Andre DeGrasse to Altis

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101

Good example of a situation in which that works well.

Just as a counter story, the most successful athlete I have coached move on to different coach with a higher-level training group one year before I was going to tell the athlete (if the athlete stayed), “You need a group and coach that is performing at a higher level than the one you have with me.” While I trust my coaching, I am not coaching internationally competitive athletes nor are there any internationally competitive athletes in my group, and I believe a training group is important.

I don’t think any of us are in a position to criticize De Grasse’s choice, nor have we seen any results I’m aware of that indicate it’s a bad choice. However, even if he never PBs again, he does have a contract with enough $$ for him to have financial security if he chooses to manage it that way.

102

Have you considered that Andre’s interest in Rio and Puma’s might not neatly dovetail together? Have you considered the difference between Jenna Prandini who signed with Puma with Andre who signed with Puma? And Ameer Webb with ALTIS running the TWO fastest USA times in the 100m (legal and wind-aided tied with Gatlin), while Andre hasn’t run a single 100 and will not in Jamaica this weekend either?

New Balance (Bromell) wants to win and Nike (Webb, Gatlin) wants to win, and even Puma (Prandini, womens’ #1 right now) wants to win if it doesn’t involve beating Bolt. But Puma has Bolt yet for the Rio Olympics, and they might not be too thrilled about their investment being upstaged by their investment. Puma may indeed want Andre to develop and wait.

103

Great great point, lkh, though some might accuse you of being overly cynical. However, it doesn’t seem to be to be an implausible conspiracy to me

104

I am missing your point? What is your point?

105

Exactly right, over-cueing is simply a way to get the athlete closer to the ideal. Achieving the stated cue is not actually what the coach wants (in this case Pfaff) but somewhere between their current position/tech. model and the overcue.

106

I’m not sure how we got to the point where people were suggesting that DeGrasse was literally forced into choosing coaches for the purpose of having a great endorsement deal/contract but obviously in the figurative sense. Of course every athlete is responsible for their own decisions and the ramifications of those decisions whether good, bad or having minimal to no effect. I think we can all appreciate one’s desire to establish a great future financially.

107

And his performance in London in 2012 was, in my judgement, one of the brightest in the history of the sport.

108

Well stated bmarcho1.

One point of refute, however. To state that what coaches say sometimes is a deliberate departure from physics implies that these same coaches have a competent understanding of physics from which they intentionally depart.

I’m not sure that there’s many coaches who have a competent understanding of physics in the objective sense (I’m not counting received wisdom in the form of dogma and credo that is often the progeny of mentor:apprenticeship).

109

Fundamentally Newton’s laws are about how forces cause acceleration. A change in net force is the fundamental reason behind changes in rates of acceleration. One example is the emphasis on dorsi flexion of the foot, increased dorsi flexion improves horizontal velocity. This reasoning is incorrect, changes in net force will alter acceleration or velocity not changes in limb repositioning.

The fact is no one know’s what the best mechanical model for sprinters are. We don’t have enough objective evidence to have a firm position.

110

Some unbiased clarification for those who are unclear, muscle force pulls bones and generates joint torque- which in turn generates human movement. The mechanical optimization of limb positions/postures allows for greater internal forces to be generated by way of the body’s interaction with the environment (i.e, an athlete performing a pushup on the ground can increase/decrease joint torque by changing their orientation with respect to the ground and the optimization of their levers will effect the gross motion quality).

This is where the discussion bifurcates, as one particular limb orientation may increase internal forces yet due to a mechanical disadvantage these internal forces will not equate to increased acceleration of the body away from the ground. Alternatively, optimizing the limb position so as to allow for the greatest acceleration away from the ground may occur at lower internal forces.

Net force is the sum of all forces that act upon an object. In sprinting, we are accounting for external (wind/air, gravitational, friction, normal, spring/dampening regarding track surface…) and internal (by way of torque that generates limb movement, tension, strain, compression, shear, stiffness, elastic…).

No doubt that there isn’t enough currently available objective evidence that has been collected regarding the world’s elite, however, I would argue that what is already known (from physics as it applies to human movement) is more than sufficient to create a model for arm action, pelvic position, leg action, foot action…

As for the foot/ankle, what is known is that dorsiflexion lengthens/pre stretches the achilles which provides for greater elastic return during ground contact due to more stiffness and less structural deformation. Alternatively, running like a Ballerina in plantar flexion does the opposite and lengthens ground contact time. Therefore, optimal dorsiflexion allows for greater force transfer during ground contact in less time which results in faster sprinting.

What is the Pfaff statement that is under review? Does someone have a link?

111

I was an intern at Altis during the time that DeGrasse showed up, and from what I could pick up he was personally interested in being a part of Atlis. He specifically mentioned that he liked the more “professional” environment, such as constant access to track-side therapists, a large concentration of coaches with experience and results, and an environment where his entire training group is legit (Ameer, Koffi, BJ, Anaso, etc).

