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PLF techniques?

 

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AlexCrowley  (A License)

Aug 14, 2005, 12:52 AM
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PLF techniques? Can't Post

First: I have 20 jumps and know nothing. This post does not intend to give the impression that I know anything at all about skydiving or landing.

Second: I am a wrestler and martial artist with over 17 years experience 'bumping'. One of the first skills you learn is to absorb impacts from throws. Like the theory of a PLF you are redirecting the impact energy in a nondestructive way.

Third, the traditional PLF seems to have been developed to absorb a straight down landing (same technique used for round canopies), or a landing with only slight movement in any direction. It would appear to me that a traditional PLF would not be the most efficient way to absorb a Ram air parachute landing. The forward movement would seem to make a PLF more dangerous if performed correctly as it would require a 90 degree twist to place the body correctly to 'roll it out' and disperse all the energy well. (of course, this is only true for those times when you still have significant forward movement when landing).

In the three time i've not been able to have a gentle landing I've found myself falling back on my other training and dispersing the energy by rolling over my shoulder (like a foward somersault but rolling from right shoulder to left hip). This feels far more comfortable and less impactful than the PLF training that I tried, and (depending on the type of ground - although I've bumped pretty much everywhere while wrestling) seems less likely to break an ankle or twist a knee than a standard PLF w/forward motion. Plus, this is the method I use to absorb impacts that are much greater than landing a canopy with a 2.52:1 glide ratio with 0.8 wingloading on a no wind day, so my muscle memory tends to default to that when it percieves danger.

I actually read something similar just a few days ago in The Skydivers Survival Manual (of course, it could have been a joke).

I am asking for opinions on PLF techniques and if there are other techniques taught elsewhere.

Like I said, so far I've only had to do this 3 times and it was an automatic reaction, they were also my early jumps during AFF.

------disclaimer: I have 20 jumps, I know nothing, even if it may have seemed for a second there that I may have given a different impression. thank you. ------


Premier skybytch  (D License)

Aug 14, 2005, 6:39 AM
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Re: [AlexCrowley] PLF techniques? [In reply to] Can't Post

PLF technique has been discussed here at least once.

The traditional PLF has saved countless people from injury or death, even under modern higher performance canopies.

edit to add - But don't let that stop you from doing what seems to work best for you. The point is to walk back to the packing area - if you know that your "default" fall works for you, stick with it.


(This post was edited by skybytch on Aug 14, 2005, 9:23 AM)


EvilLurker

Aug 14, 2005, 12:25 PM
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Re: [AlexCrowley] PLF techniques? [In reply to] Can't Post

I'd say you're right, but the current PLF technique is easy to teach and keeps the majority of people from hitting their heads into the ground. What you're describing is more difficult to accomplish without a lot of practice and if you screw it up, would most likely result in a more serious injury than a botched PLF. I agree with what you're saying, though, it's a carry-over from rounds and is best suited for vertical/near vertical appraoches, not a 30 mph downwind landing. If you add a whole day (or 2) of PLF training to a FJC, it's going to drive a lot of potential students away, I'd say. I got about 3 minutes of PLF training off a picnic table in FJC and never used it again. I'd say that's pretty typical for our DZ. A trained wrestler or martial artist could most likely survive a decent impact with the ground and walk away smiling, as long as their vertical descent rate wasn't too high, I've seen it a couple of times. I'd say teaching a good PLF is low priority at the DZs I've jumped at.
I agree 100% with what you say, though.


skydivermom  (C 36927)

Aug 14, 2005, 12:44 PM
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Re: [EvilLurker] PLF techniques? [In reply to] Can't Post

I'm scared of the PLF technique becuase both times I've attempted it I've sprained an ankle. The last time I came in for a landing (made a low turnUnsure, landed downwind) I was afraid of spraining an ankle or worse so I put my feet out in front of me and slid. I was not hurt and actually did a great landing (according to my instructor). Of course he wasn't happy about the low turn.


