So doped records are bad - but records in spring loaded shoes are OK?

That's because a trampoline is not tuned for running on.Try a surface like they use for gymnastics floor routines.

Vapor Thigh wrote:

I've talk to a half dozen people who ran either Boston or London marathons this year in Vaporfly 4% shoes... All of then said the same thing. Their QUADS and/or Calves have NEVER hurt that much in their life after a marathon. Apparently some of that 'energy' is blasting right up their leg as well. 2 of them said they would never wear them again.

If that's the case, then I feel bad for Kipchoge. I wouldn't want some stupid avant guard running shoe to give Kipchoge an injury. I hate that this event is almost more about this stupid nike shoe than the athlete. Kipchoge is what is making this record even remotely possible. Granted, I agree that it is not likely that he will do it, but he is an incredible athlete and an inspiration to watch.

I remember changing my training shoes one season in college and I developed an achilles tendon issue. Changing up your routine could cause unwanted side effects.

This conversation is leaving out a very important point... the dampening effect of the foam around the carbon fiber thing.Think of that "blade" as a spring on a car. If you just had springs on your car, it would bounce down the road like a pogo stick every time you hit a bump. So to keep that from happening, they put shock absorbers between the axle and the car body to stop that bounce. So the spring flexes to absorb the initial hit and then the shock absorber slows the rebound so things settle down. Foam in this shoe does the same thing. That carbon blade may bend and store energy, but when it tries to bounce back, the foam will slow it's return to shape and the energy is dissipated through the foam. So, the Nike shoe has a more rigid plate under foot which will make the shoe stiffer and probably negate some of that nice cushioning from the foam below, but it will not add any energy to your running. It will likely lead to extra strain on your calves by extending the lever effect of your foot against your calf muscle, but that's a different problem.

Someone mentioned the Bladerunner and his artificial feet. The blades return a huge amount of his energy because the springs are undampened. If he were to set the blades in a foam block similar to what the Nike shoes have, it would be a softer ride, but the energy return would be pretty much negated.

Vapor Thigh wrote:

I've talk to a half dozen people who ran either Boston or London marathons this year in Vaporfly 4% shoes... All of then said the same thing. Their QUADS and/or Calves have NEVER hurt that much in their life after a marathon. Apparently some of that 'energy' is blasting right up their leg as well. 2 of them said they would never wear them again.

So... 75% of the users would use them again... that's a win for Nike.

It's all about how you present the stats.

Mostly speculation and dampening isn't the word you think you need.

No, the foam (Pebax), as Nike also states, is also an energy returning component:

Pebax® resins are extremely light - usually more than 20% lighter than competitive polymers. They also offer extremely efficient energy return during repeated flexural cycling. They generally exhibit very low levels of hysteresis. This means that a high percentage of the energy put into flexing the polymer (i.e. the step of an athlete) is returned during rebound.

http://www.extremematerials-arkema.com/en/product-families/pebax-elastomer-family/

No dampening is the right word. The shoe is essentially there to smooth out the impulse spike on the foot when it contacts the ground. The foam acts as both a dampener and a spring. Source: Vibrations class

an engineer wrote:

Wetting Agent wrote:

Mostly speculation and dampening isn't the word you think you need.

No dampening is the right word. The shoe is essentially there to smooth out the impulse spike on the foot when it contacts the ground. The foam acts as both a dampener and a spring. Source: Vibrations class

No. You didn't pay attention either.

Whistleblower wrote:

However what everyone is missing is the drafting effect of the big füçk off TESLA with timing board that has been specifically told to stay 5m in front of the runners.

I didn't know about that but if true, well done for pointing it out. They will be literally getting a tow.

I hope Kipchoge doesn't end up with stress fractures and a ruined year.

I can't wait to buy these shoes.

Wet your appetite wrote:

an engineer wrote:

No dampening is the right word. The shoe is essentially there to smooth out the impulse spike on the foot when it contacts the ground. The foam acts as both a dampener and a spring. Source: Vibrations class

No. You didn't pay attention either.

The bottom line is that the first guy is talking out of his arse. The Pebax foam around the spring has high energy return and while it will dampen the whole system it certainly does NOT negate all of the carbon leaf spring...

Anyway forget the shoe. Several of their athletes were beaten in London wearing boost. It's all about the TESLA, perfect course, and no slowing for water stations.

