Beware of PowerCranks

[[email protected]]

On Jul 31, 11:02 am, Michael Press <[email protected]> wrote:
> In article
> <[email protected]>
> ,
>
>
>
> [email protected] wrote:
> > On Jun 7, 11:57 am, Andy Coggan <[email protected]> wrote:
> > > On Jun 5, 11:04 pm, "Phil Holman" <piholmanc@yourservice> wrote:
>
> > > > <[email protected]> wrote in message
> > > > > In recent times, steam RR locomotives, although not rated in Horse
> > > > > Power (but rather "tractive effort", the pull at which the wheels
> > > > > would spin) had a conversion chart to HP based on grate area in the
> > > > > fire box which governs how much heat can be transferred to steam in
> > > > > the boiler. Grate area is closely similar to lung displacement for
> > > > > physically fit racers. That is what limits climbing or TT ability,
> > > > > not ankling, pedaling style or other external means.
>
> > > > You continue to repeat this misconception. Lung displacement or lung
> > > > capacity is not the limiting factor in climbing or TTing or cycling in
> > > > general. If you understood the cause and effect elements you would
> > > > understand that extreme "out of breath" is caused by excess CO2 in the
> > > > blood stream as a result of lactic buffering.
>
> > > Great! Now we have one engineer feeding misconceptions about how
> > > physiology functions to another engineer...
>
> > No, now we have an exercise physiologist trying to correct someone
> > with a correct understanding of the limiter. I am truly amazed that
> > you haven't figured out what is going on here yet.
>
> > > Fact: CO2 plays only a very limited role in regulating ventilation
> > > during exercise.
>
> > Fact: There are two main drivers for ventilation. CO2 and O2. The main
> > one is CO2. The body adjusts ventilation to maintain the arterial
> > partial pressure of CO2 at 40torr. CO2 is the prime determiner of
> > ventilatory function at all times except during extreme hypoxia, which
> > never occurs during normal exercise.
>
> > > > That is, the limits of
> > > > aerobic capacity were reached upstream (cardiac output, blood muscle
> > > > interface limitations etc) and no further limitations are imposed by the
> > > > lungs. It wouldn't matter if you doubled lung capacity, blood lactate
> > > > concentrations wouldn't change and this is the culminating event in
> > > > limiting aerobic performance. Heavy breathing is an effect not a cause.
>
> > > In fact, mild-to-moderate arterial desaturation tends to occur during
> > > maximal exercise in a significant portion of the population (at least
> > > discounting young, healthy, untrained men!), indicating that, at least
> > > to some extent, aerobic capacity (i.e., VO2max) is limited, in part,
> > > by pulmonary function.
>
> > Phoeey. A small arterial desaturation is most likely explained by
> > increased left to right shunting and ventilation perfusion mismatch at
> > the extremes and is probably has no effect on performance because of
> > the oxyhemoglobin saturation curve. There could be other explanations
> > also such as a shift in the curve due to changes in pH. Small levels
> > of desaturation have almost no effect on oxygen carrying capacity to
> > the tissues.
>
> I am incompetent to assess these matters. I have read
> very little, but got the impression that the limiting
> factor in aerobic work capacity is the mitochondria
> themselves.
>
> --
> Michael Press

In my opinion, the limiter is the ability to deliver oxygen to the
mitochondria so the mitochonria compensate by using another mechanism
with lactic acid as an end point. Once there are enough mitochondria
in this situation the amount of lactic acid being produced overwhelms
the bodies ability to compensate for this and the "failure cascade"
starts.

 

[Michael Press]

In article
<[email protected]>
,
[email protected] wrote:

