Sprint Intensity Intervals to increase FTP

Hi all,

I’m wondering if anyone has tried Sprint Intensity Training to increase their FTP, as described in the TrainerRoad video on YouTube here: Sprint Intensity Training | Better Than Endurance and HIIT? - YouTube. Yes, it seems counter-intuitive that 30 second sprint intervals should increase your one hour time trial pace, but that’s what the research says according to that video.

I’ve done several weeks of FTP intervals (2x15’s) and another several weeks of VO2 Max intervals (4x4’s), both with gradually increasing intensity. After all those weeks my FTP went up…four watts, to 206 watts or 3.1 watts/kg. I’m in my mid 50’s, training for 30 years and I seem to be at a plateau – maybe that’s all I can do at my age, but maybe there is more I can do. I’m looking for the next thing I can do to increase my FTP. Thoughts?

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Hi Northk,

To help you we need to know more about your training. What does a week of training look like for you? (hours, intensity, frequency)

SIT can help you develop more explosive power. That is not something you need for a 20+ minute FTP. For a higher FTP you need to increase the strength and duration of the muscles to take fat and oxygen as fuel.
The primary ways to do that are:

  • long slow ride until fatigue (when it start hurting without going faster). Consider a training like that a hard day.
  • extend the duration of training just below your threshold (zone 3/4 out of 5). Consider this your hard day.

I neither give you DOMS, go longer.


I’m curious as well concerning high/maximal efforts for true masters athletes (not like Trevor, whose still a young pup). Im 57 yrs old (very soon to be 58) and have been racing since '87 and am starting to see the decline.

Since we lose muscle mass, agility, and vo2max gets closer to threshold, etc. does it make sense that "seasoned’ athletes become even more polarized ie more training above LT2, since these efforts would seem to be the ones that proportionally decline the greatest, and less at threshold/SST/Tempo?

To put it more generally, does the typical training protocol scale when it comes to true masters? Or should it be tweaked to the right?

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Hi northk,
I am not familiar with the TrainerRoad training with the 30s sprints, and from what I know and have done with my athletes 30s sprints more your anerobic capacity which could theroetically help all power above threshold but it is really about spending more time at intensity around threshold. When boosting threshold for my ahtletes I like to use intensive and extensive intervals. Intensvie are shorter at 4, 6 or 8min done at cieling of threshold and even into low VO2, so 103-107% FTP sets of 3-5. I use extensive to work fatigue resistance and schedule these at 90-95% FTP at longer durations of 12-20M. 3x12m, 3x15M, 2x25m even 1x30-40min. etc. Additionally, when working at more max power of short 30s durations actually takes away from FTP as you are working anaerobic power and your anaerobic energy system which takes away form your sustained power. As much as one would think, it is my experince and knowlegde that you can only train one energy system and capacity at a time for real gains. INSCYD testing might provide better insights as it provides a virtual report showing if VLaMax which is your high end 30sec or less power is decreased how much your FTP will increase.

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Really appreciate being called a young pup… don’t get that too often.

My response to the question (which is a great one) is, like all things related to physiology, it’s more complicated than that. Much of the research showing gains in endurance and sustainable power from sprint work was with untrained or recreationally active individuals. In that case, it’s going to improve all sides of your fitness.

We’ve also talked about how all training does hit certain pathways for adaptation, so sprint training will help everyone with endurance and sustainable power.

But, if you are a trained endurance athlete and all you did was sprint work, your threshold power and endurance are going to suffer. The sprint training is only going to be a benefit on top of the more targeted work that needs to be done to raise your FTP.


@kjeldbontenbal and others, thanks for your replies. Here is what a typical week looks like for me in spring and summer:
Mon - 60 minutes moderate to heavy weight lifting: single-leg squats, sumo deadlifts, push-ups and incline dumbbell rows.
Tues - 60 minute interval ride with 4x4 min VO2 Max intervals or 2x15 min FTP intervals at threshold
Wed - 90 minute ride zone 2 endurance pace
Thurs - Rest
Fri - 60 minute ride zone 2 endurance pace
Sat - Hard “freeride” with some zone 2, mostly zones 3 and 4, for 2 hours to 2.5 hours with 30-45 minutes of zone 4 in it.
Sun - Rest

Total TSS of 300 to 330 over 5.5 to 6.5 hours (not counting weight lifting), about 90-100 miles.

