Distinction between (CNS) and (PNS) fatigue

Understanding the distinction between Central Nervous System (CNS) and Peripheral Nervous System (PNS) fatigue can be an important component for improving training when muscle hypertrophy is the goal.

PNS fatigue occurs at the muscular level and is often a byproduct of intense training sets: as we begin the set (with a light or moderate load) Type I fibers will be recruited first. As force demands and effort increase, type II fibers (larger and stronger fibers) are recruited to make up for the fatigued fibers. This is great for hypertrophy, as it exposes more fibers to mechanical tension, and consequent growth.

Contrarily, CNS fatigue stems from the brain and spinal cord, mainly due to a reduction in the ability of the brain to effectively activate the muscles, following intense training bouts (usually as a response to high volume, but also max effort workouts).

While it does not directly contribute to hypertrophy, CNS fatigue can decrease your capacity to maintain high-intensity workouts and the overall volume necessary for maximal muscle growth.

Importantly, while it’s not a direct causation, excessive Peripheral Nervous System (PNS) fatigue can also contribute to Central Nervous System (CNS) fatigue, especially under conditions of prolonged and intense physical activity without sufficient rest and recovery. This is because when the PNS is excessively fatigued, the CNS may be stressed trying to maintain motor control and coordination, leading to a state of CNS fatigue.

However, it’s important to note that CNS fatigue can also potentially be influenced by other factors such as sleep deprivation, inadequate nutrition and more.

Ensuring an adequate balance between work and rest, coupled with attention to nutrition and stress management, can lead to sustainable and effective muscle growth, which in the long term will lead to serious results!