Heart Rate dropping on tri bars

DaveB said:

In the past I had a feeling my HR dropped when I moved onto the tri bars
but assumed because of the aerodynamics, that the lower heart rate was
because of less effort to remain at the same speed. But for the past few
months I've had the tri bars on my wind trainer bike. I've noticed that
dropping onto them, but maintaining the same cadence, almost immediately
drops the HR by 2-3 bpm. Coming back off them then increases HR by that
2-3 bpm.

I was discussing this with Gags this morning (if you can call it a
discussion when my contribution was something like - puff, pant, ...yep
...puff, gasp, ... ahuhh ...gasp puff). He was thinking it may be a more
relaxed position so less stress on the body. I was thinking it may be
lowering the body requiring less effort for the heart to pump blood
above itself. Anyone else got a theory? Has anyone else seen this? Come
on Tam/Carl I'm sure you've got info on this.

DaveB

Hey Dave, so you have a heart! (ducks)

Not suggesting any expertise on this whatsoever, just theorising and those who know may clear this up.

maybe you are breathing better when on the tri bars, either due to being more relaxed or you are opening your lungs a touch more ( usually not the case though with narrower elbow position..) better respiration lower heart rate.

Have you considered also the effect of HR drift?, not just the lag we get with HR as we warm up or exert to AT, but on a continued effort the HR goes above normal expected effort due to a number of factors, hydration, stress, temperature, etc... this may have some bearing, on how your heart rate drift pattern operates .

I kinda think you are more relaxed and thus see a lower HR for same output...

DaveB said:

In the past I had a feeling my HR dropped when I moved onto the tri bars
but assumed because of the aerodynamics, that the lower heart rate was
because of less effort to remain at the same speed. But for the past few
months I've had the tri bars on my wind trainer bike. I've noticed that
dropping onto them, but maintaining the same cadence, almost immediately
drops the HR by 2-3 bpm. Coming back off them then increases HR by that
2-3 bpm.

I was discussing this with Gags this morning (if you can call it a
discussion when my contribution was something like - puff, pant, ...yep
..puff, gasp, ... ahuhh ...gasp puff). He was thinking it may be a more
relaxed position so less stress on the body. I was thinking it may be
lowering the body requiring less effort for the heart to pump blood
above itself. Anyone else got a theory? Has anyone else seen this? Come
on Tam/Carl I'm sure you've got info on this.

DaveB

Very interesting observation. There are pressure sensors (baroreceptors)
on the carotid arteries in the neck. These pressure sensors have a rapid
response and lengthen the resting phase of the heart beat when the
pressure in the carotid arteries rises. They respond within a second or
two and form a feedback mechanism for short-term control of blood
pressure. When you lower your head the blood pressure in your carotid
arteries probably rises slightly (because the difference in hight
between heart and neck is smaller) and the feedback mechanism lowers
your heart rate. That's one possible explanation.

To take things one step further, I think the baroreceptors also affect
the constriction of all small arteries (also to control blood pressure),
but this mechanism is slower. If these theories are correct you might
see your heart rate recover partially after you have been on the tri
bars for about 30-60 seconds, as the arteries dilate a little to reduce
blood pressure. The reduction in the pressure caused by the arterial
dilation would make the baroreceptors increase the heart rate again.
There might too much other variability in heart rate and not be enough
resolution in the measurement to see these secondary effects (if they
exist).

My lazy Sunday afternoon thoughts.

Martin

--
Removed z before replying by email.

On 2007-01-07, DaveB (aka Bruce)
was almost, but not quite, entirely unlike tea:

Quoted message said:

In the past I had a feeling my HR dropped when I moved onto the tri bars
but assumed because of the aerodynamics, that the lower heart rate was
because of less effort to remain at the same speed. But for the past few
months I've had the tri bars on my wind trainer bike. I've noticed that
dropping onto them, but maintaining the same cadence, almost immediately
drops the HR by 2-3 bpm. Coming back off them then increases HR by that
2-3 bpm.