I just want to get past this fear before I really NEED to do a PLF. And yes I know ...DO NOT TURN LOW! I won't.


Premier billvon  (D 16479)
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Aug 14, 2005, 3:15 PM
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Re: [AlexCrowley] PLF techniques? [In reply to] Can't Post

> The forward movement would seem to make a PLF more
>dangerous if performed correctly . . .

The first step in a forward PLF is the same as the first step in any PLF - feet and knees together, knees slightly bent, body to one side or the other, hands protected. When you hit, make sure your feet hit first and that your center of gravity is low. That will cause you to hit feet, calves, thigh - then stop there, as you slide on your thigh. This is the best way to land with speed, because your feet are in front to absorb impacts, and the abrasion happens on your thigh, where you have a lot of mass to protect your bones.

The danger arises when people do a high speed PLF without turning their bodies or getting their CG low. Then it becomes feet-knees-face, which isn't a good way to land.


LivingLegend  (C License)

Aug 16, 2005, 2:22 AM
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Re: [billvon] PLF techniques? [In reply to] Can't Post

PLF landings dont seemed to be taught very well, if at all during AAF.
I did the military course in the Parachute Regiment and we spent 7 days swinging and dropping from the rafters and landing in every direction conceivable before we were ever let enywhere near a parachute.
Once it is drilled and second nature it works!
As Bill Von said the key point on any landing is feet and knees tigether and turn the body to induce the roll but you must also turn your feet off 45 deg to match the direction you are landing in.


Mike111

Aug 16, 2005, 6:56 AM
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"PLF Landings ... AFF"

I fully have to agree - i was told they dont want me to PLF but to run off and stand up.

Whys that? If PLF's are such good things, they seem to be in short supply in the UK. Could just be me but they specifically said to run off the landingUnimpressed

Mike


AlexCrowley  (A License)

Aug 16, 2005, 6:58 PM
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Re: [billvon] PLF techniques? [In reply to] Can't Post

In reply to:
The first step in a forward PLF is the same as the first step in any PLF - feet and knees together, knees slightly bent, body to one side or the other, hands protected. When you hit, make sure your feet hit first and that your center of gravity is low. That will cause you to hit feet, calves, thigh - then stop there, as you slide on your thigh. This is the best way to land with speed, because your feet are in front to absorb impacts, and the abrasion happens on your thigh, where you have a lot of mass to protect your bones.

I understand what you're saying here, in slower landings I can totally see the value in this sort of move.

In addition, I'm not claiming to be an expert at skydiving or PLFs or trying to discredit many years of experience that everyone here has had with the technique.

Just consider this an intellectual exercise for someone who's spent the last 24 years taking a variety of impacts from various angles, heights and intensitys. Like most people who've been in a combat sport the majority of your early training is avoiding injury from impact with the ground, much like the paratroopers training. As a wrestler I learnt another 8 or 9 methods to absorb 'bumps'. We get the insinctual 'put your hands out to stop yourself' out of our systems and then spend hundreds of hours putting those techniques into practice. In addition, I've practiced PLF techniques off the top turnbuckle of a wrestling ring many times to test my theory (hey, I had to do something in the off season). Instead of simply stepping off I would leap forward in an attempt to simulate coming in at various speeds and then try to do an 'as taught' PLF. A turnbuckle places you about 5' above ground, with jump probably coming down from 6' - a little more intense than my current landing experiences. So this experience is where the rest of my conversation comes from, please do not take it as a 'know it all attitude' as it is simply my desire to totally understand different viewpoints.

Additionally, I will discuss all these responses and thoughts with my coaches and vets at my DZ for further insight.

A standard PLF takes all your energy, displaces it in the order that you've said, with it eventually finishing up around your shoulder/head area. A PLF sideways is the only real safe way. My current high speed "PLF- Crowley Style" with plenty of forward motion is simply one of economy of movement and reduction of my chance of injury.

