Numerous athletes, including Usain Bolt, Michael Phelps, Mark Stepnoski and many others, have been users of marijuana, with many even stating that the drug has made their workouts more enjoyable. Now a recent study is showing a potential reason: an extra boost of tetrahydrocannabinol (THC), the psychoactive ingredient in marijuana, gets released during exercise shortly after marijuana is used. For some, this extra high can seem like a bonus, but for others, such as law enforcement and users facing drug testing, these results are yet another piece of the marijuana policy puzzle, particularly in identifying THC intoxication through drug tests. The Study Published in the journal Drug and Alcohol Dependence, the study, \u201cExercise increases plasma THC concentrations in regular cannabis users,\u201d involved a small sample of 15 daily marijuana users who reported smoking about one marijuana joint per day. All marijuana users in this study had their body mass index (BMI) recorded and their body fat measured at the start of the study. The subjects then submitted a blood test before a 35-minute moderate workout, and then again at the end of the workout to test for THC levels. All subjects abstained from marijuana 24 hours before the start of the test. Researchers found that levels of THC were 15 percent higher on average immediately after the workout. The amount of THC, however, also depended greatly on the subjects' individual body fat levels, with the amount increasing with higher BMIs. Subjects \u201cwith larger BMI showed a bigger increase,\u201d states Iain McGregor, lead author of the study and professor of psychopharmacology at the University of Sydney, Australia. The very slim study subjects showed \u201cno effect\u201d on their THC levels after exercise. THC in the Bloodstream It's worth noting that while study researchers state that it's \u201ctheoretically\u201d possible for moderate exercise to release enough THC to cause an additional high (the study did not look into signs of intoxication), the psychoactive form of THC (delta-9 tetrahydrocannabinol) only remains in the body's fat and bloodstream for four to 24 hours, even for heavy users. The inactive THC metabolites (including delta-11 tetrahydrocannabinol) broken down by the body, however, can remain in a person's fat stores anywhere from a few days to several months. Athleticism and Marijuana Use So what does this mean for the active marijuana user? (Contrary to popular belief, not all marijuana users are couch potatoes.) Well if your BMI is on the higher side and you have exercised recently, it may mean that higher levels of THC in your bloodstream could show up in a drug or field sobriety test long after your last joint. In fact, this phenomenon may have already caused problems for prominent athletes who have scored positive on THC drug tests without having touched marijuana in months. For even the occasional marijuana user, however, this release of THC metabolites after exercise can cause an unexpected positive drug test result. This is especially true of people dieting along with exercising to lose weight; as those fat stores deplete, any lingering THC metabolites will be released into the bloodstream, putting them at greater risk of failing a drug test. A Performance-Enhancing Drug? As far as marijuana use's effect on athletic performance, officials and experts alike have yet to reach an agreement, and in certain sports the issue of THC as a performance-enhancing drug is the subject of much debate. THC's psychoactive effects are purported to impair coordination and lower reaction time, but its\u00a0 popularity among athletes, especially during training, has many questioning whether it really does hurt performance, or if it provides some sort of advantage, albeit indirectly. With that said, the World Anti-Doping Agency (WADA) has just eased restrictions on marijuana use among athletes, from a limit of 15 nanograms per milliliter to 150. The reason, it states, is to target only the athletes who choose to use marijuana during or just before a competition. WADA members, the committee says, \u201cwant cheaters to be caught for cheating, not for recreational usage.\u201d Marijuana has been on the agency's list of prohibited substances since 2003 due to pressure from U.S. sports officials. Interestingly, exercise also stimulates the release of the body's own cannabinoid system's chemicals\u2014the natural equivalent to THC. These same cannabinoids are partially responsible for that famous \u201crunner's high,\u201d as well as those moments of calm during stressful or fearful situations. It is unclear so far as to whether this same process drives the release of stored THC into the bloodstream, but the study's research team hopes to explore this in the future. In the meantime, this study serves as a word of caution to users who exercise regularly, or perhaps who are considering losing weight: limited amounts of THC can be released into the bloodstream, making the user much more likely to fail a drug test. Conversely, the study authors also have a word of caution to health officials, stating that the release of THC after exercise may further complicate the results of THC drug tests. Whether this release of THC is helpful or a hindrance to athletes, or whether the process mirrors the body's own release of cannabinoids, this study clearly illustrates the need for more research.