fascatcoaching.com/tips/vo2-max-intervals/

This was actually the reason for one of my questions. I find that it's easier to remain disciplined about producing above-FTP power if I do them on hills. However, the longest hill I have within 50 miles takes around 1 minute to climb. Thus, why I questioned if there's any value in 30s-1m intervals.

This kind of brings me to an additional question. I've heard guys who race talk about doing Z4 intervals before, and didn't think to question why at the time. My FTP is just a few bpm shy of entering Z5, and it seems most riders are in that same general area with their FTP. So, wouldn't Z4 intervals just be training your body to do what it's already capable of doing?

So, if you're in a predominantly flat area, short and hard intervals are the way to go? And by short, are you talking 1-2min, or 5-6?


Is that 4 x 8min with 8 min rest?

Personally, I find that I output power slightly differently while climbing, while riding flats and while riding slight 1-2% downhill grades. So I try to do intervals in all three types of terrain. My recc is to focus your work on terrain you'll be riding in for whatever your event is. In your case there's no event, you just want to ride faster in your everyday terrain, which is flats. So I'd focus my interval work on flat terrain. Obviously a big descent will screw up an interval. But anything from -3% to +5-6% is great for most intervals IMO.

I'm predominantly a Time Trialist, so I work on outputting steady power in the range of grades I've listed above. The very interesting thing I've observed from riding with recreational friends is that I'm faster by virtue of the fact that I've learned how to stay on a number longer. Some of that is a fitness thing but some is mental, you're just more tenacious when you learn how to be tenacious. I learn a lot of that during very long intervals- sometimes 20, 40 or 60 minutes. Likely not appropriate intervals for you, so my point is not to advocate for them. It's more that learning to stick with a number for the entire interval I think can make you faster, regardless of FTP. It's a riding style thing.

I think the intervals you speak of -- ALL OUT EVERY INTERVAL -- have their merits. That is, your effective output will lower with each interval (which will go up as you get more fit), but it will recruit more and more muscle fibers and cause the body to really reach deep to fuel the muscles and deliver oxygen in that complete neuro-muscular effort.

That being said, I don't think that you should perform that type of interval all the time. Maybe once a week to supplement other interval training.

Do a google search on the different types of intervals.

Some intervals will have you doing 20 mins AT FTP then 10 mins at like 90% ftp, then 20 mins AT FTP, then 10 mins at 90%, etc...
Some intervals are going to be like 1-5 minutes at 120-130% ftp, etc etc...

There's a lot of research into the most effective type of interval training. Personally, I think the all-out effort type of short interval really has it's place. Look up tabata intervals. But you don't really hear them talked about that much in cycling.

Sure there's value in them but not a heckuva lot unless you're trying to get really good at going up that one hill.
No, Z4 intervals get you better at holding that power for long periods and also increase the power you can hold. FTP is power you can hold for an hour. That's a long time. Just hitting your LTHR doesn't mean anything.
No. Times and zones I mentioned before are appropriate for any terrain.

I really don't understand when people talk in the language of Power based training but without power numbers. I just can't seem to translate from the specificity of power down to the loose, ballpark-it realm of "going by feel." Maybe--hopefully-- it makes sense to you guys, but I just can't tell what's being said or how it's being assessed. I'm kinda surprised it works at all, to be honest.

Here's my take on intervals having done just about every interval under the sun. I have reduced my solo workouts down to four different rides:

1) One or two efforts of 15-30 mins at 92-95% of threshold.

2) 45-75 mins at 86-90% threshold

I do one and two a couple of times a week from Nov- March.

3) A continuous 10-20 minutes alternating 40s on at ~125% of threshold with 20s easy.

4) A Strava KOMs ride (most around are between 1 and 8 minutes) that I hit pretty close to flat-out.

I do three and four Mar-April.

Then while in the midst of full-on racing I'll hit all four at one point or another whenever the mood strikes.

Only the KOM ride is done more or less as hard as I can. Everything else is done in moderation. I'm a big believer of consistent, progressive workload so none of my workouts are viewed in the context of just that single workout. Instead they're part of a weeks-long build and are approached as such (meaning flexibility with power numbers and duration as needed).

