What Is Muscular Strength?
Muscular strength is generally defined as the ability to generate force at a given velocity of movement. One of the five primary components of physical fitness, it is generally developed using resistance training. This type of training typically aims to stimulate increased strength on a number of physiological levels. Individual strength can be an indicator of overall health, or a measure of progress during resistance or rehabilitation training programs. As such, there are a number of available methods for testing physical strength.
The fundamental purpose of skeletal muscle is the generation of force, either to stabilize and balance the skeleton or to produce movement. Muscular force is produced by a complex series of interactions between neurons, nucleotides, ions, and protein complexes within the muscle. The level of force generated can vary not only between muscles and muscle groups, but also within the range of motion of each particular muscle. Factors affecting muscular strength include age, sex, and level of physical conditioning. On a daily basis, strength levels can be influenced by nutrition, state of mind, and even time of day.
Muscular strength can refer to either isometric or dynamic strength. Isometric strength is a measure of how much force can be exerted against an immovable or fixed resistance. Standing in a doorway and pressing the hands outward against the frame is an example of isometric strength. This type of strength training is typically used more often in rehabilitation clinics than fitness centers, for example to prevent atrophy of an immobilized limb. In a sports setting, isometric training is most often used to overcome weaknesses at a particular angle of a limb's range of motion.
Dynamic strength can be further subdivided into concentric or eccentric movements. Concentric movements are those in which the force generated by the muscle is sufficient to overcome the weighted resistance, allowing the muscle to shorten and the weight to move against gravity. Eccentric movement is characterized by resisting, rather than overcoming, the weight of the load. This is typically during the downward phase of a motion, in which the muscle is lengthening while exerting force against the weight. In a rested muscle, eccentric strength can be as much as 40% greater than concentric strength.
A cable tensiometer measures the amount of tension applied to a steel cable. Originally designed to measure aircraft cable strength, it has been adapted to measure isometric strength in a fitness setting. A dynamometer tests muscular strength by assessing the amount of force used to squeeze the instrument using the hand or legs. From these measurements, overall muscular strength can be roughly estimated. More highly technological devices involving computers and electroconductive materials are also available.
In the interest of simplicity and ease of access, the most popular method of muscular strength testing is usually the one repetition maximum (1RM) test. The 1RM measures the greatest amount of weight that an individual can lift for one repetition of a specific exercise. While this is usually a reasonably accurate assessment of muscular strength, it should be carried out only with extreme caution. Performed improperly or without appropriate assistance from a spotter, there can be significant potential for injury during the test.
Written by Jessica Gore
