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Strength Training Tips
Muscle Action

Eccentric
 
Eccentric muscle action involves the elongating of the target muscle when the muscle tries to slow or control movement against external force. This is termed a “negative” movement since it is generally downward and controlled. Example: Biceps Curl moving outward, away from the body.
 
Concentric
 
Concentric muscle action involves the shortening of the target muscle when the muscle generates movement against an external force. This is termed a “positive” movement since it is generally upward against gravity or moving the external force. Example: Biceps Curl moving upward, toward the body.
 
Isometric
 
When a muscle generates tension without any visible changes or changes in joint position.
 
Isotonic
 
When a contracting muscle shortens against a constant load, as when lifting a weight.