I got a question about the effects of blood donations on athletic performance (thanks James)... and here's what I found (it's another long one- sorry!)
BTW- I got all my info from legitimate web sources (ie physisicians'/medical sites, Canadian blood services website).
Giving blood is an incredible act of goodwill. Donated blood helps to save countless lives every year. According to one US source, fewer than 5% of the eligible donors in the US give whole blood.
According to Canadian Blood Services, it takes the following number of donations to help save the life of someone undergoing the following procedures:
Cancer treatment: up to 8 donations a week
Coronary artery bypass: 1-5 donations
Car accident/gunshot wounds: up to 50 donations
Liver transplant: up to 100 donations
Other organ transplants: up to 10 donations
Brain surgery: 4-10 donations
Fractured hip/joint replacement: 2-5 donations
Although very altuisitic, giving blood is not without consequences, especially for endurance athletes.
The average person has 10 pints of blood flowing through his or her body. There are four components in blood:
Red blood cells: 40-45% of your blood. Carry oxygen to the body's tissues and remove carbon dioxide. Most relevant for athletic performance. The more red blood cells you have in your blood, the more oxygen you’re able to carry to your muscles and the harder and longer your body can go while exercising.
White blood cells: Less than 1% of your blood. Immune system's main defence against infection.
Platelets: 5% of your blood. Cell fragments that clot, which helps to prevent and control bleeding.
Plasma: 55% of your blood. It is 90% water and vital to our survival. Provides the transportation system for blood cells. Without plasma, the cells would not be able to do their work. Plasma also carries microbe-fighting antibodies that fight diseases.
When you donate blood you will be giving one pint (2 cups or 10 percent of your total blood volume). In doing so, you will be decreasing the number of your red cells (oxygen carriers) by one-tenth as well.
The reduction in total blood volume lowers the body's ability to dissipate heat and regulate its temperature. However, the fluid (plasma) portion of the blood that has been lost can be replaced fairly quickly (within 24-48 hours) with proper hydration.
As this replacement is occurring, the remaining red blood cell concentration becomes diluted. It may take up to six weeks to bring the red blood cell count back to pre-donation levels. In fact, once you donate, you must wait 56 days before donating again- to let your red blood cell count return to pre-donation levels.
In the meantime, athletes report a detrimental drop in performance by up to 10 percent. This drop in performance is most visible among distance runners, who rely heavily on aerobic capacity.
In 1995 a study looked at the effects of blood donation in 10 competitive cyclists before and after donating one pint of blood. They measured performance at two hours, two days and seven days post-donation and found that sub-maximal performance was unaffected but maximal performance was decreased for at least one week after blood donation.
The reduction in red blood cell count reduces the body's ability to carry oxygen from the lungs to the muscles. Medical personnel advise donors to drink plenty of fluids, and to increase their intake of iron prior to and after
Coaches also report a higher incidence of illness among athletes who donate blood. They blame a blood donation on a lowering of white cell count and a reduction in the body's ability to fight infections. An intense training program may exacerbate the loss of immunity and lead to a breakdown. Therefore, many coaches are apprehensive toward blood donations during the competitive season, but encourage their athletes to donate blood between seasons.
The medical director for the Boston Marathon believes that for people who engage in light to moderate exercise, blood
donation should not be a concern. Another sport physician says that in an endurance athlete, blood donation should have virtually no effect on strength or short-burst activities. As a recovery strategy, this doctor recommends hydrating aggressively throughout the day after giving blood. 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 can predispose one to fainting.
The body can detect when its red cell percentage is low, and it responds by initiating the production of more red blood cells in the bone marrow. This process can take a number of weeks. The molecule released by the kidneys to begin this process is called erythropoietin (the natural form of EPO).
