Why is the hardest part of a 2x20 the start of session 2?
neeb
Posts: 4,473
If I do 2x20 at only 95% FTP I'm feeling not too bad at the end of the first session, but then after 5mins of easy pedalling the first 5mins of the second session seem if anything harder than the last 5mins of the first... Is there a physiological reason for this, and is it connected with the training benefit you get from doing this type of interval?
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Maybe and I doubt it. Perceptions of difficulty vary across individuals and will vary for yourself day to day and session to session, and as you adapt and improve fitness. For some it's the final minutes they find most taxing.neeb wrote:Is there a physiological reason for this, and is it connected with the training benefit you get from doing this type of interval?
State of glycogen stores, use of drugs like caffeine, and circadian rhythms all have their impacts on how we perceive difficulty of effort, amongst many things (especially motivation).0 -
Interesting, thanks. I also find the final minutes the most taxing if I'm doing the intervals at a slightly higher intensity, but with 95% I feel I've got a little bit in reserve at the end of the first session so it's not so bad, but the 5min break seems to make the start of the second session harder.0
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Normally about 11 minutes into the second 20 for me.Alex_Simmons/RST wrote:Perceptions of difficulty vary across individuals ....0 -
Something I've noticed too. My idea was that after my (8 minute) rest blood flow in teh active muscles has reduced a bit and it takes a few minutes to get all the systems going again. At the end of the second interval its plain ordinary hard! Lots of lactate, the end is close but can't be hurried etc etc.0
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That makes sense, although wouldn't you then expect to find that the start of the first interval was hard too? (whereas I usually find that's the easiest bit, after 10mins easy warmup). Maybe some specific type of reduced blood flow associated with recovery, or an interaction between reduced blood flow and fatigue?ut_och_cykla wrote:Something I've noticed too. My idea was that after my (8 minute) rest blood flow in teh active muscles has reduced a bit and it takes a few minutes to get all the systems going again.0 -
I completely agree with you that the effect is real, neeb, and also that, at only 95%FTP, the end of the second interval shouldn't be too stressful. This makes it all the more odd that the first 5 minutes of the second interval seems so hard.
I'm in no doubt that it's a real, systematic, physiological effect and not a random one because I've experienced it myself so many times and so have many of the riders I coach - but I don't know the exact explanation for it. Maybe ut_och_cykla is right, but 'freshness' masks the same effect for the first interval?
Ruth0 -
What about just doing the workout as a single 40 min session? A common reason given for 2 x 20 min seems to be that it breaks the workout up a little and provides some rest in the middle, but if the rest is making the start of the second interval harder is there any point?
I'm relatively inexperienced in longer turbo intervals (sweetspot / threshold / etc) but am planning to introduce them during the current winter and into spring, so interested in others' thoughts on this. Is there any difference in training benefit between the two approaches? I'd expect not, as I would expect it is a function of the amount of time spent at a particular intensity.0 -
Not a shameless plug for my pointless blog, but I've just started doing 2x20s seriously.
http://mikespowerblog.blogspot.co.uk/
There's a 2x20 min at 100% FTP session there. The first session starts off a bit wobbly due to a bike issue and I allowed myself to relax a bit at the end of the first session as I was above the target power. Throughout the first session I felt fine.
For the second session I was fine until around 16 mins, then I had a strange drop in power before I went for it at the end of the session to use up my remaining energy and to try to get my average power for the session as high as possible.
The differences between the sessions is that my HR increases a lot quicker at the start of the 2nd session despite being roughly the same at the start. I find this with all intervals; each successive interval givesme a higher HR in a shorter time.0 -
Yes - I think freshness (lack of highish lactate level?) would account for the relatively easy start of the first one. Its something I noticed when I was a spinning instructor too - doing double sessions. First one was fine, second one was AWFUl to start but not too bad at the end. Clearing away all those biproducts in from the muscles/ blood takes some time/energy and at steady state you can just cope , but when effort decreases for a while (& blood supply is reduced) the muscles struggle at a cellular level to do their job. Similar when you stop for a longer break, or are doing big hills with long descents - the start of the next is always grim but gets easier once you get into your rythm (and blood supply increases again!)BeaconRuth wrote:I completely agree with you that the effect is real, neeb, and also that, at only 95%FTP, the end of the second interval shouldn't be too stressful. This makes it all the more odd that the first 5 minutes of the second interval seems so hard.
