25 min threshold interval

I just started outside training in the last few weeks and today I done 2 x 25 min intervals at 240 watts with an ftp of 245. Should I increase the time of these intervals or maybe do more intervals or increase intensity also?

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Are you following a plan? What does the plan say? What are your goals?

At the min I’m doing a 4/5 hour spin, a threshold effort, vo2 effort and a 2 hour endurance( a week) no plan but probably will do an ultra event next year for eg 500 to 600km.

It always better to increase time in zone and progress the interval lenght. If you have done 2x25 you can do 3x20 or even better 2x30 and then return to 20 minutes or even 15 and do 5x15 or 4x20. You can also shorten the rest between intervals and do 3x20 with shorter breaks etc.

Also interesting option is doing threshold intervals after some fatigue - for example 3x20 after 1000kJ or do them during long ride with spacing between intervals. This is completely different workout and you will be able to see if the wattage changes in time during this intervals (so holding 20 minutes threshold fresh Is not the same like holding 20 minutes after 1500kJ ride).


Yep as above - time in zone is absolutely key - when you can do 4x20 or 2x30 @ the power then up it a few Watts and go back to 3x15 and repeat… :smiley:

Sorry, I’d have to disagree with advice already given. No one should put themselves through 4 x 20 mins at threshold! If your ftp is set right, 2 x 20 will be more tham enough high intensity for a single workout, keep the rest in zone 2.

Why? If your TTE is for example 50 minutes, 40 minutes (and effectively around 30-35 minutes) is not enough stimulus. Maybe 4x20 is tad a lot, but 3x20 or 2x30 is a perfectly doable workout and I did not have any problems with recovery doing this 3x week. It all depends how your long your TTE is - if it is 35 minutes - then yes, 2x20 at the beginning should be enough - but then you want to progressive overload that threshold, to see some adaptations.

and this: https://www.youtube.com/watch?v=t9cMtn3pe8A

You want to increase time in zone or intensity - Time is zone (so more interval time or number of intervals) is a lot easier option.


For experienced cyclists this is necessary to achieve sufficient stimuli and continue adaptation. For a beginner cyclist (or any other endurance athlete for that matter) completing even 1 x 20 is a major challenge. As you develop however your ability to spend time in zone naturally increases.

FTP is the theoretical power you can put out for an hour, in its most basic definition. Thus, for most 40 minutes (2x20) is not enough stimulus to foster adaptation. Particularly as we plateau in our progress or near the limits of our physiological capabilities, you cannot simply increase watts to continue adaptation. At this point increased volume or changing the stimuli is the key.

There are a lot of things to consider when answering this question. My first question is when was the last time you tested your FTP? If it’s been a while you should retest and see if you are not actually achieving the stimulus you think you are. Perhaps you are due for an FTP bump (intensity). On the other hand, if your FTP is accurate and you have just hit a plateau then you have a couple options. One is to do what you suggest and increase the length of your intervals (volume). This can come in many forms, such as lengthening the interval itself or shortening the recovery in between. Personally, my next step would be 2 x 30 as was previously suggested. If that is not enough stimulus for you and your FTP is accurate, move on to the below method.

Since you clearly have a solid endurance engine if you can hold 25-30 minutes at your (accurate) threshold, its time to look elsewhere if you are not seeing gains. That means switching up your training and focusing on other energy systems. Based on this your weakness is definitely not on the endurance side, but I’m guessing you have some untapped potential anaerobically. Especially right now with events being cancelled, pretend you are a different kind of cyclist. Perhaps throw an imaginary crit or MTB race on the calendar using Plan Builder and run through some short power work. If we neglect our anaerobic system we naturally also limit the extent to which we can increase our aerobic capabilities. A stint in the land of VO2 and Sprint work may be just what the doctor ordered. As you upper end capabilities increase you may find more untapped potential on the lower end of things as you return to endurance focused work.


Great advice. You definitely have a point in regards me doing a lack of sprint work( barely any sprint stuff) but I am doing a vo2 workout once a week for the last few months. I’ve done a 550km cycle each of the last 3 years and have gotten quicker but feel as that my speed should have increased more so my endurance would I would say be fairly strong but definitely lack that short power.

@teamkennyg I’m guessing you’re getting ready for an ultra event. So you’re at LEAST 4 months out.

I know a little bit about you…enough to say you’re aerobic base is pretty large. Here’s what I would do. Pick one day out of the week and do an hour of power. Don’t do it by your power meter. Go find your last ramp test. Use TR analytics to highlight the 1 minute step that is closest to your FTP generated by that test…note your average HR for that highlighted section.

Once a week ride for an hour at or a little bit above that heart rate. Every week, track your power drift and average power during that hour interval. First couple of times you try this you might see substantial power drift (down) between the first 10 minutes and the last 10 minutes of the interval. Over time, average power of the interval should trend up. If it doesn’t, you’ll know you’re reaching too much & you can back off.

That’s not a workout that is well suited for most cyclists but it’s a good approach for ultra training. IMO.

And, of course, when you’re a couple months out, start to add some VO2 & anaerobic stuff. You know the drill.


That training will be tough - and yes maybe 4x20 @threshold would be a tough workout so maybe start @sweetspot 88% and move up slowly - this would have to be progressed slowly over several months to make it manageable. I have done back to back 25m tt on a weekend before so nearly an hour@ FTP on consecutive days - and it’s hard but doable so 4x20 or 2x30 @FTP is a tough but doable session. In fact a few years back in the UK the National 100m record fell on a Sunday morning to a guy who had ridden a 48min 25m tt the previous afternoon…depends how fit you are :rofl:

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Cheers, I’ll try that out. A good workout and a good measuring tool as well I guess.

agree…keep going longer, and more time in zone.

doing these at 2,000kj or beyond will definitely be great! Wrote this article that included those, let me know if it helps.

Good luck!!!