In winter I do two days of weight lifting with heavier loads, and three endurance rides zone 2 for 90 minutes each. Maybe this isn’t enough intensity or miles in the off season but the weight lifting leaves me so sore that it’s hard to think about doing any intervals. However, the weight lifting year round is like magic elixir – I feel so much better on my bike and I don’t have all the aches and pains I used to have.

I would like to increase my FTP so I can start racing time trials again. Thanks for any thoughts.

I’ve been doing 30/30s in 4 sets of 10 minutes or 2 sets of 20 minutes. Great for mountain racing! The main issue I have with the super high intensity is the soreness that follows. If I do the workout on Tuesday, I feel it in the legs the rest of the week. I can easily go back to back days subLT (2x20) with no soreness issues. One of those things were you have to find the balance.

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It looks like you are focusing your training on intensity. To increase your FTP you can shift the total amount of hours you have to extending your aerobic training duration.
Can you make that Saturday ride into a z2/z3 until failure instead of a given amount of time?
(Failure=you start to feel a burn.)

If you can, do a z1 recovery the next day for around 30 minutes. Then keep doing z1 rides until your DOMS is gone. Then hit it hard to build your anaerobic muscles. (SIT, but not 30s, but ‘until burn’)

If you lack the time for the above you can still try to take some intensity out of most sessions and have 1 hugely intensive session instead. To increase the fun in during the rest of the week, vary between z1, z2 and maybe z3 without far accelerations.
If you can plan and measure your new ‘aerobic intervals’ you should see a steady increase in power output over time.
You probably max out in 6 months and need to borrow time to shift to the first suggestion, or accept very slow increases year by year.


Just about any novel stimulus can enhance adaptive stimulus for some period of time at least. If SIT is novel, you might enjoy the process of gaining confidence & competence in performing it! Oh, and your FTP might even improve while you’re at it! :yum: The nice thing is, workout programming is not mutually exclusive. I’m about to contrast HIIT vs SIT, but I don’t mean to say one is “better” than the other. The correct answer is “yes, and”

A colleague of mine recently published a series of meta-analyses on the benefits of SIT and HIIT on time-trial performance, which sounds like is exactly what you’re interested in. His primary finding was that there was no difference in how much TT performance improved with either HIIT or SIT training. However the subgroup analyses might be of further interest:

  1. Interval duration

Longer duration HIIT (>4-min) was moderately (and meaningfully) more effective than shorter duration HIIT or SIT at improving TT performance

  1. Training status

Trained athletes (which IMO is distinct from fitness, see below) see less of an effect from either SIT or HIIT on TT performance compared to inactive (untrained) participants.

  1. Age

The only studies which included (n=2) with subjects > 40 yrs were performed with inactive subjects and so may not be representative for you in particular. But they found a large meaningful positive effect of SIT on TT performance. Interestingly, there were no studies with group mean age > 40 yrs who performed HIIT, but directionally, increasing age is associated with less (and negative) effect of HIIT on TT performance.

  1. Fitness

Higher VO2max (i.e. higher fitness) was directionally associated with less effect of SIT (to a greater degree) and HIIT (to a lesser degree) on TT performance.

Please consider this descriptive data that consider some interesting factors that maybe we haven’t thought about. This isn’t prescriptive at all for what you “should” do, and as I said, SIT or HIIT is a “yes, and” answer to improve performance & fitness (and enjoyment!).

I will post some bonus nerdery with some of his unpublished (exclusive!) plots below.


Bonus nerdery:

The way to read this forest plot is that the dots and lines represent individual study findings (means & ranges of outcomes). The diamonds represent the cumulative results from all studies in each subgroup, and the diamond at the bottom captures all studies. So the highlighted diamond captures the findings from all papers with trained subjects.

The X-axis is the percent (%) change in TT performance. The vertical dashed line is at 0% change in TT performance. If the diamond (or individual study lines) crosses the vertical zero-line, it indicates non-significant findings (change in TT performance could be due to chance). The width of the lines and diamonds indicates the variability in outcomes between individual subjects.

So there is a larger positive effect from SIT on TT performance in untrained subjects (6.02%) vs active (3.63%) or trained subjects (2.98%), with a lot of between-subjects variability that is not explained by training status.

This is a linear meta-regression… fancy way of asking the question: “as x-value (age) goes up, which direction does y-value (% change TT) tend to go?”. In this case, for increasing age, % change in TT performance goes up. Each bubble represents a study mean % change in TT. The highlighted studies as mentioned have mean age > 40 yrs. Solid line is the trendline, dashed lines are the expected variability (range of expected outcomes).

