The Definition of Strength

The definition of strength may vary, but it is usually defined as the ability to move a maximum weight. This meaning changes depending upon training goals or how it is used in a study.

Basic Definition of Strength: The ability to lift a maximum weight, or, the extent to which a maximum force can be exerted.

Force can be exerted isometrically, with no change in muscle length (e.g., pulling on a fixed bar). For training, this meaning for fits more with exerting a maximum force to develop isometric, or static, strength.

When force is exerted isotonically, where the muscle length does change (most weightlifting exercises), both definitions fit.

A certain level both types of strength is needed just to function in daily life--to stand up, to move your arm, and to lift even the lightest weight.

Physical therapists are concerned with developing functional strength for patients who need to get stronger in ways that will help them function independently in daily life. For example, a stroke patient must regain enough strength to stand, walk, and maintain balance again.

The definition of functional strength has been applied to sports training, but the definition is not so clear as it is for functioning in daily activities. Training "with a purpose" is often used.

Since the strength operates differently in various sports, the purpose changes. Most develop functional strength with activities such as core exercises, kettlebells, medicine balls, and other methods that develop stability, acceleration, and deceleration. (See Mike Boyle's DVD Set and book for developing functional strength.)

Functional Strength Coach DVD Set

Functional Training for Sports

Isokinetic strength is not natural in most activities. It involves applying force equally through a range of motion. Isokinetic machines push back with as much force as you apply. These devices are used for the rehabilitation of injuries and for testing strength levels in studies.

Because types of strength are known to be developed quite independently (based upon the specificity principle), questions are raised about how well strength developed isokinetically is really functional, or even represents strength gains in sports and daily life. For more, go to Strength Building.

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