MarathonMind wrote:

Such hypocritical BS. So if it's a given that doped up runners compete with an unfair advantage then it's also a given that high energy return shoes are also conferring an advantage. Whatever the exact increase in energy return the new carbon fiber/"magic" foam aided shoes have over older shoes from pre-Adidas Boost, there is no denying that it has been increasing with technological advances and it is quantifiable and it is significant (Nike says it's as high as 85%). So let's just wipe all the POST 2005 records off the books until the high energy returns shoes are also banned. Seems fair. Who knows what Clayton, Hill, Shorter, Rodgers et al could have run with these shoes?

Are you also advocating a return to dirt/grass tracks since artificial tracks can cut up to a second per lap? How about a return to bamboo poles since fiberglass is such a huge advantage? If these "advantages" don't bother you, I suspect you are the hypocrite.

One thing no one has mentioned is that NIke has the largest stable of elite athletes in track. If 80% of the elite marathoners in a race are Nike and all wearing Vaporfly there is no advantage -- they are all wearing the same shoes.

It doesn't really matter what you or I think. If the IAAF deems Adidas Boost or Vaporfly legal then they are legal. End of story.

Of course doped records are bad, but men winning women's races is far worse than marginal gains from shoes.

Doesn't make any difference. A highly trained altitude native will not go faster with springed heels.

In face even if you out one in a jet plane they will not gain any benefit.

Hopespringseternal wrote:

While it is well known that you are a Moran you can probably understand that feet do bend. As the body weight transfers forward it naturally bends the spring in the shoe and adds more pop to that flexion. The point is that all of the loading of the spring is going to happen anyway with no extra effort or energy expenditure from the runner.

You are talking out your ass. There is nothing in a shoe that contributes to the supination of the arch, or to plantarflexion at the ankle. The former results mainly from the windlass mechanism as the body rolls in front of the foot, and the latter a natural result of the gastrocnemius shortening at the ankle as it lengthens at the knee. And both result from the body's forward motion. The heel doesn't need to be "pushed," it is pulled up by the forward-moving leg in front of it.

What you (idiot) and other less rude posters fail to understand is that running is NOT about your feet bouncing up, it's about the rest of your body pushing forward from the contact point of your foot on the ground. Acceleration of the contact point itself can accelerate the rest of the body only if it exerts extra force to compensate for the forward motion of the platform it is pushing against. Retreating behind some guff about merely accelerating the heel makes no difference - if something pushes your heel upward, you must push against your heel or only the heel will move. You don't save effort, you just shift it elsewhere.

Trying to augment the body's natural stretch reflexes and chains of motion is putting springs on springs. Like a bike or automobile with too much suspension, it's likely to slow you down if anything. And as others have suggested, injuries of stability at the ankle, e.g. Achilles. Don't mess with what's already a highly-tuned machine and expect good results.

Bum speak. Nobody has perfect springs.

sdfgdffgd wrote:

I am no expert in biomechanics or physics, although I do have an engineering degree, so I would love to understand more about how a spring would work to "create" energy. Not trolling, I really am interested.

It doesn't "create" energy, it returns energy that is otherwise lost.

Usually, when you run, with each step you have to break your fall, then re-accelerate upwards. This is where most of the energy cost is. Assuming you are not on a hill, you are not doing any "work" moving yourself forward (though there is some work in accelerating your limbs back and forth). A shoe that can store some energy when you land and return it to you, reduces the amount of energy you spend in vertical motion, which reduces your aggregate energy cost and hence increases running economy.

I think people forget that Pronghorn and Horses have pasterns and suspensory ligaments and tendons that function like springs.

I took physics in high school wrote:

Shshhdnnd wrote:

What science demonstrates that running on springs would be beneficial? Basically the runner and his or her shoes is a closed energy loop. Without an external source of energy, shoes cannot create extra energy for the runner.

So if the spring returns more energy, it also requires the runner to produce more energy.

this is correct! There isn't a magical energy source to propel the runners - they have to put energy in to get energy back. And frankly that doesn't sound very beneficial to me.

Since you took physics in high school -- once you accelerate to a given speed, how much energy is required to maintain that speed, assuming there is no friction or other resistance ?

Now suppose there is some kind of friction or resistance, such that you spend 125 kcal to move a mile, but you have a way to reduce it by 20%. How much energy does it take to move a mile now ?