Nerve “Impulse” Training

Nerve “Impulse” Training (NIT)

The peripheral nervous system (PNS) of vertebrate has two main types of nerves. These are the efferent nerves and the afferent nerves. The distinction lies on the “direction” of nerve impulse transmission.  In efferent nerves, the nerve impulse comes from the central nervous system (CNS) and is relayed towards the periphery, particularly towards the effectors. In afferent nerves, the nerve impulse is detected from the periphery and conducted towards the spinal cord and the brain; thus, sensory nerves are considered afferent nerves. An example of this is an external stimulus detected by the body results in sensation when it is processed in the CNS through the afferent nerve pathways. Both afferent and efferent nerves are made of chains of neurons.

Interesting facts about the PNS

1. You have a C. Elegans in You
   Your entire nervous system which consists of x neurons that control your stomach and intestines has many neurons. These neurons can be traced to more primitive neurons, as far as biochemical structure. Can your entire system think for itself? Your C. Elegans intrition holds the answer!
    
2. How do nerve impulses get faster (Nerve Conduction Velocity)
   Nerve conduction velocity is an important aspect of nerve conduction studies (e.g. electromyography). It is the spread at which an electrochemical impulse propagate down a nerval pathway.

Maximizing the CNS contribution to sports performance

The CNS affects sports performance under aerobic (with oxygen) and anaerobic (without oxygen) energy conditions.

In aerobic energy metabolism and the CNS, if it were not for the depletion of muscle glycogen and overheating, the human body could potentially exercise aerobically indefinitely. The CNS however plays a crucial role in halting endurance capability. Faced with fatigue, it will shut down or least slow down an athlete’s aerobic engine. This is due to fatigue signals being sent through the receptor organs and their interpretation.

CNS training and “quickness”

As it relates to sports performance, “excitation” and “inhibition,” can broadly be equated to the functioning of effectors and receptors. The speed at which signals are sent from receptors to effectors, and back again, results in levels of excitation or inhibition. The speed of signal transference through the CNS needs to also be as fast as possible, therefore an athlete’s receptors and effectors need to be optimally “excited” and uninhibited in order to result in the optimum recruitment of fast-twitch muscle fiber. However, CNS fatigue will slow the speed of excitation, particularly within fast-twitch fibers, which fatigue much more rapidly than slow-twitch fibers. Consequently, exercises should only be performed as long as “quickness” is possible. The role of the CNS in enhancing sports performance needs special attention, as it may hold the key to improved speed and power production. Trainer and athlete need to realize the importance of the CNS and implemented strategies in training and composition to maximize its contribution to sports performance.

Intrafusal muscle fiber

Intrafusal muscle fibers are skeletal muscle fibers in “specialized” sensory organs (proprioceptors) that deflect the amount and rate of change in length of a muscle. They constitute the muscle spindle and are innervated by two axons, once sensory, and one motor. Intrafusal muscle fibers are walled from the rest of the muscle by a collagen sheath. This sheath has a spindle or “fusion” shapt, hence the name intrafusal. They are innervated by gamma motor neurons and beta motor neurons. It is by the sensory in formation from these two intrafusal fiber types that one is able to judge the position of one’s muscles and the rate at which it is changing.

Extrafusal muscle fibers

Extrafusal muscle fibers are the skeletal standard muscle fibers that are innervated by alpha motor neurons and generate tension by contracting, therefore allowing for skeletal movement. They make up a large “mass” of skeletal (striated) muscle and are attached to bone by fibrous tissue extensions (tendons). Each alpha motor neuron and the extrafusal muscle fiber is a “Neuromuscular Junction,” where the neuron’s signal, the action potential, is transduced to the muscle fiber by the neurotransmitter acetylcholine. Extrafusal muscle fibers are not to be confused with intrafusal muscle fibers, which are innervated by sensory nerve endings in central non-contractile parts and by gamma motor neurons in contractile ends and thus serve as a sensory proprioceptor.