Why am I so tired after only 2hours with 120 avg watt?


I have training for some time now.
Last year my ftp was 190, due some issues I back in the training ritme since some time now.

One of the issues I always have had is that after outdoor training between 1h and 3h with just a normal ritme: 140 avg heart rate and 120 avg watt, I come home and I am so tired for the whole afternoon that I need to sleep.

An example, yesterday a gravel ride 42 km with 2h an average 100 watt. I have drank 1 bottle (75cl) water with two energy gells. Afterwards super tired.

Could it be that my metabolism ask more food or energy input than average?

An idea could be, just thinking out loud, that based on your ftp, resting hr and then the metrics during the training that your Wahoo or Garmin tells you and gives you a fuelling scheme based on your body, metrics and other factors. Somebody should be working on such an algorithm no?

Also, could this tiredness be because of the fact that I have a lot of pain in my neck during riding? I have made a bike fit some time ago and everything is dialed on my bike to the millimeter

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Hate to say this but if 2 hours is really killing you at 55-65% FTP you need to get to see the doctor ASAP - something is not right - 99% of the time it isn’t serious but your overall health is far more important than the cycle training we all do as a hobby! - good luck


It is entirely possible that you are simply experiencing discomfort and perhaps tensing up a little on those outdoor rides. 2 Hours is still a significant chunk of time and part of the way you feel after longer rides is general discomfort that you will experience regardless of effort.

Also you could be totally ‘dialled in’ for the best race position not necessarily the most comfortable so consider that too.

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Are your rides relatively steady effort? If you’re charging up short climbs repeatedly, you might “average” 100 watts but still wear yourself out.

Also, how confident are you that your FTP is correct? If it was 190 a peak number last year, it may have dropped a bunch during your time away from training.

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It was a little more intense then I thought when looking at the numbers

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2 hours at over 1 IF seems like it would ruin anybody


Average HR 140 seems relatively high for an average power of 120. I fully realize HR is individual (ie you’re 140 is my 100 etc…). But, everyone using HR and power should have a good idea about their HR to power relationship in every zone.

If your relationship seems not normal then PM not accurate perhaps.

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You could of course be anaemic or have some vitamin deficiency.


Another thought is hydration. 1 bottle for 2 hours? I drink 1 bottle in 1 hour on the trainer. When outside, I have to do at least that much. No idea what the temperature was, but if it is hot, I need at least 2 large bottle per hour (and still lose the hydration battle).

Looking at your metrics – I would say that is a pretty intense ride.

What was your fueling like before the ride?


That’s not only measuring one side by any chance is it?

200 TSS seems an awful lot for a 2 hour ride at 100 watt average (unless of course your FTP is set to around the 100 mark).

There is not one obvious answer but:

Your 2hr ride shows an IF over 1 which is impossible Your FTP is higher than your device thinks but probably significantly lower than 190

Fatigue is going to track NP not avg power.

A ride with a 140avg HR is a very tough ride.

I’m going to guess that your 2hr ride was at 80-90% of your current FTP

So you are tired because it was a challenging ride in your current fitness state. All this new fangled mathematical fitness stuff is very sensitive to starting with accurate current data.

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The TSS and IF you’re seeing here is based on whatever training zones and FTP you’ve set in the Wahoo app. What do you see when you upload the ride to Trainer Road?

I have the same problem now in the winter. I’m much more tired when I go outside and ride 2h at endurance pace, than when i do a 2h Sweet Spot workout indoors. I think the cold weather is what makes me tired. I don’t have this problem in the summer.

Thanks already for the feedback!

Well if your ftp number is accurate (135) and you did 2hr at a normalized 125, it’s pretty reasonable to feel tired. FTP doesn’t tell the whole story either; your base and current fitness will impact how much of a tole 2hr takes on you.

When riding on gravel, your body has to absorb lots of little shocks, so the ride didn’t only stress your legs, but also your core muscles and your arms. Indoors on the trainer, you don’t get that, and it’s really only your legs doing the work. Do you do any core strength work? The tiredness together with your sore neck makes me think your core muscles might need a bit of extra training.

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Have you been riding regularly for long? It can take years to build an aerobic base and become fat adapted. We are also exposed to lots of stats from cyclists at the pointy end of the sport. Some of us are just normal average Joes. I am for sure.

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true but the same basic rules apply - if you are constantly tired then a blood test is always in order - even for just peace of mind.

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125/135 is an IF of 92%. Your being tired would be normal, in addition to the comments above. If your ftp is correct, then a Z2 ride would be between 55-75% of your ftp. Hence, 75-100.