Why do you get tired?

[Barkingcat]

One of the several reasons that folks with packs get tired is that handy sternum strap -- many people pull it too tight.

I concur -- this happened to me after I began using a new pack a couple of years back and until I figured out that I needed to adjust the sternum strap. Since then, the problem has gone away.

 

[grog]

The biggest problem is not getting oxygen into the lungs, but getting it to the muscles where it can be used. This is where training and diet comes in.

I always wear a sternum strap to keep pressure off my shoulders. I've had 2 dislocated shoulders playing football and multiple frozen shoulders which usually take up to 4 months to heal. From 40 years of doing concrete and masonry I have a lot of nerve damage so I pay a lot of attention to anything affecting my joints.

Through proper training and paying attention to detail I feel better now than I have since I was 11 years old when I first got Osgood Schlater disease, and a lot of it has to do with taking up hiking as an excercise for the last 14 years, which I consider by far to be the best exercise for the legs.

grog

 

[Sasquatch]

I guess I'm just a simpleton: to me you get tired because you're doing more than your body is able to handle.I used to get tired after 10 miles and think I just did something quite remarkable.Now I can run a pemi-loop in day or a winter presi traverse with a heavy pack,something I would have never thought possible, and not be tired.I chalk it up to building up to a higher level of fitness.Then I think I'm quite the machine until I get passed by a pemi-loop runner who is far supeior to me.
Equipment issues,overly wordy medical concepts, and other questionable antics are just attempts to put into words or rationalize what is impossible to quantify-what's in a man's(or woman's) heart.

 

[DuctTape]

Picking up on the nutrition thread...

Does anyone know the molecular basis of fatigue?

I have read that muscle fatigue is directly related to muscle glycogen depletion but I find that explanation to be a bit lame.

Like, if your gas tank is half empty your car has difficulty getting up a hill? Doesn't make sense to me.

Here's an interesting article on the subject.

I remember reading something a while back about this. The conclusion was that there isn't a definitive explanation as to what causes fatigue. The other problem was in defining it. You specifically mentioned muscle fatigue, but fatigue can be for a variety of other reasons inclusing but not limited to : cardiovascular efficiency, energy supply (ATP), thermoregulatory, and psychological. Your gas tank analogy is based on energy supply so while a human with not enough stored ATP will feel fatigue, it is not muscle fatigue. Muscle fatigue, I think, is a manifestation of muscle trauma (which is what we feel as soreness later) which decreases the force output of the muscles (assuming the same energy/oxygen input). The analogy I would use is that of a rubber band which is stretched and released so much that it loses its elasticity. Unlike a rubber band, human tissue can repair. Or I am full of it.

 

[Tom Rankin]

I always wear a sternum strap to keep pressure off my shoulders.

I find that by keeping my lower strap tight I can keep a lot of weight off my shoulders.

 

[Neil]

Equipment issues,overly wordy medical concepts, and other questionable antics are just attempts to put into words or rationalize what is impossible to quantify-what's in a man's(or woman's) heart.

Could be, or they are an attempt to understand the beauty of it so we can disassemble it, reassemble it and then manipulate the hell out of it in order to achieve more glory.

Btw, note carefully the thread title.

I don't get tired.

 

[sardog1]

Equipment issues,overly wordy medical concepts, and other questionable antics are just attempts to put into words or rationalize what is impossible to quantify-what's in a man's(or woman's) heart.

I guess we understand now why they live alone . . .

 

[Sasquatch]

No pack strap can slow this Sasquatch down

 

[J.Dub]

I get tired because I didn't run enough in the preceding weeks.

^^^This iz korrket.


I express it in simpler terms, however: 'I get tired because I'm a wuss.'


My dewussification is a work in progress...

 

[Neil]

Could be, or they are an attempt to understand the beauty of it so we can disassemble it, reassemble it and then manipulate the hell out of it in order to achieve more glory.

Just like I said.

Fatigue Can Be Alleviated With Experimental Drug

The discovery of the calcium leak in fatigued animals and athletes is the first time anyone has pinpointed a precise mechanism for the involvement of a defect in calcium handling in limiting exercise capacity.

The researchers then used the similarity between athletes and patients to their advantage to see if an experimental drug could increase exercise capacity and reduce fatigue.

The researchers gave the drug -- which plugs the leak of calcium -- to mice before the animals started a 3-week regimen of swimming. Without the drugs, mice are exhausted after three weeks of daily 3-hour swims. With the drug, the mice were still energetic, had lost less exercise capacity after 3 weeks, and their muscles showed fewer signs of calcium leakage, atrophy, and less muscle damage.