There are two things that I think have put my cycling fitness over the top, the first is consistency, just riding, period. Since I'm (and have been for 30-years) a cycling commuter, I have a lot of consistency in riding. The second thing (and I believe it's the icing on the cake) are intervals of all types, including all-out sprints from a dead stop. My cardio at 52-y/o is outstanding because of this; I have a resting H/R in the mid-40's and a max H/R in the low 190's and I can sustain a HR of over 160 for a very long time.

However, because of this I'm prone to over-training and have done things to force myself to ride slower more often. But, lately I've failed and now I think I'm feeling the effects of burning myself out -- I just can't stop riding faster.

I just saw this article, hopefully it slows me down:) The Art of Riding Slow : Keep Your Heart Rate Low | Bicycling

I'm not sure if you can do it too hard, but you can definitely do them too much. That's my problem, it's very hard for me to NOT do a sprint after sitting at a red light. No matter how hard I push it, now that I've been doing them for years, I can recover very well, use to be that only a couple of those sprints could ruin my ride, but not now; however, doing them day-after-day, does definitely have a beat-down effect on me.

Go by breathing. That is a good measure of oxygen consumption until panting starts. Then it's a measure of CO2 removal.

Zones, whether figured by power or heart rate are based around the effort one would use to ride hard steadily for 1 hour, finishing by falling off the bike in complete exhaustion. Heart rate based, it's called lactate threshold (LTHR). Power based, it's called functional threshold power (FTP). Whatever it's called, it's when you're breathing as fast as you can while still breathing deeply. The ability to keep this up for a long time, up to an hour, is a result of a terrific amount of hard and consistent training.

Further:
Z1: breathing deeply but slowly. Starting to sweat a little. Easy to ride all day.
Z2: breathing deeply and steadily. The top of Z2 is when you notice that your deep breathing rate is starting to increase more rapidly. A conditioned cyclist can ride for hours at this pace.
Z3: breathing deeply and fairly rapidly, tiring but not going hard enough to exhaust one in the near future.
Z4: breathing deeply and quite rapidly. Pain in legs begins to increase from lactate buildup. 20 minutes is a long time at this pace.
Z5: Over LTHR and FTP: panting. Deep breathing no longer possible. This is the start of anaerobic effort. You're not burning much oxygen to get energy. Instead, you're panting to try to get rid of CO2 buildup. 8-10 minutes is maximum.

The boundary between zones 3 and 4 is ill-defined and somewhat arbitrary. Zone 3 is an area where you tire yourself but aren't going hard enough to get a good training effect.

Andrew Coggan and countless others would disagree with you on that. Working that boundary between zone 3 and 4 (upper z3, lower z4) gives you one of the greatest bang for the buck workouts you can get, and once that's repeatable and sustainable for quite a while. It's generally called "sweetspot" training and is generally around 88-95% of FTP.

I consistently put more time in that zone during the winter months than all the others when I'm only getting in 7-8 hours a week.

Gives an excellent training effect. Same for just straight-line z3. 60-90 min steady in z3 is a very nice workout.

That is true, and I do the same, but it's all about training volume and goals. Probably for low volume and the goal of general fitness, sweetspotting is very good. I supposet there are good arguments to be made for highly polarized training even at low volumes, but those are fine point distinctions most relevant to specific athletes, some of whom may respond better to either method.

In short, there's more than one way to catch a fish.

Agree. 2x30' in the sweet spot is my bread and butter all through spring.

Sure there is. I can't sustain highly polarized training throughout a winter and then a season. I like to get "strong" through general tempo/threshold work and then get "sharp" through race efforts when that time rolls around.

i respond quickly to high intensity work so it's unreasonable for me to do polarized training for any longer length of time. I spent my first five seasons doing that and I'd come out roaring in April and be nowhere in July. With nationals and lots of good NRCs coming through the summer and into September, I'd much prefer to be able to sustain race fitness through the summer with a more periodized (general to specific) approach that is sustainable for a much longer time.

Reviving this thread for a little more education, now that I'm beginning a new season with a rested set of legs and ready to get regimented.

First, perhaps this is too simplistic of a view, but are intervals not essentially akin to weightlifting, in that if you want to be able to lift X, you have to lift X once, which will gradually allow you to lift X in higher repetitions and eventually increase the value of X and begin the process over again? The reason I ask, and I'm sure there's a perfect physiological explanation for this, but I regularly see recommended intervals with target power values less than FTP (say 85% or 95%), but what does riding below what you're already capable of actually accomplish if increasing your FTP is your goal?

