When the grass does become usable it’s usually spring summer. Would this phenomenon work in reverse - i.e. winter on the track then move to grass pre-season… would the muscles and tendons still compensate for the softer surface durig this short time?
According to some of the studies posted in the beginning of this thread, the body begins compensating almost the instant you step on to a more/less compliant surface. So, what I’m wondering is, is there really any steady adaptation gained from sprinting on grass that isn’t gone just about the instant you step onto the track?
Perhaps grass best use is it is more natural and less abusing on the legs?
OR, and this is something I’ve been throwing around in my head. What about doing all of one’s warming up on the grass (body has compensated) and then doing the maximal sprints on the track? (Perhaps before body can acclimate due to such a quick change of pace?).
Afterall, majority of tracks I know/use have a grass infield right next to lane 1.
[QUOTE=Jstu3565]The second is when your foot hits the ground the amount of stiffness(lack of bend at any of the joints in the legs). QUOTE]
Sice when has there ever been an athlete/sprinter, who landed with a nearly straight leg?
The amount of bend at the joint angles are huge. (thigh to torso angle, lower leg to thigh angle).
Is there anyone that can show a picture or slow mo vid of a decent sprinter, landing with not much bend in the leg?
(not a picture of the start block push out, but of when the sprinter is actually running close to or at full speed.)
Since when did a runner/sprinter land with a nearly straight leg? I have never seen it.
You are right that at first the changes in stiffness only occur while you are on a particular running surface, but if you keep repeating these runs on a compliant surface then these changes become more permanent. This happens through a process called activity dependent plasticity. Activity dependent plasticity is the idea that changes in motor control start out as temporary changes, but with repeated practice, these changes become more permanent(not entirely permanent since obviously if you stop practicing you eventually lose alot of that skill). This concept doesn’t apply to only running on different surfaces though. The same thing applies to regular sprinting or lifting. If you only lifted or sprinted every two weeks for example, you probably wouldn’t notice any substantial gains. This is because those skills haven’t been done enough to make any lasting changes. But if you lift/sprint 2-3 times per week for example you are much more likely to see improvements in those skills.
Definately agree that running on grass can be easier on the legs too.
The amount of bend at the joint angles are huge? Oh really?
Joint angles are huge? Oh really? Like 180:) ?
From reading this thread I have picked up that it is the muscles not the tendons that become stiffer, I was wondering if there is any relationship between muscle stiffness and flexibility?
Would the muscles get tighter as they got stiffer?
i.e are tighter muscles stiffer muscles?
Thanks
I think you are referring to one of the poster’s responses. If you look at the studies posted tendon stiffness does indeed increase with softer surfaces according their results.
Oh ok. That makes my question irrelevant then
I thought more ‘compliant’ tendons resulted in faster sprinting? This is how Martyn? explained it in another thread… a ‘stiff’ tendon is not elastic…
On the subject, how compliant does the surface have to be? For example, would sprinting in triple jump spikes (1cm cushioning) instead of sprint spikes cause ‘stiffer’ (or more ‘compliant’ as it may be) tendons??
Keep in mind I’m by no means well versed in this topic, which is why I started the thread. But from what I can gather sprinting on softer surfaces forces your body to make better use of the stretch reflex. This causes some adaptation in the muscles and tendons (appears to be increased stiffness from the numerous studies in those links referenced) and once a transition to the track is made the body still has this adaptation so it is used. However, the body realizes it does not need this adaptation as the ground helps here (harder ground = ground does more work for you) so the tendons and such lose that adaptation (stiffness I believe). The body’s primary goal is survival and a product of this is accomplishing tasks with the most efficiency. If the body can allow something else, the ground in this instance, to do work it (the body) doesn’t have to do, then it will do so.
So, softer shoes, even minorly softer will cause different stiffness but I think the difference between different spikes is going to be pretty much negligible.
[quote=“mortac8”]
It had to be you, to respond with that.
The way the other guy suggested that the legs would be nearly straight upon impact, was a grose exageration. The legs are nowhere near straight upon impact. The angles are way beyond walking angles, and are nowhere near straight.
Depends who you are talking about and the framerate of your film. I don’t think you can globally say they are “huge”.
[quote=“Goose232”]
You are kind of misunderstanding the point.(Or maybe I didn’t explain it well enough, I don’t know.) What I mean by not having bend in the leg, I mean that there should be minimal bending after the foot hits the ground.
