Strength -- The application of muscular force in any endeavor (speed and distance are
not factors of strength) -- such as to a barbell, a ball, or to the ground underfoot. There are 5 broad categories of strength, each with its own special training requirements: absolute, limit, speed, anaerobic and aerobic.
There are many different factors that affect strength, and they fall into 4 broad categories:
1. Structural/Anatomical: muscle fiber arrangement, musculoskeletal leverage, ratio of fast- vs. slow-twitch fibers, tissue leverage, motion-limiting factors (scar tissue and adhesions), tissue elasticity, intramuscular\intracellular friction, and others.
2. Physiological/biochemical: stretch reflex, sensitivity of the Golgi tendon organ, hormonal function, energy transfer systems efficiency, extent of hyperplasia (muscle splitting), myofibrillar development, motor unit recruitment, cardiovascular and cardiorespiratory factors, and others.
3. Psychoneural/learned responses: "psych" (arousal level), pain tolerance, "focus" (concentration), social learning, "skill" (coordination), spiritual factors, and others.
4. External/environmental: equipment, weather and altitude, gravity, opposing and assistive forces.
The foregoing discussion notwithstanding, a more traditional way(despite being less precise) of classifying strength is to divide it into general, specific and special categories:
General strength. In this category, you train all the muscle groups without concentrating on the muscles that assist your particular event. Training for general strength will give you a base for your event - specific strength.
Specific strength. Training for specific strength is an intermediate type of training that takes into consideration only one aspect of a specific demand. It has an important function in joining general and special strength training together.
Specific strength will help you improve your techniques as you develop the strength needed to execute the exact movements of your event, whether they are jumping, throwing, or running.
In other words, once you have developed general (overall) body strength, you should then work on the strength of the particular muscle groups that will be most involved when you perform the event in which you compete.
Special strength. The term special, as it is used here, means "specialized." Each sport or event requires a specialized type of strength. Shot putters, for example, need starting strength and explosive strength, while wrestlers need anaerobic strength endurance. While the exercises for building specific strength are often of different intensity and duration than those of the typical agnostic movement, the exercises done for special strength training have to reflect all the components of the agnostic movement.
The base of special strength drills is represented by the complete movement in that the development of the most peculiar physical properties (strength, speed, endurance) is applied. When strength training is poured into the complete movement, respecting its dynamical-mechanical characteristics, it is called "special strength training."
Strength training -- Using resistance weight training to build maximum muscle force is the traditional way of defining the practice of strength training. However, a more global definition would account for the metabolic circumstances under which force is being applied (i.e., the energy contribution from ATP/CP, glycolytic or oxidative sources).
Stress -- The general physical and psychological response of an individual to any real or perceived adverse stimulus, internal or external, that tends to disturb the individual's homeostasis. Stress that is excessive or reacted to inappropriately, may cause disorders.
Stress fracture -- A partial or complete fracture of a bone bec ause of the remodeling process's inability to keep up with the effects of continual, rhythmic, nonviolent stresses on the bone. Cf. overuse.
Stress management -- A group of skills for dealing with stresses imposed on an individual
without suffering psychological distress and/or physical disorders.
Stress test -- See graded exercise test.
Stretching -- Lengthening a muscle to its maximum extension; moving a joint to the limits of its extension.