Drinking This Before You Exercise May Cause Blood Clots, Experts Warn


Staying hydrated while working out is essential not only for your overall health, but also for your exercise endurance. After all, it's key to balancing your electrolytes, helping your joints and muscles function optimally, keeping your energy up, and of course, quenching your thirst as you sweat. But experts say there's one type of beverage that may be putting you in harm's way when you work out, and it's used by many athletes to keep their energy up. Studies say that drinking this one thing may in fact raise your risk of blood clots when paired with acute episodes of strenuous exercise. Read on to find out which beverage can cause serious health complications—and whether you have reason to worry.

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Drinking caffeinated beverages may lead to a higher risk of blood clots, one study found.

Many athletes seeking to enhance their performance rely on caffeine for a pre- or mid-workout boost. Yet experts have found that there may be a potentially serious side effect to your preferred pick-me-up. In a recent study published in the journal Medicine & Science in Sports & Exercise, researchers learned that drinking caffeine increases coagulation during acute sessions of strenuous exercise, putting you at higher risk for blood clots.

The research team orchestrated two workout sessions for 48 young men with an average age of 23 and normal body mass index. Study participants were given a beverage—first a placebo and later a caffeine-laden drink—before completing a challenging workout on an exercise bike. They then had their blood drawn. The researchers observed that after consuming caffeine, coagulation levels were significantly higher, putting the study subjects at elevated risk of conditions such as heart attack, stroke, deep vein thrombosis, or pulmonary embolism.

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You're at greatest risk if you have certain underlying illnesses.

However, some experts say that while caffeine may indeed elevate coagulation levels, this doesn't mean everyone is at serious risk of clotting. "For most people, caffeine is safe, and so is exercise," Paul Nagelkirk, PhD, the director of the Integrative Exercise Physiology Laboratory at Ball State University, told Runner's World in 2019. "Healthy adults who currently enjoy the benefits of caffeine as a pre-workout or pre-competition routine have little reason to worry about blood-clotting potential," he added.

However, those with high blood pressure, high cholesterol, or a history of smoking—all blood clotting risk factors—may wish to avoid caffeine surrounding their workout.

There is a specific threshold for safe caffeine intake for most people.

So, just how much caffeine is too much? According to the Mayo Clinic, "Up to 400 milligrams (mg) of caffeine a day appears to be safe for most healthy adults." Their experts note that 400 milligrams is equivalent to roughly "four cups of brewed coffee, 10 cans of cola or two 'energy shot' drinks."

Some people, including those who are pregnant, wishing to become pregnant, or are currently breastfeeding, may benefit from limiting their caffeine intake to under 200 milligrams daily. Even among healthy adults with no notable health considerations, "caffeine may not be a good choice for people who are highly sensitive to its effects," adds the Mayo Clinic.

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Avoid caffeine powders and pills, as well as certain energy drinks.

If you wish to limit your intake, the Mayo Clinic says it's best to cut out caffeine powders and pills, which can have staggeringly high amounts of caffeine in them—more than consumers often realize. "Just one teaspoon of powdered caffeine is equivalent to about 28 cups of coffee. Such high levels of caffeine can cause serious health problems and possibly death," the clinic warns.

The further note that energy drinks—for some considered a workout staple—differ widely in the caffeine content depending on brand. "Keep in mind that the actual caffeine content in beverages varies widely, especially among energy drinks," the Mayo Clinic says. Given the elevated risk of clotting associated with exercise, this is especially important advice for those who rely on the beverage as part of their gym routine.

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