An interesting hypothesis was presented a few years ago by Dr. Kamal Jabbour. He suggested that an athlete may actually be able to enhance his or her performance by giving blood. After red blood cells are removed from the body, a rejuvenation effort is initiated through the natural production of EPO, as described above. Often, however, this red blood cell production process may not shut off immediately upon reaching pre-donation levels. As a result, the red blood cell concentration may actually overshoot the baseline slightly before eventually returning to normal. Anecdotal evidence relates that this can vary anywhere from four to six weeks after blood donation.
If the above hypothesis holds true, it suggests that an athlete can safely donate blood, recover gradually without overtraining, then peak temporarily for a superior performance before returning to normal. Timing is critical and requires a lot of practice, much to the delight of the local blood banks.
Some other possible benefits of blood donations:
Some research has shown that donating blood may reduce the risk of heart disease for men andstimulate the generation of red blood cells. They say that differences between men and women in heart attack risk may be due to circulating iron levels which are reduced in women by menstruation. Donating blood may reduce men's risk to that of women's, but the link has not been firmly established.
Weight loss a goal? A donor effectively burns about 650 calories by donating one pint of blood.
Can blood donation cause anemia?
Blood donation results in a drop in hemoglobin of approximately 10 g/L, depending on the size of the donor. Normal, healthy donors produce new red blood cells to replace those that were donated, within about 56 days. However, iron is an essential mineral necessary to produce new red blood cells. It is therefore very important for blood donors to have an adequate amount of iron in their diet. This is especially important for female donors, who have lower iron reserves due to loss of iron in menstrual periods and reduced iron reserves.
Hemoglobin levels are measured before a blood donation. In order to be able to donate, both men and women must have a minimum hemoglobin level of 125 g/L (12.5 g/dL).
Approximately 10% of female donors do not meet minimum hemoglobin criteria on a given donation. If your hemoglobin level is below 110 g/L (11.0 g/dL) you should see your physician to have further testing to confirm if anemia is present and determine the underlying cause. If anemia is present, you should not return to donate until the cause of the low hemoglobin has been identified and corrected.
It is quite rare for male donors to have a hemoglobin level below the minimum blood donor criteria. Male donors with a hemoglobin level below the acceptable level of 125 g/L (12.5 g/dL) are likely to be anemic. If your hemoglobin was below the acceptable level, further testing should be done by your physician to confirm if anemia is present and what is the underlying cause.
Criteria for donating:
Canadian Blood Services and Héma-Québec have the sole responsibility for collecting blood and administering the blood supply in Canada. They have established basic criteria that blood donors must meet before they can give blood. They include that you must:
- Be between 17 and 71 years old to be a regular donor (17 to 61 to be a first-time donor).
- Weigh at least 110 pounds.
- Be in general good health and feeling well when you donate.
- Complete a screening questionnaire.
- Meet minimum haemoglobin requirements (test done at clinic). Since blood donation results in the loss of iron and hemoglobin, individuals with inadequate iron stores who require iron supplementation are not good candidates for donation.
Certain people are not allowed to donate. they include:
- People who lived in Cameroon, Central African Republic, Chad, Congo, Equatorial Guinea, Gabon, Niger and Nigeria who may have been exposed to a new strain of HIV.
- People who received a blood transfusion while visiting those countries or who have had sex with someone who lived there.
- People who spent three months or more in Britain or France between 1980 and 1996. They may have been exposed to variant Creutzfeldt-Jakob disease (CJD).
- All men who have had sex with another man, even once, since 1977. Statistics show they are at greater risk for HIV/AIDS infection than other people. This one was under review in 2006 but no word yet as to any changes to it.
- Anyone who has taken illegal drugs intravenously.
If you've recently had part of your body tattooed or pierced, you're also excluded as a blood or bone marrow donor — but for six months only.
The eight major types of blood (and the percentage of the population that have them) are:
- O positive (about 38%)
· O negative (about 7%)
· A positive (about 34%)
· A negative (about 6%)
· B positive (about 9%)
· B negative (about 2%)
· AB positive (about 3%)
· AB negative (about 1%)
People who are O negative can donate blood to anyone. People who are AB positive can receive blood from anyone.
Blood Donation Facts: