Tempo on grass increases foot contact times?

From Oztrack/futuresprinting:

Michael Johnsons turnover was higher & would have resulted in higher efficiency due to less loss of energy in the early stages of each foot contact. But it cant be forced to be faster. Faster turnover is a result mostly of quicker contact times with the ground and to a lesser extent better leg recovery dynamics. The way to improve turnover is to get stronger and more powerful - be up higher on the support leg, run with less of a quad pushing action and with more with hip extension. I have also found that a small volume of hurdle bounces on two legs eg 6 x 2 hurdles set at a high height will help in this area.

Contact times are also to do with how “active” the contact is and whether the athlete is too high up on the front of their feet and then need to roll onto the ground more (creating a delay before toe off). Foot contacts can also be improved by athletes doing smart low volume [plyometrics and making sure the athletes ankles are strong with heel/toe walking, sandpit mini bounces done barefoot.

Good core stability will also help decrease contact times as it will decrease energy lost on ground contact through absorption in the centre of the body.

I believe also that faster turnover can only be optimized by doing relaxed tempo training on the actual race surface - excessive use of grass tracks will result in increased contact times - as the surface returns less energy and because the athletes hold themselves slightly lower to improve stability because the surface is not smooth.

Charlie and others. What do you think of the last bit in bold?

Obviously doing tempo on grass increases ground contact times but as we know reguardless of surface the pace of tempo runs is too slow to have any positive effect on turnover improvement anyway. Likewise we do not do tempo in racing spikes so the ground contacts is completely different anyway.
Dont know what this persons definition on tempo is …maybe he is refering to actual relaxed all out sprinting as tempo? If so then I agree, sprinting on the grass will not have the same impact on speed development as sprinting on the track due to longer ground contacts of the softer surface.

I’ll go with Quick here, the objectives are different and the benefits from tempo can’t be overlooked!

Others?

Tempo is tempo - active recovery. As long as form does not fade, does ground contact time really matter?

I agree…Tempo is active recovery.

The author proves the point himself. The reason the increased ground contact time on grass will not hurt sprinting is because the surfaces are different. Increased contact time is caused by the nature of the surface itself, not what the athlete is doing. Why then would this be carried over to the track? Also, as stated tempo is not a race rehearsal or even a time to work from, it is a means of recovery and aerobic development.

Didn’t seem to hurt Ben Johnson’s 100m performances. And all his tempo was done on grass over his whole career.