If 1 was true, then the 100m would be dominated by small guys.Um, no. 1 is true. But sprint performance is not just about power to weight.
2 True, in that weight is related to height, but taller people have larger lungs. Which is irrelevant. Lung capacity is not a limiting factor. Parts of the oxygen delivery system that may be enhanced in larger athletes are local factors (more glycogen storage, more slow twitch muscle fiber, more mitochondria, etc). But for the most part, the faster of the tall marathon runners are very, very skinny and don't weight that much more than their shorter counterparts (e.g. Paul Tergat, Alan Culpepper)3 Shorter legs have to be moved at a faster cadence to make up for a shorter stride, and so tire more quickly at high speeds. It's not nearly that simple. You don't need to "reach" with your leg the way you do with walking -- during most of your stride, your feet are in the air, not on the ground. The real picture is not so simple. Shorter runners generally do not necessarily select a substantially faster turnover. What happens is that the shorter person has to use a slightly shorter ground contact time for the same pace and cadence, and that requires greater ground contact forces, which requires more energy/oxygen. But they also save energy by being (for the most part) lighter, and by having shorter limbs (less expensive to move them back and forth). So it's a tradeoff (which is why the best runners aren't midgets).5 Since taller runners can take longer strides, No. See above.Haven't seen much evidence for your conclusion. For every Kenenisa Bekele and Haile Gebrselassie there's a Paul Tergat or a Craig MottramTergat weighs about the same as Geb, even though he's much taller. Mottram isn't a marathoner.