I was discussing this with Gags this morning (if you can call it a
discussion when my contribution was something like - puff, pant, ...yep
..puff, gasp, ... ahuhh ...gasp puff). He was thinking it may be a more
relaxed position so less stress on the body. I was thinking it may be
lowering the body requiring less effort for the heart to pump blood
above itself. Anyone else got a theory? Has anyone else seen this? Come
on Tam/Carl I'm sure you've got info on this.

Diversion time:

It's amazing what you learn at height safety certification courses,
but the heart apparently doesn't pump with enough pressure to pump
bloody back up from the legs -- it's a pump, not a vacuum cleaner.

When upright, the body relies on you constantly moving your legs which
does the pumping. So it's not fidgetting, restlessness or nervousness
that causes you to walk around and jiggle your feet when you're up in
front of an audience giving a talk -- it's your circulation in action.

This enters into height training via what happens when you suffer
suspension trauma after being fall arrested. Even if not unconcious,
cycling (ha! bicycle reference!) your legs on an invisible bicycle is
not enough to pump the blood -- you need to be pushing up against
something. Or merely having your thighs pulled level with your hips
is good enough (there are straps on harnesses for this reason), but
not stretched out vertically. If suspended from your back, stuck
vertical but not able to rescue yourself (if suspended the usual way
from your back, unless you have some structure nearby to help maneuvor
yourself, you won't be able to resue yourself), for more than 20
minutes before rescue, then the blood pools in your legs, and starts
getting poisioned with CO2. You will be unconcious at this point.
Standard first aid will also now kill you. After fainting, standard
first aid teaches the first aider to place the body level and if
possible, feet up in the air. This will then cause poisioned blood to
rush to your brain. The suspension trauma victim must be made to sit,
legs level with their hips to get the blood to recirculate, but
*slowly*. Their body must never be allowed to be level with their
legs, for several hours until recovered. Of course, by this time, the
paramedics with specialist instruction in suspension trauma are
already there, right?

Here endeth longest diversion in history.

So yeah, having the height difference between the heart and feet
lowered leading to less stress on the heart sounds plausible.

--
TimC
C Code.
C Code Run.
Run, Code, RUN!
PLEASE!!!! --unknown

DaveB said:

In the past I had a feeling my HR dropped when I moved onto the tri bars
but assumed because of the aerodynamics, that the lower heart rate was
because of less effort to remain at the same speed. But for the past few
months I've had the tri bars on my wind trainer bike. I've noticed that
dropping onto them, but maintaining the same cadence, almost immediately
drops the HR by 2-3 bpm. Coming back off them then increases HR by that
2-3 bpm.
DaveB

well don't know about being an expert but from fairly extensive Tribar use, yes Heart Rate drops anywhere from 2 to 5 BPM. Think you might find it will just be a gravity thing, blood does not have to travel as far up, so takes less effort from you heart to get it to your noggin and everything else which is now lower. Hence things like when working out Tri specific heart rate training zones, you tend to take this into account if you want to be really padantic, hence one of the contributing factors why you are able to get your heart rate higher when running VERY easily, where as it takes a little more effort while cycling. Swimming as well, you are flat, blood does not have to travel as far. This was my reasoning behind it and I think I read something similar later on while doing some research as well maybe on Trinewbies.com

I actually find my aerobar position far from comfortable, however, as you have found in terms of heart rate it is much more efficient, drag wise as well.

TimC said:

It's amazing what you learn at height safety certification courses, but
the heart apparently doesn't pump with enough pressure to pump bloody
back up from the legs -- it's a pump, not a vacuum cleaner.

I find that hard to believe. I've seen too many people stand *very* still
for extended time periods, certainly long enough for there to be some loss
of circulation if this were the case. However sitting, especially in a
safety harness, constricts the flow so you can get some blood pooling in
the feet.

Quoted message said:

If suspended from your back, stuck vertical but not able to rescue
yourself (if suspended the usual way from your back, unless you have
some structure nearby to help maneuvor yourself, you won't be able to
resue yourself), for more than 20 minutes before rescue, then the blood
pools in your legs, and starts getting poisioned with CO2.

