Upon further review...

Some video frame grabs from recent practices.

Nathalie shows excellent triple extension here (ankle, knee, hip, shoulder), allowing her to apply maximal force off the front pedal. Also note how the lead leg is maintaining a good angle that allows her to step down/back -- and not out.

When that lead foot does strike the ground, she's well up on the ball of foot, and the toe is just behind the hip, allowing a strong angle in that shin and great push on the second step. Good example of how to get off the blocks and accelerate.

Mollie has a break in her extension at the hip. Good extension at ankle and knee to hip but then a bend, which often leads to a "step out," which happens because of the bend that causes some rotation. To avoid stumbling, the front leg steps out to avoid a potential stumble. Compare this to Nathalie's to see the difference.

When the lead foot hits the track, you can see how far it is ahead of the hip. When you bend, the hips go backward at the same time support foot moves forward. You can't apply much force in the right direction when this happens.

Mollie's extension into step 2 is great. Nice line. Good arms. The first step should look more like this.

Joe has good extension here.

Toe right under hip and right on our tape mark.

A pro start. Note shin angles. Arm split. Full extension. If you compare our shin angles to this, you can see how our front leg angle is more than 90 degrees while this shows less than 90. 90 would be typical.

Bolt.