No you are correct. We are interested in the muscle being able to work almost isometrically during the stance phase, from touchdown to toe off. We want the tendons to be more compliant in that we want them to do all the stretch shortening work rather than the muscle belly. Yes tendons have a certain level of stiffness otherwise they would be useless, but a tendon that is able to stretch shorten quickly (a balance between elasticity and inelastic action) will allow the muscle to utilize energy more efficiently. This will of course mean that you can sprint further before you have used up your phosphates and have to rely on glycolytic pathways, and apply more force more quickly. The stiffer the muscle ( isometric) the more force can be applied and the less energy used. A compliant tendon will then do the work of muscle by stretch shortening and saving the muscle from doing unnecessary work. Muscle adaptation on a morphological level will transfer. The initial adaptation to different surfaces is a neural adjustment but for fiber adaptation and deeper morphological and physiological adaptation that will transfer to the track, you must probably use a compliant surface for some time. That length of time is probably dependent on number of sessions, the surface, giftedness of the athlete and experience. As an aside it takes about a year for high jumpers to restructure their achilles tendons to take on the demands of their event. We are trying to affect both muscle and tendons so its would not be just a simple case adaptation.
The increased stiffness in the muscles will cause the tendons to compensate by being improving their stretch shortening cycle, AKA COMPLIANCE AKA SSC (stretch-shortening cycle). Stiffness in muscle is brought about by ISOMETRIC CONTRACTION.
For meaningful and deep adaptation, a relatively long period of training on compliant surfaces in rotation with other surfaces as suggested by CF is probably the way forward or as good a start as any.
It is likely that the increased muscle stiffness developed from running on compliant surfaces will transfer to a harder surface.
not sure what to make of this however, in this rear view slow-mo-shot at 2:26 of powell and gay striking the ground, you could see Gay calf muscle noticeably violently contract(this with wearing spikes). Meanwhile, with Powell, it seems his calf muscle doesn’t contract as violently as Gay(this while wearing softer running flats)
http://www.youtube.com/watch?v=gr9oVGBqCn4
Might this imply that when sprinting with softer running shoes(or more foregiving surface than rubber mondo or asphalt/concrete for that matter), the muscles are under slightly less stress and tendons are under slightly more stress?
Since you linked the German version of the Japanese documentary that people were keen to get a translation of, I thought I’d summarise the main points made in this video about Powell’s biomechanics.
First, they compare his initial couple of steps to those of Gay and reach the following conclusions:
a) Gay steps from side to side, whereas Asafa’s feet go straight forward.
b) Gay’s footplant only involves the balls of his feet whereas Asafa’s involves his mid-foot.
c) Gay’s foot contact is shorter than Powell’s (Gay spends 0.86s on the ground during his first 6 steps and Powell 0.99).
[The problem with all of this is that Gay is running in spikes from a three-point start and Powell in sneakers and from blocks.]
They then go to Japan for some biomechanical analysis and find that Powell’s longer foot contacts allow him to generate much more forward drive. His first step accelerates him to 10.5m/s compared to 9.4m/s for Asahara (a Japanese 10.02s sprinter, generally considered to be a good starter).
[Again, Powell is running in sneakers and Asahara in spikes.]
They then do MRI scans and find that Powell has a massive psoas major that is twice as big as that of Asahara. They conclude that this enables him to recover his legs very quickly, thus allowing for his fast start and good knee lift.
Asahara states that he could never run like Powell because he doesn’t have the necessary power.
They then analyse video footage of Gay’s and Powell’s best race (9.84 and 9.74 respectively) to look at their biomechanics at maximum speed. They find that Gay reaches top speed at 70m and Powell at 60m. At top speed, Gay’s stride rate is 4.9 strides per second and his stride length 2.42m. For Powell it’s 4.96 and 2.60, meaning he’s better at both. At 40m, btw., Gay’s stride rate is still higher than that of Powell whose long strides during the acceleration phase result in a slower stride rate in the early stages of the race.
To figure out how he can achieve such superior stride rate and frequency, they determine the force needed to stretch his tendons (they are getting him to contract his quads, so I guess they are looking at the patella tendon) by 1cm. The average person needs 43kg of force to do this. For Asahara it’s 59kg and for Powell 114kg. They thus conclude that his superior tendon stiffness allows him to have both, a very high stride rate and a great stride length.
They then talk about Osaka and conclude that he lost this race because he lost control over his body resulting in co-contraction of agonists and antagonists in his legs. Co-contraction is usually prevented by spinal reflexes and involvement of the brain messes this up. This is why his maximum stride length in this race was only 2.40m.
They also show some interesting footage of him in bed the night before the final. He nervously plays with the light switch of his bedside lamp and repeatedly tells his roommate that he’s going to win the gold.
Towards the end, they show some footage of Asafa refusing to follow his coach’s instructions and complaining about having to train too hard.
Then they show the hill Powell used to run on as a child and some footage of him attending church.
Finally, Asafa talks about the immense pressure he is under to keep his family and country happy.
Hope this is of some help,
Robin.
Thanks for the summary. As you pointed out, it’s too bad they let Powell do most (all?) of his runs in sneakers.
Thanks for the plethora of information. What about dragging the left foot coming off the launch pad. I can’t remember where this was discussed on why this was done. Might it serve as a reference or starting point of the feel
of low flat heel recovery.