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# Importance of Acceleration Thru Impact

## 95 posts in this topic

How important is acceleration through impact, and what are some of the symptoms you are likely to see if you are not doing this?

FWIW: I'm speaking of full swing scenarios like hitting off the tee or approach shots... not putting as that has been discussed in depth on another thread I read.

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Rory's Kenetic Chain done by sports science. The line that has the biggest spike is the arms. Basically how fast the arms are rotating in the swing. The two vertical black lines are top of the swing (first), impact (second). Since this is Degrees/Second rotation speed, acceleration would be degrees per second squared. Basically change i rotation over time. If you look at the graph, its hard to tell, but Rory's arm swing is parabolic, then just before impact the acceleration is basically Zero, meaning the graph is cresting. If you look in the backswing, you see the arms peak in a bell curve, at the bottom of that curve, acceleration is zero. That same crest happens in the downswing just before impact.

This is good because its showing that Rory is very good at maximizing his speed at impact. If you look at Amateurs, they peak way before impact and there arm speed actually slows down (deaccelerating). You also don't want to be accelerating into impact, because then your max speed is after impact not before.

The problem with thinking accelerating through impact, your try to really swing hard through and you peak way before impact. Its far more better to practice the impact position, meaning, Flat left wrist at impact, hands slightly ahead of the ball. This means you delaying all that energy till the last moment and delivering it with maximum speed.

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Accelerating what through impact?

The thing that people believe should accelerate through impact is the clubhead, and even that should reach maximum speed at the ball. If it's still not reached maximum speed until after the golf ball, you've wasted speed with bad timing.

Everything slows down incrementally, and everything is decelerating after impact (or should be).

P.S. It's quite literally impossible for a human being to accelerate the clubhead during impact with a golf ball. Unless, perhaps, the golf ball is barely touched.

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Originally Posted by saevel25

Rory's Kenetic Chain done by sports science. The line that has the biggest spike is the arms. Basically how fast the arms are rotating in the swing. The two vertical black lines are top of the swing (first), impact (second). Since this is Degrees/Second rotation speed, acceleration would be degrees per second squared. Basically change i rotation over time. If you look at the graph, its hard to tell, but Rory's arm swing is parabolic, then just before impact the acceleration is basically Zero, meaning the graph is cresting. If you look in the backswing, you see the arms peak in a bell curve, at the bottom of that curve, acceleration is zero. That same crest happens in the downswing just before impact.

This is good because its showing that Rory is very good at maximizing his speed at impact. If you look at Amateurs, they peak way before impact and there arm speed actually slows down (deaccelerating). You also don't want to be accelerating into impact, because then your max speed is after impact not before.

The problem with thinking accelerating through impact, your try to really swing hard through and you peak way before impact. Its far more better to practice the impact position, meaning, Flat left wrist at impact, hands slightly ahead of the ball. This means you delaying all that energy till the last moment and delivering it with maximum speed.

This is a very good explanation, but to put it in simpler terms and something you can try to incorporate into your swing:

The moment of impact is a lot later than you would think, so the feeling of swinging the fastest right after impact is probably best for the majority of people. Once you start hitting top SS at impact, just focus more on maintaining that feeling throughout your clubs.

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The only person i have seen who might look like he's accelerating way into his finish is Greg Norman, with the way he bounced his club off his back.

But if you look at Rory, Tiger, even Bubba, they are slowly way down into there finish, showing they are deaccelerating after the ball.

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Originally Posted by iacas

Accelerating what through impact?

yes.. the club head... its the only thing moving that has "impact"

so other than losing power/speed... what other issues result from decelerating as opposed to accelerating up to the point of impact? does ball flight typically change one way or the other?

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Originally Posted by divot dave

yes.. the club head... its the only thing moving that has "impact"

so other than losing power/speed... what other issues result from decelerating as opposed to accelerating up to the point of impact? does ball flight typically change one way or the other?

Impact is a point in time, so you could be talking about anything to that point.

The ball doesn't care if the clubhead is accelerating or decelerating at impact. It only knows the speed of the clubhead, nothing more.

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Originally Posted by iacas

Impact is a point in time, so you could be talking about anything to that point.

The ball doesn't care if the clubhead is accelerating or decelerating at impact. It only knows the speed of the clubhead, nothing more.

so to drive the point home: (pun slightly intended)

hypothetically speaking, with two swings, all things the same (and lets assume "textbook" swings here -- whatever that means), the only difference being swing A is accelerating to the point of impact and swing B is decelerating, the ball should start out on the same line and follow the same path except swing A will travel farther.... correct?

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Originally Posted by divot dave

yes.. the club head... its the only thing moving that has "impact"

so other than losing power/speed... what other issues result from decelerating as opposed to accelerating up to the point of impact? does ball flight typically change one way or the other?

the whole golf swing is about a second, so i doubt someone can deliberately slow down a swing before impact, you can pull out, but not slow it down to impact...you may be thinking swinging it slower throughout the swing....ie: Hogans 4 iron 155 yards

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Originally Posted by divot dave

hypothetically speaking, with two swings, all things the same (and lets assume "textbook" swings here -- whatever that means), the only difference being swing A is accelerating to the point of impact and swing B is decelerating, the ball should start out on the same line and follow the same path except swing A will travel farther.... correct?

No, the balls will travel the same distance if they're hit when the clubheads are traveling the same speed (i.e. the same impact conditions: AoA, clubface alignment, path, clubhead speed, contact point, etc.).

