The most effective way to improve your running speed is through targeted speed training as opposed to long-distance training. According to the general adaptation syndrome model, one of the basic concepts in exercise physiology, speed training exercises such as sprints result in improvements in the speed of muscle contraction. Distance training develops endurance capability, not speed.
General Adaptation Syndrome
All exercise and training activities deliver predictable results according to the principles of the general adaptation syndrome. The general adaptation syndrome model describes your body's physiological response to stress and, under its principle of specificity, states that the benefits derived from an exercise or training program are specific to the type of stress applied. So lifting heavy weights builds strength, speed training improves quickness, and endurance training improves stamina.
Muscle Fiber Type and Characteristics
Each one of your muscles is composed of a mix of muscle cells, or fibers, described as either fast-twitch or slow-twitch. Fast-twitch muscle fibers are capable of rapid contractions but lack the capacity for endurance. Slow-twitch muscle fibers are capable of prolonged, repetitive workloads but cannot contract as quickly as fast-twitch fibers. Exercises targeted toward your fast-twitch fibers improve your speed while those targeted toward your slow-twitch fibers improve your endurance.
Training for Speed
Speed training targets your fast-twitch muscle fibers and can improve your speed and quickness. Speed training exercises are performed at high intensity and low volume or, in other words, at a quick pace but for relatively short periods. Running 30 to 100 meter dashes at nearly full speed are examples of speed training exercises.
Training for Endurance
Long-distance training, also known as over-distance training, involves running long distances at moderate speeds, otherwise known as high-volume, low-intensity training. This type of exercise stresses your slow-twitch fibers and helps to develop their ability to delay the onset of fatigue. However, it does not build much in the way of speed.
References
- "Exercise Science"; Warren Rosenberg, Ph.D. and Ciaran Cullen, D.C.; 2008
- Track and Field News; Speed Training; Bernie Dare and Bevery Kearney; Spring 1988



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