Pioneer:
Star61, I am not aware of any research that does indicate that with respect to toe off, though as Izzle1989 states, I too have seen some research that does indicate that for touchdown. Maybe someone else can cite the article(s)?
Further on toe off, I’ve seen personally witnessed numerous examples of athletes (with improper postural alignment) who’s heels came up higher than would be considered optimal. It was pointed out by Winckler at a track camp I worked at in the 90’s that those athletes who’s heels came up higher behind them than the norm (for lack of a better term) in almost every case had too much forward lean at or near maximal velocity-backs not held straight/possibly even slightly rounded forward and the pelvis down and not held neutral or “up”. This (heels coming up fairly high behind the athlete) was considered a symptom of overstriding-excessive back kick or butt kick.
I believe that part of the explaination I’ve heard over the years is that the athlete with the pelvis tilted “upwards” or in neutral will also have the advantage over those who don’t of placing the hip flexors on great stretch and thus the instant the foot leaves the ground this stretch (along with correctly and actively working the arms) will cause the knee of the support leg to move and actually be pulled forward which should be considered at least closer to ideal. Those athletes who’s pelvis is down tend to have their heels go up first with the knee moving forward later than would be considered optimal thus resulting in the extra dangle time and overstriding.
The elites have their knees moving forward once the foot of the support leg toes off with only minimal back kick whereas a non elite may or may not have this happen and a large part of this phenomenon appears to be a reaction to the stretch and the postural alignment but also as part of the arm action or in each case, possibly a lack of.
This is exactly what I have learned about myself over the last four years. I had a lot of back-kick which would cause me to over stride and ease up during the latter parts of my races in fear of pulling a hamstring. Since then I have made it a focus to improve posture which I believe is the reason why I haven’t pulled a hamstring in over two years.