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  #31  
Old March 21st 09, 03:04 PM posted to rec.bicycles.tech
Jay Beattie
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Posts: 4,322
Default Mostly OT/Head Injury and Death

On Mar 21, 12:33*am, "
wrote:
On Mar 20, 10:45*pm, Bret wrote:





On Mar 20, 2:57*pm, Frank Krygowski wrote:
On Mar 20, 3:27*pm, Dan O wrote:
On Mar 20, 9:06*am, Frank Krygowski wrote:


In another article,http://www.msnbc.msn.com/id/29772691/*:


"The National Ski Areas Association (NSAA) of the United States
estimated 43 percent of skiers and snowboarders wore helmets in the
2007-08 season, against 25 percent five years earlier.
...


"The increase in the use of helmets has not reduced the overall number
of skiing fatalities," the NSAA said in a statement. "More than half
of the people involved in fatal accidents last season were wearing
helmets."


So more than half the fatalities were in helmets. *But fewer than half
wear them. *IOW, helmet use is _positively_ correlated with
fatality.


Risk compensation, anyone?


People who intend to ski as fast as they possibly can are the ones
more likely to wear a helmet.


Would they ski quite as fast, or in quite as risky a manner, if they
did not wear a helmet?


Judging by those figures above, probably not.


It's a chicken and egg question. Are people *wearing helmets because
they're doing something dangerous or doing something dangerous because
they're wearing helmets? You think it's the latter. The former makes
much more sense to me but I don't know. You seem pretty sure of
something that is unknowable without more information. Maybe you're
the type *that just doesn't know how to day "I don't know".


This argument about ski helmets and behavior also
suffers from a lack of information. *We don't have any
idea whether the ski fatalities discussed refer to
only in-bounds or also out-of-bounds skiing, and
whether they are strictly impact related accidents.


Good point. The recent deaths on Mt. Hood resulted from helmetless
boarders hitting skiers and from boarders going head first in to tree
wells. Morbidity/mortality for skiers tends to be related to binding
release problems (much of the time at low speeds), collisions with
trees, collisions with each other and ordinary crashes. Injuries tend
to be to legs, knees and shoulders. I know one guy who broke his
neck. Head injury seems to be pretty rare based on my lift ride
conversations. I think tree wells kill more people than collisions.

On a bike, the main cause of getting hurt is crashing,
but this is not always so in skiing. *Even if you
only consider crashing and rule out avalanches,
most ways of riding bike are pretty safe (excluding
at night without lights, and some extreme downhill
MTBing). *This is not so true of downhill skiing, where
style can have a big effect on how likely you are
to get hurt.


I hesitate to get involved in a helmet thread, but IMO
looking at fatalities is not a great way to measure
whether helmets do anything. *Many fatalities (ski or bike)
occur in impacts where only a helmet the size of a Green
Bay Cheesehead could have helped. *IMO the effect of
helmets is more likely to occasionally mitigate what
would have been a bad concussion into a mild
concussion, or a mild concussion into just a sore spot.
Whether this is worth anything is up to the wearer.


Helmets also help prevent scalp injury and focal injuries -- blunt
object causing skull fracture. They do not reduce diffuse axonal
injury or rotational injury where the brain sloshes around in the
cranium. In fact, I had one doctor tell me that boxing helmets were a
bad idea because they increase the target area and mass of the head
and increase rotational injury. I also think that some of the early
ski helmets that were big and bulky probably created a greater risk of
neck injury -- which is more likely than head injury in the usual ski
fall, IMO (because snow is usually pretty soft). The newer, lighter
helmets are better, and I think they are a good idea for a crowded
resort or for skiers who like the trees. -- Jay Beattie.
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  #32  
Old March 21st 09, 03:24 PM posted to rec.bicycles.tech
Tim McNamara
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Posts: 6,945
Default Mostly OT/Head Injury and Death

In article
,
" wrote:

On Mar 20, 8:07*pm, Tim McNamara wrote:
" wrote:

When I whacked the side of my head in a CX race I also got a
bunch of gravel cuts (actually it was the second time I'd fallen
on this short loose descent). We had a friend who was an EMT at
the race and she cleaned up my cuts while making a lot of small
talk with me, which later I realized was also a subtle way of
doing a mental/head-injury evaluation.