 

[ferrisjrf]

From a 2008 NYT article:

So the day may come when there is an antifatigue drug.

That idea, “is sort of amazing,” said Dr. Steven Liggett, a heart-failure researcher at the University of Maryland. Yet, Dr. Liggett said, for athletes “we have to ask whether it would be prudent to be circumventing this mechanism...If you could will yourself to run as fast and as long as you could, some people would run until they keeled over and died."

Maybe you'll eventually be able to 'wack yourself to death, Neil.

Jason

 

[Neil]

Actually. I know why we get tired. It's our body's way of telling us we've had enough and that maybe we need some rest.

I Kind of like the idea of spiking my goo with anti-fatigue meds though. You could skip all of that training and still do a Presi traverse and a Pemi Loop - in one day!

 

[deanmacg]

I get more tired sitting in front of this computer than playing outdoors.

 

[Little Rickie]

"One of the several reasons that folks with packs get tired is that handy sternum strap"

I think the same thing happens with a too tight waist belt, it slows blood flow into the legs, especially if your pulling in a big gut.

I get tired because:

I'm out of shape and my machine can't deliver the energy need to keep up a decent pace.

I'm out of fuel, a little food can make a big difference.

When I'm tired I can slow down even more and but can keep going, up to a point. That's probably because I'm fat burning and walking on a level surface.

Adding poles or arm swings raises my effort 3-5%. Grabbing branches, roots, pushing down, and pulling up adds way more effort and causes me to go anerobic for short periods of time. Repeated recovery takes a lot out of me.

 

[Rik]

I'm a little late jumping in on this one and haven't read the links people put up so my apologies if this has already been said. I think fatigue is a brain thing. If you buy into the 'brain as a regulator' theory then fatigue is just our brain telling us that if we keep going at the same intensity we will eventually run out of fuel. It's our brain's job to slow/stop us before we get to that point. If I run until I can't run anymore (no fuel) then what am I to do if I'm attacked by a predator? Our brain protects us from these situations by slowing us down while we still have some fuel left. To use Neil's example of fuel in a car I think of fatigue like a "low fuel light". It's a signal to us before we run out. People can over ride this signal.

 

[Little Rickie]

I think fatigue is a brain thing. .

Bingo! That's a common problem, not enough brains.

 

[--M.]

I guess I'm just a simpleton

Or just enjoying a simpler life! I think these things are highly subjective and varied, and what was once a simple matter of walking from here to there somehow became complicated enough that I now call it "hiking" and have to be careful about my food & rest intake, lest I forget how to walk somewhere.

But I love seeing what kind of intellecshul firepower can be mustered on a board like this: Also highly subjective and varied!

Good stuff!

 

[Stash]

So why is it that one day I can walk/bike forever and another I'm draging after a relatively short time. Both are preceded by similar days of sleep/exercise/nutrition or, in many cases, I do better when I start tired. My though is that there's something in the brain that just says it wants to go that day. And "good days" usually last all day, as do "bad days".

 

[Neil]

But I love seeing what kind of intellecshul firepower can be mustered on a board like this:

Good stuff!

So why is it that one day I can walk/bike forever and another I'm draging after a relatively short time.

Sounds like a horoscope thing to me. You should check it before heading out.

 

[Hobbitling]

It's not that the fuel supply isn't adequate, it's more that the fuel hose is clogged, or the injector nozzles are gunked up. The average person has plenty of calories stored, but unless you're in shape, your body can't efficiently access and use those calories.

Glycogen is short term energy, and even the fittest person is going to use up their muscle glycogen pretty fast. Then the liver releases it's glycogen, which takes a little while, because the liver has to realize it's supposed to. but even that will be gone within a few hours. Then you move on to fat burning. And of course any food you eat will help to supplement the process.

A fit person is able to deliver that fuel more quickly because the biochemistry of the fat cells and liver cells are much more efficient, and are geared towards accessing energy (burning fat), rather than storing energy (AKA, getting fat). The enzymes and biochemical pathways involved in tranforming fat into useable calories (sugar) are "up-regulated". A fit person will have much less lag time between their body signaling "we need energy" and the energy stores being mobilized.

Also, blood supply to muscles (and many other parts of the body including the brain) increases when you are fit. So excercise actually helps your muscles and brain work better and use fuel more efficiently.

The body doesn't really store much ATP, that's made on-demand in the cells themselves. When you run out of ATP, that's called rigor mortis.