Strychnine is used in small doses to turn off inhibitory neuronal control in the pyramidal tracts in the brain.
In short . . .
There are a group of neurons in the body whose responsibility is to downplay the incoming signals to the brain. For exapmle, you do not usually “feel” your wristwatch, but when the clasp breaks, you become instantly aware of it. This is because a set of neurons is giving off inhibitory signals to kind of slow the general input of sensory information into the brain. It would only confuse you if you continually felt like you were wearing a watch, but if you became numbed to it, you would never feel it falling off.
It just so happens that these nerves that “inhibit” neural activity are exquisitely sensitive to strychnine. When you get a small dose of strychnine, the inhbitory effects of these neurons are lessened. This leads to both an increase in musclular contraction, but also a large increase in extraneous information making it into the brain.
In the good old days, LSD was “laced” with strychnine. This wasn’t because your local drug dealer wanted to injure you, but strychnine enhances many effects of hallucinogenic drugs. LSD “short circuits” the correct pathways that are used for interpretation of the senses. When strychnine is present, there is a huge increase in the information coming in from the senses. Strychnine has a large potentiating effect on almost all hallucinogens and psychoactive compounds.
Therefore a small hit of acid boosted with strychnine gives the same basic effect as a large hit of acid. Therefore the dealer could cut his pure LSD with strychnine and increase his profits while still maintaining the potency of his material.
Nowdays, good strychnine is harder to get than decent acid, so you never see the two combined anymore. I believe that this is entirely due to the fact that the old acid cookers had PhD’d in chemistry, and new some of the pharmacology behind their cooking, while the new batch of freakoids never got out of high school.
As for strychnine’s effects on athletes, it also has to do with the lessening of the activity of the inhibitory tracts of the brain. It is a “bass-ackwards” stimulant: it doesn’t perk you up per se, but suppresses the body’s way of calming down. Therefore it also enhances the effects of any true stimulant you took with it.
Like Emo Phillips used to say, I always thought that my brain was my most important organ until I realized who was telling me that.