> On Jul 31, 11:02 am, Michael Press <[email protected]> wrote:
> > In article
> > <[email protected]>
> > ,
> >
> >
> >
> > [email protected] wrote:
> > > On Jun 7, 11:57 am, Andy Coggan <[email protected]> wrote:
> > > > On Jun 5, 11:04 pm, "Phil Holman" <piholmanc@yourservice> wrote:
> >
> > > > > <[email protected]> wrote in message
> > > > > > In recent times, steam RR locomotives, although not rated in Horse
> > > > > > Power (but rather "tractive effort", the pull at which the wheels
> > > > > > would spin) had a conversion chart to HP based on grate area in the
> > > > > > fire box which governs how much heat can be transferred to steam in
> > > > > > the boiler. Grate area is closely similar to lung displacement for
> > > > > > physically fit racers. That is what limits climbing or TT ability,
> > > > > > not ankling, pedaling style or other external means.
> >
> > > > > You continue to repeat this misconception. Lung displacement or lung
> > > > > capacity is not the limiting factor in climbing or TTing or cycling in
> > > > > general. If you understood the cause and effect elements you would
> > > > > understand that extreme "out of breath" is caused by excess CO2 in the
> > > > > blood stream as a result of lactic buffering.
> >
> > > > Great! Now we have one engineer feeding misconceptions about how
> > > > physiology functions to another engineer...
> >
> > > No, now we have an exercise physiologist trying to correct someone
> > > with a correct understanding of the limiter. I am truly amazed that
> > > you haven't figured out what is going on here yet.
> >
> > > > Fact: CO2 plays only a very limited role in regulating ventilation
> > > > during exercise.
> >
> > > Fact: There are two main drivers for ventilation. CO2 and O2. The main
> > > one is CO2. The body adjusts ventilation to maintain the arterial
> > > partial pressure of CO2 at 40torr. CO2 is the prime determiner of
> > > ventilatory function at all times except during extreme hypoxia, which
> > > never occurs during normal exercise.
> >
> > > > > That is, the limits of
> > > > > aerobic capacity were reached upstream (cardiac output, blood muscle
> > > > > interface limitations etc) and no further limitations are imposed by the
> > > > > lungs. It wouldn't matter if you doubled lung capacity, blood lactate
> > > > > concentrations wouldn't change and this is the culminating event in
> > > > > limiting aerobic performance. Heavy breathing is an effect not a cause.
> >
> > > > In fact, mild-to-moderate arterial desaturation tends to occur during
> > > > maximal exercise in a significant portion of the population (at least
> > > > discounting young, healthy, untrained men!), indicating that, at least
> > > > to some extent, aerobic capacity (i.e., VO2max) is limited, in part,
> > > > by pulmonary function.
> >
> > > Phoeey. A small arterial desaturation is most likely explained by
> > > increased left to right shunting and ventilation perfusion mismatch at
> > > the extremes and is probably has no effect on performance because of
> > > the oxyhemoglobin saturation curve. There could be other explanations
> > > also such as a shift in the curve due to changes in pH. Small levels
> > > of desaturation have almost no effect on oxygen carrying capacity to
> > > the tissues.
> >
> > I am incompetent to assess these matters. I have read
> > very little, but got the impression that the limiting
> > factor in aerobic work capacity is the mitochondria
> > themselves.
>
> In my opinion, the limiter is the ability to deliver oxygen to the
> mitochondria so the mitochonria compensate by using another mechanism
> with lactic acid as an end point. Once there are enough mitochondria
> in this situation the amount of lactic acid being produced overwhelms
> the bodies ability to compensate for this and the "failure cascade"
> starts.

Minor biochemistry quibble here.
As I understand the matter, the mitochondria are not
involved directly in the process leading to lactic acid
production. Rather it is ATP hydrolysis outside the
mitochondria that produces H+, which is then buffered
by lactate in the cell, outside the mitochondria. The
necessity for buffering H+ occurs only when the
mitochondria are working at full capacity and cannot
metabolize any more H+. (The mitochondria runs
ADP + n H+ + other stuff -> ATP + other stuff)

I would like to know how much O2 concentration varies
in the tissue and how that affects mitochondria
capacity during heavy exercise, and if O2 concentration
is the, or a, limiting factor.

--
Michael Press

 

[Michael Press]

In article <[email protected]>,
Joe Riel <[email protected]> wrote:

> Michael Press <[email protected]> writes:
>
> > I am incompetent to assess these matters. I have read
> > very little, but got the impression that the limiting
> > factor in aerobic work capacity is the mitochondria
> > themselves.
>
> That's why I am desiging nanopowercranks;
> they allow the mitochondria to train themselves!

Ooohhhh! Here you go--$$$$$$$$$
When can I get some nanopowercranks?

--
Michael Press

 

[Doug Taylor]

On Tue, 31 Jul 2007 11:30:58 -0700, [email protected] wrote:
>
>In my opinion, the limiter is the ability to deliver oxygen to the
>mitochondria so the mitochonria compensate by using another mechanism
>with lactic acid as an end point. Once there are enough mitochondria
>in this situation the amount of lactic acid being produced overwhelms
>the bodies ability to compensate for this and the "failure cascade"
>starts.