Its easy for someone to see a race and judge like an armchair QB, “oh yeah clearly his coaching change isn’t working out.” Meanwhile, people who make those assertions have no clue what is going on behind the scenes. Do you know what the training was like? Any injury or tissue restriction issues? Any significant outside/life stressors at play? All of these factors have a role.

Anyone who knows track and field knows that no two seasons are alike, and comparing how you did this week vs that week of this season vs that season is a pretty poor predictor of eventual performance.

112

James, I think the premise here (not yours, what you are responding to) is not quite correct. In the one instrumented measurement that I know about, it appears that the application of GRF is what matters, rather than the magnitude of the force itself:

The main result of the present study is that a higher level of acceleration and overall performance in the 100m are mainly associated with a higher ability to apply the resultant GRF vector with a forward orientation over the acceleration. In contrast, resultant GRF magnitude was not related to acceleration and overall 100m performance, but it was to top running velocity. Specifically, the world-class athlete tested did not show an outstanding total force production capability but he was able to produce much more horizontal force than the other subjects (national level sprinters and non-specialists), especially at high running velocities.

Jean-Benoit Morin, Pascal Edouard and Pierre Samozino
New Insights Into Sprint Biomechanics and Determinants of Elite 100m Performance
IAAF NSA, 28:3/4; 87-103, 2013

Form does matter, ground contact time does matter, eccentric power applied does matter, everything that impacts the application of force in the direction of the sprint does matter. It is not just angular momentum and the raw application of force developed in the gym or with sleds.

113

Yeah, the Morin et al paper is very interesting to me.
One the reasons the old “just get a really strong deadlift and sprint a little twice a week!” approach doesn’t actually pan out.

114

Agreed which is why Triple jumpers encounter higher ground reaction forces than sprinters, most notably on the second of the three contacts while moving no where near as fast as 100m sprinters at max V due to longer GCT. All is a function of time.

115

Unless you’re a team sport or strength coach who hides behind the claim that your athletes are not sprinters (wink).

116

[QUOTE=ATHLETEX;254904]I was an intern at Altis during the time that DeGrasse showed up, and from what I could pick up he was personally interested in being a part of Atlis. He specifically mentioned that he liked the more “professional” environment, such as constant access to track

How did you find the intern program to be. I am thinking of doing it myself?

117

You are confusing braking force, negative horizontal ground reaction force (GRF)) and propulsive force (positive horizontal GRF).

118

Show me the experimental data to support the claims ?

119

Its actually the magnitude of the net force.

You are also confusing total force compared to Net positive horizontal force.

120

Indeed ground reaction force was misprint on my behalf Sharmer, thank you for catching that. As for the dorsiflexion, you already know that a 90 degree angle between applied force and a rotating lever (say a wrench) provides the maximum moment arm and, as a result, the highest torque at the axis of rotation.

You also know (from tensile and compression forces) that, regarding the ankle, by mitigating the differential between rotation between the point of ground contact and the point of toe-off requires less time (due to less compression and subsequent expansion) then the ankle having to rotate further upon ground contact (due to being plantar flexed) prior to toe-off.

It’s a question of deformation to the Achilles/gastroc. Dorsiflexion reduces the distance the achilles/gastroc shortens upon making ground contact, thus the overall distance of shortening and re-lengthening is less in comparison to when the ankle is plantar flexed, in which the achilles/gastroc is pre-shortened prior to GCT, thus it must lengthen and shorten again prior to toe-off thereby experiencing greater deformation (compression and expansion).

Because of this, the lengthened/pre-stretched achilles/gastroc, by way of dorsiflexion, creates a longer moment arm at the achilles/gastroc and minimizes the conversion time of muscle lengthening and shortening during ground contact and increases stored elastic energy.

Clearly we do not have prescriptions as to (dorsiflex the ankle to _______ degrees prior to ground contact) however, the physics of what’s happening is clear enough to distinguish between what is happening during dorsal and plantar flexion prior ground contact, the variance in length of moment arm, and why none of us are able to provide a video link of a sub 9.8sec 100m man who points his toes prior to ground contact.

In fact, biomechanical research on cheetah’s reinforces the value of the lengthened moment arm of the gastroc in regards to greater joint torque than greyhounds:

study link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3077520/

In the distal limb, the majority of muscles were of a similar mass in both species but, when grouped by function, cheetahs had significantly larger muscle mass for tarsal flexion, digital flexion and digital extension. The gastrocnemius muscles had a similar mass in both species, but the cheetahs had longer fascicles and therefore a smaller PCSA. Despite this, the elongated calcaneus in the cheetahs provides the gastrocnemius with a longer moment arm at the tarsus enabling it to generate much larger joint torques than in the greyhounds (Fig. 7B). The gastrocnemius is a biarticular muscle also functioning to flex the stifle (where we also see an elongated moment arm in the cheetah; Fig. 7B). This muscle is active during the stance phase when the tarsus and stifle flex (Goslow et al. 1973, 1981) and acts to resist the large ground reaction force joint moment that exists at the tarsus (Colborne et al. 2006).

High quality slow motion cheetah footage (note the position of the phalanges prior to ground contact): https://youtu.be/NuyeVN7PuTM