While the PLF is designed to accept and dissipate downward movement, it cannot absorb a great deal of lateral movement. While the feet, shin, knee, thigh, hip , side are nice and flat any undissipated movement will whiplash the neck, risking a head/neck injury (as the energys natural path is out through the top of your head).

Turning before hitting the ground and PLFing stops downward movement but does nothing to dampen any horizontal movement - yes, I banged my head a few times, whiplash seems pretty likely in that situation - of which I'm quite familiar :)

Turning as you hit (trying to spin on the balls of your feet) requires timing and co-ordination (thought) and increases chances of sprains and tendon pulls/tears in your knees, again due to the additional horizontal movement pushing you forward/sideways as well as down. On a flat surface this would be a concern, on a rough field more so, this in addition to the head/neck risk above.

The roll over method I used is a basic move that anyone with more than a few days of judo/karate training knows well, by taking both downward and, in our case more importantly, forward movement and dissipating them. By rolling you have created a longer energy 'muffler'. In a similar position to start the PLF you simply accept the foward motion and roll, tucking your head to oneside (protecting head and neck from impact), then hitting the ground with shoulder, trap muscles, hip/butt/thigh back to feet. This avoids any whiplash, doesnt rely on careful timing to move to one side or the other, and allows you to absorb much greater amounts of energy and inertia because you're not driving that energy downwards into the ground but moving it forward through the air , so if there's anything left your feet slap the ground a little harder rather than your head.

I figured it was just me, I really asked about this stuff since I'd never seen it in skydiving books until last week.

Hopefully the expanded version of this will clarify what I'm trying to say.

Again, this isnt meant to disrespect anyones knowledge or experiences, only to try and bring another idea into the light.


(This post was edited by AlexCrowley on Aug 16, 2005, 7:00 PM)


jtlmd

Aug 16, 2005, 7:13 PM
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Re: [AlexCrowley] PLF techniques? [In reply to] Can't Post

I have enjoyed reading these comments from a warrior of the ring. I have lots of respect for the pro wrasslers because Minnesota is home to many of the greats (e.g. Baron von Raschke the Clawmaster, Adnon Al Kasie, Jumpin' Jim Brunzelle, and many many more). One thing I don't seem to understand in your comments is that part about the conventional PLF "putting the energy into your head and neck area". How is that ? Seems to me that the conventional PLF transfers the kinetic energy into the rotational movement across the back with the feet and legs of opposite side ending up "slapping the ground" at the end of the maneuver. What have I missed here ?

Oh yes--one more thing. How do you guys keep from getting killed by the Pile Driver move ? Is this an optical illusion or what ?

Thanks.

J.T. Lee, MD
St Paul MN


(This post was edited by jtlmd on Aug 16, 2005, 7:14 PM)


Premier skybytch  (D License)

Aug 16, 2005, 7:46 PM
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Re: [AlexCrowley] PLF techniques? [In reply to] Can't Post

In reply to:
with it eventually finishing up around your shoulder/head area.

???

I've done hundreds of PLF's and my head has never touched the ground. I've watched hundreds more PLF's and have never seen a head touch the ground.


veter_

Aug 16, 2005, 8:07 PM
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Re: [AlexCrowley] PLF techniques? [In reply to] Can't Post

It's hard to visualize without video what you're trying to describe. Just remember that the speeds in skydiving are far greater than the speeds in martial arts. A downwinder at 30mph has 36x more kinetic energy than a 5mph judo throw. What works in judo, can cost you life in skydiving.

For example, for a high-speed downwinder on a nice grassy landing area, sliding on your thigh is obviously the best (I did a 20-25mph sliding landing once, worked wonderfully; rolling PLF most likely would have broken me something.) For a high-speed downwinder on concrete, you should better roll, or ears will be all left of you. Laugh


phoenixlpr  (D 3049)

Aug 16, 2005, 10:30 PM
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Re: [veter_] PLF techniques? [In reply to] Can't Post

Do you think you have any credibility without filling your profile, Mr Pornstart?


wmw999  (D 6296)

Aug 17, 2005, 4:53 AM
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Re: [AlexCrowley] PLF techniques? [In reply to] Can't Post

I used to teach PLFs from a 4' platform, and I did have students jump out as well as down. Done (what I think is) right, a PLF does have a "continue" pattern.