Pardon me if I switch topics, but now that Frank is posting I want to
get back to the subject of Powercranks and strength training .

Jobst Brandt has opined - I hope I am not misconstruing him - that the
full circle muscular movement that Powercranks train, is not really
used when pedaling a bicycle. Good old stomping is how regular cranks
work mechanically.

I'm still a beginner on my Powercranks and usually manage a low
cadence. I trained them on the basement trainer over the winter, and
now use them only about twice a month (hint: they are absolutely
perfect to use when taking a spin with your S.O. if she, or he, is a
less strong cyclist. They slow you, or at least me, down enough so
that we actually can ride together.)

Anecdote: I took out my single speed maintain bike this evening for
the first time this season and the first time ever after using
Powercranks. Anyone who climbs on single speeds knows that the
gearing is much higher than what would be used on a multi geared bike,
and that standing and grinding at a very low cadence, rather than
sitting and spinning, is what gets you up and over. I found that an
approximation of a circular pedaling motion works much more
efficiently than stomping in this venue, and that I was noticeably
stronger over terrain that in the past was much more difficult.

So, anecdotally and subjectively, I'm thinking these puppies have made
me stronger.

FWIW.

 

[[email protected]]

On Jul 31, 7:54 pm, Doug Taylor <[email protected]> wrote:
> On Tue, 31 Jul 2007 11:30:58 -0700, [email protected] wrote:
>
> >In my opinion, the limiter is the ability to deliver oxygen to the
> >mitochondria so the mitochonria compensate by using another mechanism
> >with lactic acid as an end point. Once there are enough mitochondria
> >in this situation the amount of lactic acid being produced overwhelms
> >the bodies ability to compensate for this and the "failure cascade"
> >starts.
>
> Pardon me if I switch topics, but now that Frank is posting I want to
> get back to the subject ofPowercranksand strength training .
>
> Jobst Brandt has opined - I hope I am not misconstruing him - that the
> full circle muscular movement thatPowercrankstrain, is not really
> used when pedaling a bicycle. Good old stomping is how regular cranks
> work mechanically.
>
> I'm still a beginner on myPowercranksand usually manage a low
> cadence. I trained them on the basement trainer over the winter, and
> now use them only about twice a month (hint: they are absolutely
> perfect to use when taking a spin with your S.O. if she, or he, is a
> less strong cyclist. They slow you, or at least me, down enough so
> that we actually can ride together.)
>
> Anecdote: I took out my single speed maintain bike this evening for
> the first time this season and the first time ever after usingPowercranks. Anyone who climbs on single speeds knows that the
> gearing is much higher than what would be used on a multi geared bike,
> and that standing and grinding at a very low cadence, rather than
> sitting and spinning, is what gets you up and over. I found that an
> approximation of a circular pedaling motion works much more
> efficiently than stomping in this venue, and that I was noticeably
> stronger over terrain that in the past was much more difficult.
>
> So, anecdotally and subjectively, I'm thinking these puppies have made
> me stronger.
>
> FWIW.

First, Jobst is wrong. Everyone pedals in circles to some degree, in
that they do some work on the back stroke, the only question is how
much do they do? People get confused when they look at measured pedal
forces and they see everyone with negative forces on the back stroke
and very large forces on the down stroke. They construe this to mean
that stomping is the way to go. What they forget is the effects of
gravity on those measured forces.

By way of example Let's say you measure your forces and find that you
are putting 50 lbs of force on the down stroke each revolution and a
negative 5 lbs on the up stroke. From this you think you are a masher.
However, If you consider that each leg weighs perhaps 25 lbs what
this really means is you are really pulling up with 20 lbs force when
you see those negative 5 lbs on the pedal and that 25 lbs of the
downward force is actually the weight of the leg such that you are
only actually pushing with 20 lbs of muscular force on the downward
portion. So you are actively pushing with 25 lbs force and pulling
with 20 lbs force, what almost anyone would call close to pedaling in
circles, even though the forces on the pedals do not look like that
at all. If all PowerCranks does is make the rider completely unweight
then they only have to pull up another 5 lbs and now they are pushing
with 25 lbs force and pulling with 25 lbs force, what anyone would
consider pedaling in circles I am sure, even though the forces on the
pedals would be 50 on the downstroke and 0 on the up.

