Anyone who's donated blood before has been told to "wait a day before heavy lifting." But how long defines "a day," and what about other forms of exercise? Whether you're a casual or highly competitive athlete, waiting at least 12 hours after giving blood before resuming your normal exercise schedule helps you rehydrate and rebuild strength. If you return to exercise too soon or exercise too vigorously, you risk dehydration, fainting and injury.
It takes the average person approximately 24 hours to replenish the plasma and approximately four to six weeks to fully replenish the red blood cells lost during blood donation. Because donating blood causes your body to experience a temporary decrease in red blood cells -- the cells responsible for delivering oxygen to your muscles -- blood donation may affect athletic performance. Exercising too soon after donating blood can result in bleeding from the site of needle entry. Additionally, the loss of fluid coupled with the loss of red blood cells can cause dizziness and fainting.
How Long to Wait: Casual Athletes
The American Red Cross advises individuals donating blood to wait until the day after blood donation -- a minimum of 12 hours -- to undertake any form of exercise, whether aerobic or anaerobic. For example, if you donate blood at 6 p.m., you should wait until at least 6 a.m. the next day to work out. However, some individuals may need to wait up to 24 hours, depending on their gender, age, height, weight and circulation. If it's your first time exercising after donating blood, try to wait at least 24 hours to be on the safe side.
How Long to Wait: Competitive Athletes
If you generally engage in exercise at a high level of performance -- such as marathon running or highly competitive sports -- you may find that it takes five to seven days to return to your normal level of performance. Studies have shown that competitive cyclists who had donated blood performed at a submaximal level for approximately one week afterward, according to Dr P. A. Lambeti (MBBcH) in an "Omega Cycling" article. Therefore, if you're a competitive athlete, try to schedule your blood donations a minimum of seven days before any competition. If you are a regular blood donator, talk to your doctor about the long-term effects of iron deficiency on your athletic performance.
Returning to Exercise
Once you to exercise, be alert for signs of dizziness or lightheadedness. Loss of blood can result in decreased strength, so try to exercise at no more than 75-percent capacity for the first several days after giving blood. Pay attention to your body; if you feel weak or exhausted, take a break or stop for the day. During a blood donation, your body temporarily loses fluid, which is replaced within approximately 24 hours. In order to prevent dehydration, especially if you are exercising less than 12 hours after donating, double up on fluids before, during and after exercise. Eat healthy, iron-rich foods to supplement the loss of iron that your body has experienced. Exercise with a spotter or friend for safety if you become dizzy or faint.
Exercising Before Donating Blood
If you don't want to miss a day of exercise, work out before you give blood, rather than afterward. If you exercise the day before or the day of your donation, make sure to drink plenty of fluids and eat a well-balanced, iron-rich meal before donating. This will help prevent dehydration and fainting during blood donation.
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