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Donating Blood

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—for example, when coaches advise student-athletes to decline donation requests. A recent blood drive sponsored by the student council at Totino Grace High School in Fridley, Minnesota, became mildly controversial when some athletes decided not to donate. Joe Rodriguez, MA, chair of Totino Grace's department of physical education and health and head cross-country running coach, says it's difficult making blood donation recommendations to student-athletes. Though giving blood is itself a teaching opportunity, Rodriguez says he would rather err on the side of keeping student-athletes safe. "My policy is to tell them what happens physiologically when they do give blood, and let them decide," he says, pointing to a need for more hard evidence and double-blind studies. "This needs to be clarified by someone with more authority than just a coach," he says.

Active people and athletic administrators often turn to physicians for advice; however, few studies on blood donation and exercise have been published. More often, recommendations are based on what physicians know about basic hematology and exercise physiology. 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).

Competitive Athletes

It seems clear that blood donation is contraindicated for endurance athletes who will soon be competing. In a recent report (2), E. Randy Eichner, MD, a hematologist and internist in Oklahoma City, and editorial board member of The Physician and Sportsmedicine, contrasts the physiologic effects of blood doping with those of blood donation, and maintains that blood donation is "ergolytic" for competitive athletes.

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 Schnirring


  1. Mollison FL, Engelfried CP, Contreras M: Blood Transfusion in Clinical Medicine, ed 8. Boston, Blackwell Scientific Publications, 120217
  2. Eichner ER: Donating blood: altruistic but ergolytic. Sports Med Digest 2021;23(3):25
  3. Panebianco RA, Stachenfeld N, Coplan NL, et al: Effects of blood donation on exercise performance in competitive cyclists. Am Heart J 1995;130(4):838-840
  4. Janetzko K, Bocher R, Klotz KF, et al: Effects of blood donation on the physical fitness and hemorheology of healthy elderly donors. Vox Sang 192021;75(1):7-11

Field Notes

Help Golfers Avoid Foot Hazards
Now that golf season is in full swing in most parts of the country, the American College of Foot and Ankle Surgeons (ACFAS) highlights foot problems that can occur in seasoned golfers.

Repeated movement and weight transfer during the golf swing is often the culprit. During the follow-through part of the swing, golfers can overextend the big toe joint of their back foot, leading to hallux limitus. "Those who have played the game avidly for several years can eventually wear out the cartilage or jam the big toe joint," says Daniel Hatch, DPM, a podiatric surgeon based in Denver, in a press release from the ACFAS. If left untreated, the condition can develop into arthritis, which makes it difficult to play golf. He notes that a history of big-toe trauma or having a long first metatarsal puts patients at greater risk for hallux limitus. Hatch notes that orthoses can often provide relief, but that advanced cases may require surgery.

Weight transfer to the front foot during follow-through can lead to a neuroma at the bottom of the foot.

Poorly located spikes on a golf shoe are another cause of foot injury. Spikes directly beneath the ball of the foot can cause locally acute pain and swelling, Hatch says. He adds that removing the offending spikes can relieve symptoms without sacrificing traction.