What is marijuana and how does it affect the body?

Marijuana is an illegal drug produced from the dried leaves, stems, seeds and/or flowers of the hemp plant, cannabis sativa, that is usually smoked by the user. There are many slang terms for marijuana, including, pot, grass, weed and Mary Jane. "All forms of marijuana, including the stronger sensemilla and hashish varieties, are mind-altering (psychoactive) drugs," says Wadler. "They all contain THC (delta-9-tetrahydrocannabinol), the main active chemical in marijuana that effects changes in the brain of the user." Marijuana's effects depend on the strength or potency of the THC, which is only one of more than 400 chemicals present in marijuana. Highly fat-soluble, THC and other related chemicals rapidly enter the brain and fat stores of the body.

What are the effects of marijuana on performance?

• Impairs skills requiring eye-hand coordination and a fast reaction time
• Reduces motor coordination, tracking ability and perceptual accuracy
• Impairs concentration, and time appears to move more slowly
• Skill impairment may last up to 24 to 36 hours after usage
• Reduces maximal exercise capacity resulting in increased fatiguability
• Marijuana has no performance-enhancing potential

Because marijuana is stored in the body fat, its effects may be long-lasting. "It has been shown that performance skills can be impaired for as long as 24 hours after marijuana usage," says Wadler, "which casts doubt on the commonly held belief that the social use of marijuana the evening prior to an athletic event will not affect performance."

What are the short-term adverse health effects of marijuana?

• Memory and learning problems
• Difficulty concentrating
• Perception distortions involving vision, sound, touch and time
• Thinking and problem-solving difficulties
• Increased heart rate and drop in blood pressure
• Sudden feelings of anxiety, including panic attacks, and paranoia
• Runny nose, sore throat, wheezing

What are the long-term adverse health effects of marijuana?

"Because marijuana users often inhale the unfiltered smoke deeply and then hold it in their lungs as long as possible, chronic marijuana use may play a role in the development of chronic respiratory problems," says Wadler. Animal studies have suggested that THC may adversely affect the immune system. Additionally, long-term use has been associated with motivational problems including apathy, impaired judgment, loss of ambition and an inability to carry out long-term plans.

Can marijuana be addictive?

Chronic marijuana use has been associated with the development of tolerance in which the user may have a tendency to increase the amount of marijuana used. "Physical and psychological dependence in frequent users is associated with signs and symptoms of withdrawal upon discontinuation," according to Wadler. "These signs and symptoms begin about 10 hours after discontinuation and peak at 48 hours and include anxiety, insomnia, sweating, loss of appetite and craving for THC." According to a report from the Substance Abuse and Mental Health Services Administration (SAMHSA), almost 196,000 people entering drug treatment programs reported marijuana as their primary drug of abuse, indicating that they needed help to stop using the drug.

Is marijuana included in drug testing in sports?

There is not a uniform policy regarding drug testing in either professional or amateur sports. "Though not explicitly banned by the International Olympic Committee (IOC)", says Wadler, "a working group of the IOC has been formed to review and make recommendations about the use of marijuana in Olympic sports." It is banned by the NCAA and various national governing bodies. Because of its high solubility in body fat, marijuana can be detected for as long as two to four weeks by current drug testing methods.