# What exactly does 2x20 for an interval mean?



## .steve (Jul 13, 2005)

For intervals, what does the 2x20 or 4x40 or whatever they suggest to use when you are wanting to do interval training? Are those numbers ratios, times of pushing a big gear vs. rest, what? I have no clue and feel stupid for asking but whatever. Thanks!


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## Andrea138 (Mar 10, 2008)

Usually the second number is the length of the interval & the first one is how many times you repeat it.


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## BassNBrew (Aug 4, 2008)

Two intervals, 20 minutes in duration each.

Anyone doing 4x40s is da man.


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## wim (Feb 28, 2005)

Usually, 2 x 20 would mean 2 work intervals of 20 minutes each. Your training program or coach would tell you the time of the rest interval(s) between the 20-minute work intervals, the effort at which you should be riding the work intervals and the rest interval(s) and, sometimes, an exact gear size for the work intervals. There are many variations on this, sometimes involving sets of intervals. Sets are packages of intervals in between which you are given more time to rest completely—like 2 sets of 5 x 4, for example. Contrary to what you sometimes hear, intervals aren't random periods of time during which you just go "as fast as you can." They're much more structured than that.

4 x 40 doesn't sound realistic.


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## function (Jun 20, 2008)

Regarding intensity, don't start too hard otherwise your power will drop off too much around the 10minute mark. Try and keep the intensity the same throughout.


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## Creakyknees (Sep 21, 2003)

Most of the time people that talk about 2x20's are referring to threshold pace. I.e. the fastest steady pace you can sustain for at least 20 minutes. 

Like a time trial. In reality your actual pace will be a bit lower, because it's not an all-out effort where you sprint at the end. And, you have to leave fuel in the tank for the next 20.

Usually the rest period is 5 or 10 minutes. The idea being spin around slow n easy till your legs, heart and lungs are completely back to baseline so you can make the second as strong or stronger than the first. But make no mistake. Properly done 2x20's hurt. 

Pace can be measure in a number of ways. Perceived exertion - i.e. feeling your legs - is a reliable way (with experience). Heart rate _Can_ be useful, if you know what you're doing. Same with power meter, or just a stopwatch, a loop, and your gears.


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## shawndoggy (Feb 3, 2004)

Creakyknees said:


> Most of the time people that talk about 2x20's are referring to threshold pace. I.e. the fastest steady pace you can sustain for at least 20 minutes.


You don't need to do them quite that hard this time of year. I'd shoot for more like 95% of your *one hour pace*. 

4x40... yeah, that'd be badass. I've done 1x90 several times and 4x25 once.


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## gatorling (Jun 25, 2008)

2x20 usually refers to 2 sets of 20 minute intervals done at 90%-100% of your best 1 hour pace, also known as FTP (Functional Threshold Power).
(If you're doing them at your best 20 minute pace then this falls inbetween threshold and VO2Max. Lots of people I know like concentrating on raising their threshold power since it's believed that it's much more trainable than VO2Max).

You could do 60 minutes at FTP but that would suck, and if it doesn't suck then you're not doing it at FTP. FTP is defined by your very best effort for a 1 hour time trial, if you can go longer than 1 hour at your FTP then your FTP is wrong 

That's why people do 2x20 (because an hour at FTP sucks soooo very bad), it's mentally less taxing and much more sustainable.

If you're new to threshold intervals even 2x20 might be too much. I'd suggest starting at 2x10 then moving to 3x10 and eventually to 2x20.


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## .steve (Jul 13, 2005)

Wow, thanks for the responses! And yeah, the 4x40 was just a combo of numbers that I thought of as I posted the message. I am new to the interval thing but have been logging data with my 305 all year so I THINK I know my FTP at this point. I tried my first 2x20 with a 10 minute warm-up before and recovery in between yesterday on my trainer and I was pleasantly surprised at the workout but the best part was the fact that it made the hour on my trainer go by MUCH faster. Thanks for all the info!


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