Short time on stance and landing just in front of the centre of gravity are two aspects of the same thing. Short time on stance is efficient provided cadence is fast, so that the airborne time on each stride is not very long. Long airborne time would make it necessary to bounce too high on each step. (I deal with this issue in the calculations in the side panel of my blog). However the price of short time on stance is an increased stress on the foot. If you spend a half the gait cycle on stance, the average upwards ground reaction force exerted on the foot is twice body weight; if you spend ¼ of the gait cycle on stance, the average upwards ground reaction force is 4 times body weight. Unless your feet are well conditioned to this stress, then a force greater than about 4 times body weight is likely to produce an appreciable risk of stress fracture over a long distance such a marathon, as a result of repetitive strain.
Lifting the foot high behind the hip decreases the length of the swinging leg so that it requires less effort to swing it forwards, but as I remarked in my reply yesterday, if the foot executes a loop that it too high, there is a risk that the foot will not move forward quickly enough
The third recommendation in the advert is lifting the knee high. This requires strong hip flexor contraction in addition to hamstring contraction and will help get the foot forward quickly, thereby avoiding the problem of a trailing foot, so I agree with lifting the knee. However, the swing forwards must be controlled. It is crucial to avoid extending the knee too much as the foot descends, as this would result in landing too far in front of the centre of gravity, which takes us back to the first point.

Overall I agree with the principles expressed in the advert, though they all need to be interpreted in light of the potential problems that they might create if not executed properly.

With regard to the utility of power cranks, I agree that they will promote development of the muscles that act to get the foot off the ground quickly and move it forwards efficiently. The most noticeable difference between cycling with power cranks and running is the absence of eccentric contraction of quads on foot fall with the cranks. The advert claims that the lack of impact is a virtue because it minimizes stress on the joints, which is true. However, if you want to run a fast marathon it is crucial to make the quads fit enough to cope with repeated eccentric contractions. Overall, I think the material in advert is true but does not tell the whole story.

It is necessary to get the foot forwards fairly quickly if cadence is to be rapid, so one cannot afford to let the foot trail behind for too long, so dragging the foot along a long loop behind the buttocks is unlikley to be efficient.
But overall, as far as I am aware, there is a lack of scientific evidence to demonstrate the most efficient way to lift the leg from stance.

http://www.women-running-together.com/exerciseinducedasthma.html

And second, a question;
on your decription of good running form you mention Gebresalassie and how he uses his hamstrings to pull his heels up behind his butt, But can you be sure, a high knee drive on its own can bring the heel high up behind the butt without the need to use the hams, are there any scientific reports on the matter!

I know that higher quality and a greater percentage of quality/volume can be an effective method for aging athletes. That’s pretty much what one of my training partners, Kathy, does – and she would be one of the best 53-year-old runners in the country. She runs around 50-55k per week, but with 2 to 3 high quality (and a high volume of quality) sessions per week.

It’s strange about the asthma – you’d think that would respond positively to aerobic exercise. Maybe it is the cold weather. Not much can be done about that, except train indoors, or move to Queensland.

Rick, thanks for the tip about iron. I will look into that possibility