Speed Training For Fast Twitch Muscles

Next time you lose a sprint or fail to dunk a basketball, blame your genetics and your training. The composition of your muscles, although invisible to the naked eye, can be the difference between a weekend warrior and an explosive Olympic-level athlete. Fortunately for all athletes, advancements in physiology have begun to shed light on specific training methods that can be used to make muscles faster.

Muscle Fibers

Successful speed training for faster muscles is a discipline that places very specific demands on the body. This is because muscles are primarily composed of two main fiber types: type I, and type II. The fibers that make up the muscles of a particular athlete go a long way in determining which training methods will bring about the best results. Type I fibers are called slow-twitch fibers. Slow-twitch fibers respond best to endurance training, where a lot of repetition at low power output is involved. Another characteristic of slow-twitch fibers is a high resistance to fatigue, making these muscles suitable for tasks like running long distances or carrying objects for extended periods of time. Type II fibers are further split into type IIa (fast-twitch red) and type IIb (fast-twitch white).

Speed

With regard to muscular speed, type IIa is between type I and type IIb. This intermediate fiber type is characterized by moderate force output, moderate contraction times and moderate resistance to fatigue. The fastest of all muscle fibers, type IIb, develops a high level of force, fatigues quickly and contracts rapidly.

Research

The theory throughout the 1980s held that the ratio of slow-twitch to fast-twitch muscle fibers was fixed, based on genetics. However, as a result of more recent studies, as reported, for instance, in a 1991 article in "Physiological Reviews," there is growing evidence that the ratio of fast-twitch to slow-twitch fibers can adapt to different kinds of training, showing changes in fiber size and structure.

Recruitment

Recruitment is the term used to describe the amount of muscle fiber that is activated during a contraction by a motor unit. A motor unit is made up of one motor neuron and a group of muscle fibers. The motor neurons determine many of the characteristics of muscle fibers. While a slow-twitch motor unit contains less than 180 muscle fibers, fast-twitch motor units contain upwards of 300 muscle fibers. In addition to having more fibers to recruit, fast-twitch motor neurons have faster contraction times when compared to slow-twitch fibers. In the world of sports, more muscle recruitment plus faster contractions leads to more power and more speed.

Training

What all this means with regard to training your muscles for speed is that regardless of the muscle fiber genetics that you are born with, your muscles have a tremendous ability to adapt to training regimens. You can force certain fibers to grow in size and even convert one muscle fiber into a completely different type of fiber. So dunking that basketball is not completely out of the realm of possibility.