1. reaction time,
2. frequency of movement per time unit, and
3. speed of travel over a given distance.
The correlation between these three factors assists the assessment of the performance of an exercise requiring speed. Thus, in sprinting, the final outcome depends on the athlete’s reaction at the start, the speed of travel throughout the body of the race (i.e., force of propulsion) and his/her stride frequency.
- GENERAL speed, which is defined as the capacity to perform any kind of movement (motor reaction) in a rapid manner. Both general and specific physical preparation enhance general speed.
- SPECIAL speed on the other hand, refers to the capacity to perform an exercise, or skill, at a given speed, which is usually very high. Special speed specific for each sport, is developed through specific methods explained briefly in this section. Whatever the type of speed sought, a positive transfer cannot be expected unless the structure of movement, both kinematic and dynamic, is similar to the skill pattern.
Factors Affecting Speed
- HEREDITY As compared to strength and endurance training, which are more trainable (following an adequate training the athlete may achieve spectacular improvements without having of extraordinary talent), speed training requires more natural talent, and is determined by heredity. Hence, the mobility of the nervous processes, the quick alternation between excitation and inhibition, and the capacity to regulate the neuro-muscular co-ordination pattern (DeVries, 1980), may lead to a high motor frequency. In addition, the intensity and frequency of the nervous impulses represent determinant factors in achieving high speed.
The property of skeletal muscle represents a limiting factor in speed potential (Dintinman, 1971). This reflects the difference in make-up and proportion of slow twitch muscle fibers (red muscle), and fast twitch fibers (white muscle) which contains a lower quantity of reddish pigments, making the muscle fibers look rather pale. The white muscle fibers contract faster than their red counterparts, which is a great asset for a sprinter. Therefore, according to DeVries (1980) the ultimate maximum speed capacity is limited by the intrinsic speed of the muscle tissue, thus suggesting that heredity represents an important factor in performing quick movements.
- REACTION TIME Also an inherited feature, reaction time represents the time between when an individual is exposed to a stimulus and the first muscular reaction or Che movement performed by him/her. From a physiological standpoint reaction time has five components (Zatzyorski, 1980):the appearance of a stimulus at the receptor level,the propagation of the stimulus to the CNS,the transmission of the stimulus through the nervous path and the production of the effector signal,the transmission of the signal from the CMS to the muscle, andthe stimulation of the muscle to perform the mechanical work. The most time elapses during the third component.Reaction time to both simple and complex or choice situations must be made in sports (Dintinman, 1971). Simple reaction is the predetermined, conscious response to a previously known signal performed unexpectedly (i.e., the gun in sprinting). Choice or complex reaction time, on the other hand, refers to the case where an individual is presented with several stimuli and has to choose between them. Obviously, the latter is the slower, and the time delay increases as a result of increasing the number of choices. Reaction time has to be distinguished from reflex time, which is an unconscious response to a stimulus (i.e., the tendon’s reflex to an external contact). Similarly, another term of high importance in speed training is movement time, or the time that elapses between the start and finish, of a movement.
Reaction time is a determinant factor in most sports and may be improved with proper training. Zatzyorski (1980) suggests that the reaction time to a visual stimulus is Shorter for trained (0.15-.20 seconds) as opposed to untrained individuals (0.25-0.35 seconds). The reaction time to sonar stimuli is slightly shorten.
- ABILITY TO OVERCOME EXTERNAL RESISTANCE In most sports, power, the force of a muscle contraction or the capacity of an athlete to display force, is one of the determinant factors in performing fast movements. During training and athletic competitions, external resistance to athletes quick movements exist in the form of gravity, the apparatus, environment (water, snow, wind), and the opponents. In order to defeat such opposing forces the athlete has to improve his/her own power, so that by increasing the force of muscular contraction he/she is capable of increasing the acceleration of his/her skills. Often a skill must be performed not only quick, but must also be repeated in the same manner for a long period of time. Therefore, in speed training the development of power has to be complemented with the development of muscular endurance which facilitates the display of quick but prolonged work.
- TECHNIQUE Speed, frequency of a movement, and reaction time are very often a function of technique. The acquisition of a rational, effective form facilitates the performance of a skill quickly by shortening levers, correctly positioning the center of gravity, and utilizing energy efficiently. In addition, an important role must also be given to the performance of a skill with ease and a high degree of co-ordination as a result of conscious and reflex relaxation of the antagonistic muscles.
- CONCENTRATION AND WILLPOWER It seems that rapid movements are facilitated by a high degree of power. Consequently, the speed of a movement is determined not only by the mobility and the harmonious character of the nervous processes, but also by the frequency of the nervous impulses, by their precise manner, and by strong concentration. Willpower and strong concentration are important factors for the achievement of high speed. Therefore, the incorporation of special sessions to solicit the athlete’s psychological qualities are imperative in speed training.
- MUSCLE ELASTICITY Muscle elasticity and the ability to relax alternatively the agonistic with antagonistic muscles are important factors in the achievement of a high frequency of movement and correct technique. In addition, joint flexibility represents an important ingredient for performing movement with high amplitude (I.e., long strides) which in any sport requiring fast running is paramount. Consequently, the inclusion of daily flexibility training is imperative, especially for ankles and hips.