Oh man…look at how much typing you made me do.
I also use the word “longer”, not long. You are referring to a study (Weyland’s) about how pulling weighted sleds effect high speed running mechanics, correct? In resisted running, as in starting, it is beneficial (some might say a requirement) to spend more time on the ground in order to apply more force for overcoming resistance…I agree with that statement. Just as when an American football running back needs to drive his way through a linebacker, he needs to spend more time on the ground to do that. Running through a linebacker doesn’t have a whole bunch to do with high speed sprinting. There is also quite a bit of disagreement out there in athletics community as to whether his weighted sled pull study is even applicable to the actual biomechanics of max velocity sprinting…at all. The stronger your drive phase the more momentum you will have for your max velocity running…this is obvious. Good for specifically training the max velocity biomechanics…no. My opinion is that Weyland’s sled pull study does not have much to do with max velocity sprinting…block starts and drive phase, absolutely. There is an obvious optimal balance of force application and frequency in max velocity sprinting. My comment assumed that this was understood. To dispute small GCTs in max velocity mechanics with data from a weighted sled pull study is disturbing to me…if I can borrow your word. As to Weyland’s other point you mention, I don’t coach any four legged animals so I haven’t done any research on what makes them fast. I have studied Ralph Mann who has done a ton of research over the last couple of decades on what makes two-legged humans fast, and his research shows that a “critical general performance descriptor for the short sprints at maximum velocity” is that the fastest folks spend less time on the ground than the slower folks…while running fast. The fastest are able to apply the most force in the shortest amount of time. Now of course, if those same fast folks reduce their ground times too much, they will not be able to apply enough force to run their fastest. Again, there is obviously a relationship between the two that is optimal. I’ve heard Tellez, Pfaff, Bosch, Mann, Seagrave, Winkler…the list goes on, all talk about reducing ground contact times in sprinting. I’ve seen Pfaff, Bosch, Seagrave and Winkler all put athletes through training that is specifically designed to create these short GCTs. Rudiment jumps are the most commonly known method. Pursuing short GCTs, which you say makes “no sense”, seems to make plenty of sense to all of these world class coaches. I’m hopeful you’ve heard of a few of them.
As it relates to slower pace races, an elite sprinter touches his foot down 6-8 inches in front of COG at top speeds. Mann says that the fastest people do 85% of their force application during those first 6-8 inches before the foot arrives directly under COG. This creates a shorter GCT than any of the longer distance races. Long sprinters contact the ground further out in front of their COG, as much as 20% further. Add over and inch of distance to support phase and a slower 100m pace and GCTs have to become longer and less dynamic to save energy in order to complete the race. If a 400m runner tried to run with 100m pace GCTs, the athlete would run too fast of a split for first 200 then tie up and fall apart before 250m…limp across finish lines constantly. As for slower paced races, like 800m through marathon. It is silly to think that an athlete in the 10K would contact ground at same distance from COG as sprinter and be able to apply 85% of force app in those first 6-8 inches they are on ground. The GCT/flight time ration can not remain the same at slower paces. I don’t know exact data for this but my guess is that a 10K to marathon type athlete’s force application distribution might be inverse of 100m elite, and apply 15% of effort in front-side ground mechanics, 85% in backside ground mechanic. Watch slo-mo film of any long distance athlete and this will be evident. This would create more time on ground behind the body as well. I have heard Tellez talk about this optimal GCT relationship between the race paces several times. Actually, the turn of phrase that is “troubling” you is actually borrowed from his explanation of Seb Coe’s mechanics when running 1/4-mile races. The context is Coe running faster training races (in relays) versus a short sprinter moving up to ¼-mile race. Tellez describes how each strives to adjust GCT in relation to the rhythms they are used to at their preferred race distances. There is a lot of footage on the web of Bolt running 400m races where you can see that the emphasis of his force application happens later in his support/stance phase versus where his force application emphasis is occurring in his 9.58…which there is also a lot of footage of out there…Universal has best version in my opinion.
To sum up, yes…if you are running short sprint races while pulling a weighted sled, then yes…it would benefit you to spend a little more time on the ground to apply force while trying to run your fastest in that context. If you are racing short sprint races with only your own body weight then it would benefit you to spend very short periods of time on the ground… for men no more than .087 seconds and women no more than .083 seconds, at elite levels. Those numbers are straight out of Mann’s last publication. Google “Neuro-Biomechanics of Maximum Velocity Sprinting” co-authored by Seagrave. It is a good place to begin researching max velocity running mechanics (he mentions elite level GCTs). Also, I have not been able to teach my athletes how to have four legs. Let me know of your successes coaching your four legged athletes. I understand that they are not limited by human sprint mechanics.