L-Glutamine actually participates in a series of reactions that results in it being converted into glucose. I don't think that's what he meant, though, probably was referring to proteins being used in aerobic metabolism through deamination etc.
To the original poster - I would strongly discourage running if you want to keep your knees healthy with a damaged ACL. There's a HUGE possibility that your gait is already flawed and that it will get progressively worse over the next few years, effectively boning any chance of being pain free in the next 10.
If you genuinely enjoy it, use sparingly, but remember that it is completely unnecessary for heart health. Using a higher volume weight training routine that's well designed (reasonably high intensity, shortish rest periods, etc) will produce favorable heart adaptations as well. Tabata method squats (or maybe jump-chins, or squat thrusts, whatever you like) would be a better alternative barring preferences.
Or sprints, though the method recommended by combat medic isn't actually sprinting. Not a bad method of running, but not the best.
If you want to run for distance once in a while, running first thing before eating is musculature suicide, running after eating a few meals is better, and running after eating a few meals and putting a glucose/BCAA mixture in your water bottle is best. Surge would work okay too, but wouldn't be the best option.
If you're truly interested in keeping that knee healthy, periodic evaluations by someone with a pretty advanced understanding of biomechanics would be a good idea. Chiro, someone with an advanced degree in kinesiology, physical therapist, whatever's convenient.