Good call, that was probably exactly what he was doing. *"Who's the
President" is really not that great a question for assessing these
things. *Also, since problems can develop over time, he was
probably re-checking periodically.


She.


Missed that.

I don't remember if she actually re-evaluated me, but since we
were more or less in the same place over the next couple of hours and
I was capable of holding a conversation with the rest of the
hangers-on at the scorers' tent, effectively yes.


If she was good at her job, I'm sure that she did exactly that.

I had a bad headache and sat around at the scorer's tent with my
friends who were running the race, occasionally helping a little,
until all the races were done and we cleaned up, by which time I
was just kinda sore and fine to drive home. *In retrospect it
seems like an obvious concussion, but the word or thought never
crossed my mind at the time. *This seems like a common reaction,
much like the impulse to get back on your bike w/o realizing that
you're dripping blood.


That's a common reaction to an accident, especially in a race.
*It's probably (1) a survival instinct and (2) the competitive
spirit.


Adrenaline does a lot of things. We have a theory on rbr about this.
Even if you aren't injured, you tend to jump back in the race
without fully checking the situation. I once fell in a CX race and
twisted my bars. I straightened them and continued. Unfortunately,
I was using a threaded stem drilled as the cable stop for a front
canti brake, and it sank slightly in the process, so later in the lap
I got to a tricky descent and discovered I had no front brakes.


Fun!

I think it's at least in part an extension of the survival instinct.
Injured animals try very hard to conceal their injury, because showing
it makes one a target for predators. In the case of sports, it shows
your competitors that you're at a disadvantage. And in racing the thing
we train ourselves to do is to go forward as fast as we can, so when
we're standing by the race course not going forward it creates a sense
of distress and urgency.

And not only adrenaline (short term) but testosterone (long term), too.
People who had higher levels of in utero testosterone exposure tend to
be more aggressively competitive in personality and also to have some
biological advantages (e.g., greater cardiac efficiency). An
interesting cue to this is the ratio between the length of the index
finger and ring finger (2D:4D ratio)- the longer the ring finger is
compared to the index finger, the higher the in utero exposure to
testosterone. UK researcher John Manning was able to predict the
outcome of a foot race with remarkable accuracy by only looking at the
2D:4D ratio of the competitors; of the 10 competitors he accurately
ranked 8 of them in this way. The two errors were runners who reversed
their predicted finish order. There's a PBS show about this that was
quite interesting. There was also a correlation between this ratio and
aggressiveness in personalities in men, ability to connect emotionally
to others, eye-hand coordination, etc.

Once when the same gang was running a multi-lap MTB race, we had a
guy go by the scorer's table with blood dripping from his forehead.
My pal Rod had to run up the hill after him to force him to stop. He
really wanted to continue and Rod had to be very firm to persuade him
to stop and get bandaged up. This guy was ~50 and not a reckless
youngster.


I think there's probably no age limit on this sort of thing.

Amusingly, another time we kept seeing this woman go by the
start/finish with blood seemingly dripping down her inside leg. We
were a little freaked out, but she didn't notice. It turned out to
be a cherry flavored energy gel that she had tucked under her shorts
hem and had burst somehow.


Bleagh. And kind of humorous, as it turns out.

Topic drift alert. The last 'cross race I promoted (in 2000) included
one of the strongest of the women racers; she had given birth about 6
weeks earlier. She was off her game as far as racing went, but dang-
she was out there. Chicks are tough!

FWIW:

http://en.wikipedia.org/wiki/Concussion

http://www.mayoclinic.com/health/concussion/DS00320


Yeah, I looked this stuff up afterwards, and have now internalized
the parts about evaluation and not losing consciousness, but you
generally don't think of these things after you yourself get whacked.


Nope, we really don't. I remember losing the front end on an off-camber
straightaway in a 'cross race and going down hard, whacking my head and
getting that sort of stinging dazed feeling in my sinuses. But what did
I check first when I jumped up? The bike, not myself.