Equation at the top can be used to predict % TT change. So for every +1 yr of age, a 0.11% additional positive change in TT performance is expected (+1% per 10 yrs age).

The two highlighted studies have an outsized influence on the slope of the trendline since they are so far to the right of all the other studies (bubbles). Take them out and the trendline would probably be flatter (less or no difference in % TT change with age). So maybe take this finding with a grain of salt. Also, as mentioned, the two highlighted studies are in untrained subjects, so a larger effect might be expected (as per above forest plot). Additional studies with trained subjects > 40 yrs might show around the same outcome on the y-axis as with younger subjects.

More meta-regressions for VO2max (fitness) on TT performance for both HIIT and SIT. For every +1 ml/min/kg higher VO2max, %TT performance is expected to improve by 0.04% LESS following HIIT, and 0.12% LESS following SIT. i.e. TT performance typically still improves, but it improves less in athletes with higher VO2max following HIIT. And EVEN LESS following SIT.

But another way to describe this is to say that subjects with lower VO2max may tend to see greater improvements in TT performance by following SIT compared to HIIT. The trendline is higher at low x-values for SIT, than for HIIT.

I like to visualise data like this to think about where an athlete lies across multiple dimensions of age, fitness, training status, sex, etc. to predict how they might respond to an intervention. And especially to appreciate the variability I should expect in their response. Then to re-calibrate things if and when they drift outside of that expectation.


This discussion is interesting. As a 60+ masters athlete I too struggle to increase muscular endurance and feel like just maintaining the status quo is a lot of work in and of itself.

Joe Friel in “Fast After 50” (which was written in 2015) opines that older athletes primarily see a decline in VO2max due to muscle loss as we age. He advocates for a focus on maintaining VO2max capacity to (some extent) over the sub-threshold work younger athletes need to build FTP.

Curious what this community thinks about building and maintaining muscular endurance in 50+ and 60+ athletes. Is Joe Friel correct in highlighting a different training focus?


The thing that jumps out at me that hasn’t been mentioned is the duration of these training blocks. If you’re looking for a big push on FTP through training at FTP, you probably need more than a few weeks. I don’t know what “several” is, but I surmise that this is probably two training blocks, 3 weeks of FTP, 3 weeks of VO2max. I would push FTP intervals for more time than that for an athlete whose fractional utilization indicates they have room to grow.

In addition, depending on your periodization, progress the duration (time in zone) of the FTP intervals rather than increasing power, assuming this is “base” work and not close to race season.

I’m not sure that Friel advocates for a different training focus. Rather, I think he highlights the need for VO2max/MAP interval maintenance on a much more regular basis than other athletes. So, this doesn’t mean that all or most of what you do is MAP intervals, it just means that where a younger athlete might spend a few months working intervals around FTP in addition to their volume riding, an older athlete probably needs some MAP/VO2max work in there as well.

In application, during base development, I have one of my master’s athletes doing MAP intervals of 2-minutes duration at a lower volume (4x or 5x) every two weeks in place of one of his threshold workouts. Wasn’t needed in race season, but maintaining intensity year-round for this 64-year-old athlete with a deep base of fitness seems beneficial for him… YMMV.


Thanks everyone for your responses! A lot to think about here.

And, to answer @Kurt.braeckel last question on training block duration, I did 7 weeks of 2x15 FTP intervals followed by 9 weeks of 4x4 VO2 max intervals. I also took a rest week of three short and easy rides every fifth week, with no intervals.

Increasing time in zone is really tough because those intervals never got much easier even after doing them all those weeks in a row. In other words, I was pretty spent after a 4x4 VO2 max workout the first week, and still just as spent after the ninth week of 4x4 VO2 max intervals at only a slightly higher wattage. And the same with FTP intervals. It seems like this has been the case as far back as I can remember doing intervals…which is many years.

I get that you are supposed to progress time in zone (more intervals or longer intervals at the same watt targets) as the training block progresses – that makes logical sense and is pretty much how every pre-built training plan works. But that has always been very difficult (nearly impossible) for me. I’ve never understood why that is so hard for me. So I’ve never had very good luck with pre-built training plans because my body just can’t follow the time-in-zone progression increases. I quickly reach a point where I can’t complete the additional time-in-zone and end up under-recovered too. To top it off most training plans don’t work in strength training into the schedule so they don’t work every well if you are lifting weights year-round.