That's what I was talking about above. It's a fairly well known thing in
rock climbing circles that you can't simply hang in a harness for too
long, so if you think you'll have to you take larger seats so there's
scope for wriggling. You can also do this to a limited extent in the
harness.

--
Dave Hughes | [email hidden]
"Reading computer manuals without the hardware is as frustrating as
reading sex manuals without the software." - Arthur C Clarke

From the MAPP:

Body Position on the Bike will Influence Heart Rate. Let's say I am riding on an indoor bicycle trainer with my upper body parallel to the ground (Hands on the drops) at a heart rate of 145. Raising upright while continuing to cycle at the exact same workload will result in an increase in heart rate of about 5 beats per minute. Trust me I have experimented with this effect on many a winter evening! This is due to decreased venous return in the more upright position. Heart rate increases to compensate for the slightly decreased venous return and stroke volume, keeping cardiac output constant. Whe I return to the drops, the heart rate drops again.

DaveB said:

In the past I had a feeling my HR dropped when I moved onto the tri bars
but assumed because of the aerodynamics,

<snip>

Quoted message said:

Anyone else got a theory?

It's simple. Using tri-bars makes you a triathlete, and thus you no longer
require blood to feed the brain. Your heart therefore does less work.

</troll>
--
Dave Hughes | [email hidden]
"SCSI is *not* magic. There are fundamental technical reasons why it is
necessary to sacrifice a young goat to your SCSI chain now and then."
- Daniel M. Drucker

On 2007-01-07, MikeyOz (aka Bruce)
was almost, but not quite, entirely unlike tea:

Quoted message said:

DaveB said:

In the past I had a feeling my HR dropped when I moved onto the tri
bars
but assumed because of the aerodynamics, that the lower heart rate was
because of less effort to remain at the same speed. But for the past
few
months I've had the tri bars on my wind trainer bike. I've noticed
that
dropping onto them, but maintaining the same cadence, almost
immediately
drops the HR by 2-3 bpm. Coming back off them then increases HR by
that
2-3 bpm.

well don't know about being an expert but from fairly extensive Tribar
use, yes Heart Rate drops anywhere from 2 to 5 BPM. Think you might
find it will just be a gravity thing, blood does not have to travel as
far up, so takes less effort from you heart to get it to your noggin
and everything else which is now lower.

Fsck! Another think the bent riders have on us, apart from being able
to grow really good beards!

--
TimC
Jun 26 14:08:17 kernel: troll-o-meter (pid 15134) killed: memory exhausted

On 2007-01-07, Dave Hughes (aka Bruce)
was almost, but not quite, entirely unlike tea:

Quoted message said:

DaveB said:

In the past I had a feeling my HR dropped when I moved onto the tri bars
but assumed because of the aerodynamics,

<snip>

Quoted message said:

Anyone else got a theory?

It's simple. Using tri-bars makes you a triathlete, and thus you no longer
require blood to feed the brain. Your heart therefore does less work.

Also, they have no heard anyway -- it's just the legs pumping blood.

Quoted message said:

</troll>

--
TimC
hey Beavis, we're segfaulting, heh heh heh, I know, Butthead, so let's
SIGBUS from inside the handler, heh heh heh --Stephen J. Turnbull

In aus.bicycle on Tue, 9 Jan 2007 12:30:42 +1100

TimC said:

On 2007-01-07, MikeyOz (aka Bruce)
was almost, but not quite, entirely unlike tea:

Quoted message said:

well don't know about being an expert but from fairly extensive Tribar
use, yes Heart Rate drops anywhere from 2 to 5 BPM. Think you might
find it will just be a gravity thing, blood does not have to travel as
far up, so takes less effort from you heart to get it to your noggin
and everything else which is now lower.

Fsck! Another think the bent riders have on us, apart from being able
to grow really good beards!

Well would be cause and effect wouldn't it? Where the blood is, the
beard follows? Would explain why the upright riders shave their
legs....

Zebee