Reducing Ground Contact Time...

Expert Discussion Strength Training
1

Which Strength exercises would you guys recommend for reducing ground contact time???..

And are there any specific muscles calfs/quads maybe that helps decrease your contact time???..

Any comments…

2

Thanks,

I’m going to look into some equipment similar to what you mention.
I’m very interested in doing some in-house research on GCT.

Thanks.

Kenny Mac~~

3

I would try to reduce contact times trough sprinting. Thus leaving weightlifting to improve power.

4

plometric exercises -
starting with the most basic -
skipping or as in the US - jumping rope.

5

I’ve search some data about Angella Issajenko in Helsinki’83 and Roma’87 from my slow motion tapes (100 and 120HZ), to see some basic parameters at maximum speed and what made differences.
Mean results for 8 strides:

Helsinki // Rome
100m time (s) 11.22 // 11.09
max speed (m/s) 10.26 // 10.41m/s
Stride Length (m) 2.22 // 2.21
Stride Frequency (HZ) 4.62 // 4.71
G Contact time (s) 0.091 // 0.088
Flight Time (s) 0.126 // 0.124
SL/GCT 24.4 // 25.1

This example illustrates an increase of speed mainly due to GCT reduction, leading to a higher stride frequency, while Stride length remains about the same.
The indice SL/GCT indicates a more efficient forward propulsive thrust as SL was the same, even after reduction of GCT.

Charlie can you tell us which training made this improvement on Angella?

6

I would definitely agree. Just doing plyo’s won’t do much. It will help, but one needs the overall strength that weight training gives. Sprinting+recovery+weights + plyo’s + 5x drills drills drills!!!(all given at the right time in the right amount)= reduced ground contact times. That’s my thinking

7

Power developed across the full spectrum of training can reduce contact time. Thoughts?

8

There were a number of issues at work here, in particular that Angella had a sciatic injury in Helsinki, and that the 11.09 final in Rome wasn’t her best run of the meet either, though the principle you describe is exactly right. A more graphic picture of the concept would be the diff between the Helsinki final, which you have and the Rome QF or SF- both in 10.99- which you probably have as well. Can you use this as an illustration? Remember as well that the DISTRIBUTION involved in the AVERAGE stride length does change with increased efficiency and power.

9

Unfortunately, i don’t have high speed films for the preliminary rounds she ran in Rome. I have her 10.97 PB in Köln on tape, but the frame frequency isn’t high enough to make this sort of analysis.

10

pierrejean:

I have a quick question regarding Issajenko’s total # of steps over 100 m during the two races. Did she take less strides during her fastest race of the two you posted?

What does one need to measure GCT, or how can you tell if their GCT is out of range?

Thanks pierrejean that is some good material.

Kenny Mac~~

11

Originally posted by Kenny Mac
pierrejean:

I have a quick question regarding Issajenko’s total # of steps over 100 m during the two races. Did she take less strides during her fastest race of the two you posted?

What does one need to measure GCT, or how can you tell if their GCT is out of range?

Thanks pierrejean that is some good material.

Kenny Mac~~

Angella Issajenko did 49.4 steps during 11.22 and 49.7 during 11.09. For her 10.97 in Köln, she did 48.0.

To measure GCT during competition, you need to have a slow motion tape of the race, where you can see clearly the touch-downs and take-offs. If the film frequency is 1000 frames/sec, it’s perfect, you just need to count frames during support. If the frequency is less, you need to divide frames, or make the analysis for several consecutive strides. Also, significant differences can be found between left and right feet.
For female athletes, at full speed, “normal” data is between 0.075 and 0.095.