 

[Ben C]

On 2007-08-03, [email protected] <[email protected]> wrote:
> On Jul 31, 7:54 pm, Doug Taylor <[email protected]> wrote:
>> On Tue, 31 Jul 2007 11:30:58 -0700, [email protected] wrote:
[...]
> First, Jobst is wrong. Everyone pedals in circles to some degree, in
> that they do some work on the back stroke, the only question is how
> much do they do? People get confused when they look at measured pedal
> forces and they see everyone with negative forces on the back stroke
> and very large forces on the down stroke. They construe this to mean
> that stomping is the way to go. What they forget is the effects of
> gravity on those measured forces.
>
> By way of example Let's say you measure your forces and find that you
> are putting 50 lbs of force on the down stroke each revolution and a
> negative 5 lbs on the up stroke.

Very few people actually apply 5lbs to the cleat on the up stroke. Many
riders pull the leg up a little bit, enough perhaps to lift about half
its weight. This counts as a contribution towards forward motion in that
it saves leg B lifting the entire weight of leg A, but leg A is still
being pushed up by the pedal. If you lifted the whole weight of leg A
(so there was 0 force on the cleat) or more (so there was say 5lbf
pulling shoe A up out of the cleat) you would be doing a great deal of
lifting and definitely pedalling in circles. But they've done studies
and no-one actually does that.

> From this you think you are a masher. However, If you consider that
> each leg weighs perhaps 25 lbs what this really means is you are
> really pulling up with 20 lbs force when you see those negative 5 lbs
> on the pedal and that 25 lbs of the downward force is actually the
> weight of the leg such that you are only actually pushing with 20 lbs
> of muscular force on the downward portion. So you are actively pushing
> with 25 lbs force and pulling with 20 lbs force, what almost anyone
> would call close to pedaling in circles, even though the forces on the
> pedals do not look like that at all. If all PowerCranks does is make
> the rider completely unweight then they only have to pull up another 5
> lbs and now they are pushing with 25 lbs force and pulling with 25 lbs
> force, what anyone would consider pedaling in circles I am sure, even
> though the forces on the pedals would be 50 on the downstroke and 0 on
> the up.

 

[[email protected]]

On Aug 3, 2:14 am, [email protected] wrote:
> Everyone pedals in circles to some degree, in
> that they do some work on the back stroke, the only question is how
> much do they do? [...] What they forget is the effects of
> gravity on those measured forces.

You're saying that on the moon your cranks would be one-sixth as
effective?

 

[Doug Taylor]

On Fri, 03 Aug 2007 02:58:02 -0500, Ben C <[email protected]> wrote:
>
>Very few people actually apply 5lbs to the cleat on the up stroke. Many
>riders pull the leg up a little bit, enough perhaps to lift about half
>its weight. This counts as a contribution towards forward motion in that
>it saves leg B lifting the entire weight of leg A, but leg A is still
>being pushed up by the pedal. If you lifted the whole weight of leg A
>(so there was 0 force on the cleat) or more (so there was say 5lbf
>pulling shoe A up out of the cleat) you would be doing a great deal of
>lifting and definitely pedalling in circles. But they've done studies
>and no-one actually does that.

Anybody have any comment as to whether or not there are any
substantial differences between lower cadence pedaling while climbing,
as opposed to higher cadence pedaling while spinning on flatter
terrain? In my experience, it seems the steeper the climb, the
greater the load, the more muscular power required, the lower the
cadence, the more "circular" the stroke.

 

[[email protected]]

On Aug 3, 1:37 am, [email protected] wrote:
> On Aug 3, 2:14 am, [email protected] wrote:
>
> > Everyone pedals in circles to some degree, in
> > that they do some work on the back stroke, the only question is how
> > much do they do? [...] What they forget is the effects of
> > gravity on those measured forces.
>
> You're saying that on the moon your cranks would be one-sixth as
> effective?

One-sixth as effective as what? bicycle cranks? training devices to
train "circular" pedaling on earth? training devices for space?