I'm in no doubt that it's a real, systematic, physiological effect and not a random one because I've experienced it myself so many times and so have many of the riders I coach - but I don't know the exact explanation for it. Maybe ut_och_cykla is right, but 'freshness' masks the same effect for the first interval?
Ruth0 -
Everyone on this forum thinks there has to be a physical reason for everything, and entirely negates the influence of their mind on performance.
Of course, only the pros will acknowledge this is the case.
Oh, and the hardest bit is getting off the sofa.All the above is just advice .. you can do whatever the f*ck you wana do!
Bike Radar Strava Club
The Northern Ireland Thread0 -
No-one is downplaying psychological factors, but it's just as easy (far easier in fact) to attribute everything to something as fuzzy as psychology and ignore physical explanations, isn't it?dw300 wrote:Everyone on this forum thinks there has to be a physical reason for everything, and entirely negates the influence of their mind on performance.
Of course, only the pros will acknowledge this is the case.
Oh, and the hardest bit is getting off the sofa.
Separating the two completely is impossible of course, the mind is ultimately physical (if astoundingly complicated) and states of mind influence the body through the nervous system and hormones, while the condition and state of the body in turn influence the mind.
It's certainly interesting to look at areas where the distinction is most blurred though. The one I have the biggest problem with is "maximum efforts". I don't really believe that anyone is capable of producing a genuine maximum effort without a massive psychological investment in the outcome, e.g. a one time chance to achieve a major life goal, or literally having a a gun at your head. The question is how steeply does this tail off until we get to the situation where you are trying to do a "maximum effort" just to see how your FTP has changed in the last 4 weeks...0 -
dw300 wrote:Everyone on this forum thinks there has to be a physical reason for everything, and entirely negates the influence of their mind on performance.
Of course, only the pros will acknowledge this is the case.
Oh, and the hardest bit is getting off the sofa.
Not everyone.0 -
For me the hardest parts are the middle quarters of the first 20 and the last 5 of the last. During the first one I think it's a mix of it's starting to feel hard plus there's a long way to go - the last 5 of the last because of fatigue. I tend to do them as hard as I think I can sustain though unless I'm tired or easing my way back into these kind of sessions.
it's a hard life if you don't weaken.0 -
Just do a 1 x 40, don't need to worry about the start of the second 20min set :P0
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That's what I suggested above, but I was also looking for some feedback from some more exprienced turbo users, especially those that do a lot of longer intervals.danowat wrote:Just do a 1 x 40, don't need to worry about the start of the second 20min set :P
If the workout is less than FTP, then surely completing 40 mins is perfectly achievable, so why break it into 2 x 20? If it's just to "break it up" then surely this is only beneficial if you don't end up feeling worse on starting the 2nd interval.0 -
"An athlete should do the least amount of the most specific training that brings continuous improvement." - Joe Friel, The Cyclist's Training Bible0
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JGSI wrote:"An athlete should do the least amount of the most specific training that brings continuous improvement." - Joe Friel, The Cyclist's Training Bible
While I undersand where he's coming from, this isn't a very helpful quote because:
For most people it's hard to achieve a continuous improvement, life and the body do not work like that.
As a result it's hard (if not impossible) to determine what the least amount is,
Or what the best (most specific) training actually is.
And why not do more than the minimum to achieve a greater continuous improvement?0 -
GiantMike wrote:JGSI wrote:"An athlete should do the least amount of the most specific training that brings continuous improvement." - Joe Friel, The Cyclist's Training Bible
While I undersand where he's coming from, this isn't a very helpful quote because:
For most people it's hard to achieve a continuous improvement, life and the body do not work like that.
As a result it's hard (if not impossible) to determine what the least amount is,
Or what the best (most specific) training actually is.
And why not do more than the minimum to achieve a greater continuous improvement?
Finding the most specific training should not be that difficult if one knows the event one is training for and the athlete. Determining the least amount is difficult. I think many cyclists try to do too much in the belief more must be best. Friel understands that if you do not get the right recovery & rest you can damage months of work by getting overtrained or a bit run down which leaves you vulnerable to infection and makes you stale. 'Stale' or 'Flat' athletes do not perform at their best or make good progress in training. I think it is better to err on the 'perhaps not doing quite enough' side rather than the done too much side, particularly if they are doing a lot of anaerobic work.0 -
And that's the problem. Most cyclists are not single-event athletes. They're general all-rounders.0
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dgstewart wrote:so why break it into 2 x 20? If it's just to "break it up" then surely this is only beneficial if you don't end up feeling worse on starting the 2nd interval.
