Competitive endurance athletes who aren’t competing at the elite level would probably never consider any sort of blood doping. Yet, many amateur runners, cyclists and skiers serious about racing might be setting themselves back by doing just the opposite: donating blood.

Blood doping refers to the illicit practice of boosting red blood cell count to increase performance. Red blood cells deliver oxygen to the muscles. In endurance events, the greater the oxygen-carrying capacity of the blood, the harder the muscles can work.

But the opposite is also true. If you reduce your supply of red blood cells, you hinder the delivery of oxygen to muscles, and performance lags.

That’s why many endurance athletes simply won’t give blood.

Jenny Ruiter, a 27-year-old Bend native, played volleyball in college and then started competing in triathlons and marathons after graduating. Her twin sister and de facto coach, pro cyclist Chrissy Ruiter, advised her not to donate blood during the racing season.

”She just discouraged it,” Ruiter says. ”I do it in the winter, when I’m not training as much, or in the fall. I just say, ‘I can’t do it’ in the summer or the spring when I’m training more.”

She describes herself as a serious recreational triathlete. In 2005, she completed two half Ironman triathlons (70 miles of biking, running and swimming) and an Olympic triathlon (35 miles), as well as running in the New York Marathon.

Those kinds of endurance events rely on great cardiovascular fitness to delivery oxygen over the course of the race.

Normally, the body has plenty of excess oxygen-carrying capacity. So for most light to moderate activity, there’s more than enough red blood cells even after donation. But when it comes to endurance events that tax the limits of the body’s blood delivery to the muscles, donating blood can have a significant impact on performance.

A 1995 study by researchers at the Nicholas Institute of Sports Medicine and Athletic Trauma in New York City tested 10 male amateur competitive cyclists. The subjects were tested one week before donating blood, then two hours after, two days after and seven days after donating. Dr. Robert Panebianco and his colleagues found that when the cyclists were exercising at maximum effort, they scored lower on all performance measures in each of the three post-donation tests.

At two hours and at two days after donation, VO2 max, a measure of the capacity to generate the energy required for endurance activities, was down about eight percent. Even a week a later, VO2 max had improved to only seven percent below pre-donation levels.

Experts believe it may take as many as three to four weeks for performance to return to normal after donation.

Earlier this year, researchers led by Dr. Mark Brunley, a professor in the sport and exercise science department at the University of Wales, reported the results of a similar study with physically active but not highly trained athletes. Eleven men and one woman volunteered to perform exercise tests on a stationary bike, twice before giving blood and once 24 hours after donation. The 24-hour delay gave their bodies time to restore their blood volume through increased hydration, but not enough time to replace the red blood cells. The subjects donated a pint of blood, reducing their blood’s oxygen carrying capacity by about 5 percent.

The athletes were told to cycle at maximum efforts as long as they could. After donating blood, the test subjects’ time to exhaustion dropped by an average of 54 seconds or about 14 percent.

The researchers found that a five percent reduction in hemoglobin, the oxygen-carrying component of red blood cells, resulted in a four percent drop in VO2 max.

But the researchers also found that performance at lower levels of exercise weren’t affected. That suggests that other less strenuous types of exercise should be fine a day or more after donation.

The American Red Cross advises against strenuous activity in the day after donating blood. Fitness experts recommend using the donation day as a rest day in fitness programs.

The Red Cross also recommends drinking plenty of fluids. Blood plasma volume drops 7 to 13 percent with donation, but generally recovers within 24 to 48 hours. Aggressive hydration over the course of the day – drinking 4 cups of non-alcoholic beverages – can help restore blood volume.

Some sports doctors recommend a nice steak dinner after donating to help provide the body with the necessary building blocks, such as protein and iron, to get back to normal.

That’s another reason Ruiter refrains.

”Women have to worry about being anemic, especially when you exercise,” she says. Donating blood could exacerbate the problem.

Athletes who would like to help others but are unwilling to donate whole blood, can donate just their platelets, leaving their red blood cell count intact. There is a particular need for platelets for patients undergoing chemotherapy. They can take drugs to boost their red and white blood cell counts, but have no way to replace the platelets lost during their treatment. However, platelet donation is a bit more involved and takes about two hours rather than the single hour for regular donation. Many donation centers have special chairs with DVD players or other distractions for platelet donors.

And of course, there are plenty of ways to help the Red Cross fulfill its mission other than donating blood. There are plenty of fundraising and other volunteer efforts that athletes can engage in.

Markian Hawryluk can be reached at 617-7814 or mhawryluk@bendbulletin.com.