The ham is lenghtened by the quad.
In the CF Fundamentals 1: Speed & Strength video Charlie talks about Lombard’s Paradox, where the hamstring, when it works on certain angles, becomes a knee extensor along with the quads.
At triple extension. If you run frontside the hammy becomes a break for the quads.
when the back leg is brought forward out of the blocks, initially there has been a little knee extension as the back foot leaves the block but momentarily later the hip and the knee both flex to clear the ground and the leg is brought forward to place the foot on the ground as the knee and hip then both extend. However, the issue on the other page was about the foot drag which is the hip/knee flexion phase here.
The front leg also has to flex at both the hip and the knee to clear the foot of the ground (a light drag being allowed).
If the knee did not flex along with the hip, then the athlete would go knowwhere, the foot would plough into the ground.
Lombards Paradox is irrelevant here. This is a simple issue of the knee flexing (along with the hip) to allow ground clearance for the foot out of the blocks. Watch youtube, watch yourself…
The knee angles become more acute (flexion) as the feet are brought forward out of the blocks to place on the ground ahead! Look at Usains back leg angle as it comes forward, the other leg will do similar. Only at the end of the swing phase does the knee/hip extend again.
Ok both these posts effectively say the same thing but there you go.
I added it to the discussion, not because it’s relevant to start mechanics, but to avoid blanket statements like, “hamstrings bend the knee, they don’t extend it.” Didn’t mean to offend. 
no it’s ok, I knew that really, was just seperating the discussion, cheers
The toe drag is a result of increasing stride length.
Not offended. In the context of high knees at the start and frontside mechanics the hammy is a stabiliser for the quads.
I view it as an effort to quicken the first few steps as if one was doing a ladder drills. Sprinters with longer strides would normally take fewer strides in the first 5m of race anyways. This practice of dragging the toe seems to exaggerate the “tripping motion” that the body is trying to compensate for in the beginning. The result is a faster stride rate that is comparable to their counterparts.
IMO
Did you know that if you drop a 16lb shot and fire the most powerful handgun at the same time the bullet and shot will hit the ground at the same time.
They both have to be at the same height at start.
Shot is dropped and gun fired at 90% to shot.
Have another look at the start, longer not faster.
He is talking biomechanics.
If you’re going from knee height to the ground, the shortest way is straight down, but, if you quickly swing your foot out front, your foot will hit the ground further out, but, it will still hit the ground at the same time as dropping your foot directly down. Therefore, all you did by swinging your foot out front, is, increase stride length.
The constant in this, is Gravity.
Hopefully that explains it?
WhenLinford broke the WR every coach started teaching sideways movements out of the blocks…
When driving a drag car
it is shorter in a straight line
1st to the finish not 1st to leave the start
When the next fastest person appears the majority will copy something.
Enjoy what you are doing.
Because the hamstring is acting as a stabiliser for the quads as opposed to a break ( lift the foot). The less breaking force a muscle has the faster it will perform.
What would I know I am only a level4 coach. lol
THis helps. You guys are on such a level so I am always looking to learn. I was once told that learning can feel uncomfortable. I can see what your saying now I have to apply it to what I am seeing and using. THanks again.
Linford Christie never broke a world record (to my knowledge).
All sprinters “side-step” to some extent in the early strides from the blocks. It is a case of delivering power to overcome inertia from the set to first step, also a case of “making space” to drive the pelvis through, also a process of making time to coordinate arms and legs in this early acceleration phase. I cannot think of a sub-10 100m runner who has not side-stepped. But you need to straighten it up sooner rather than later. However it is a completely natural movement and process which shouldn’t be over-ridden because the textbook says the shortest distance between two points is a straight line. Just my opinion.
He set a 200m indoor world record in 1995 running 20.25s.
Thankyou Robin I did not know that.