Feet, knees, thighs, hips, across back to opposite shoulder -- that gives your whole body the opportunity to roll over (dissipating energy). It's not hard to end up getting up from such a motion. Or, if you really landed like a sack of shit, to lay there and be glad that it worked (which it has so far).

But I may be misunderstanding either current teaching of PLFs (based on a conversation this last weekend) or what you're saying. It sounds like you're proposing going straight back over the shoulder, which strikes me as having some potential for hurting the neck if you haven't practiced the motion a whole lot. But I could be misunderstanding.

Either way, thanks for bringing up the issue.

Wendy W.


velvetjo  (D License)

Aug 17, 2005, 5:04 AM
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Re: [AlexCrowley] PLF techniques? [In reply to] Can't Post

One of the DZ's I jump at teaches PLF's for x-wind, obstacles, and botched flare landings. It's a great tool for those situations. Done properly, it can absorb a fair amount of horizontal speed, too. Student wind limits help a lot here too.

On the other hand, that DZ teaches a flared baseball slide technique for downwind landings. They do this for just the reasons you noted. Seems like you're better off trying to slide than any kind of roll for high horizontal speeds. The downside to a slide it that you have to protect your tailbone from vertical impact by flaring properly and tucking a foot under your butt.

Lance


veter_

Aug 17, 2005, 6:56 AM
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Re: [phoenixlpr] PLF techniques? [In reply to] Can't Post

In reply to:
Do you think you have any credibility without filling your profile, Mr Pornstart?

At 10x number of jumps per year compared to yours 45.8JPY, and being a pornstar, I'm too busy to prove my credibility to Internet drones. Angelic


goose491  (A 7123)

Aug 17, 2005, 9:22 AM
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Re: [veter_] PLF techniques? [In reply to] Can't Post

In reply to:
...downwinder at 30mph has 36x more kinetic energy than a 5mph judo throw. What works in judo, can cost you life in skydiving.

Veter... I think you should volunteer yourself to be thrown around by a Judo master. lol.

Trust me, there is some serious speed involved. I have been involved in different martial arts for several years. One time I was the rag-doll for a Judo demonstration by one of the greats. We had been dialing his throws in with me all day and he was letting go early and I would travel quite a distance still ariborn.... it was a sight to see man.

Anyway, there is some serious speed generated by these tosses. Falling chimney effect dictates that you will see it's effects when you land. lol.

Anyway, one time my feet hit the lights which were hanging from the ceiling! Shocked Because of this, I was unable to rotate properly upon release and could not break the fall properly. I landed squarely on the back of my head.

"Swelling of the grey matter" is what they called it when my brain swole up too big for my skull. (it wasn't a concussion as I didn't lose conciousness ??) I had one pupil diallated much more than the other for a few weeks. One side of my body responded quite a bit slower than the other. I was drooling and mumbling and had a hard time remembering stuff for a short while... I was a sight to see man!

Anyway, the only reason I'm sharing this is to reinforce the idea that Martial Artists know how to PLF... they pretty much have to because the forces involved in some throws... are not to be downplayed my friend.


riggerrob  (D 14840)

Aug 17, 2005, 10:24 AM
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Re: [velvetjo] PLF techniques? [In reply to] Can't Post

In reply to:
One of the DZ's I jump at teaches PLF's for x-wind, obstacles, and botched flare landings. It's a great tool for those situations. Done properly, it can absorb a fair amount of horizontal speed, too. Student wind limits help a lot here too.

On the other hand, that DZ teaches a flared baseball slide technique for downwind landings. They do this for just the reasons you noted. Seems like you're better off trying to slide than any kind of roll for high horizontal speeds. The downside to a slide it that you have to protect your tailbone from vertical impact by flaring properly and tucking a foot under your butt.

