Reaction Time The time required to react to a stimulus is greatly affected by the nature of the stimulus. Response to a sound or a touch is shorter than to a light signal. The reaction time to all types of stimuli will be lengthened if the stimuli is complicated. Sound signals which continually vary in pitch and loudness are very difficult to react to. Intermittent distracting noises slow up reaction, but a continuous noise does not seem to affect reaction time. Reaction is usually faster to easily perceived stimuli. If the sound signal is very faint or the light signal is short, small, dim, or hazy, the reaction is slowed. There is probably maximum limit of strength of stimuli, beyond which increases in loudness, size, and brightness will not speed up reaction and may even slow it down. Men react faster than women and shortest reaction times in both sexes are during the age period between 21 and 30 years. There are great differences in reaction time among individuals. Practice considerably shortens reaction time but does not erase differences in individuals. Champion athletes have better than average response times and sprinters react faster than distance runners. Speed of Movement Work is accomplished at a faster rate if component movements are in a continuous curved motion than if movements involve abrupt changes in direction. Maximum velocity of movement is inversely related to weight handled. Also, the time required to attain maximum velocity is correlated with weight. Horizontal motions are more rapid than similar motions in a vertical plane. Urging an individual to move more rapidly will increase his speed of movement, but accuracy will be decreased. Reaction time is unaffected. Precision Manual tasks in which movement is away from the body are performed with less error than those in which movement is toward the body. Movement in a downward plane is inaccurate because of a tendency to overshoot. Under stress of speed, muscle tension is increased, which in turn decreases motor coordination and results in more errors. Some workers tend to preserve stability of performance under stress and thereby maintain efficiency. Positioning movements are made most quickly and accurately with the right hand if movement is in a counterclockwise direction, and with the left hand in a clockwise direction. Accuracy and speed of manipulation is best when both hands are used. One hand, either right or left, is 90 per cent as effective as when both are used together. Positions demanding muscular distortion, such as reaching backward or above shoulder level, are made with difficulty. Motions directly forward or to right or left are made more quickly and accurately. Estimations of displacement of limbs and parts of the body depend somewhat on the physical effort involved during the judgment; more effort leads to greater accuracy.		Home Components of Physical Fitness Clinical Examination Differences Between Fit and Unfit Men Physiological Elements of Fitness The Step Test The Effects of Training on the Physiological Systems Work Output Physical Condition of Muscle Application of Muscular Force Maintaining Optimum Strength Tests of Muscular Strength Strength and appearance Strength as a measure of physical fitness Strength as affected by organic problems Strength as prophylaxis Role of inactivity in production of disease Lack of Sociability in Work Lactic Acid System Muscular Form Capillary Growth Heart Size Heart Rate Training produces physicochemical changes Muscular Strength Nervous Stimulation and Muscular Strength Quality of Champions Factors Which Limit Skill Kinesthesis Balance Reaction Time Muscular Tension Visual Aim Skill Center in the Brain Endurance for Exhaustive and Moderate Work Distribution of Energy