And notsohard, plenty of people are decelerating into impact. They reach their max clubhead speed prior to impact and are, thus, decelerating.

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No, the balls will travel the same distance if they're hit when the clubheads are traveling the same speed (i.e. the same impact conditions: AoA, clubface alignment, path, clubhead speed, contact point, etc.). And notsohard, plenty of people are decelerating into impact. They reach their max clubhead speed prior to impact and are, thus, decelerating.

I am not sure how this would apply to golf, but if the acceleration is increasing at impact then the "jerk" should be higher. Jerk is the derivative of the acceleration, and often used in impact studies. The only thing I do not know is if club heads are designed to take advantage of this or not. If they are, then it would give some credibility to the acceleration through impact theory. Except that the acceleration needs to be increasing as well.

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*NOTE- the line i was talking about in the graph is the club speed. I was wrong to say it was the arm speed. Red is Hips, Green is Thorasic (abdominal area), Blue is Arms, Gold is club

This would a simplistic version of the club curve on that graph,

Its a parabola in shape, i marked 3 points, each of them possible points in time for impact.

1) before peak in speed, meaning your accelerating up to and past impact

2) at the peak, meaning your acceleration is zero, you are at maximum speed

3) Just after peak speed, your deaccelerating.

But if you look at 1 & 3, they are the same speed, meaning the ball will go the same distance if all other factors are the same. So the assertion that accelerating through the ball  will give you more distance is false. The best thing to do would be is to live in that small range at the top, were your around the peak.

But a diagnosis at impact would be

Hips, thorasic, Arms are all deaccelerating greatly and have lost near have there rotation speed. All this speed is transfered into the clubhead. this is why the graphs have a progressively larger from hips to thorasic to arms to club, because its a transfer of energy from the ground up. But the key is, not to expend that energy way before the golf ball, like most amatuers do. I think the reason is they want to hit the ball so hard, so they try to accelerate into the ball and they end up jumping the gun so to speak.

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As mentioned already it is the club head which should still be accelerating through impact. In reality what most do not understand the hands and arms have already started decelerating assuming a full swing at impact. They have to in order for the shaft to unload the stored energy during the downswing. to allow the whip to crack as I call it for the lever between arms and club shaft to straighten out aka lag. Maximum club speed happens when the shaft unloads and forms a straight line with the lead arm. If the hands and arms are still accelerating at impact, then the club shaft would still be loaded (bent) and lagging to far behind. You need the lever to be straight in line with the lead arm at impact for maximum club head speed and acceleration.
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Originally Posted by Lihu

I am not sure how this would apply to golf, but if the acceleration is increasing at impact then the "jerk" should be higher. Jerk is the derivative of the acceleration, and often used in impact studies.

Acceleration of the clubhead does absolutely nothing. It's speed at impact that's all that matters.

Originally Posted by dereckbc

As mentioned already it is the club head which should still be accelerating through impact.

The clubhead accelerating at impact is a sign of an inefficient swing. The clubhead should reach maximum speed at impact. Why would you want your maximum speed AFTER impact? Makes no sense.

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Originally Posted by divot dave

How important is acceleration through impact, and what are some of the symptoms you are likely to see if you are not doing this?

FWIW: I'm speaking of full swing scenarios like hitting off the tee or approach shots... not putting as that has been discussed in depth on another thread I read.

Well, I'll bring an example of a bad swing (from "decelerating" before hitting the ball) i made because I tried to ease it.  Par 5, 540 downhill, drop off tee shot with fairway stopping at 230 out from green because of a river crossing fairway.  I've hit my 3-wood in the water from this distance, and with my driver I can't carry it. So one time I tried to ease up on my 3-wood, and at the top of my backswing I felt like it was still too much and pretty much stopped my swing on the way down (at least it felt like it).  I ended up hooking the snot out of it.  Another time, same thing happened only I sliced the snot out of it.  So, short version, with a "non-fully accelerated" swing, everything kinda brakes down if you can't hold it together.  In my case, I felt like I put too much weight forward and I released the club way too early.

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Acceleration of the clubhead does absolutely nothing. It's speed at impact that's all that matters.

So, it seems like kinetic energy is the dominant factor. Thanks for the verification.

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The key is proper impact position, because that is what maximizes all the transfer of that energy to the ball (in terms of clubhead speed) that was built from the ground up.

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Let me just throw something out there in defense of "acceleration through impact" as a factually incorrect piece of advice that could be interpreted as trying to promote something good for your swing.

It's pretty natural for a lot of people to essentially take a back swing, and fire hard right from the top, or very near.  Most people see that and just think over swinging, and the one sentence tip for that is usually just "swing easier".  But if you maintain the same relative timing of firing or effort or whatnot but just give less overall effort and speed, you might become slightly more consistent, but not so much as you'd want, especially if you're losing distance while not gaining much consistency.  IMO, this is because snapping or firing with the max effort you're going to put into the swing near the top can lead to all kinds of killer mistakes:  spinning out with the hips or shoulders too early, never getting the weight forward, losing your spine angle right at the start of the down swing, etc.

For me at least, in order to make more consistent swings I have to basically feel like I'm not swinging at all until near A6.  When it's working, I can play MUCH more consistent golf while at the same time hitting the ball 95-100% as far as when I'm trying to murder the ball from the top (not counting the 1/20 hitting that way that just luckily comes together perfectly, and that one shot of course goes 5-10% further).

Maybe a charitable interpretation of "acceleration through impact" is that it's a way to encourage not trying to snap from the very top and getting a velocity curve that looks more like Rory's?

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