Sat Oct 1st

WOD
A- power clean - 265 (few gd attempts at 281, no dice)
B- 3 HPC/ 30m hill sprint, 3 sets- 225/ 225/ 225
C- GHD situps x10 @ 3030, 30lbs x3 sets
D- Sorrenson hold x1- 152sec

some thoughts on blood donation i put up the other day from a question that someone had... fig'd i'd repost here... hopefully it asks a few more questions i suppose...

when giving blood, whole blood leaves you, about 1 Unit worth [300-350mL]. This is about 1/20 of an individuals blood volume [5-7L] depending on the size of the individual [~70-80ml/kg is the rough estimate of an individuals blood volume based on weight... this is probably more accurate when talking about the pediatric population, and is the basis of pediatric blood volume calculation when figuring out blood/fluid needs, balancing ins/outs, etc].
so.. after all that, lets say that Brent gave 300mL blood and his blood volume is 6L [1/20 of his blood volume]... how is that relevant?
Well, blood has a wide variety of components and complexity of uses in the human body... so I won't get into those details... but, let's look at how blood is involved in respiration... O2/CO2 exchange... it brings O2 to the tissues [from the lungs] and takes CO2 from the tissues to the lungs [in our workout model... tissue is muscle].
In order to calculate how much O2 is being delivered some really smart guys back in the day figured that out as the following:

DO2 = CO x [1.34 x Hb x SaO2 + 0.0031 x PaO2]

this may seem a little much... but let me define things a bit and hopefully break it down...
DO2 = delivery of O2... i know i don't have any units on the above... but the this is a volume of delivery of oxygen [since the right side of the equation includes cardiac output]
CO = cardiac output... this can also be broken down, or thought of as heart rate multiplied by the volume of each heart beat [stroke volume]
1.34 = this is a constant that is actually calculated from the amount of oxygen [in mL] each gram of Hb can hold
Hb = hemoglobin... molecule in the blood that is Fe [iron] based and can carry up to 4 oxygen molecules.
SaO2 = this is the oxygen saturation... how saturated the hemoglobin in your blood is... its the number that is recorded when your doctor or nurse puts a pulse oximiter on you and says [97 or 99, or 100% or whatever]... its a device that goes on your finger/toe/earlobe...
.0031 = another constant relating to the amount of dissolved oxygen in the blood.
PaO2 = this is basically how much O2 gas is dissolved in the liquid that is your blood, not bound to hemoglobin. It is dependent on atmospheric pressure of oxygen. This number is important and comes into play is some circumstances [hyperbaric oxygen therapy (part of the reason it works), high altitudes, etc].

Under normal circumstances hemoglobin [Hb] is ~15. After giving a unit of blood [~300mL], the 'rule of thumb' that you'd expect is for the hemoglobin to be affected by 1, i.e. 14 after donating 1 unit of blood.

so, now, looking at the equation and breaking it apart...
hemoglobin dependent portion [and filling in typical normal values]
1.34 x Hb x SaO2 [1.34 x 15 x 0.99 ~ 20]
this is typically the most important portion that affects Oxygen delivery under most circumstances

hemoglobin independent portion [and filling in typical normal values]
0.0031 x PaO2 [0.0031 x 100 ~ 0.31]

if you fill in typical numbers the hemoglobin dependent portion is 65 times as effective at carrying oxygen to tissues as what is dissolved in the blood and after 1 unit of blood loss is 60 times more 'dominant' than the portion that's dissolved in the blood.

one question is when does that portion that is hemoglobin independent become imperative and important in oxygen delivery... well, the reasons are many, and a few examples are: when someone has a low Hb for whatever reason [anemia is typically defined as Hb < 10], or a trauma patient who lost a lot of blood and is in shock with a hemoglobin of < 6, people with poor oxygen saturation for whatever reason [example: COPD], or when you want to change the atmospheric pressure of Oxygen [hyperbarics], which increases the fraction that the hemoglobin independent portion of the equation [0.0031 x PaO2] has on the delivery of oxygen to the system. Conversely, if the PaO2 is low [as it is at high altitude], the body senses this, and the system is affected just enough that when it occurs chronically [long term], the body is stimulated to produce blood, specifically in attempt to increase hemoglobin, in a process called erythropoiesis [means red blood cell generation] This is sensed by the kidneys and erythropoietin [epo] is produced and secreted which stimulates the bone marrow... etc. In the end, this affects the hemoglobin dependent portion of the equation [1.34 x Hb x SaO2] to the point that people that live at higher altitudes [say Tibet] are known to have Hb >18.

the body also senses acute blood loss in a variety of ways... and as long as an individual has enough fe to make the hemoglobin... erythropoiesis will be stimulated.

So can this system be stressed?
Well, i think that answer is yes, but how does cardiac output affect it?

remember how cardiac output is multiplied by both the hb dependent and independent portions, giving total oxygen delivery?... well when you stress the system, if you were to workout with a cardiac output of 18L/m [100mL/beat x 180 beats/min = 18 L/min of output], the delivery would be roughly 365 [18 x 20.31] normally. After a unit of blood donated this would be 340 [18 x 18.88] or about 93% of the oxygen at the above heart rate [assuming that blood volume is adequate replaced, as this will slightly affect heart rate... but not usually this amount in a healthy individual as the body has compensatory mechanisms in the vessels to account for small volume losses/gains].
But lets look at this the other way... he'd have to get his HR up to 193 beats per minute to deliver the same oxygen to his muscles as if he were pumping away at 180 beats per minute before the donation of the unit of blood...
So, if he is able to work hard enough that is heart rate is going 180bpm before and after the donation, he's working in a 7% oxygen debt, and his muscles are going to be affected. Roughly the same volume is going through his vasculature but now he's also going to have a difference in the removal of CO2, a mechanism performed by both hemoglobin and lactate, a topic i'll avoid delving into too deeply as i fear i've been rambling on enough already....
Also, as i stated, it's imperative to have the volume replace and drink adequately, because if you feel your going to pass out, the most likely cause would be a volume / vagal issue. The brain and cerebral circulation shouldn't be affected by this lower hemoglobin in a normal individual and has it's some special ways of dealing with CO2.
Anywho, working in this O2 debt and CO2 excess can be a unique training stressor [not that i recommend going and giving blood on a regular basis just for this stressor] that may potentially elicit or hormonal response not attained otherwise, perhaps 'recovering' from donating blood sooner.

This is something i've contemplated for some time, since back in med school and carefully eased by way into working out [harder each time] after giving blood. Although i definitely felt the effects on the system in post-donation workouts, they seemed to fare me well the the following weeks for getting back. I suppose that all this is food for though and just take caution and if you don't feel well or something isn't right, of course just back off... but, in my humble opinion, if done correctly, you can use the week after giving blood advantageously...

whew... sorry for the long ramblings y'all... lars... hope i answered some of your questions and at the same time raised a few more...

~gm2