^^ Hey man, their heels all touch the ground, they must suck balls right?
some of them suck. the others who don't suck don't really touch. with reference to the video you posted:
http://www.youtube.com/watch?v=7jrnj-7YKZE&feature=player_embeddedthat touch sensitive surface video shows that with a barefoot runner there is massive pressure on the forefoot and just barely a momentary kiss on the heel.
i told you it was all about the spring action. what force curve do you think a spring would plot out if the amputated guy ran in that lab ? it would plot out a symmetrical bell curve just as the barefoot runner plotted out. this is the proper way to run and the way you achieve this spring-like behavior is by using mostly your calf as a spring.
if you don't use the calf and land on the heel you create that ugly spike which doesn't represent spring-like behavior. you can think of that initial spike as energy loss. the bell curve of a spring represents recycling of energy and the spike energy loss - the ERROR in your technique.
now since i am a perfectionist i don't touch with my heel at all, and neither does usain bolt in an all-out sprint wearing sprinter's shoes. check it out:
http://www.shoeguide.co.uk/media/main/nike_zoom_aerofly.jpgcan you tell this shoe is not designed to make heel contact ? check out the huge spikes on the forefoot and basically nothing on the heel.
but if you are running long distance your calf will be tired and you may compromise a bit by touching lightly with your heel but still landing forefoot. its not a yes or no thing - it is gradual. the better your technique, the more power your calves have and the faster you are running the more your weight is going to shift from the heel to the forefoot. obviously when usain bolt is walking he does it using his heels. but if he tried using his heels while running sub 10 second he'd break his legs.
it's difficult to avoid touching your heel if you are not running fast - that's why i don't run slow any more. you need a certain speed to get a nice natural bounciness to your stride. with my super-cushy nike air max 2010 shoes:
http://www.anpshoes.com/NewImage/2010/images/Boy%20Children%20Nike%20Air%20Max%202010%20Running%20Shoes%20(12).jpgi can run anywhere from medium speed to very slow, and can walk very comfortably, but i can't run very fast in them. on the other hand with my nike free 3.0 shoes:
http://1.bp.blogspot.com/_pEADhcSTYTU/S_34N5eyY4I/AAAAAAAAC0Q/kWc1HgEHfVQ/s400/Nike+Fee+3.0.JPGi can run anywhere from medium to fast, but i can't run slow, and they aren't comfortable for walking.
fast forward the following video to 4.00 minute mark for slow motion:
http://www.youtube.com/watch?v=U0vRSuqMJlgi like how when he runs you can't even tell that he makes contact with the ground at all. looks more like he is pedaling in continuous circles mid-air than running. you need to have this kind of smooth flow for maximum efficiency, and you simply can NOT have it if you smash your heels into the ground.