"hammer and nail" idea of sprinting

What do you all think about the hammer and nail description of sprinting? Here is a former elite 800m runner talking about this in a video. https://www.youtube.com/watch?v=7qEBNuYSnjs

Basically the idea is the propulsion forces and “power” in sprinting come from the foot accelerating from the air to the ground, and once your foot touches the ground very little pushing is needed, like when someone hammers a nail, the power to drive the nail in comes from the swing, not when the hammer contacts the nail and they try to push it in further. Any thoughts on this?

This is an oversimplification and leaves out multiple elements of key significance. Horizontal and vertical ground reaction forces result from the vector angles, velocity, and acceleration, associated with the foot approaching contact and the resultant and associated mechanics of ground contact. Understand that when it concerns elite male 100m sprinters the duration of ground contact occurs in around .08 of a second. Hence the fantastic impulse and impact forces associated with +12m/s maximum velocities.

Jquick, I really do not understand the purpose of the new threads you are generating on an almost daily basis. Who on earth picks this sort of random YouTube clip for a thread - a guy who ran 800m 20 years ago.
What are you trying to achieve - are you in any way involved in any sport at all as a participant or coach ? You are the only poster I have ever seen that will not reference their own training or coaching - not even as a complete beginner asking for some starter tips.

You really need too explain who you are and what you are trying to achieve.

If you are trying to do some sort of research paper just say so…

Im just someone who is trying to get faster. I’ve never competed in track, don’t have a coach and my background is basketball in high school. I don’t know much about sprint mechanics so I’m just reading old,threads and posting new ones trying to get some answers.

No research paper. Not sure Why you bought up Some random guy running 800’meters

I agree 100%- Why are you posting all these random questions ???

how are these questions random? Random would be asking how to improve one’s comprehension skills on a sprinting forum

Just the opposite, in fact. As narrow comprehension ability is often the limiting factor related to coaching dysfunction and the reason why sprint training is so poorly understood, not only by non-track coaches but even certain track coaches.

Random because, one minute it’s weight training then it’s about hills,then hammer and nails from a 800m runner. To me that’s random. Buy some products from the site, get out and run and report back. Then posters a lot smarter than me will be able to help.

“Percy taught me the difference between running and sprinting - that while you run on the ground, you sprint over it, with the briefest possible foot contact. It’s like the spinning of a bicycle wheel; a sharp slap of the hand will impart more speed to the wheel than would a more prolonged stroke. The strongest sprinters spend the least time in pushing along the ground. They focus instead on moving their legs up and down, and are barely conscious of how their force is translated into horizontal impetus.” - Speed Trap, p. 29

This is the stepping down sensation.

As the man says, start training. Once you start i guarantee you will be asking different questions and questions more relevant to your own goals and abilities.

I love this lesson. It’s a lesson that’s taken a couple years to teach me.

I knew very early on in my own training that it’s not just force, it’s impulse that gets you down the track faster. Think I was too dumb to fully understand what that meant, but I always pounded the track HARD (not fast) and wondered why everyone left the blocks: “see ya later!” When I first started coaching a couple athletes, I told them to push hard for the first 4 steps to the hurdle. They had the same problems I did. My second coaching stint with a new bunch of athletes and reflecting on some of the mistakes, I employed the bike spokes analogy. Some got it.

jquick posted a sweet video. There are a lot of ways to describe and cue what the swing leg has to do to get back down on the track. Push was a good idea but implied longer ground contact times. 'Punch!" is a good one that addresses the quick strike required. Push vs Pull — learned that one from Nick Winkelman on Twitter. Hammer the nail is the same idea. At Max V, a great cue is to tell the athlete to whip their hip back. This one is fabulous. Every athlete that has trouble keeping their hips up and always feels like they’re working but not going anywhere should consider violently whipping their hips back… it’s magic.

Most important, more than cues in my judgement, is knowledge of what actually distinguishes the world’s elite from the rest. In this regard, and as I elucidate in my upcoming book in reference to my criticism of strength coaches misunderstanding speed development, it is critical to understand that the difference maker, much more than force development, is the horizontal ground reaction force vector and magnitude of impulse.

The GCT is naturally longer during initial acceleration, just as the contact times for the slaps on the wheel are longer when you’re first getting the wheel going from a standstill. As you referenced, however, the objective is always impulse; particularly through kinematic optimization (ergo the way in which the impulse/mechanics of ground contact occur)

What do you mean by whip their hips back?

Do you mean

  1. Forcefully extending back with support leg?


  1. Focus on quicker, more powerful heel recovery?

I mean whipping your swing leg (and hip) back right under you when it is at the greatest knee height. This is an excellent video: https://twitter.com/atletico_dev/status/560599548897161218

Well said - the size of the horizontal component of the applied force determines the magnitude of the force applied to the ground propelling the athlete forwards.
Simplistically put, a force applied vertically (only) will resultant in a bounce straight upwards at 90 degrees to the ground. Obviously. The shallower the angle at which the force is applied the greater the horizontal force propelling forward. This of course is why a lean forward in the drive phase optimises force and hence acceleration in the A=F/M equation
This is no doubt obvious to all concerned.

The interesting point is that stepping down and cycling queues are effective in creating up and down movement of the legs, however they tend to encourage vertical movement, and hence force being applied directly downwards. Thats my personal opinion by the way. Therefore the question is how to make the force more horizontal`.

BTW I seem to have been re-christened as PJ - weird database error I guess…

Wouldn’t forcefully extending the support leg back result in long ground contact times and lost of posture/front side mechanics? From what I’ve read lately it seems like quick ground contact is the key to faster top speed running.

And while it was performed on a treadmill, albeit an instrumented one, this fantastic study (few years old), that includes your super talented countryman Christophe Lemaitre, highlights these very important facts: http://www.european-athletics.org/files/development/Innovation_Awards_2012/Coaching_-Winner-_Manuscript.pdf

  1. The swing leg is the leg in the air. The support leg is the leg on the ground. It is an important distinction.

  2. Nothing happens on the ground. Sprinting occurs in the air. By “whipping your hip back” you are from the knee-high position, whipping your leg down to the ground. The action is in the air. You are working before you hit the ground. Optimal joint firing patterns (extension of the hip > knee > ankle) will let you hit the ground QUICK and HARD.

  3. When athletes are really good at ‘whipping’ they will feel more action in the front, able to pick the feet on the ground up faster (more ‘scissor’ action) and think sprinting is easy.

I advise you to reconsider how you’ve phrased that. While those with sprint knowledge are able to understand the point you’re making, the language you are using here has the potential to mislead hordes of less knowledgable individuals. Namely because the reaction forces responsible for flight are generated on the ground (albeit by way of the manner in which the foot strikes the ground)- no matter how short the duration of ground contact.

I want to clarify…

When you say whipping your hip back, you really mean being quick and powerful in “step down and applying force”, and doing so by having good knee drive, so that you can strike the ground really hard and quick? basically that powerful downward movement of the foot from highest knee height sets you up for that quick powerful support phase where you apply force that you have built up from that downward swing?

And when you say sprinting occurs in the air, and not on the ground, you really mean that you can’t try to apply more force more quickly once you’re foot is on the ground and only can do so by having powerful strike down while you’re foot and body is still in the air? In another words, being very strong and fast with “negative foot speed”?

So you wouldn’t not try to push backward during contact, but be powerful and quick while the foot is on the way down and back towards the ground.

Thank you.