Training stress I'd imagine, might have to look at my data tonight and see the TSS difference between 2 x 20 and 1 x 40....0 -
danowat wrote:Training stress I'd imagine, might have to look at my data tonight and see the TSS difference between 2 x 20 and 1 x 40....
Would be interested to know what you find. I can't see how it could provide a different TSS, as I understand this to be calculated as TSS = (sec x NP x IF)/(FTP x 3600) x 100 (from Joe Friel's site). Therefore 2 x 20 and 1 x 40 for the same NP, IF and FTP, would give the exact same TSS in total. Note, this ignores the contribution from the 5 mins or so recovery in between the 2 x 20, but surely that's pretty small.
I could see the benefit if it was something like 4 x 30, at a power level that could not be sustained for the full 120 mins in one go, therefore recovery breaks would be required to actually complete the workout. Whether that would be a sensible session is another matter, just using it to illustrate the point
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dgstewart wrote:as I understand this to be calculated as TSS = (sec x NP x IF)/(FTP x 3600) x 100 (from Joe Friel's site).
since IF = NP/FTP, then it's far easier simply to use:
TSS = IF^2 x hours x 100
where IF^2 = IF x IF0 -
Alex_Simmons/RST wrote:since IF = NP/FTP, then it's far easier simply to use:
TSS = IF^2 x hours x 100
where IF^2 = IF x IF
Of course, you're right. I did notice this the first time I looked at the equation a while back, but forgot when I was posting last night. Makes it even simpler to see that 2 x 20 and 1 x 40 at the same power gives the same TSS (again ignoring rest period).
Any thoughts on potential benefit of doing 2 x 20 vs. 1 x 40 then? Is it just that some people find it easier, but if you find the rest makes the 2nd inteval hard to get going then you'd be better just keeping going for the 40?0 -
dgstewart wrote:Any thoughts on potential benefit of doing 2 x 20 vs. 1 x 40 then? Is it just that some people find it easier, but if you find the rest makes the 2nd inteval hard to get going then you'd be better just keeping going for the 40?
If you find it easier to do a 1x40 rather than a 2x20, isn't this a reason to do the 2x20 as it's an area of relative weakness?0 -
Could it just be that the specific benefit of doing a 2x20 requires that you do them hard enough so that you would not be able to do a 1x40 at the same intensity? Obviously that would go against conventional wisdom because you would always doing them at slightly more than 100% FTP.
Or perhaps it's just that TTS is not infallible as a measure or how much recovery will be required, especially for shorter intervals? It's just a simple model after all and necessarily imperfect.0 -
2 x 20, for me, is no mans land, not long enough or hard enough to be of much benefit, to me, and my competing, 1 x 40 is much more relevant.
FTR, the TSS for my 2 x 20 is actually higher than my 1 x 40.........0 -
Mentally it can be difficult for someone to actually do 40 mins in training at their FTP, hence breaking it down into 20-30 min chunks. 20 mins at FTP shouldn't be in no mans lands really, the effort should be telling towards the end of each interval, if it isn't do them slightly harder than FTP. As Alex has said many times, they are pretty self correcting in terms of the effort they can be completed at.
If the TSS for 2 x 20 mins (excluding the rest period) is higher than a 1 x 40 mins, then you have done the 40 mins of the 2 x 20 harder than the straight 40 mins.0 -
It takes your body between 30-40 mins to start producing endorphins as a result of exercise. These help quell pain and give you a lift. So for a typical 2x20 session, you've started the 2nd 20 before the endorphins have kicked in so you will still feel some of the effects of the 1st 20, plus the psychological negative of having another 19 mins to go in the session. After 5-10 mins you're feeling the endorphins as then start to come on stream plus you've broken the back of the interval.
Physical + psychological
FCN3: Titanium Qoroz.0 -
Wrath Rob wrote:It takes your body between 30-40 mins to start producing endorphins as a result of exercise. These help quell pain and give you a lift. So for a typical 2x20 session, you've started the 2nd 20 before the endorphins have kicked in so you will still feel some of the effects of the 1st 20, plus the psychological negative of having another 19 mins to go in the session. After 5-10 mins you're feeling the endorphins as then start to come on stream plus you've broken the back of the interval.
Physical + psychological
And if I do a 20 minute warm-up, I get endorphined somewhere betrween the middle and end of the first interval?0
