The question is basically in the title. What are you supposed to do? I’ve read that a sprinter is supposed to drive through the ground and “leave their feet behind them,but at the same time I read that it is essential to minimize backside mechanics, which seems contradictory. Your guys’ thoughts?
Triple extension at the start vs minimizing backside mechanics?
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Participant
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Participant
The question is basically in the title. What are you supposed to do? I’ve read that a sprinter is supposed to drive through the ground and “leave their feet behind them,but at the same time I read that it is essential to minimize backside mechanics, which seems contradictory. Your guys’ thoughts?
I have never heard anyone say not to extend fully at the start. Can you note what coaches or literature says not to?
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Participant
the goal is to minimize backside mechanics when upright. For some. referring to backside mechanics would also be relative to body position (angle(s) of tibia/femur/torso). You need positive shin angles and full extension, but you will still have a nearly-streamlined position, ideally.
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Participant
Brooke, i too have never heard of any coach promoting anything less than full extension from the blocks. However, to me it just seems that aiming for full extension for the first few steps of the race would conflict with minimizing backside mechanics.
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Participant
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. 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 in a nutshell push out hard then sweep/push instead of cycle for the first few steps.
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KeymasterJust to pile on here, Brooke, Davan, and Josh are correct. Backside / Frontside mechanics are relative to the trunk regardless of its orientation with respect to the ground. Backside mechanics should be minimized at all points of the race. Early on this will occur when complete pushes are made and the pushoff foot recovers relatively low to the ground rather than kicking up towards the butt in a high cycling action.
ELITETRACK Founder
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ParticipantWow, Allyson Felix does pretty well then considering…
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Keymaster
There are always exceptions to every rule and it’s certainly possible to succeed in spite of poor coaching, poor technique, etc. For example, Lauren Williams won several world championships with a large anterior pelvic tilt and relatively low knee lift; Mo Greene ran dozens of sub 10s and won world and Olympic championships with what I’d consider as less than ideal postural alignment during his acceleration; Dwight Phillips put his foot out excessively at takeoff in the earlier years of his career but still won world and Olympic championships. My point is, we need to look at what is successful across a broad spectrum of athletes rather than one person who may be succeeding for a variety of reasons other than one what is seemingly distinguishing them.
ELITETRACK Founder
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Participant
Ok thanks guys, I kinda figured it that way but at the same time i wasn’t sure (I’m by no means an expert, just a 17 year old sprinter with a drive to improve). The question just arose when I watched a video of Latiff Thomas’ emphasizing full extension in the first few steps and pushing behind the COM. It made sense, but at the same time the extension was definitely causing the runner to have a more significant backwards leg swing rather than a quick tuck, but I’m guessing it’s necessary for a proper acceleration?
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ParticipantCould you post the video if it’s available?
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Participant
the goal is to minimize backside mechanics when upright. For some. referring to backside mechanics would also be relative to body position (angle(s) of tibia/femur/torso). You need positive shin angles and full extension, but you will still have a nearly-streamlined position, ideally.
What do you mean by streamlined? The leg straight and in line with the spine?
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Participant
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 sprinterThis 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 -
Participant
[quote author="davan" date="1275703319"]the goal is to minimize backside mechanics when upright. For some. referring to backside mechanics would also be relative to body position (angle(s) of tibia/femur/torso). You need positive shin angles and full extension, but you will still have a nearly-streamlined position, ideally.
What do you mean by streamlined? The leg straight and in line with the spine?[/quote]
Nearly, yes. This is only when at full extension, of course.
https://i199.photobucket.com/albums/aa258/thefreshprince101/Sports Pictures/Seoul_StartoftheCentury.jpg
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Participant
[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 sprinterThis 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)?
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Participant
I should have been clearer, but yes that was what I was saying. That is why I said “Ideally as close to that line as possible”. It was meant to emphasize that at top speed, there should be a vertical emphasis on force rather than horizontal. Vertical force increases as your toe off becomes closer to the midline/bottom dead center or in other words, toe off that occurs far behind the midline results in excessive attempts horizontal force.
However I do agree with Davan. I have no way to quantify force in this situation. I would imagine that 90%+ of force is delivered in the first 50% of ground contact and the rest of GCT is you leg lagging behind as your switch it “off” from the step down/support phase and “on” to the swing phase.
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