Is CNS Recovery a Legitimate Factor for Bodybuilders?

Time and time again I read about people discussing the importance of CNS recovery for proper bodybuilding. But often times they use vague terms, forego any in-depth description of what is occurring on a cellular level, and instead resort to speculation and unsubstantiated anecdotal evidence, which ends up helping no one.

CNS stands for the Central Nervous System. The CNS controls many of the major functions within our body but for our purposes the significant function of the CNS are on behavior, controlled by functions within the brain. Our behavior, strangely enough, is dictated by the lack of or surplus of specific components that have roles within the brain. These compounds are referred to as neurotransmitters. The two primary ways in which we can alter our behavior is either by creating more neurotransmitters (food/sleep) or by manipulating the role of neurotransmitters (drugs).

The idea of what exactly constitutes CNS fatigue or what the role of CNS recovery is within bodybuilding are highly incongruent. Some say that bodybuilding “stresses” the CNS which depletes neurotransmitters while others say bodybuilding simply causes an imbalance in chemical compositions within the brain. The most specific statement I could find regarding CNS recovery was on Bodybuilding.com, it stated, "Some evidence exists showing that when neurotransmitters like acetylcholine, dopamine, and norepinephrine get depleted, physical and cognitive performance suffers."

The affect of the example above is one that we are all familiar with; namely fatigue. When these neurotransmitters are depleted our body sends signals that tell us we need sleep. That is because sleep is how our body replenishes these compounds.
Recall that one of the primary ways we can alter behavior is through drugs. Almost all of the popular drugs used in modern society affect the neurotransmitters outlined in the quote above. While alcohol certainly affects these neurotransmitters, stimulants have an especially high affinity for manipulating neurotransmitters such as dopamine, adrenaline, noradrenalin, and acetylcholine. In fact their affects are directly associated with there interaction with these compounds. Stimulants release adrenaline (energy) while inhibiting the reuptake of dopamine (motivation). Furthermore these mechanisms by which stimulants affect our body are inherently more significant than any natural cause of neurotransmitter depletion. The “crash” or “comedown” that is often associated with stimulant use is simply the result of acute neurotransmitter depletion; you end up feeling less energetic and lack motivation.

This is relevant to the issue at hand because many bodybuilders use stimulants. Nicotine, caffeine, yohimbe, xanthines, ADHD medication, and ephedrine all stress the CNS far more than exercise is capable of doing. They stress the CNS two ways, first by unnaturally releasing adrenal neurotransmitters (as well as manipulating dopamine), and second by inhibiting deep REM sleep. Deep REM sleep has been shown to be reduced with stimulant use (the study used caffeine). This is significant because during this sleep is when our body naturally replenishes compounds such as dopamine.

In conclusion bodybuilding does have an affect on our CNS, one that arguably requires rest for optimal performance in the future. However within the context of modern lifestyle CNS fatigue generated from weightlifting is highly negligible and certainly not a concern for those involved in most standard bodybuilding regimens.