Bill Nealy had some funny cartoons about this in his books on mountain
biking.

Avoiding concussions is a good thing.


Yes, it certainly is. Fortunately, concussions in cycling are a rare
thing unlike high-contact sports like boxing, rugby, football, etc.
  #33  
Old March 21st 09, 03:35 PM posted to rec.bicycles.tech
Tim McNamara
external usenet poster
 
Posts: 6,945
Default Mostly OT/Head Injury and Death

In article
,
Bret wrote:

On Mar 20, 2:57*pm, Frank Krygowski wrote:
On Mar 20, 3:27*pm, Dan O wrote:



On Mar 20, 9:06*am, Frank Krygowski wrote:


In another article,http://www.msnbc.msn.com/id/29772691/*:


"The National Ski Areas Association (NSAA) of the United States
estimated 43 percent of skiers and snowboarders wore helmets in
the 2007-08 season, against 25 percent five years earlier.
...


"The increase in the use of helmets has not reduced the overall
number of skiing fatalities," the NSAA said in a statement.
"More than half of the people involved in fatal accidents last
season were wearing helmets."


So more than half the fatalities were in helmets. *But fewer
than half wear them. *IOW, helmet use is _positively_
correlated with fatality.


Risk compensation, anyone?


People who intend to ski as fast as they possibly can are the
ones more likely to wear a helmet.


Would they ski quite as fast, or in quite as risky a manner, if
they did not wear a helmet?

Judging by those figures above, probably not.


It's a chicken and egg question. Are people wearing helmets because
they're doing something dangerous or doing something dangerous
because they're wearing helmets? You think it's the latter. The
former makes much more sense to me but I don't know. You seem pretty
sure of something that is unknowable without more information. Maybe
you're the type that just doesn't know how to day "I don't know".


There is some chicken-and-eggness, but the numbers are quite
interesting: fewer than half (43%) of skiers wear helmets and yet more
than half of the fatalities were wearing helmets. Clearly a fatal
skiing accident is more likely among helmet wearers than non-helmet
wearers.

The reasons for that are unclear. Risk compensation is certainly one
possible explanation, e.g., that people are likelier to take risks on
the assumption that they are protected by the helmet. Or, conversely,
non-helmet wearers might ski more cautiously.

There are other possible explanations. For example, novices might be
more likely to wear helmets and more likely to suffer an accident
through inexperience, underestimating dangers and lack of skills. The
presence of a helmet could be completely extraneous to the cause of
death- they'd have been killed either way.
  #34  
Old March 21st 09, 04:49 PM posted to rec.bicycles.tech
Frank Krygowski[_2_]
external usenet poster
 
Posts: 7,511
Default Mostly OT/Head Injury and Death

On Mar 21, 11:35*am, Tim McNamara wrote:
In article
,



*Bret wrote:
It's a chicken and egg question. Are people *wearing helmets because
they're doing something dangerous or doing something dangerous
because they're wearing helmets?


There is some chicken-and-eggness, but the numbers are quite
interesting: *fewer than half (43%) of skiers wear helmets and yet more
than half of the fatalities were wearing helmets. *Clearly a fatal
skiing accident is more likely among helmet wearers than non-helmet
wearers.

The reasons for that are unclear. *Risk compensation is certainly one
possible explanation, e.g., that people are likelier to take risks on
the assumption that they are protected by the helmet. *Or, conversely,
non-helmet wearers might ski more cautiously.

There are other possible explanations. *For example, novices might be
more likely to wear helmets and more likely to suffer an accident
through inexperience, underestimating dangers and lack of skills. *The
presence of a helmet could be completely extraneous to the cause of
death- they'd have been killed either way.


The other thing to remember is this: We're dealing with VERY small
sample sizes. There are something like 40 deaths per year in US
skiing. (There must be many millions of hours spent skiing.) Compare
to about 40,000 deaths from motoring.

This tells us two things: First, any calculations will be heavily
influenced by random variation. (For example, if we get 45 skiing
deaths next year, the helmeteers will yell "It's a 13 percent
increase!!!!" But it will be just random variation.)

