Does Working Out Help to Pass Urine Drug Test?

Daniel Miller
Daniel Miller, Ph.D, Drug Testing Specialist

Last updated on Apr 8, 2024

The rumor that working out in the days or hours leading to a drug test could lead to positive results is currently at its peak.

Sources (including university research studies) that support this idea claim that fat-stored THC is released into the blood and later into the urine by exercising.

They say that this could increase your risk of failing a urine test.

How true are these claims? Should you get worried?

Well, let’s dig to the rock-bottom of this and set the facts right here and now.


Exercising leads to the release of fat-stored THC. This could make you fail a drug test.

In my opinion, there are two sides to this claim. If at all, working out does indeed increase THC metabolites’ concentration in urine, then this could also prove that exercising could aid in detoxification.

These are the two possibilities that we’ll be screening the studies below against.

Studies on Exercises and THC Concentration Levels

The most recent study that most sources base their claim on is research done by the University of Sydney and published in the Journal of National Institutes of Health in 2013.

In this experiment, 14 regular cannabis users were made to exercise for 35 minutes on a stationary bike in a fed or a fasted state.

The researchers recorded the subjects’ plasma THC levels before the exercise, immediately after the exercise, and 2 hours after the exercise.

The results showed a small but significant increase in plasma THC concentrations in subjects who were in a fed state. Although not a surprise, they found out that the subjects with a higher BMI showed higher exercise-induced plasma THC increases.

It was also found out that fasting did not induce a significant increase in plasma THC levels.

Importantly, the researchers noted that the THC concentration in plasma had subsided to its baseline 2 hours after the test.

This study proves that exercising does spike the THC levels in blood plasma for 2 hours. This means that you could fail a blood test if it is done at least one hour after a moderate workout session, even if you last smoked days ago.

What of a urine drug test?

As we all know, labs don’t test for THC in urine drug tests. Instead, they look for its metabolite, THC-COOH, which is mostly removed through the urine.

Unfortunately, the 2013 study above didn’t consider the THC-COOH levels in urine in this test. But it cleared the way for the experiment to be conducted.

Another recent study recorded in the same journal aimed at investigating whether moderate physical exercises or food fasting could lead to an increase in THC levels in blood serum and urine of chronic cannabis users who had abstained for some time.

This study involved six subjects in a rehabilitation center. Urine specimens were collected in the subsequent seven days. During days 3 and 5, the subjects were randomly required to either take a 45-min physical exercise by running on a treadmill or go on a 24-hour food deprivation (FD).

The urine samples and serum from the blood samples were refrigerated for analysis.

To summarize the results, the researchers concluded that, true to the previous study’s findings, there was a slight and transient increase in THC increase in the THC concentrations in plasma during exercise.

They also confirmed that fasting did not trigger any notable increase in plasma THC concentrations.

Also, there wasn’t any notable change in THC-COOH levels in urine after the moderate workout session and even after fasting for 24 hours.

The researchers concluded that neither exercising nor fasting could alter the THC concentration in serum or the THC-COOH levels in urine during a test.

In the light of these findings, it’s, therefore, safe to say that;

With these observations, one might wonder why the levels of THC-COOH in the urine failed to change even with the significant change of THC in blood plasma.

To understand this better, you’ll need to familiarize yourself with THC metabolism and how your body systems deal with it after a toke.

Read on.

THC Metabolism, Storage, and Excretion

Once you’ve smoked weed, it gets you high almost instantly. On the other hand, it takes you close to 2 hours to get a ‘HIGH’ from a pot brownie and other edibles.

Either way, marijuana goes through the following stages in your body; consumption, metabolization, storage, and release.


Consumption can either be through smoking (or vaporization) or by ingestion in edibles. With smoking, THC penetrates through the lungs into the blood system.

On the other hand, THC goes through the stomach lining into the bloodstream upon ingestion, where it is transported around your body.

Metabolism and Storage

As the THC moves around the body via the blood, it is taken to the liver for metabolism. The THC is converted into THC-COOH and later into a glucuronide molecule (THC-COO-glucuronide) for excretion.

Not all THC in the liver is converted into glucuronide molecules, though. Some of it re-enters the bloodstream and starts circulating in the body.

Also, some THC-COO-glucuronide molecules are excreted into the small intestines via bile juice. A portion of it is converted into THC-COOH and reabsorbed back into the blood system.

Since THC is highly fat-soluble, a certain amount of it is absorbed in your fatty cells and gets trapped there. As you continue to pump more THC into your system, THC molecules continue to stack against each other to form layers.

There is anecdotal proof that people with a high BMI tend to have more fat. Consequently, they tend to store more THC and also tend to take longer to detox.

This makes some heavy smokers with a high BMI test positive for marijuana for up to 90 days after quitting.

How is fat-stored THC released for excretion?

The THC trapped in the fat cells is released when the cell that is holding it is burned up for energy. Now, the body likes to use glycogen for metabolism, but it also taps into its fat content when need be.

Whenever a THC-carrying fat cell is used, the THC molecules get into the bloodstream, where it may either go to the liver or re-absorbed back into the fatty cells.

However, as the studies above prove, while a significant THC is released into the blood system after working out, it does not automatically lead to an elevated THC-COOH level in urine.

In my opinion, this does not eliminate the possibility of some THC-COOH metabolites getting into the urine.

In 2 hours, a portion of the small amount of THC released from fats is converted into THC-COOH metabolite, and another portion is reabsorbed into the fat cells again.

Another portion gets into the enterohepatic recirculation, where some of it is excreted through feces, and the rest is reabsorbed through the stomach walls.

This means that the amount of THC converted to THC-COOH is insignificant to alter the results in a urine test.


So, as a recap of what we’ve just seen, you might test positive for a random blood test if you have worked out within the last 1-2 hours, even if you last smoked a few days earlier.

But it’s not true that exercising in the hours leading to a urine test does increase your chances of failing the test.

Importantly, remember that passing or failing a urine test depends on the number of THC metabolites that are already available for detection in your urine.

While exercising does not increase the THC level, failing to exercise does not reduce it either.

This means that if you last toked the previous day, and you’ve not tried anything to reduce the THC metabolites in your urine to below the cut-off level, there is still a high chance of failing the test whether you’ve worked out or not.

So if you really want to pass with flying colors, I recommend using the products proven to work:

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Clear Choice Sub-Solution is the perfect solution for passing a drug test. It contains a clean synthetic urine that is biocide free and completely undetectable.

It also comes with their patented heat activator formula that raises the urine’s temperature to normal body temperature within seconds, so you don’t need to worry about having to heat it up yourself.

Furthermore, the standard size container makes it easy to conceal, and it is unisex, so it can be used by both male and female users.

The information on this website about detox products and synthetic urines is for educational purposes only. We do not endorse or condone their illegal use. Always consider the laws in your area and the potential legal consequences. Consult with a healthcare professional before using any products. Your responsibility and well-being are paramount.