[quote author="Josh Hurlebaus" date="1275717931"]You are looking at backside mechanics wrong. Its not a simple line that is parallel with the ground throughout the phases of the race. Imagine a line running from your shoulders through your hips and to the ground. Anything behind that line is backside mechanics. Toe off ideally happens as close to that line as possible…
In this video of Asaffa,… https://www.youtube.com/watch?v=KRZvlQTTCMg ….there appears to be full extension on the first few steps only and he toe offs well behind the line after he becomes upright. At MaxV, you touchdown on/near the line, so doesn’t toe off have to occur well behind the line?
However, the angle of the line changes as you progress through acceleration until you are upright and at maxV. Because of that, when you are in the blocks the angle tilts forward. Full extension is not behind the line but rather directly on the line. Where excessive backside mechanics comes in is if you then cycle your leg up and over the knee after full extension, thereby making it pass behind the imaginary line
So for the first few steps..
– toe off on the line with full extension
– leg recovered with a sweep, no cycle or step over
– touchdown in front of the line which is still behind the point directly under the sprinter
This gradually transistions to…
– touchdown closer and closer to the line as it moves from behind the sprinter to directly underneath the sprinter
– toe off, without excessive triple extension, moving from on the line when it is behind the sprinter to slightly behind the line as the line moves from behind the sprinter to directly under the sprinter
– leg recovered with more of a cycle motion with step over[/quote]
In general, this is probably about right with some issues being:
-Does Asafa have optimal technique in this video and is it the same technique demonstrated at full speed?
-Related: Would a high speed camera (like the one in this video) show us something different in the races (with regards to achieving triple extension).
-I don’t know how it could/would be quantified and discussed, but while toe off may be occurring behind the athlete, how much of this is simply because of the athlete moving so quickly over his foot strike and no longer accelerating (likely decelerating and slowing down)?