Second, we're once again comparing infinitesmals. Even if your odds
of dying while skiing helmeted are greater than your odds of dying
while skiing unhelmeted, both odds are negligible. Professional
handwringers and helmet lobbyists will never admit that, of course.

Anti-disclaimer: I haven't downhill skied for about 40 years, so this
kerfuffle's effect on skiing doesn't matter much to me.

- Frank Krygowski
  #35  
Old March 21st 09, 04:56 PM posted to rec.bicycles.tech
Frank Krygowski[_2_]
external usenet poster
 
Posts: 7,511
Default Mostly OT/Head Injury and Death

On Mar 21, 3:33*am, "
wrote:

I hesitate to get involved in a helmet thread, but IMO
looking at fatalities is not a great way to measure
whether helmets do anything.


Well, when helmeteers start saying "Someone died, therefore everyone
must wear helmets," looking at fatalities becomes very pertinent.
Especially when doing so disproves the helmeteers point.

Many fatalities (ski or bike)
occur in impacts where only a helmet the size of a Green
Bay Cheesehead could have helped. *


Right. Which is why robust data shows they've never had a positive
effect on fatalities.

IMO the effect of
helmets is more likely to occasionally mitigate what
would have been a bad concussion into a mild
concussion, or a mild concussion into just a sore spot.


Or most likely, a minor scratch into no scratch at all.

But to a helmeteer, every minor scratch is still a dreaded "head
injury!!!!"

.... because they can use the imprecise definition of "head injury" to
terrify people, and to claim helmets prevent "up to 85% of head
injuries."

- Frank Krygowski
  #36  
Old March 21st 09, 08:49 PM posted to rec.bicycles.tech
Michael Press
external usenet poster
 
Posts: 9,202
Default Mostly OT/Head Injury and Death

In article
,
" wrote:

On Mar 20, 10:45*pm, Bret wrote:
On Mar 20, 2:57*pm, Frank Krygowski wrote:
On Mar 20, 3:27*pm, Dan O wrote:
On Mar 20, 9:06*am, Frank Krygowski wrote:


In another article,http://www.msnbc.msn.com/id/29772691/*:


"The National Ski Areas Association (NSAA) of the United States
estimated 43 percent of skiers and snowboarders wore helmets in the
2007-08 season, against 25 percent five years earlier.
...


"The increase in the use of helmets has not reduced the overall number
of skiing fatalities," the NSAA said in a statement. "More than half
of the people involved in fatal accidents last season were wearing
helmets."


So more than half the fatalities were in helmets. *But fewer than half
wear them. *IOW, helmet use is _positively_ correlated with
fatality.


Risk compensation, anyone?


People who intend to ski as fast as they possibly can are the ones
more likely to wear a helmet.


Would they ski quite as fast, or in quite as risky a manner, if they
did not wear a helmet?


Judging by those figures above, probably not.


It's a chicken and egg question. Are people *wearing helmets because
they're doing something dangerous or doing something dangerous because
they're wearing helmets? You think it's the latter. The former makes
much more sense to me but I don't know. You seem pretty sure of
something that is unknowable without more information. Maybe you're
the type *that just doesn't know how to day "I don't know".


This argument about ski helmets and behavior also
suffers from a lack of information. We don't have any
idea whether the ski fatalities discussed refer to
only in-bounds or also out-of-bounds skiing, and
whether they are strictly impact related accidents.
On a bike, the main cause of getting hurt is crashing,
but this is not always so in skiing. Even if you
only consider crashing and rule out avalanches,
most ways of riding bike are pretty safe (excluding
at night without lights, and some extreme downhill
MTBing). This is not so true of downhill skiing, where
style can have a big effect on how likely you are
to get hurt.

I hesitate to get involved in a helmet thread, but IMO
looking at fatalities is not a great way to measure
whether helmets do anything. Many fatalities (ski or bike)
occur in impacts where only a helmet the size of a Green
Bay Cheesehead could have helped. IMO the effect of
helmets is more likely to occasionally mitigate what
would have been a bad concussion into a mild
concussion, or a mild concussion into just a sore spot.
Whether this is worth anything is up to the wearer.


