Muscle Fatigue vs Lactic Burn

gcwebbyuk

I never seem to experience burning muscles like some people describe. Instead, my legs just seem to get seriously fatigued to the point that I have to give up. This is both on the turbo trainer and out on the road.

During an FTP test for example, I push myself to the point that I can barely continue, but still don't feel any lactic burn.

Is this just how it is, or is this more mind over matter to push through the fatigue?

BenjoMunro

It's probably down to individual physiology i.e. how quickly your body can remove the lactic from the muscles. The fatigue from long efforts such as a FTP test will be lactic build up but it'll be a gradual increase whereby your removing lactic as quickly as it's being produced for most of it. If you can push through the fatigue your more than likely to feel the burn.

The worst burn I've encountered was my first hill climb event last year. Just over 2 mins of hard effort and the burn lasted a good 10mins afterwards. Probably didn't help that I sat down and didn't spin out.

JBrown23

Interesting question! I've personally experienced the burn. I would agree with BenjoMunro and would say that it's the shorter, more intense efforts i.e. after kicking to break when you are more likely to feel this pain. It is the increase in intensity which will likely do it, especially over a long period e.g. hill climb or ramp test.

Alex99

gcwebbyuk wrote:

I never seem to experience burning muscles like some people describe. Instead, my legs just seem to get seriously fatigued to the point that I have to give up. This is both on the turbo trainer and out on the road.

During an FTP test for example, I push myself to the point that I can barely continue, but still don't feel any lactic burn.

Is this just how it is, or is this more mind over matter to push through the fatigue?

Just to clarify on a few points... are you a long time cyclist, or fairly new to it? When you say "barely continue", what is stopping you if your legs aren't burning with lactic? Are you heavily out of breath, are you willing your legs to pedal but they aren't listening? Are you experiencing pain at all?

If you said it only happens sometimes, I'd immediately think of chronic fatigue or over training.

Alex99

Alex99 wrote:

gcwebbyuk wrote:

I never seem to experience burning muscles like some people describe. Instead, my legs just seem to get seriously fatigued to the point that I have to give up. This is both on the turbo trainer and out on the road.

During an FTP test for example, I push myself to the point that I can barely continue, but still don't feel any lactic burn.

Is this just how it is, or is this more mind over matter to push through the fatigue?

Just to clarify on a few points... are you a long time cyclist, or fairly new to it? When you say "barely continue", what is stopping you if your legs aren't burning with lactic? Are you breathing and sweating heavily, are you willing your legs to pedal but they aren't listening? Are you experiencing pain at all? How motivated are you? A 20 minute true maximal test on the turbo is very hard.

If you said it only happens sometimes, I'd immediately think of chronic fatigue or over training.

gcwebbyuk

Been back to cycling for about 3 years now after a long period off due to spinal surgery.

Barely continue due to legs just not wanting to turn over. No pain no burning and no breathing issues - I could probably talk/pant. Heart rate would probably be around 170s whereas my measured max is 198bpm.

Midlands Grimpeur

It sounds more like a general lack of aerobic fitness, at a certain point the muscles ability to metabolise energy efficiently decreases hence your legs feel like they just can't turn the pedals. At a heart rate of 170 you will reach this point on most rides. The lactic burn comes when you are constantly riding above threshold which as you suggest is different to what you are experiencing.

If it is an aerobic issue some longer steady state rides at a HR slightly below what you are doing now should see improvements.

gcwebbyuk

Have a look at my most recent FTP test: https://www.trainerroad.com/cycling/rid ... e-ftp-test

I was wrong on the bpm, it is actually around the 180s where this kind of fatigue is setting in.

An example of a workout where I just couldn't keep the power up to finish the interval, and then completely gave up on the next interval: https://www.trainerroad.com/cycling/rid ... thian-peak

With running, I have similar issues, no burn, not completely out of breath, just hips feel like they are totally knackered.

Midlands Grimpeur

Those examples do indicate (emphasis on indicate, I am not an expert, just giving advice based on informed experience!) that you may benefit from more aerobic based training.

