I'd like to preface everything I’m about to write with this: I don't support the use of alcohol or marijuana for athletes. I believe anything that may have negative net effect on an athlete should be removed from that athlete's life if possible (evil girlfriends included).
That being said, I would like to delve into the topic of recreational drug use by athletes. Though high intensity sports discourage many athletes from using any recreational drugs, alcohol and marijuana are still in use by many.
Mainstream American culture tends to accept the use of alcohol and demonize the use of marijuana. For a man to say he's going to celebrate a win with a beer is normal. Replace beer with joint and it's headline news. Recently, I have noticed an increase in the acceptance of marijuana use in the MMA, BJJ, and grappling community. I believe the reasons for this are physiological.
Both alcohol and marijuana are used as a kind of stress relief. Because of its illegal status, marijuana can be less of a communal activity, though in many social circles it is used for the same reasons as alcohol: stress relief and peer bonding.
Alcohol, however, causes far more problems for an athlete's body than does marijuana. A short list of alcohol's effects on athletes: impaired ability to repair tissues (muscles), impaired glycogen production (less energy), dehydration, impairs ATP production (decreases endurance), impairs absorption of micronutrients needed for ATP production, increased weight gain (the body treats alcohol much like it treats fat, very detrimental to athletes that need to maintain weight), impairs learning ability, weakens the immune system, and impairs the sleep cycle.
Marijuana is noted for decreasing cardiac stroke volume (how much blood your heart pumps per beat), an increased heart rate (bad for endurance), impairing learning ability, impairing the immune system, and creating respiratory problems if smoked. There are also some studies suggesting marijuana can lead to an increased risk of developing psychological issues if used before the brain is fully developed. For this discussion, I will assume we're just talking about adults.
As you can see, for most athletes, marijuana is less detrimental to athletic performance. This is especially true for sports where aerobic capacity is not as important, such as MMA, BJJ, and grappling. I think an honest assessment of these drugs must be made. Just looking at the effects of these two recreational drugs, I believe alcohol will always have a detrimental net effect on athletes. I believe the argument that marijuana can have a positive net effect on athletes can be made, depending on the amount of stress the drug relieves.
Personally, I have never used marijuana and I don't plan to any time soon. I drink approximately one alcoholic beverage a month, if that. My main drug is coffee. I believe stress relief can be accomplished without the use of any drug (including prescription drugs). I urge young athletes to seek out non-drug methods of stress relief. One method I have found to be quite pleasant is the use of binaural frequencies. Several programs are available (Brain Wave in the apps store). There are also many songs using this technology available online. I find it gives me a little endorphin rush and helps with relaxation.
That’s all I have for now. If you want my sources, ask for them. If you disagree, bring your arguments.