From the Guidelines
It is recommended to avoid vigorous exercise for at least 24 hours before a blood test to ensure accurate results, as strenuous exercise can temporarily alter certain blood markers, potentially affecting test outcomes. This is based on the most recent and highest quality study available, which emphasizes the importance of preanalytical conditions in blood testing, including avoiding vigorous exercise before collection 1.
Key Considerations
- Strenuous exercise can increase white blood cell counts, alter glucose and cholesterol levels, and elevate certain enzymes like creatine kinase, leading to potentially misleading results and unnecessary follow-up testing.
- For routine blood work, avoiding vigorous exercise for 24 hours before the test is a general guideline, but it's crucial to follow specific instructions provided by the healthcare provider, as some tests may have different requirements.
- The type of blood test being conducted is also a critical factor, as some tests may be more sensitive to the effects of exercise than others.
Evidence-Based Recommendations
- The American Heart Association recommends that subjects should not perform unusual physical efforts for at least 12 hours before exercise testing 1.
- However, the most recent study from 2023 suggests that avoiding vigorous exercise the day before collection and adhering to laboratory guidelines can help minimize measurement errors and ensure more accurate results 1.
- It's essential to document any confounding variables, such as diurnal variations or nutritional aspects, to allow for accurate interpretation of test results.
Clinical Implications
- Healthcare providers should inform patients about the importance of avoiding vigorous exercise before blood tests and provide specific instructions based on the type of test being conducted.
- Patients should be encouraged to ask questions and seek clarification if they are unsure about pre-test instructions or have concerns about how exercise may affect their test results.
From the Research
Exercise and Blood Tests
- There is no direct evidence to suggest that exercising before a blood test is harmful or will affect the results of the test 2, 3, 4, 5.
- However, one study suggests that strenuous physical exercise can cause fluctuations in circulating blood lymphocytes and serum cortisol levels, which may be relevant for certain types of blood tests 6.
- The study recommends that patients should be rested for at least 15 minutes before venesection (blood sampling) to ensure accurate results 6.
- It is generally recommended that individuals engage in regular physical activity for overall health benefits, but it is unclear whether exercising immediately before a blood test is necessary or advisable 2, 3, 4, 5.
Physical Activity Guidelines
- Current guidelines recommend at least 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous-intensity aerobic activity per week for substantial health benefits 2, 3, 5.
- Older adults should also engage in strengthening activities that involve all major muscle groups at least two days a week, and those at risk of falling should add exercises that help maintain or improve balance 5.
- Generally healthy adults without chronic health conditions do not need to consult with a physician before starting an exercise regimen 5.
Blood Pressure and Exercise
- Exercise blood pressure is a mandatory safety measure during graded intensity clinical exercise stress testing, and excessive rises in submaximal exercise blood pressure can be associated with adverse cardiovascular events and mortality 4.
- Delayed blood pressure decline during recovery is also associated with adverse clinical outcomes, and careful attention should be paid to correct measurement of exercise stress test blood pressure using a standardized approach 4.