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Sep 2013
11:56am, 13 Sep 2013
19,031 posts
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eL Bee!
I think it was a discussion that David Coulthard was having with some engineer on the telly box a couple of seasons ago
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Sep 2013
11:57am, 13 Sep 2013
29,077 posts
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Hills of Death (HOD)
This racing car chat reminds me of around El bees pad when I had my first POSE lesson 
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Sep 2013
11:58am, 13 Sep 2013
19,032 posts
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eL Bee!
Hey! That's a good metaphor, that one!
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Sep 2013
10:32am, 17 Sep 2013
778 posts
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Canute
There are three main adaptations that a runner needs to develop. These differ in importance for different distances.
Sprint - 1500 m: develop and harness power
3 Km – 30 Km: efficient use of oxygen
30 Km upwards: efficient use of fuel
Forefoot is better for developing and harnessing power and hence better from sprint to 1500m
3 Km to 30 Km: foot strike probably doesn’t make much difference to efficiency or effectiveness. The priority is improving capacity to deliver oxygen to tissues and to utilise glucose.
30K upwards: heel-strike is more efficient. Fuel conservation is even more important, so developing ability to utilise fats is crucial.
Burning fat consumes more oxygen to produce a given energy output than burning glucose, so for distances from 3 Km to 30 Km it is more effective to use glucose than fat. The aerobic enzymes that catalyse the burning of glucose also catalyse the burning of fat, so training that improves aerobic enzymes improves capacity to burn both glucose and fat. However, the process of mobilising fat and transporting it into cells are different from the processes of mobilising glucose and transporting it into cells. It is possible to enhance fat burning over glucose burning by lots of long slow running, but this will lead to slightly less efficient use of oxygen and hence might not be best for 3 Km – 30 Km.
But surprisingly HIIT it appears that is good for developing capacity to utilise glucose and also for improving capacity to burn fat. So HIIT appears to meet all requirements but further evidence of effectiveness in practice is required. Whatever allows you to do a lot of training without injury or illness is likely to be best of all.
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Sep 2013
10:37am, 17 Sep 2013
779 posts
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Canute
Maybe I should have added a fourth adaptation: strength of connective tissues. A gradula build up to lots of running is probably the best thing for developing this
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Sep 2013
11:24am, 17 Sep 2013
3,293 posts
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daviec
I'm trying a thought experiment in my head, with all of the obvious downsides to that type of experiment, and I just can't see how any heel strike can happen which couldn't be replaced by a midfoot strike and not be at least as efficient. Unless it's by landing in front of cog with all of the attendant braking on each step. Granted, again, I'm not really concerned with the speeds mentioned in the papers previously as even my planned MP will be above 15kph, so those distances you've mentioned are arbitrary and would differ per runner.
And also, as has been alluded to, wouldn't fuel efficiency only matter if you're going to run out of fuel? Surely in a race fuel efficiency is less of a concern than speed. Most long distance racers will be able to carry, or collect, some sort of fuelling to get them to the end of the race. So really it's about getting the right balance of speed that will get you to the end of the race as fast as possible, and personally that means, for me, all distances up to marathon will be my normal midfoot strike. And I doubt I'd change that for an ultra either actually.
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Sep 2013
11:47am, 17 Sep 2013
780 posts
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Canute
Re-fueling during a long race is not straightforward as the body absorbs food less easily during a race than when relaxed. So it is almost certainly best for an ultra runner to optimise ability to utilise fats.
As for how heel striking could be more efficient at slow paces, I think the lesser requirement for tension in the leg muscles at foot strike accounts for the greater efficiency, at least relative forefoot striking. I think that the difference between mid foot (in which weight is evenly distributed along the sole and heel strike) is probably very minor, though I suspect it still slightly favours heel strike. Many forefoot and mid foot runners do automatically adopt heel strike in the later stages of a long race, probably because they automatically reduce the tension in the leg muscle when tired.
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Sep 2013
12:00pm, 17 Sep 2013
781 posts
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Canute
Daviec
Certainly the boundaries between distances for which different adaptations matter are not sharp boundaries and probably differ between runners. For a fast marathoner, the difference in efficiency between heel strike and midfoot is likely to be trivial, though the Spanish data does suggest there might be a benefit for heel strike even at 15 km/hour – but that observation had a greater than 1 in 20 chance of being a random finding, so at this stage I do not think the evidence is strong enough to argue strongly in either direction. If I were you I would not worry about any difference in efficiency between heel or midfoot strike for a marathon.
I think all marathon runners need to develop good fat burning capacity
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Sep 2013
2:03pm, 17 Sep 2013
3,948 posts
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paul the builder
davie - I think there's no obvious or intuitive way to judge 'efficiency'. So I don't think your thought experiment results could be stood behind. Even by you, in your own head
My couple of contributions of logic to this:
1. Both heel-striking and "non-heel-striking" can be easily found in elite marathoners. So it's highly unlikely that one is *definitely* better than the other for all of that group.
2. I reckon pretty much *everyone* sprints with a forefoot strike, but walks with a heel-strike. And thereofre everyone transitions from one to the other at some speed in between. For some people it's already happened at a slow running pace. for some others, it doesn't happen until *much* faster. I think I would still be heel-striking at 1500m, and maybe shorter distances too. To cut to the chase - everyone has a pace where heel striking is more efficient than forefoot/midfoot striking. It's not the same pace for all of us.
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Sep 2013
3:24pm, 17 Sep 2013
3,294 posts
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daviec
That was my conclusion Paul. I can see how a heel strike that isn't too far out in front can still be efficient, but I can't see how that wouldn't compare closely with a midfoot or forefoot strike in the same position relative to COG. On the other hand, reaching forward can only really result in a heel strike, and that surely must introduce high braking forces due to the positioning rather than the fact it's a heel strike. My point, I suppose, is that you can't judge efficiency from footstrike, or speed, or a combination of both. It's going to be entirely individual.
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