Running economy is the energy cost associated with running at a particular speed. It's usually given in O2/min or O2/mile. Running efficiency is often used interchangeably and is usually given in O2/kg/min.
George, I agree completely that it would make more sense to invert it and use mile/O2. For instance with cars we talk about miles per gallon. Then again, runners like to talk about their pace in min/mile rather than their speed in miles/hour. Oh well.
Here are a couple interesting articles on running economy.
If you do a search on pponline for running economy you can find some more.
Originally Posted by Patrick Donnelly
Garrett, I have no doubt in my mind that a forefoot strike is the best way to run. I simply wonder what the reasoning was behind defining "running economy" as oxygen consumption. I can see that burning more oxygen means you're burning more calories, but if you're also using more muscles, then that could help slow the occurrence of fatigue/cramps in specific muscle groups. That would permit you to run for a longer time, therefore making it more effective, at least in one sense, even if more calories are burned.
I wonder how much of the increased oxygen consumption came from the calves alone. In heel-toe, the calves don't play any substantial role, since the impact is all absorbed by the minimal elasticity of the cartilage in your joints (a bad idea, but that's what happens). With a forefoot strike, all of that force absorption is immediately assumed by the calves. Muscles absorbing force takes energy (and therefore oxygen); joints absorbing force just causes pain. Is 0.25 L/min a huge difference? Just thinking.
This would have to mean that VO2max is increased by pose running. I don't think this has ever been shown. Pose has claimed though that their running style is more efficient.
I also think that measuring oxygen consumption was a relatively poor way of measuring running economy (efficiency). The best distance runners (or endurance anything athletes) don't necessarily have the highest VO2max, and I'm not sure that oxygen consumption necessarily gives a good impression of perceived exertion or actual work output (it would seem to be quite an assumption).
Oxygen use is a pretty good indicator for energy use for aerobic work. There's generally a direct correlation between running economy and performance. A 1% improvement in economy will lead to roughly a 1% improvement in performance. It's true that VO2max isn't the best indicator of performance. A better metric would be something like lactate threshold velocity (LTV), the speed at which large amounts of lactate begin to accumulate. VO2max tells how much work you are capable of performing. Lactate threshold is the maintainable rate of energy usage. For an elite distance runner it might 85-90% of VO2max compared to 60-70% for a recreational runner. Efficiency determines the speed you can achieve at that oxygen rate.
The comments in the original link are excellent and definitely worth reading. This is my favorite.
P.S. I think that the biggest problem that Romanov might have is that Pose isn't all that different from a good Ball-Striking style. He points out how he found a group of high-level African runners, who he believed were running Pose (without having learned it). He showed them videos of Pose runners and analysed them against videos of the Africans. The Africans saw little or no similarity in their running styles. Second, many coaches advocate a high stride rate (at or above 180), and many champions (short, mid, & long distance incl. marathon) have stride rates that are above 200. Third, many coaches advocate ball-striking for faster, more efficient running. Fourth, anyone with a rudimentary understanding of Physics can see that landing significantly in front of the center of gravity is going to introduce braking action (i.e. inefficiency). Heel landing indisputably has more of this--that's just basic physics. The interesting question here is whether Pose is better than other ball-strike methods. The only thing that Romanov has going is a relatively simple (3 elements) method to get you to do these things."
In walking, the heel hits the ground in front of the center of mass. Does that mean we apply a huge braking force while walking? Did we evolve so that our primary means of movement is inefficient? The first link I listed above shows that walking is more efficient than running. The second link talks about how the Kikuyu women are able to avoid applying a braking force while walking. I find that keeping the feet dorsiflexed while walking or running seems to help eliminate braking force, increase energy return, and eliminates over extension of the ankle and knee. Give it a try with walking.
We squat through our heels. It doesn't mean we keep our toes off the ground while squatting. Running on the balls of your feet doesn't necessarily mean you have to keep the heels off the ground.
Running to me seems to be (like most functional movements) just an explosive opening of the hip. Actually I think you could probably argue that running was the driving force behind the evolution of powerful opening of the hip.
The idea of pulling and falling with you leg under your center of mass never really made sense to me. It's kind of like saying that you row by putting the oar in the water and pulling it straight out.
While the foot is on the ground it's moving backwards relative to your center of mass at the same speed that you are moving forward. Once it comes off the ground, momentum will cause it to continue moving back and up. Once it is back, gravity will cause it to swing forward like a pendulum setting it up in position for the next explosive opening of the hip. At least that's how I envision it. Running is a pull, but pulling isn't necessary to get the foot off the ground.