 

[[email protected]]

On Aug 3, 5:48 am, Doug Taylor <[email protected]> wrote:
> On Fri, 03 Aug 2007 02:58:02 -0500, Ben C <[email protected]> wrote:
>
> >Very few people actually apply 5lbs to the cleat on the up stroke. Many
> >riders pull the leg up a little bit, enough perhaps to lift about half
> >its weight. This counts as a contribution towards forward motion in that
> >it saves leg B lifting the entire weight of leg A, but leg A is still
> >being pushed up by the pedal. If you lifted the whole weight of leg A
> >(so there was 0 force on the cleat) or more (so there was say 5lbf
> >pulling shoe A up out of the cleat) you would be doing a great deal of
> >lifting and definitely pedalling in circles. But they've done studies
> >and no-one actually does that.
>
> Anybody have any comment as to whether or not there are any
> substantial differences between lower cadence pedaling while climbing,
> as opposed to higher cadence pedaling while spinning on flatter
> terrain? In my experience, it seems the steeper the climb, the
> greater the load, the more muscular power required, the lower the
> cadence, the more "circular" the stroke.

I think people naturally gravitate to lower caadences when they need
the most power because they naturally sense when they are the most
efficient, so generating the most power for the same (or, usually,
increased) effort. Another possible reason, is few have the gearing on
their bike that would allow them to maintain a 90-100 cadence up any
kind of reasonable climb without going way beyond their power
abilities. Want to ride like Lance you need to put out power like
Lance. Unless you are putting out 400+ sustainable watts climbing at a
cadence of 90 is not for you.

 

[Tim McNamara]

In article <[email protected]>,
Doug Taylor <[email protected]> wrote:

> On Fri, 03 Aug 2007 02:58:02 -0500, Ben C <[email protected]> wrote:
> >
> >Very few people actually apply 5lbs to the cleat on the up stroke.
> >Many riders pull the leg up a little bit, enough perhaps to lift
> >about half its weight. This counts as a contribution towards forward
> >motion in that it saves leg B lifting the entire weight of leg A,
> >but leg A is still being pushed up by the pedal. If you lifted the
> >whole weight of leg A (so there was 0 force on the cleat) or more
> >(so there was say 5lbf pulling shoe A up out of the cleat) you would
> >be doing a great deal of lifting and definitely pedalling in
> >circles. But they've done studies and no-one actually does that.
>
> Anybody have any comment as to whether or not there are any
> substantial differences between lower cadence pedaling while
> climbing, as opposed to higher cadence pedaling while spinning on
> flatter terrain? In my experience, it seems the steeper the climb,
> the greater the load, the more muscular power required, the lower the
> cadence, the more "circular" the stroke.

IIRC there were studies showing that mountain bikers tended to have a
more "circular" spin than road bikers, with the hypothesis being that
they developed this from spinning tiny gears up steep inclines while
seated to maintain traction. Maybe this was in VeloNews? Man, it was
years ago and maybe my memory of it is FUBAR'd.

 

[Carl Sundquist]

"Doug Taylor" <[email protected]> wrote in message
news:[email protected]...
> On Fri, 03 Aug 2007 02:58:02 -0500, Ben C <[email protected]> wrote:
>>
>>Very few people actually apply 5lbs to the cleat on the up stroke. Many
>>riders pull the leg up a little bit, enough perhaps to lift about half
>>its weight. This counts as a contribution towards forward motion in that
>>it saves leg B lifting the entire weight of leg A, but leg A is still
>>being pushed up by the pedal. If you lifted the whole weight of leg A
>>(so there was 0 force on the cleat) or more (so there was say 5lbf
>>pulling shoe A up out of the cleat) you would be doing a great deal of
>>lifting and definitely pedalling in circles. But they've done studies
>>and no-one actually does that.
>
> Anybody have any comment as to whether or not there are any
> substantial differences between lower cadence pedaling while climbing,
> as opposed to higher cadence pedaling while spinning on flatter
> terrain? In my experience, it seems the steeper the climb, the
> greater the load, the more muscular power required, the lower the
> cadence, the more "circular" the stroke.

I would offer that the greater the power/wattage for a given rpm, the more
circular the stroke, with "circularity" dropping off at lower end of the rpm
range. Angle of climb is irrelevant.