To that end, could intervals be done simply by feel? ie, riding at a pace that you know for certain is beyond what you could possibly sustain for an hour?

Now, putting rubber to the road, my next question: how do you translate %FTP values for a given interval over to HR (for those without a power meter)? For example, VO2max I often see is upwards of 106% power, but if I tried to do an interval at 106% of my LTHR, I wouldn't last more than a minute or two on my fittest day. Is there a more targeted %LTHR to utilize for those training with HR? If I wanted to do, say the aforementioned 6x5x1, or true VO2max, what HR values am I looking to attain to benefit?

Yes, HIIT type activities and weightlifting can be seen in the same light, because (for one) they are both Anaerobic, and not aerobic.

I can't type anymore, since I'm just up and haven't even had my first cup of coffee....

So I'll just post this link which talks about comparing weightlifting and HIIT. But it's not to say HIIT is better, personally I think both are needed to keep a strong, healthy body, especially as we age.... https://www.newscientist.com/article...rval-training/

This is long, but it and part 1 (and a whole bunch of the other wko webinars) are well worth the watch.

This year I've adjusted my interval routines quite a bit.

Over the winter I did:
1) a lot of 5-6 mins at vo2 with 4-5 in recoveries (usually 5-6 repeats) in the fall.
2) very long sweetspot intervals, building from 90 minutes to a final 3 hours (but now back in the 1 hour to 90 minute range)
3) some extended ftp work to a minimum of 30 minute repeats.

Currently (March) I'm doing:
1) harder and harder ftp work (20-30 mins and pushing the wattage higher)
2) 30-35 second all out hill repeats with 8-10 mins in between.
3) big, long, hard kitchen sink type group rides at 300+ tss on the weekends.

The season starts in earnest in two weeks in which case I will likely go back to only:
1) 5-6 min vo2 repeats
2) 60-90 mins sweetspot
3) 20-30 min ftp

over the course of two weeks or so as those are things that I've noticed start to go away with the either "full-gas or full-chill" scenario of racing a lot.

In my experience with hr in correlation with power, you've got to wait for and expect a big lag. To give you my number, about 180-183 is what I'll hit for a full on 6-8 minute vo2 max effort. In my interval training, I may hit 178-179 by the end of the first 5 min repeat, 179-180 by the end of the second, all the way up to 182-183 by the end of the fourth or fifth (usually if I try a sixth it starts going back down because I'm dead).

At no point am I ever sprinting or going harder in the beginning to illicit that hr response, because as you've pointed out before (and I've experienced numerous times myself), it completely tanks the rest of the workout.

I think at the end of the day, you've got to realize that just because your hr isn't in a particular zone doesn't mean you're still not benefitting from an effort that will eventually put you in that zone. Your ultimate goal is to maximize time spent at that effort to give you the biggest training stimulus, so you've got to plan for that.

And 6x5x1 is not a vo2 max workout in my opinion. No way to continually hit vo2 after the second or third repeat with only one minute rest. You're going to be falling back towards ftp pretty quickly.

I've always done the 6x5+1 intervals with a 105-108% of FTP target, which is just about the boundary between FTP and VO2max. If I do them right it usually goes something like:
#1: ugh
#2: okay this is not too bad
#3: I am awesome!
#4: uh, how many more?
#5: please kill me
#6: this sucks but this is the last one, c'mon clock, how frickin' long can 5 minutes be?!?

Before I got a PM, I tried to correlate HR but in retrospect I did the first 2 way too hard and the last 2 not hard enough because of the HR lag. You still get good training out of it, but I would pay more attention to RPE than HR if you don't have a PM. Probably the best way to do them without a PM is by speed if you have a nice consistent grade hill.

But that's something a bit different. I'd suggest if you're trying to maximize gains in vo2 max, you need to do them quite a bit harder (115%+). And the only way to do that is with quite a bit more rest (generally in the realm of 1:1).

The 6x5x1 is more like something I'd expect to be more specific to FTP (especially in that 105%-110% range) and giving it a bit of a "pull up".