Kinematic Kinetic & Electromyographic study of female sprinters

Expert Discussion Biomechanics and Physiology
1

Tom Green posted this link but it should really go into Biomechanics.

Thanks for digging this one up Tom!

http://www.education.ed.ac.uk/track-ath/papers/cdj.html

I found it fascinating and there are some very interesting discussion points. I put this here so I can remember to come back to summarise some of the most interesting points so that we can discuss further. So little time… :frowning:

As a side note, look at the variance in flight time when a study is done properly. Pretty dramatic. Sorry Mr. Weyend :frowning:

2

There is a variance of 15m/s in flight phase.

The girl with the shortest flight phase has the fastest speed. Note she doesn’t have the shortest contact phase. Hmmm.

3

For further reference, the times for these girls for the flying 20m (with 20m accel) on which the above is based are:

BA = 2.20
BB = 2.27
HA = 2.30
PS = 2.25

4

could someone give a better definition of the different phases of sprinting mechanics? e.g. swing leg, braking
thanks

5

Here you go. It’s a bit crude but it illustrates what the figures above are depicting as far as phases.

I knocked this one up for Ben’s right leg.

Note that this is for one leg not both so I could better illustrate the concepts.

In reality when the left leg makes contact, the flight phase is replaced by the contact phase of the left leg until the left leg leaves contact. It would take too many vidcaps.

6

Nice diagram Dcw, I am sure that helped a lot of novice athletes and coaches. Great job!

7

Good series of shots, but, unfortunately in the wrong spot in the race. This occurs after Ben has shut down (note his head turning to the side to confirm his margin). A series fron a little earlier in the race would be helpful.

8

Couple of thoughts about the girls’ stats. With an inadequate 20m accel phase before the timed 20m segment, the stats are skewed by the fact that the fastest girls will still be in a more pronounced accel position entering the timed zone, influencing the results, and velocities are not maximal for all but the slowest girls tested.

9

Originally posted by Charlie Francis
Good series of shots, but, unfortunately in the wrong spot in the race. This occurs after Ben has shut down (note his head turning to the side to confirm his margin). A series fron a little earlier in the race would be helpful.

Yeh, yeh, yeh, I know. It was the clearest vidcap that I had that let me show the phases. I got 15 minutes into the job and I thought, damn, what’s happening with his head and arms. Then I realised which segment I had got to and it was too late to turn back.

Anyway… I just wanted to give a guideline of what the numbers mean so I continued with this footage. It’s still right, just not the greatest example.

10

Originally posted by Charlie Francis
Couple of thoughts about the girls’ stats. With an inadequate 20m accel phase before the timed 20m segment, the stats are skewed by the fact that the fastest girls will still be in a more pronounced accel position entering the timed zone, influencing the results, and velocities are not maximal for all but the slowest girls tested.

Good point.

Actually, after re-reading, I was wrong about the 20+20, the incorrect grammar got me. It was a 45m total flying 20m sprint. The 25m acceleration period is definitely less than the quickest girl would need to reach max v, which is probably why the times are slower than you would expect for girls of this level as they were no longer accelerating through the 20m measurement period.