The Central Nervous System
Today our blog looks at the central nervous system, what it is and how it works. As this has a significant role to play in exercise and sporting activity, having a good understanding of the central nervous system is useful for personal trainers and fitness instructors, whether they are working with professional athletes or those new at training for fitness.
HOMEOSTASIS AND THE CENTRAL NERVOUS SYSTEM
The central nervous system works in conjunction with the endocrine system (see our blog on The endocrine system) to maintain homeostasis.
While the endocrine system helps to keep the body in balance by synthesising and secreting hormones, the central nervous system is a lot more responsive, supporting homeostasis through a complex web of nerves.
WHAT IS THE CENTRAL NERVOUS SYSTEM?
The body’s nervous system has two key divisions: the central nervous system (CNS) and the peripheral nervous system (PNS). Although these systems have different functions, they work closely together.
The PNS connects the CNS to the rest of the body and the outside world through a series of nerves, allowing the CNS to receive sensory information from receptor organs such as the eyes, ears and muscles.
Comprising the brain and spinal cord, the CNS interprets this sensory information and reacts accordingly. The range of responses is very broad, from simple reflex actions to complex emotions and thoughts.
SOMATIC AND AUTONOMIC NERVOUS SYSTEMS
Within the CNS system, there are two further subdivisions:
Somatic nervous system – the nerves responsible for controlling voluntary movement, which serve the outer body and skeletal muscle. This sends the signals that allow us, for example, to move our limbs at choice.
Autonomic nervous system – this supplies neural input to the involuntary systems such as the endocrine glands, the heart and the digestive system. It keeps essential functions working at all times, for example, ensuring that the heart continues to beat while we’re asleep.
NEURONS AND THEIR RELEVANCE TO THE CNS
Neurones are responsible for carrying signals from one part of the body to another and when a personal trainer is working with a client in the gym, it is possible to challenge this system to improve its function (see our blog on Neuromotor exercise training).
The cells of a neuron resemble most other basic cell structures, with a nucleus and organelles (the internal organs of a cell). The nervous impulses travel along a cylindrical projection from the neuron called an axon, which is covered in a myelin sheath that insulates the axon and facilitates the rapid transmission of impulses.
THE CNS AND PERSONAL TRAINING
One of the roles of a personal trainer or fitness instructor is to teach exercise technique, especially when they are working with a new client. The more the body goes through a particular movement – what is known in sports conditioning as movement patterns – the better the nervous system will adapt to this movement.
So if a client starts by learning the correct technique for a lunge or a squat, the more they carry out the exercise, the more it becomes an automatic, instinctive movement. This can help them train for strength, rather than size and mass, and to learn functional movements designed to help with the activities of daily life (see our blog on Functional Training – a new tool for fitness professionals).
Studies have shown that when sports professionals train over a long period of time, their central nervous system will start to programme muscular recruitment and patterning in a particular way. This can end up influencing the way that they perform other movements.
In cases where sporting professionals need to work on their speed and power, a sports trainer should plan sessions that train the central nervous system.
In a 2005 article on “Periodisation Training for sports” by T Bompa (2nd ed Human Kinetics), it’s noted that the speed of signals through the CNS cause differing levels of excitation or inhibition. A sprinter will need rapid signals to be transferred through the CNS, so their receptors and effectors should be as excited and uninhibited as possible.
In weight training, Bompa suggests one to three repetitions of 90%+ of one rep max in order to optimise the contribution of the central nervous system by increasing excitation and neural stimulation.
If someone has become adept at a particular sport or exercise, it can be useful for a fitness professional to challenge them with a different range of movement. Equally, if someone has been training for a while but following bad technique, a personal trainer may have to spend some time retraining them so that they can perform exercises better – this is known as corrective exercise and is essentially the re-training the of central nervous system.