Friday, June 30, 2006
Donating Blood affects Perrformance?
I have been comtemplating whether i should go donate my blood this weekend, as the last time i offloaded some of my red stuffs was abt 5 mths ago and there is reported shortage at the blood bank now! But, in less that the 3weeks, i will attempting my Mount Kinabalu's Recce Hike in preparation for the coming MK Climbathon race and i am afraid that my body may not recover fully in time to handle high altitude ! From my own experiences, my body takes abt 2-4weeks to restore n recuperate after a blood letting session. Hmm... Decision time...
Blood is a complicated tissue with many different roles. When you donate blood, you give up a pint of fluid containing mostly water along with various proteins and cells in solution. During high-intensity endurance activities however, it is hemoglobin, found within our red blood cells, that is most important.
Hemoglobin delivers oxygen to our tissues, and when we exercise our muscles require increased amounts of oxygen. If we lack sufficient hemoglobin, anaerobic, or without oxygen, metabolism will ensue (producing lactic acid) at even seemingly moderate levels of intensity.
Donating a pint (450cc) of blood results in a depletion of about 10 percent of your total blood volume. Of that, only about 160cc are red blood cells. The fluid component, the remaining 290cc, is replaced within hours, but the red blood cell replacement takes about two months, (which is why you may not donate more often than every two months). What then are the lasting effects of this red blood cell loss?
Assuming that your cardiac output (the amount of blood pumped by the heart) remains constant, a drop in hemoglobin concentration associated with donating blood will reduce your oxygen delivery to working muscles by 10 percent. Still, when you are at rest, or even during moderate levels of exercise, oxygen delivery, even at this decreased capacity, far outpaces demand.
However, once you reach a heart rate that is around 5 to 10 percent below your usual anaerobic threshold, your body's demand for oxygen will outpace its supply. For example, if your metabolism typically becomes anaerobic at a heart rate of 170, then after donating blood you will become anaerobic at a heart rate of between 157 and 164 beats per minute. This value will fluctuate because your hemoglobin level will be rising slowly each day, thus the most significant effect will be felt in the first few days after donating.
The key to recovery is ensuring your body has the necessary building blocks -- specifically protein and iron -- to replace the lost hemoglobin. For most people, eating a balanced diet with adequate protein and iron intake is sufficient. For some, however (specifically vegetarians and some women), iron supplementation may be required. Talk to your doctor to determine if this kind of supplementation may be right for you.
More here... http://www.runnersweb.com/running/rw_news_frameset.html?http://www.runnersweb.com/running/news/rw_news_20040809_BloodDonation.html
What Active People Need to Know
Competitive athletes and those who work out often wonder if donating a pint of blood will impair their athletic performance or fitness goals. They have good reason to wonder. After all, blood donation can influence hydration status and the oxygen-carrying ability of red blood cells.
In some situations, athletic pursuits and the public's need for blood are cast as competing interests!
After donating 450 mL (1 U) of whole blood, plasma volume falls 7% to 13%, then recovers within 24 to 48 hours. The hemoglobin level decreases by 10 to 20 g/L. With an adequate iron supply, hemoglobin returns to baseline after 3 to 4 weeks (1).
It seems clear that blood donation is contraindicated for endurance athletes who will soon be competing. He notes that many variables make it difficult to predict how much or how long donating a pint of blood will affect athletic performance. However, he notes that recovery after blood donation is fairly fast. Eichner writes: "In my anecdotal experience, maximal performance can return to normal within 1 to 2 weeks, and surely returns to normal after 3 to 4 weeks."
A study (3) on the effects of blood donation on 10 competitive cyclists before and after donating 1 U of blood found that maximal performance was decreased for at least 1 week after blood donation. (Cyclists were measured at baseline and at 2 hours, 2 days, and 7 days after phlebotomy.) Although researchers found that maximal performance was decreased, submaximal performance was unaffected.
Exercisers and Recreational Athletes
Marvin Adner, MD, a hematologist and internist in Framingham, Massachusetts, and medical director of the Boston Marathon, says that blood donation should not be a concern for active people who are not world-class athletes—as long as they are not iron deficient. He notes that though hemoglobin values will be lower than normal a few weeks after donation, blood donation does not erode fitness effects.
Adner cautions active people who donate blood to avoid taking regular iron supplements unless they are iron deficient from giving blood. Iron intake can cause symptoms in patients who have hereditary hemochromatosis. Iron supplements can also mask the anemia of colon cancer and damage the heart. "Unfortunately, many athletes—especially those who don't eat red meat—have borderline iron deficiency," he says.
Donald M. Christie, Jr, MD, an internist and sports physician in Lewiston, Maine, says hydration is the best recovery strategy. Donors need to drink not only what is offered afterward at the blood donation center, they need to aggressively hydrate over the remainder of the day, says Christie, who is an editorial board member of The Physician and Sportsmedicine. "Noting the color of the urine is a good way to gauge hydration status," he says.
He advises endurance athletes to think of the blood donation day as a rest day, and to tread cautiously the next day because hydration stores may not be replenished and delayed vasovagal effects may occur. Christie says though the performance decrement would be slight in an endurance athlete, blood donation should have virtually no effect on strength or short-burst activities.
In a study (4) that sought to determine the effects of blood donation on older exercisers, researchers measured submaximal and maximal working capacity and blood viscosity in younger donors, older donors, and older controls the day before and after blood donation. They found that mean submaximal and maximal values increased the day after donation in all groups, but that increases were only significant in the younger donors. Plasma viscosity decreased significantly in both donor groups. The authors concluded that a single blood donation did not alter the physical fitness of otherwise healthy people.
-- Lisa SchnirringMinneapolis ... more click here.. http://www.physsportsmed.com/issues/2001/06_01/news.htm
Posted by Run HappyFeet at 8:48 AM