Humans are very well adapted to long distance walking or running, much more than any 4 legged animal. Four legged travel is an energy hog when you consider that humans can do the same with half the appendages. In addition humans have very low physical comparative mass over those legs than just about any 4 legged animal.
I doubt it has much to do with the number of legs...heat regulation is our advantage, we sweat and can shed heat more easily than other animals...
Most animals also overheat quicker than humans. Most animals have a very oily sweat whereas we've evolved a very watery sweat.
It's the physiology of the proportion of weight to legs. In humans compared to 4 legged animals much of our weight is in our leg muscles, in animals they have proportionately less muscle in their legs compared to the body mass they have to carry. The other advantage is our ability to balance our whole weight over those legs vertically, something animals can't do. This is why close relatives like Chimpanzees can't walk or run as fast as we can.
, humans can walk faster than a bear but don't ever imagine you could get away from one should they decide you're lunch, they'll have you in no time.. .surprisingly difficult to find figures for that, best info I can find is the average chimp can run at 25mph, the very best human can hit 27mph, so I can only assume the average chimp is faster in sprint than the average human...and I'll speculate that no human can out accelerate a chimp over a short distance...then there is terrain to consider four legs are more stable and quicker over uneven ground...
If we were chasing down cheetah's we could. However, if they were chasing us, it's a different thing.
4 legged animals have to have 4 legs with two each being able to support and thrust their own wieght. We have two legs with one leg being capable of thrusting our own weight. I'm not a physiologist but all it takes is some simple math and it's apparent 4 legged animals use more energy, regardless of sweat, than 2 legged. Our power is consolidated, and we don't need to balance as much, hence no tail.
But there are some animals that can run faster than humans in short bursts.. I think I read that an alligator can run 30 miles and hour in a short burst. Is that true?
two legs is all about balance...it is heat regulation/cooling...thrusting weight is applicable to sprinting, distance running is leaning/falling forward and putting out one foot then the other, very little strength/thrusting involved in the process... no tail, makes us less manuverable then animals with tails...
the same thing I did when I ran down a rabbit and it started kicking me with those clawed hind legs(ouchie), I let it go...that would probably sooner with a cheetah...
Yes, being in close proximity to a gator is not very healthy. However, gators are ambush predators. Typically you won't see one until it's too late.
hmm that's a an interesting thought, their build suggests they were sprinters...even if were all marathon runners I'd guess once a T_Rex eyeballed you you'd be dinner...
But we don't need to "maneuver" as much, obvious in the fact that we evolved it away. But I've never seen a four legged creature back-pedal or side-step either.
In terms of stamina, it's largely determined by how large one's heart is compared to their bodies. Humans aren't spectacular in that respect based on some sources I've read. However, it's also based on how well you can dissipate heat. If your muscles make too much heat too quickly, you will overheat and have to rest. Humans can...sweat! From their..skin! They're extremely good at heat dissipation (which is why dogs and cats don't mind the winter cold usually, but humans, unclothed, would freeze to death in a (*)(*)(*)(*) hurry).
It depends on a lot of things. How the animal moves, how efficient its muscles are, heat dissipation, navigation strategies, etc. Human intelligence is a big part of the reason why humans are so good at endurance hunting--hunter-getherers (and this much was observed in contemporary hunter-gatherers) had enough specialized expertise to know how to pace themselves to keep up with the prey without expending large amounts of energy in the process. If you can effectively predict where the prey will go, you don't even have to keep it in visual range.
We probably developed the sweat glands because we have shelter and fire to keep us warm, fur is no longer needed. I've owned 3, never seen one backpedal. Let alone as fast as a fit human.