The 2nd example gives you an NP of 82% of FTP for around an hour which is mid tempo pace, if this kind of effort brought about fatigue that would suggest you could improve your aerobic fitness. You would expect someone with good aerobic fitness to hold this effort for 2-3 hrs and a well trained cyclist could hold an even higher intensity for the same period.

sungod

you won't feel 'lactic burn' because it's not lactate that causes it, that idea arose a long long time ago, but as is often the case, correlation is not causation

science suggests that it's actually hydrogen ions from atp breakdown, and that rising lactate actually helps clear these, delaying the onset of the burning sensation

i.e. the lactate myth says pretty much the exact opposite of what lactate really does

none of which helps you of course

as above, lack of aerobic fitness could well be it, you can't sustain the level of effort to create the conditions that cause the burning sensation - fwiw coming back from a broken hip it took quite a long time before i could train at that intensity again, the legs were willing but the cardio was weak!

gcwebbyuk

I will switch back to doing steady state aerobic workouts then. Might be a good time to do some fasted workouts to shift weight too.

Would something like: https://www.trainerroad.com/cycling/rides/5987688-gibbs be a good choice? (with some food on the bike too)

Thanks for all the help people

Alex99

sungod wrote:

you won't feel 'lactic burn' because it's not lactate that causes it, that idea arose a long long time ago, but as is often the case, correlation is not causation

science suggests that it's actually hydrogen ions from atp breakdown, and that rising lactate actually helps clear these, delaying the onset of the burning sensation

i.e. the lactate myth says pretty much the exact opposite of what lactate really does

none of which helps you of course

as above, lack of aerobic fitness could well be it, you can't sustain the level of effort to create the conditions that cause the burning sensation - fwiw coming back from a broken hip it took quite a long time before i could train at that intensity again, the legs were willing but the cardio was weak!

I can accept that it's drop in tissue pH that causes the "burn" regardless of where the proton comes from, but it still sounds odd to me. When I lost fitness, I get the burn much more readily that when I'm fitter. I don't get the sensation of the biological brakes being on, and no burn :?

sloppyschleckonds

gcwebbyuk wrote:

Might be a good time to do some fasted workouts to shift weight too.

And who gave you that advise?

sungod

Alex99 wrote:

I can accept that it's drop in tissue pH that causes the "burn" regardless of where the proton comes from, but it still sounds odd to me. When I lost fitness, I get the burn much more readily that when I'm fitter. I don't get the sensation of the biological brakes being on, and no burn :?

aside from fitness, i'd think genetics plays a part as well, probably also perception of the sensations involved

the_jackalcp

I sometimes experience similar episodes and it's definitely not fitness related for me. I struggle to get my HR past a certain zone, limited by fatigue.

For me these episodes occur when I'm tired eg after a long day/week at work and resolve quite quickly after decent rest. Occasionally they occur randomly but then go just as unpredictably.

bobmcstuff

I wouldn't say I usually get lactic acid burn during FTP tests either - it's normally on shorter, sharper efforts which I couldn't hold over a whole FTP test.

I believe that an FTP test should be roughly similar to your lactate threshold (although they're not the same thing, exceeding your lactate threshold during an FTP test would be a problem) so if you were doing the FTP test right you wouldn't exceed the lactate threshold anyway. As above it looks like so-called lactic burn isn't really to do with lactate anyway, although the two are roughly coincidental (https://www.unm.edu/~lkravitz/Article%2 ... shold.html) so for the purposes of relating "the burn" to an FTP test seems to make sense.

Alex_Simmons/RST

bobmcstuff wrote:

I wouldn't say I usually get lactic acid burn during FTP tests either - it's normally on shorter, sharper efforts which I couldn't hold over a whole FTP test.

I believe that an FTP test should be roughly similar to your lactate threshold (although they're not the same thing, exceeding your lactate threshold during an FTP test would be a problem) so if you were doing the FTP test right you wouldn't exceed the lactate threshold anyway. As above it looks like so-called lactic burn isn't really to do with lactate anyway, although the two are roughly coincidental (https://www.unm.edu/~lkravitz/Article%2 ... shold.html) so for the purposes of relating "the burn" to an FTP test seems to make sense.

Depends on what you mean by lactate threshold as there are, broadly speaking, two intensity levels associated with the term "lactate threshold", one of which is sustainable at a power akin to Functional Threshold Power (a maximal metabolic control limit), however there is also the classical definition of LT which occurs at an intensity sustainable for several hours and at ~15% lower power than FTP, give or take.

VamP

There's also the stochastic nature of power delivery, which really means that when at your functional limit, you will edge over and drop below repeatedly. So for me it's quite normal to be up to 10% over the FTP at times during the test. And below. Probably can be smoother on a turbo.