Leg fatigue vs. cardio preventing going harder

Am I in the majority where the hurdle to going harder is leg fatigue and generally not cardio fitness?

Does this mean I need to do more leg strength off the bike?

IME, This is an indicator of built up fatigue.


If leg fatigue is preventing you from doing workouts, the last thing I would do is add more leg workouts.


No. It means you need to address that particular type of effort on the bike.

But at some point, it is gonna hurt….that is the point of those types of intervals, whether they are VO2 Max, Threshold, etc. They will hurt…it never goes away. If the pain goes away, you need to adjust your training levels.

1 Like

It’s not preventing workouts. Just that my relative weak spot between cardio and strength I’ll call it, is strength. My lungs could go harder and longer if my legs kept up with essentially.

1 Like

I’m in the same place. I assumed that was true for everyone, but maybe I’m wrong. Some days Z2 just feels like Z4 in my legs and that’s when I know I need to rest.

I also quit ramp tests because my legs can no longer turn, not because my heart explodes.

1 Like

For what it’s worth, that’s my experience as well. It’s not the cardio that limits my vo2 or threshold; it’s that the legs can’t keep pushing.

I’m doing some extra gym work increase leg strength this autumn in a hope to remedy this.

Depends, IME. :grin:

What length of interval? What %age of FTP? What cadence?


Great questions as there is too little info given. Add in recent training history (plan and workout types) and general discussion of fueling and recovery between workouts.

I have been in a similar situation with 2 minute v02 intervals. I can hit them well for about 4 reps then slowly fall apart. Poor sleep didn’t help a couple times and <90second efforts I can knock out repeatedly. Ill do a PL6.2- 1 minute interval workout and feel great, but 2 minute efforts at the same PL, I struggle.
I think it has to be trained and maybe more zone 2, not sure. I do know they’ve been tough for me. My tte for threshold has been amazing and I would hope because that was my weakness before. I guess what you water grows :man_shrugging:

How fast do you spin?

I have a friend who rides at 75 RPM, for him it’s all about legs. I ride at 95-100RPM, for me it’s cardio.

1 Like

I took a poll on this a while back about why people stop the ramp test. Legs give out for the majority of people.


Hot take - that is still a cardio failure. Cycling is primarily an aerobic sport. (runs away after throwing chaos grenade)

But again, VO2 Max and threshold workouts will always hurt and be very uncomfortable. Doing leg strength work is not going to make that discomfort disappear.


Disagree. Does anyone here in the middle of a training block come into workouts completely without leg fatigue?

You can surely be correct. I’ve got no idea about the science behind this. What I do have is the feeling that the legs can’t push the pedals, but the heart and breathing are “fine”, ie, not at max.

And there can be a multitude of reasons why that happens, but ultimately that is what fails in for those types of workouts…you can look into things like cadence, etc. to help gain some additional time / watts, but when those efforts end / fail, it is almost always gonna feel like it is in the legs.

1 Like

I have seen both sides:

  1. when joining TR and started structured endurance training first time, did ramp test, had to stop because could not gasp enough air
  2. many blocks later (1.5-2yrs, iirc), with successes/failures mix, cardio caught up and that point burning feeling in legs became limiter
  3. now (1.5yrs since [2]), after long high volume low intensity block, cardio is limiter again

I even remember one specific Ramp test where both sides were in balance, felt very nice. Had to stop because could not go on but did not feel terrible either side. If I remember correctly, it was highest jump in FTP at that time (5%, usually progress 1-3% per block)

Not sure the Ramp Test bunny trail is helpful here? The OP has not clarified the use case(s) yet, but I suspect it is for workouts in general. It’s possible the RT relates, but I think it is not relevant to the OP unless they tie it together.

1 Like

Of course not. Do they then look at deep fatigue and say, “I know how to solve that, I’ll add even more hard work!”

Yea, I hear ya. This is definitely an area where you need to rely on your past experience and know your own body.

1 Like