Your last paragraph is very interesting.
Given the earlier observation that there is a lot of intensity in your week, you may be better capable of extending your intervals if you get more rest/low intensity sessions for the rest of the week.


Piling all these observations together, I’d suggest a couple of things:

  1. You’re not recovering well enough, as mentioned. Maybe because:
  2. Your target power on your threshold sets is too high.

You should be able to progress time in zone at threshold and threshold shouldn’t leave you trashed, particularly not 2x15.

  1. By consistently progressing power, there’s a good chance you’re consistently training above your threshold, since your baseline functional threshold doesn’t change quickly (heat, fatigue, sleep, etc. can impact it on a day-to-day basis). This is why a time progression is generally a better idea unless you’re actually trying to progress to maintain a certain power for a certain duration (e.g. build training for a specific TT).

You might find more success by targeting a somewhat lower power and extending duration.

Which leads to my question:

  1. How are you determining your FTP and thus your FTP interval training power? The protocol you choose (or model you’re using) can make a big difference, and there’s a chance you’ve got your FTP overestimated… and then when you progress intensity rather than duration, you’re just compounding the problem. You might choose a longer protocol, or even an “hour power” test, or better dial in your “feel” for threshold and progress duration. Lots of ways to skin the cat.

Re: strength training… you might find success by putting your strength sessions on the same day as your interval sessions, if you can spacing them out by 4hrs (strength at least 4hrs after intervals). This will help you maximize your recovery and easy days, rather than trying to do strength on what should be your recovery days.



Your comments are very astute. I think you are probably right on both counts (too high of an FTP setting, and I need to do less intensity and longer rides at lower intensity instead).

I didn’t think I was doing too much intensity (as measured by minutes in zone). Time in zone at zones 4, 5 and 6 is about 23% over the last three months according to Training Peaks. But when I think about the heavy weights day once per week, that adds a lot of intensity. So, I am actually doing three days of intensity per week – one heavy strength day, one FTP or VO2 Max interval day, and one hard and fast weekend ride, in addition to two more easy rides. That may be too much for me as a mid-fifties athlete along with working full-time.

I also think you may be right that my FTP may be set too high. I don’t think I could actually hold 206 watts for an entire hour. I do use a standard FTP test protocol using a warmup with high-end burn-off before the 20 minute test. It’s either from Training Peaks or from Zwift. Here is what it looks like:

  1. Warm up I - 20 minutes at zone 1/2
  2. Warm up II - Ramp up 3 min @ 60-80 % of FTP
  3. VO2 Max Burn 1 - 20 sec @ 90 % of FTP
  4. VO2 Max Burn 2 - 20 sec @ 110 % of FTP
  5. VO2 Max Burn 3 - 20 sec @ 130 % of FTP
  6. Recovery - 3 min @ 60 % of FTP
  7. VO2 Max Burn 4 - 3 min @ 110 % of FTP
  8. VO2 Max Burn 5 - 2 min @ 120 % of FTP
  9. Recovery - 6 min @ 55 % of FTP
  10. 20 Min FTP Test - 20 min @ 100-120 % of FTP
  11. Recovery - 5 min @ 55 % of FTP

Despite that, I think it could be set too high. I’m pretty sure I could probably do 190-195 watts for an hour, but probably not 206. Riding a real 60 minute test is the only way to be sure, but that is very exhausting and would require a lot of rest time before and recovery time after.

Also, I’ve noticed that my heart rate time in zone often doesn’t match my power in zone. Frequently on endurance rides that are supposed to be zone 2, my power shows 20% - 30% of the time in zone 1 but my heart rate shows maybe 5% - 10% in zone 1. So, heart rate is in the correct zone 2 but power is not. I’m pretty sure my max heart rate is pretty close to accurate at 181 BPM, since I haven’t seen anything higher than that in years even at full sprinting and other all-out efforts. So, heart rate zones should be pretty accurate I think.

I have tried doing strength training on the same day as intervals (morning and evening split), but that leaves me so exhausted and sore that I’ve needed 2-3 days of rest afterwards. But, maybe it would work better if I do less intensity overall for each week.

Many thanks for your thoughtful responses. I think I need to make some changes and we’ll see how it goes!

I think he also mentioned the importance of weight lifting for the older riders. For me, that includes core exercises, since they are muscles. That and I think working on muscular endurance, among other things. So my rides up mountains at a lower cadence helps with the muscular endurance.