Why do people get tired when exercising?
Discussion
Ok, I know its sounds like a numpty question (and probably is) but I was thinking about this last night at the gym. If the human body had enough fuel (food) and oxygen from breathing wouldn't the body act like an engine and keep going until one ran out?
And as one person is fitter than another, what exactly is fitness? Each person has lungs, muscles, etc? Why can one person run further than another? (I accept that sheer strength is down to muscle size).
And as one person is fitter than another, what exactly is fitness? Each person has lungs, muscles, etc? Why can one person run further than another? (I accept that sheer strength is down to muscle size).
Frimley111R said:
Ok, I know its sounds like a numpty question (and probably is) but I was thinking about this last night at the gym. If the human body had enough fuel (food) and oxygen from breathing wouldn't the body act like an engine and keep going until one ran out?
And as one person is fitter than another, what exactly is fitness? Each person has lungs, muscles, etc? Why can one person run further than another? (I accept that sheer strength is down to muscle size).
Short version:And as one person is fitter than another, what exactly is fitness? Each person has lungs, muscles, etc? Why can one person run further than another? (I accept that sheer strength is down to muscle size).
Engine effect can happen in steady state activity as long as there is sufficient fuel
Fitness depends on efficiency and capacity and physiological changes happen in training to make you more efficienct
Long version:
To a certain extent the 'engine effect' happens, for example myself and several of the guys I run with at uni will be able to do 8-12 miles at a constant effort, feeling fine as long as we have eaten sufficiently beforehand. Feeling tired afterwards is probably part of the recovery process, your body is replacing lost sugars and repairing damaged muscles so your blood glucose level is lower as you replace stored muscle glycogen, and your brain is telling you to rest to help the repair process.
It also depends which energy system you are using. The body breaks down Adenosine Triphosphate (ATP) to Adenosine Diphosphate (ADP) to provide energy to the muscles, and our metabolic systems recycle ATP into ADP using either Glucose or Phosphocreatine (PC). There is only enough ATP to last for a short burst of activity (around 1-4 second's worth). If we define 'being tired' as needing to rest to recover then:
The PC system is very fast acting but only lasts for ~10 secs as the stores of PC are used up, but you recover around 80% of the PC stores in a minute and it is also anaerobic (no oxygen required). So in short maximal efforts (e.g a 1 rep max) your body will need to rest to recover the PC stores.
After this the lactic acid system (anaerobic and incomplete break-down of glucose) kicks in which has lactic acid as a by-product. After a certain amount of time (depending on ultimate intensity and LA tolerance but maybe 45 secs for a purely LA activity) you will need to rest to clear the build up of lactic acid (also known as repaying the oxygen debt).
The final stage is the aerobic phase, this doesn't permit the same intensity of activity but can go for as long as there is glucose to break down (the 'engine effect') and this is also the most efficient form of ATP regeneration (4xmore ATP/unit glycogen in comparison to the LA system) as it utilises the complete breakdown of glucose using oxygen when the rest and recovery phase is focused on refueling.
When you say about fitness it mostly comes down to efficiency and capacity. For example endurance athletes undergo physiological changes such as capillarisation (increased no's of capillaries around the muscle fibres and lungs) which allows them to get more oxygen to the muscles and hence a greater %energy from complete breakdown of glucose, as well as a larger lung capacity (again more oxygen) and lower weight so they are not having to use as much glucose and so can go for longer.
P.S I knew I studied A level PE for a reason
What I find fascinating is our place in the animal kingdom - how a man can beat a horse in a race, but only over long distance.
The idea that we're naturally long distance runners, next to a horse or lion or whatever, because we have an air con unit built into - most mammals pant to coop down, where we sweat.
This from reading 'Born to Run', BTW ; )
What's interesting, is the notion that we have a signal that says 'stop' well before we're exhausted - BtR covers this, but I've experienced it myself - I'd only ran 5 miles in the months leading to my first half marathon, and yet when faced with crowds and competition, I could treat the 13 as a sprint!!! Well, I finished in 1:45 but with a few minute piss break and getting stuck behind fatties...
My (scattered) thoughts on exercise ; )
The idea that we're naturally long distance runners, next to a horse or lion or whatever, because we have an air con unit built into - most mammals pant to coop down, where we sweat.
This from reading 'Born to Run', BTW ; )
What's interesting, is the notion that we have a signal that says 'stop' well before we're exhausted - BtR covers this, but I've experienced it myself - I'd only ran 5 miles in the months leading to my first half marathon, and yet when faced with crowds and competition, I could treat the 13 as a sprint!!! Well, I finished in 1:45 but with a few minute piss break and getting stuck behind fatties...