And now that you are involved, head injuries beyond abrasions
are from stopping and sloshing, and from neck twists,
neither of which are ameliorated by bicycle helmets.
Even when a bicycle helmeted head strikes an object, the head
decelerates. Helmets do nothing to prevent neck twists.

--
Michael Press
  #37  
Old March 21st 09, 08:57 PM posted to rec.bicycles.tech
Michael Press
external usenet poster
 
Posts: 9,202
Default Mostly OT/Head Injury and Death

In article
,
" wrote:

On Mar 20, 9:26*am, Bret wrote:

I once fell on my face while skiing at Aspen with enough violence that
my plastic sunglasses broke. I thought I was ok at first but on the
next chairlift ride I started developing vertigo and became nauseous.
It was all I could do to side-slip down from the top of Ajax mountain
and walk to our rented condo where I went straight to bed. The guy I
had been skiing with kept skiing, but eventually he told some other
people in our party (large company ski trip) what had happened and
after a couple of hours they woke me up saying it was dangerous to
sleep after a head injury. One of them was a nurse and she shined a
flashlight in my eyes and said my pupils were dilated indicating a
concussion. Since someone else in our party had already died that day
of pneumonia in a different condo, they were really worried that the
company ski trip's death rate would climb to an embarrassing level. So
they wouldn't let me sleep and they wouldn't let me drink. I had to
sit there with the worst headache of my life and listen to them talk.
At one point one of them said that we should go out drinking because
that's what Steve (the dead guy) would want them to do. We didn't. I
was allowed to sleep for brief intervals overnight and only had a bad
headache the next morning and so I went skiing. I don't remember why I
didn't go to the hospital.


I think the sleeping danger is not that sleeping will
make it worse, but that it could mask a more serious
loss of consciousness. If you'd gone to the hospital
they would also have shined lights in your eyes and
might have let you sleep at some point, but
probably would wake you up every couple of hours
to make sure they could still wake you up.

When I whacked the side of my head in a CX race
I also got a bunch of gravel cuts (actually it was the
second time I'd fallen on this short loose descent).
We had a friend who was an EMT at the race and
she cleaned up my cuts while making a lot of small
talk with me, which later I realized was also a subtle
way of doing a mental/head-injury evaluation.

I had a bad headache and sat around at the scorer's tent
with my friends who were running the race, occasionally
helping a little, until all the races were done and we
cleaned up, by which time I was just kinda sore and
fine to drive home. In retrospect it seems like an obvious
concussion, but the word or thought never crossed
my mind at the time. This seems like a common
reaction, much like the impulse to get back on your
bike w/o realizing that you're dripping blood.


It is the nature of a concussion to impair thinking.
A concussed person is the last to know.
Send me in, Coach!

--
Michael Press
  #38  
Old March 21st 09, 09:00 PM posted to rec.bicycles.tech
Michael Press
external usenet poster
 
Posts: 9,202
Default Mostly OT/Head Injury and Death

In article
,
Bret wrote:

On Mar 20, 9:45*pm, "
wrote:
On Mar 20, 8:07*pm, Tim McNamara wrote:

" wrote:


When I whacked the side of my head in a CX race I also got a bunch of
gravel cuts (actually it was the second time I'd fallen on this short
loose descent). We had a friend who was an EMT at the race and she
cleaned up my cuts while making a lot of small talk with me, which
later I realized was also a subtle way of doing a mental/head-injury
evaluation.


Good call, that was probably exactly what he was doing. *"Who's the
President" is really not that great a question for assessing these
things. *Also, since problems can develop over time, he was probably
re-checking periodically.


She. *I don't remember if she actually re-evaluated me,
but since we were more or less in the same place over
the next couple of hours and I was capable of holding
a conversation with the rest of the hangers-on at the
scorers' tent, effectively yes.


I was once in that situation and was asked what day it was, I
answered "They tell me it's Thursday". Apparently, I'd already been
asked that question and been corrected.


-- What day is it?
-- Four.

--
Michael Press
 




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