 

[[email protected]]

On Aug 3, 6:35 pm, [email protected] wrote:
> On Aug 3, 1:37 am, [email protected] wrote:
>
> > On Aug 3, 2:14 am, [email protected] wrote:
>
> > > Everyone pedals in circles to some degree, in
> > > that they do some work on the back stroke, the only question is how
> > > much do they do? [...] What they forget is the effects of
> > > gravity on those measured forces.
>
> > You're saying that on the moon your cranks would be one-sixth as
> > effective?
>
> One-sixth as effective as what? bicycle cranks? training devices to
> train "circular" pedaling on earth? training devices for space?

I don't know. I'm asking. You're saying that everyone but you forgets
acceleration due to gravity. So can you estimate the difference in
power an astronaut could make if he used a regularly-cranked ergometer
on the ISS?

 

[[email protected]]

On Aug 3, 10:21 pm, [email protected] wrote:
> On Aug 3, 6:35 pm, [email protected] wrote:
>
> > On Aug 3, 1:37 am, [email protected] wrote:
>
> > > On Aug 3, 2:14 am, [email protected] wrote:
>
> > > > Everyone pedals in circles to some degree, in
> > > > that they do some work on the back stroke, the only question is how
> > > > much do they do? [...] What they forget is the effects of
> > > > gravity on those measured forces.
>
> > > You're saying that on the moon your cranks would be one-sixth as
> > > effective?
>
> > One-sixth as effective as what? bicycle cranks? training devices to
> > train "circular" pedaling on earth? training devices for space?
>
> I don't know. I'm asking. You're saying that everyone but you forgets
> acceleration due to gravity. So can you estimate the difference in
> power an astronaut could make if he used a regularly-cranked ergometer
> on the ISS?

regarding your comment that everyone but me "forgets" acceleration due
to gravity - Have you ever seen anyone else mention that the forces on
the pedals do not actually represent the muscular forces involved? I
haven't, at least in any of these threads.

I am not sure what an astronaut can or would do on the ISS. Their
problem is going to be that unless they are somehow glued to the seat
their forces have to be completely balanced or they are going to fly
off the seat. I am sure this takes a little (or a lot of) getting used
to and since their main job is not to see how good they can get on the
exercise bike but, rather, simply maintain enough muscular and
cardiovascular fitness such that they might be able to actually stand
up when they return to earth, I suspect most of them see substantial
drops in power compared to what they could do on the earth before they
went into space.

 

[[email protected]]

On Aug 4, 7:51 pm, [email protected] wrote:
> On Aug 3, 10:21 pm, [email protected] wrote:
>
>
>
> > On Aug 3, 6:35 pm, [email protected] wrote:
>
> > > On Aug 3, 1:37 am, [email protected] wrote:
>
> > > > On Aug 3, 2:14 am, [email protected] wrote:
>
> > > > > Everyone pedals in circles to some degree, in
> > > > > that they do some work on the back stroke, the only question is how
> > > > > much do they do? [...] What they forget is the effects of
> > > > > gravity on those measured forces.
>
> > > > You're saying that on the moon your cranks would be one-sixth as
> > > > effective?
>
> > > One-sixth as effective as what? bicycle cranks? training devices to
> > > train "circular" pedaling on earth? training devices for space?
>
> > I don't know. I'm asking. You're saying that everyone but you forgets
> > acceleration due to gravity. So can you estimate the difference in
> > power an astronaut could make if he used a regularly-cranked ergometer
> > on the ISS?
>
> regarding your comment that everyone but me "forgets" acceleration due
> to gravity - Have you ever seen anyone else mention that the forces on
> the pedals do not actually represent the muscular forces involved? I
> haven't, at least in any of these threads.
>
> I am not sure what an astronaut can or would do on the ISS. Their
> problem is going to be that unless they are somehow glued to the seat
> their forces have to be completely balanced or they are going to fly
> off the seat.

Then what would an astronaut be able to do on Mars?

 

[roadtrip]

Thanks for the insight! Now I won't have to spend a lot. Will rely on the effects of good old training to beat my personal records.

 

[Sunflogun]

Good old training will always be the way to go, supplements might help, but we always need to train.

 

[CAMPYBOB]

Hey! Now that we all have cheap Watt meters and ones that map the output at various rotational positions it should be dead-nut simple to prove or disprove the Power Cranks hype.

 

[likeascroll]

I had a friend who had a problem with theirs. Glad I learned the right way instead of having to go through that bad experience.