My (scattered) thoughts on exercise ; )
MocMocaMoc said:
What's interesting, is the notion that we have a signal that says 'stop' well before we're exhausted - BtR covers this, but I've experienced it myself - I'd only ran 5 miles in the months leading to my first half marathon, and yet when faced with crowds and competition, I could treat the 13 as a sprint!!! Well, I finished in 1:45 but with a few minute piss break and getting stuck behind fatties...
My (scattered) thoughts on exercise ; )
You only ran 5 miles leading upto a half marathon then did it 1hr 45mins, with toilet breaks and getting held up? that's a lie isn't it? My (scattered) thoughts on exercise ; )
MocMocaMoc said:
What I find fascinating is our place in the animal kingdom - how a man can beat a horse in a race, but only over long distance.
The idea that we're naturally long distance runners, next to a horse or lion or whatever, because we have an air con unit built into - most mammals pant to coop down, where we sweat.
This from reading 'Born to Run', BTW ; )
Great book.The idea that we're naturally long distance runners, next to a horse or lion or whatever, because we have an air con unit built into - most mammals pant to coop down, where we sweat.
This from reading 'Born to Run', BTW ; )
What I find interesting (sad) is that a fit man will out run a fit horse over a huge distance.......but your average man would have a heart attack before the horse realised it was a tad hungry!
Humans must be unique in that the average one is so far removed from the best!
nick s said:
You only ran 5 miles leading upto a half marathon then did it 1hr 45mins, with toilet breaks and getting held up? that's a lie isn't it?
Ha, no. Well, I'd regularly run 5 miles - maybe a couple times a week, plus a bit of cylcing. I used to run more, say between 5 - 8, but not more than 5 more months leading up to the GNR.Tiggsy said:
Great book.
What I find interesting (sad) is that a fit man will out run a fit horse over a huge distance.......but your average man would have a heart attack before the horse realised it was a tad hungry!
Humans must be unique in that the average one is so far removed from the best!
Good point! A symptom of us developing an interest in 'other' areas of life... such as Call of Duty, and pies.What I find interesting (sad) is that a fit man will out run a fit horse over a huge distance.......but your average man would have a heart attack before the horse realised it was a tad hungry!
Humans must be unique in that the average one is so far removed from the best!
While stupid animals are stuck with their 'running' and 'jumping' and other sh*te!
Mon the humans.
; )
InertialTooth45 said:
We're the only animal with such a huge variation in lifestyle though aren't we so it's not difficult to see why.
Fantastic book that is. About time I read it again I think.
yep....if every human was raised and lived the same way, we'd all be very similar. You'd still have the odd human who'd be faster/stronger (like any animal) but we'd all be closer. Its why its such a joke when fat (women normally) say stuff like "I'm happy being 20 stone, its how I meant to be"Fantastic book that is. About time I read it again I think.
There should be a series of physical tests that (if you are in otherwise ok health) you should be able to do...and if you cant, its a wake up call!
Run 5k for example....anyone that cant jog a gentle 5k without stopping - sort yourself out!
Frimley111R said:
And as one person is fitter than another, what exactly is fitness? Each person has lungs, muscles, etc? Why can one person run further than another? (I accept that sheer strength is down to muscle size).
Cookie covered the energy systems pretty well.Strength isn't predominately about muscle size.
Ok could some explain this to me then?
Climbing, i used to do a lot of it but never any other form of exercise... Occasionally I would have a few mates come along, all can run/row/cycle 10K where as i collapse after 2. However after a around 2 hours of hard climb they would be done in but i would be fine and able to carry on (used to do 5 hours twice a week)
Why when they were generally accepted to be "fitter" than me were they not able to keep up?
Climbing, i used to do a lot of it but never any other form of exercise... Occasionally I would have a few mates come along, all can run/row/cycle 10K where as i collapse after 2. However after a around 2 hours of hard climb they would be done in but i would be fine and able to carry on (used to do 5 hours twice a week)
Why when they were generally accepted to be "fitter" than me were they not able to keep up?
geeks said:
Ok could some explain this to me then?
Climbing, i used to do a lot of it but never any other form of exercise... Occasionally I would have a few mates come along, all can run/row/cycle 10K where as i collapse after 2. However after a around 2 hours of hard climb they would be done in but i would be fine and able to carry on (used to do 5 hours twice a week)
Why when they were generally accepted to be "fitter" than me were they not able to keep up?
What you have described is the difference between cardiovascular fitness (them) and muscular endurance (you).Climbing, i used to do a lot of it but never any other form of exercise... Occasionally I would have a few mates come along, all can run/row/cycle 10K where as i collapse after 2. However after a around 2 hours of hard climb they would be done in but i would be fine and able to carry on (used to do 5 hours twice a week)
Why when they were generally accepted to be "fitter" than me were they not able to keep up?
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