Lance

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Ouch!
That sounds like a recipe for knee and ankle injuries.
Far wiser to slide on your thigh, using the large muscles to protect your femur, pelvis and spine.


veter_

Aug 17, 2005, 11:19 AM
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In reply to:
"Swelling of the grey matter" is what they called it when my brain swole up too big for my skull.

Now I understand why you keep sending me your 2-page long PMs (7, no less!) and writing long posts on a subject you have no business in (Death Game). Your brain swole up too big for your skull.


wmw999  (D 6296)

Aug 17, 2005, 11:29 AM
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Oh goodness -- I think everyone can participate in the death game. All they need is some judgement. Or none, depending on which end of the death game they're in.Smile

Wendy W.


AlexCrowley  (A License)

Aug 17, 2005, 11:44 AM
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Re: [jtlmd] PLF techniques? [In reply to] Can't Post

ok, here's my very limited experience with how a PLF feels verses a regular bump of equal intensity.

If you only know a PLF then I'm sure its the absolute safest bet for you, far more safe than trying anything that I'm talking about without taking some martial arts lessons and spending serious drill time learning them.

Ok, basic math time...urm...25 years.....average 3 sessions per week.............conservative 20 bumps per session, 10 years sickdays, vacations, parenting - urm,.....46,800 bumps....damn, no wonder I'm broken :) Hmm. I know 4 basic ways to minimize impact (more, but they're mostly just modifications of the first 4). So I've practiced each technique approximately 11.7k times.

That's quite a bit more practice than an afternoon leaping off a table to get the PLF technique down.

Reason PLF makes me nervous? starting at the feet and working your way up, by definition means that your head is near the intended final body area to absorb the energy, rolling across your shoulders/back dissipates energy but in an uncontrolled situation I would find that an unacceptable risk. It would seem that I am more likely to be able to control the first moment of a fall (the instant of impact) and therefor get my head out of the equation as soon as possible (or does that make no sense to anyone but me? I'm willing to accept being totally wrong---maybe). I base this on landing on uneven ground and not always being totally in control of the situation for the perfectly timed PLF - especially if you're having to perform the little twist to catch the right plf angle.

Reason sliding in makes me nervous? Yeah, the thigh will protect you, but as any one who's spent time in a canvas ring practicing baseball slides will tell you: its that one time where your shoe gets caught on a seam (or say for example, a tuft of dirt/grass in a landing field) that it jams your leg and snaps it in half...or slightly less noisy but as painful, tears your various knee tendons and ligaments to shreds - happens way more often than you'd imagine in a ring. Again, that doesnt mean I'll not slide a landing in but there are certain qualifications to taking that action. first and foremost gauging how much skill its going to take to avoid being broken.

BTW, in a high speed landing I"m not sure I want my feet slapping the ground to bleed off any excess inertia, when they 'slap the ground' on a less than perfect surface you're again risking your ankle, knee, shin continuing movement after your legs have stopped - if youre on uneven ground..

Excess inertia probably accounts for 90% of my wariness about traditional PLF technique in higher speed landings.

Additionally, we talk about the differences in flying over certain terrain, but not many about the different types of landing terrain. My approach on a grassy field is never going to be the same as a freshly ploud field, or a recently harvested one full of stalks.

Maybe I'm just going too far ahead of myself, for which I apologize.

Veter, you may be an awesome skydiver......urm....... you may be a skydiver, but from your comments I'd imagine that your experience was either very limited or non-existent. As far as intensity of falls in my current experience, other than being nearly killed during training too many times to count. The last time I took a fall at 5mph was when I was 10, or when I was teaching the student how to perform the technique. Mostly I'm getting bounced around by guys who are twice my bodyweight and think its fun to toss around the little guy as hard, high and fast as they possibly can - it looks better they say, but I think it's just because they can.

