Galen Mittermann
Influence of blood donation on O2 uptake on-kinetics, peak O2 uptake and time to exhaustion during severe-intensity cycle exercise in humans.
Burnley M, Roberts CL, Thatcher R, Doust JH, Jones AM.
Department of Sport and Exercise Science, University of Wales Aberystwyth, Ceredigion, UK.
We hypothesized that the reduction of O2-carrying capacity caused by the withdrawal of approximately 450 ml blood would result in slower phase II O2 uptake (VO2) kinetics, a lower VO2peak and a reduced time to exhaustion during severe-intensity cycle exercise. Eleven healthy subjects (mean +/- S.D. age 23 +/- 6 years, body mass 77.2 +/- 11.0 kg) completed 'step' exercise tests from unloaded cycling to a severe-intensity work rate (80% of the difference between the predetermined gas exchange threshold and the VO2peak) on two occasions before, and 24 h following, the voluntary donation of approximately 450 ml blood. Oxygen uptake was measured breath-by-breath, and VO2 kinetics estimated using non-linear regression techniques. The blood withdrawal resulted in a significant reduction in haemoglobin concentration (pre: 15.4 +/- 0.9 versus post: 14.7 +/- 1.3 g dl(-1); 95% confidence limits (CL): -0.04, -1.38) and haematocrit (pre: 44 +/- 2 versus post: 41 +/-
3%; 95% CL: -1.3, -5.1). Compared to the control condition, blood withdrawal resulted in significant reductions in VO2peak (pre: 3.79 +/- 0.64 versus post: 3.64 +/- 0.61 l min(-1); 95% CL: -0.04, - 0.27) and time to exhaustion (pre: 375 +/- 129 versus post: 321 +/- 99 s; 95% CL: -24, -85). However, the kinetic parameters of the fundamental VO2 response, including the phase II time constant (pre: 29 +/- 8 versus post: 30 +/- 6 s; 95% CL: 5, -3), were not altered by blood withdrawal. The magnitude of the VO2 slow component was significantly reduced following blood donation owing to the lower VO2peak attained. We conclude that a reduction in blood O2-carrying capacity, achieved through the withdrawal of approximately 450 ml blood, results in a significant reduction in VO2peak and exercise tolerance but has no effect on the fundamental phase of the VO2 on-kinetics during severe-intensity exercise.
PMID: 16431932 [PubMed - indexed for MEDLINE]
----- Original Message ----
From: "Long, Steve"
To: galen mittermann
Sent: Thursday, July 26, 2007 11:16:16 AM
Subject: RE: [OBRA Chat] Vino's Reality (doping works)
You can't even get into that post. Can you post the article?
-----Original Message-----
From: obra-bounces@list.obra.org [mailto:obra-bounces@list.obra.org] On
Behalf Of galen mittermann
Sent: Thursday, July 26, 2007 11:10 AM
To: obra@list.obra.org
Subject: Re: [OBRA Chat] Vino's Reality (doping works)
There was just an interesting thread about this on the google wattage
lists. Some of the posting, regarding "How much does doping help?" is
copied below. For clarity: AWC = anaerobic work capacity, CP = critical
power, FTP = functional threshold power
The whole thing is here, in case anyone is subscribed
http://groups.google.com/group/wattage/browse_thread/thread/d3391fb39060e818/7e6b8af72e1217de#7e6b8af72e1217de
"I thought I saw this sort of calculation here before, but haven't had
any luck finding it. To keep things simple, let's just consider
EPO/blood transfusions.
Suppose you have an FTP of 400 and you use EPO or tranfusions to raise
your hematocrit from
42 to 49. How much would Vino's -- er, I mean "your"
FTP increase to?
For extra credit, would this have accounted for the entire gap in the
ITT?
-- jens "
"I don't know but I thought this was interesting. . .
If I understand the abstract, reduce haematocrit by 3%, reduce VO2max by
3%,
I couldn't tell you the direct effect on FTP.
http://tinyurl.com/2reu98
Jason. "
"Hematocrit was reduced from 44% to 41% ( 93.2% ), reducing VO2peak
from 3.79 to 3.64 (96.0%). This is suggests a transfer ratio of
ln(0.960)/ln(0.932) = 0.57.
So Rider V's CP, assuming proportional to VO2peak, would increase
(49/42)^0.57 - 1 = 9.2%.
Assuming AWC stays the same, and AWC/CP = 2 minutes, then AWC accounts
for 1/30th of the power in a 1 hour time trial, and therefore FTP
increases by 30/31 * 9.2% = 8.9% to 436 watts. This would shave a bit
more than 2 minutes from a 1 hour time trial.
Dan "
_______________________________________________
OBRA mailing list
obra@list.obra.org
http://list.obra.org/mailman/listinfo/obra
Unsubscribe: obra-unsubscribe@list.obra.org
____________________________________________________________________________________
Pinpoint customers who are looking for what you sell.
http://searchmarketing.yahoo.com/