What is fatigue?

Out of energy compound, out of oxygen.

When both of these are gone, as in death, you get so called rigor mortis... And that's pretty stiff! :eek:

Bruce Diesel said:

One of the things I haven't been able to figure out is:

What exactly is fatigue? What causes your muscles to stop being able to push the pedals?

Is it because a particular energy system runs out of fuel when operating at the level that stresses that system? If this is the case, why does motivation play a significant role in performance?

I am aware of research being performed here in South Africa by Prof. Tim Noakes and his "Central Governer (sp?)" theory.

Fatigue is often multi-factorial. You already know that.

Part of it is certainly metabolic. Between the state of total glycogen availability and total glycogen depletion, there are all the steps in between. During these steps, in other words during the process of depletion, the systems that use mostly glycogen as main fuel probably loose part of their efficiency.

In my humble opinion, that's where motivation can make a difference. In my opinion (I did not read on this topic), a motivated athlete will send stronger nervous signals to the muscles. These stronger nervous signals may favor stronger contractile impulses, or may favor more muscle motor unit to be sollicited etc...

You know, I wouldn't be surprise to learn that the impact of motivation on performance is also multi-factorial, just like fatigue. I already mentionned about nervous signals. The release of hormones such as epinephrin, or any other hormone that may enhance performance, or lower feeling of pain etc probably plays a role as well.

[quote="SolarEnergy"]Fatigue is often multi-factorial. QUOTE]

Yes the fact that your sitting on the ground dead on your ass means your fatigued. 😄

sogood said:

Out of energy compound, out of oxygen.

If you look at a real simple situation, like an isometric maximum knee extensor force, you can see that maximum force can only be maintained for a few seconds before the muscle starts to fatigue and force declines. I highly doubt oxygen figures into that kind of fatigue at all.

[quote="bladegeek"]

SolarEnergy said:

Fatigue is often multi-factorial. QUOTE]

Yes the fact that your sitting on the ground dead on your ass means your fatigued. 😄

I think holding 98% Max Heart Rate for the last 10 minutes of an uphill race then collapsing (bike and all) on the finish line and not moving for 15 minutes is a good sign of fatigue. What's the cause? The Effing 12k Hill with the last two k's averaging 17%. Jesus that hurt....

When your spirit says, "Go",
But your legs say, "No!",
That's fatigue.

Jono L said:

I think holding 98% Max Heart Rate for the last 10 minutes of an uphill race then collapsing (bike and all) on the finish line and not moving for 15 minutes is a good sign of fatigue. What's the cause? The Effing 12k Hill with the last two k's averaging 17%. Jesus that hurt....

Thats just Effing stupid...

I'm assuming you rode Mt William yesterday? 🙂

parawolf said:

Thats just Effing stupid...

I'm assuming you rode Mt William yesterday? 🙂

oh yes, the stats lie, that hill is sooo much harder than it sounds.

Jono L said:

oh yes, the stats lie, that hill is sooo much harder than it sounds.

Ah I wasn't doubting your numbers at all, just mentioning that is a crazy amount of endurance. 98% would be 196bpm for me.. crazy as.

parawolf said:

Ah I wasn't doubting your numbers at all, just mentioning that is a crazy amount of endurance. 98% would be 196bpm for me.. crazy as.

No doubt about that, it took some serious motivation and I doubt I'll see stats like that for a long time...

What I was I was trying to say was that climb stats lie. 12k at 7% sounds like nothing, but someone forgot to tell me the last 2k are at something stupid like 15-16% with a max of 22%!!!!! Doh.:o

Bruce Diesel said:

One of the things I haven't been able to figure out is:

What exactly is fatigue? What causes your muscles to stop being able to push the pedals?

Is it because a particular energy system runs out of fuel when operating at the level that stresses that system? If this is the case, why does motivation play a significant role in performance?

I am aware of research being performed here in South Africa by Prof. Tim Noakes and his "Central Governer (sp?)" theory.

Hope you werent looking for a serious answer, seems everyone here pulled out the joker card, except SolarEnergy

jeff828 said:

Hope you werent looking for a serious answer, seems everyone here pulled out the joker card, except SolarEnergy

🙄