I watched a race recently where one sprinter had a nice start using a shortened backstroke on the drive out of the blocks. The arm moving back at the gun, stopped moving back just past the hip and then started moving forward again. It wasn’t bent very much – maybe 120 degrees at most.
The runner next to him had a backstroke that was longer. In fact, the arm was back almost straight and at least as high as the shoulder.
Lead arm mechanics were about the same for both.
Both appeared to get out at the same time but the first sprinter gained about a half step on the second runner very quickly. At the end of the 60, the margin of difference between the two runners was a tenth of a second.
I thought the second runner was slow escaping the blocks because of that backward moving arm that went back too straight, too high and took too long to move back to the front because of the mechanics used moving it backward, resulting in longer and slower strides coming out.
It got me thinking about starting mechanics. How much bend should be in the arm moving backward and how far back should it go? I see a lot of variation out there and haven’t seen much discussion.
It made sense to me that the sprinter who emphasized the front side and minimized the backside arm mechanics had a much more rapid turnover that helped gain an advantage. Given that you are only stepping over the ankle at that point with low shin angles and not into the stepping over knee phase yet, the shortened backside arm mechanics seem to make sense.
Or am I missing something here? I always thought that the back arm should go back vigorously in a full range of motion in opposition to the front arm punching forward-upward. After watching this race, I started to question that.