Should you exercise after donating blood?

January is National Blood Donor Month, a chance to acknowledge the contributions of those who donate blood and raise awareness about the importance of blood donation. The effect of blood donation on exercise is the topic of my Health & Fitness column in the Aiken Standard this week.

Donating blood is one of the simplest ways you can help others who have been injured, undergo surgery, or who are being treated for conditions like cancer or blood clotting disorders. According to the American Red Cross, over 9 million Americans donate blood each year, but that is a fraction of those who are eligible.

Donated blood contains red blood cells that carry oxygen, platelets that are important for blood clotting, and plasma, the liquid component that also contains factors used to treat clotting disorders. Whole blood can used to replace what is lost due to injuries and surgery or can be separated into individual components, so one pint of blood can be used help multiple people.

A typical blood donation involves the removal of 450 ml, or about one pint, of blood. Since this is only about one-tenth of an adult’s blood volume, it is safe for those who meet the age, weight, and other health criteria to donate. After donation, the plasma portion of your blood, which is mostly water, is replaced by your body within 24 hours, but it can take 4–6 weeks to completely replace the red blood cells.

Blood donors are usually instructed to avoid strenuous activity for 24–48 hours. Donors may feel symptoms of low blood pressure, such as dizziness or lightheadedness. Vigorous activity can make this more likely, and staying hydrated can help reduce these symptoms. Since the red blood cells are responsible for carrying oxygen to your tissues, including your muscles, donating blood may limit your ability to exercise, especially if it is intense.

Research, including a study done in our lab at USC Aiken, shows that donating a pint of blood can decrease peak aerobic power, a key measure of fitness, for up to 3 weeks in healthy young adults. Athletes and others who are engaged in vigorous training may need to take it easy for a few days after donating.

The effect of blood donation on exercise makes sense when you think of it as the opposite of blood doping, the technique used by some endurance athletes to boost performance. Blood doping is accomplished by infusing either whole blood, usually that the athlete “donated” to themselves, or injecting erythropoietin (EPO), the natural hormone that stimulates the body to produce more red blood cells. Both have a similar effect: a higher number of red blood cells delivers more oxygen to the muscles, allowing the athletes to run, cycle, and ski faster and longer without fatigue.

Blood doping is illegal and athletes who get caught are fined, suspended, or even banned from their sport. You may remember that Lance Armstrong, the celebrated American cyclist, lost both fame and fortune after his doping scandal became public. This is something we are certain to hear about again as the winter Olympics get underway next month and athletes are looking for ways to improve their chances of winning a gold medal.

In contrast to blood doping, blood donation is legal and encouraged! The great many benefits of blood donation far outweigh the potential effects on exercise performance, which are unlikely to disrupt most people’s exercise programs.

There is still time to celebrate National Blood Donor Month by visiting a local blood center. Or, if you prefer, you can celebrate the Olympics by doing the opposite of blood doping—donating blood!

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