jtlmd..........ahh one of the secrets of prowrestling......hmm pay attention to the move when its done and you can work it out I think. The far more valuable secrets are 1) it isnt as fake as you think it is, 2) it hurts..a lot, when you start wrestling your body breaks down by microfracturing bones, which then reheal stronger - first 3 months is excrutiating and then your body aclimatizes - most schools have a 95% dropout rate during the breakdown period. See? Fascinating behind the scenes info Wink

Wendy, I understand what you're saying, and I'm not trying to reject the PLF as a method of landing (hell, in a situation I think it'll work I'll use it before anything else), Mostly Im thinking aloud, mostly I remain unconvinced of its universal utility as "THE OFFICIAL PLF" when the flight characteristics of canopies have altered. Sure, new techniques are not something you can bang out easily in an afternoon, but neither was learning stability and movement in freefall. Neither was I rejecting the 'slide it in philosophy', there are situations where this would be a natural reaction. I guess my inquiry is only that I believe that there may be other tools that skydivers could put to use and reduce the risk of injury even further if 1) they realized there were additional options, 2) someone was willing to translate their experience to teach it.

Yes, I have only 20 jumps. I sincerely believe that I know a don't know a damn thing about flying a canopy. But I have approx 46000 landings, and I think it may be fair to consider one or two of those as being a transferrable skill.Tongue



Smile


veter_

Aug 17, 2005, 12:08 PM
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Re: [AlexCrowley] PLF techniques? [In reply to] Can't Post

No kidding: there are freefly coaches, RW coaches, canopy control coaches, but no PLF coaches! I would take paid coaching from somebody who does PLF really well (like you do). I do want my teacher show PLF in real action, though - jump and PLF downwind landing, half-brakes/weak flare landing, rear riser landing, etc.

You can become Scott Miller of PLF!!!!!!! Wink


Premier billvon  (D 16479)
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Aug 17, 2005, 12:18 PM
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Re: [veter_] PLF techniques? [In reply to] Can't Post

> Your brain swole up too big for your skull.

Your one warning.


Premier billvon  (D 16479)
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Aug 17, 2005, 12:21 PM
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Re: [AlexCrowley] PLF techniques? [In reply to] Can't Post

>Turning before hitting the ground and PLFing stops downward
> movement but does nothing to dampen any horizontal movement -

That's right, and you don't _want_ to stop rapidly, you just want to get yourself into the right position. The position you want to end up in is the same position you see a baseball player sliding into home plate with - feet in front, sliding on one thigh. You can dissipate a lot of speed that way without injury (as baseball spectators know.)


BigSky  (B 28752)

Aug 17, 2005, 12:50 PM
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Re: [AlexCrowley] PLF techniques? [In reply to] Can't Post

I am with you on this Alex. I also am no expert by any means but, the PLF in my opinion dose channel a lot of the horizontal force to the neck and head.

I have been an avid skier for years and naturally a lot of your hard falls come sideways in which you pretty much automatically do a PLf of sorts. However you learn pretty quickly to role these out otherwise you have some serious head and neck smacks.

I think the move you are talking about works best and is easy to do. I know they taught us this in elementary PE class. we would get out the mats and put them on the gym floor line up and all take turns. Run, hop step, roll on shoulder and stand back up. I think they called it tumbling.


jtlmd

Aug 17, 2005, 1:41 PM
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Re: [AlexCrowley] PLF techniques? [In reply to] Can't Post

Thanks for the inside poop on "microfractures". I have never heard of that before. Just be careful in that ring--some of your guys have been killed doing stunts.

I shall continue to study the Pile Driver. Looks like to me if it is not done exactly by BOTH parties, the coroner might be easing into the story. I do notice that the "victim" in the Pile Driver has his hands on the lower legs of the "attacker" so maybe this is what keeps the head from hitting the mat. Of course, the tremendous "bang" from feet landing on the surface is part of the effect I think. All due respect of course !!!

What is your ring name and where can we see you on TV ? I think it is cool as hell that we have our own wrestler in the sky diving world. It will drive the non-wrestling types completely nuts.


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