However, Dr. Stephen Sidney — MD, MPH, the Director of Research Clinics and a senior research scientist with the Kaiser Permanente Northern California Division of Research — has a slightly different take. He agrees that there isn't enough research to truly know what working out high could do to the body. But he wouldn't necessarily advise against it if a patient came to him for advice on the topic. "Are they putting selves at risk? I don’t think we have definitive information," he says. "In general, a person's experience with marijuana use is a personal one, and some react differently... It may or may not cause heart problems. Patients should understand how they react and understand it can cause difficulties in coordination."