Locomotion - Humans

The animal world is amazing! I want to tell you a bit about how amazing it actually is. I want to talk about locomotion. lets start with terrestrial (land-based) locomotion.

First off, what is locomotion? Locomotion is the ability to move from one place to another, now we do this very well in fact. Dean Karnazes, one of humanity's best runners, is said to be able to run for three days and nights without stopping, back in 2005 he ran a crazy 560 km in 80 hour and 44 mins, non-stop!

Our universal energy currency is ATP (Adenosine triphosphate), we can get into all about ATP but that will be for another time. So when we need energy we convert ATP into ADP (Adenosine diphosphate), hence removing a phosphate group. We can recycle this ADP back into ATP in a process called respiration which uses up oxygen and glucose. ATP is constantly being used up by many metabolic reactions including muscle contraction and cannot be stored in our bodies and so its no wander we recycle about our body mass everyday!

Ok, so we've now decided we're gonna get up stop being lazy and get a six pack for this summer. You start doing some intense pull ups and its getting to you start feeling burns. You see when in desperate need for more ATP, your body starts its Anaerobic (the absence of oxygen) pathway, this releases a little ATP but creates lactic acid as a biproduct. Lactic acid is what causes the burning sensation and is very toxic in higher concentrations in the blood.

The point at which you can no longer physical carry on is called you lactate threshold, the point where your body cannot get rid of the Lactic acid quick enough and therefore starts accumulating. For Dean Karnazes this limit is none existing, he never feels burns or cramps! "To be honest, what eventually happens is that I get sleepy", really!? If he was a predators i don't think ill even start running, i'll just accept my fate!

Mind you this is actually a hunting technique that has been used for around 2 million years and is still used today, although its very rarely within few groups such as the Kalahari bushmen and the Tarahumara people of Northern Mexico. This hunting method takes full advantage of our endurance. You pick a target, normally they choose the male antelope with the biggest horns, thinking it will get tired the quickest and then you chase it with a spear.

The antelope is much faster than the hunters because they are quadruped, but its also because of this very reason why they can catch them. You see moving produces a lot of heat, and in order for the enzymes in our body to work most effectively we need to keep our core body temperature at a very stable rate. One way we cool down if we're too hot is by panting, however for quadrupeds there's one big complication. Quadrupeds have a stride to breath ratio of 1:1, you can see from image A to B how the lungs change in volume during a stride, now this is a problem as they need to stop in order to pant and loose that extra heat.

Human's bipedal locomotion means that we have a breath to stride ratio of 2:1 when running but we can achieve up to 3:1 or even 4:1 when jogging. We can also sweat and carry around water in pouches which means that we can regulate our core temperatures for much longer and out endure the prey and chase it down until it on the brink of death by simply overheating. And there is a nice and safe meal.

Now there's something to stroke your goatee on!





Sources
http://en.wikipedia.org/wiki/Dean_Karnazes
http://www.theguardian.com/lifeandstyle/the-running-blog/2013/aug/30/dean-karnazes-man-run-forever
http://archive.wired.com/wired/archive/15.01/ultraman.html
http://en.wikipedia.org/wiki/Persistence_hunting
http://en.wikipedia.org/wiki/Quadrupedalism
http://wannahearsomethinginteresting.blogspot.co.uk/2010/12/running-and-breathing.html
http://podbay.fm/show/93224169/e/1283540400?autostart=1
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